ISS

• 外傷重要度スコア injury severity score Injury Severity Score
• 特発性低身長 idiopathic short stature

WordNet

1. the 9th letter of the Roman alphabet (同)i

PrepTutorEJDIC

1. 『私は』私が
2. iodineの化学記号

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/21 13:50:57」(JST)

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国際宇宙ステーション

組み立てミッションを終えて離脱したスペースシャトルからみたISS（2011年5月30日）。
国際宇宙ステーションの記章
詳細
COSPAR ID	1998-067A
コールサイン	Alpha
乗員数	6人
打上げ日時	1998年–2011年
発射台	ケネディ宇宙センター LC-39, バイコヌール宇宙基地 LC-1/5およびLC-81/23
質量	344,378 kg (759,222 lb)
全長	73 m (240 ft) PMA-2からZvezdaまで
全幅	108.5 m (356 ft)
全高	約20 m (約66 ft)
居住空間	約373 m³ (約13,172 ft³)
気圧	101.3 kPa (29.91 inHg)
近地点	413 km（2013年8月17日）
遠地点	418 km（2013年8月17日）
軌道傾斜角	51.6419 度
平均速度	27,743.8 km/h (17,239.2 mph, 7,706.6 m/s)
公転周期	約91 分
周回日数	6087日 （2015年7月21日）
滞在日数	5376日 （2015年7月21日）
総周回数	約96066回 （2015年7月21日）
軌道減衰	2 km/月
2009年11月27日現在
脚注:
詳細図
2011年3月現在のモジュール構成図 （分解組立図）

CGによる完成予想図。

国際宇宙ステーション（こくさいうちゅうステーション、International Space Station、略称：ISS）は、アメリカ合衆国、ロシア、日本、カナダ及び欧州宇宙機関 (ESA) が協力して運用している宇宙ステーションである。地球及び宇宙の観測、宇宙環境を利用した様々な研究や実験を行うための巨大な有人施設である。地上から約400km上空の熱圏を秒速約7.7km（時速約27,700km）で地球の赤道に対して51.6度の角度で飛行し、地球を約90分で1周、1日で約16周する。なお、施設内の時刻は、グリニッジ標準時に合わせられている。

1999年から軌道上での組立が開始され、2011年7月に完成した。当初の運用期間は2016年までの予定であったが、アメリカにより少なくとも2024年までの延長が検討されている。運用終了までに要する費用は1540億USドルと見積もられている（詳細は費用を参照）。

参加国・関係国

国際宇宙ステーションの開発は、1988年9月に締結された日米欧の政府間協定により着手された。1998年にはロシア、スウェーデン、スイスを加えた国際宇宙ステーション協定が署名され、これによりISS計画の参加国は、アメリカ、ロシア、カナダ、日本、ESA加盟の各国（ベルギー、デンマーク、フランス、ドイツ、イタリア、オランダ、ノルウェー、スペイン、スウェーデン、スイス、イギリス）の15カ国となっている。これとは別に、ブラジル宇宙機関がアメリカと二国間協定を結んで参加している。また、イタリア宇宙機関はESAを通じてだけでなく、NASAとの直接契約で多目的補給モジュールを開発している。

中国はISSの参加を打診したことがあると発言しているが、2009年9月末現在は実現していない。インドもISSへの参加を希望しているが、他の参加国の反対に遭い、ロシアに協力を求めている。

計画推移

「フリーダム宇宙ステーション」も参照

国際宇宙ステーション計画が最初に持ち上がったのは、1980年代初期の米大統領のレーガンによる冷戦期における西側諸国の宇宙ステーション「フリーダム計画」である。この計画は、西側の結束力をアピールしてソビエト連邦に対抗する政治的な意図が非常に強いものであった。搭乗人数は出資比率によって定められたが、米国、欧州、カナダ、日本の飛行士がそれぞれ、必ず年間を通して滞在できることになっていた。しかし、米国や欧州の財政難、スペースシャトル「チャレンジャー」の爆発事故、続く冷戦終結による政治的アピールの必要性低下によって計画は遅々として進まなかった。計画は「アルファ」に変更、ステーションの規模も大幅に縮小され、米国を含めて搭乗人数を削減し、各国の滞在期間も短縮した。

一方、ソ連は「サリュート」に続く宇宙ステーション「ミール」による宇宙滞在を実現していたが、1991年末のソ連崩壊による混乱と財政難で、ミールは宇宙空間で劣化した。米国はロシアを取り込む目的もあって、アルファとミール（ミール2）を統合する計画を持ちかけたが、ロシアは新しいモジュール「ザーリャ」他を打ち上げる意欲を示した為、完全な新型宇宙ステーションとしてISS計画が開始された。しかし、ISS計画ではロシアの発言力が非常に大きくなり、常時ロシア人飛行士が滞在することとなった為、日欧加飛行士の滞在期間や搭乗人数は増加しなかった。

1998年にロシアが製造したザーリャモジュールが打ち上げられてISSの建設が開始されたが、2003年にスペースシャトル「コロンビア」の空中分解によって建設は一時中断し、その後の調整で建設規模が縮小、米露はともかく、日欧加の飛行士がどれだけ滞在できるかは未知数となった。

宇宙飛行士の滞在

詳細は「国際宇宙ステーション長期滞在一覧」を参照

ISSに滞在するクルーは当初は3人、コロンビア号事故後しばらくは2人であったが、2009年5月29日からは6人に増加された。

ISSに滞在する正式クルーは政府間協定締結国に限られている（滞在権について各国・機関毎に枠がある）が、参加国・機関が別途民間人と商業契約を結び、自国枠を提供しISSに滞在させる宇宙飛行関係者という区分があり、これまでロシアのみが商業契約を結び、民間人を滞在させている。

建設

国際宇宙ステーションの構造物を運ぶエンデバー。

ISSの建設は50以上の組立部品及び作業のための打ち上げが要求される。それらの打ち上げの39回はスペースシャトルによる打ち上げである。比較的小型な部品はプログレス補給船といった無人宇宙補給機によって運ばれる。組立が完了した時点のISSは、体積1,200立方メートル、重量419トン、最大発生電力110キロワット、トラス（横方向）の長さ108.4メートル、進行方向の長さ74メートル、最大滞在人数は6名となった。

ステーションはいくつかのモジュール及び要素で構成される。

ISSの主要な部品の組立順序については「国際宇宙ステーション組立順序」を参照

すでに打ち上げられたもの

• 「ザーリャ」 (FGB) 基本機能モジュール 米（製造は露）1998年11月20日
• 「ユニティ」 (Node 1) 結合モジュール1 米 1998年12月4日
• 「ズヴェズダ」 居住モジュール 露 2000年7月12日
• 「デスティニー」 米国実験棟 米 2001年2月
• 「クエスト」 エアロック 米 2001年7月
• 「ピアース」 ロシアのドッキング室・エアロック(DC-1) 2001年9月
• 「カナダアーム2」 (SSRMS) カナダ 2001年4月
• 「トラス」

• Z1トラス 米 2000年10月
• P6トラス 米 2000年12月
• S0トラス 米 2002年7月
• S1トラス 米 2002年10月
• P1トラス 米 2002年11月
• P3/P4トラス 米 2006年9月
• P5トラス 米 2006年12月
• S3/S4トラス 米 2007年6月
• S5トラス 米 2007年8月
• S6トラス 米 2009年3月

• 「ハーモニー」 (Node 2) 結合モジュール2 米（製造は欧）2007年11月
• 「コロンバス」 欧州実験棟 欧 2008年2月
• 「きぼう」 日本実験棟の船内保管室 日 2008年3月
• 「きぼう」 日本実験棟の船内実験室とロボットアーム 日 2008年5月
• 「きぼう」 日本実験棟の船外実験プラットフォームと船外パレット - 日、2009年7月（船外パレットは輸送のみに使い回収）
• 「ポイスク（ミニ・リサーチ・モジュール2 :MRM-2）」 - 露、2009年11月
• 「トランクウィリティ」(Node 3) 結合モジュール3 米（製造は欧）2010年2月
• 「キューポラ」 欧 2010年2月
• 「ラスヴェット（ミニ・リサーチ・モジュール1 :MRM-1）」 露 2010年5月
• 「恒久的多目的モジュール (Permanent Multipurpose Module: PMM)」:MPLM「レオナルド」を改造 - 欧 2011年2月
• 「アルファ磁気分光器(AMS-02)」 - 大型実験装置、米 2011年5月

定期的な補給ミッションで使用

• 多目的補給モジュール (MPLM) 米（製造はイタリア）(シャトルの退役に伴い退役)

「レオナルド」、「ラファエロ」の2基を使用

プロトンロケットによる打ち上げを予定

• 多目的実験モジュール(MLM) 露、2017年頃
• 欧州ロボットアーム (ERA)、欧 2017年頃、多目的実験モジュールと同時打ち上げ

キャンセルされたモジュールや構成要素

• ロシア研究モジュール 1基に削減
• ドッキング保管モジュール (DSM×2) - 露、キャンセル
• 科学電力プラットフォーム - 露、キャンセル
• 汎用ドッキングモジュール - 露、キャンセル

多目的実験モジュールと統合

• 暫定制御モジュール - 米、キャンセル

ズヴェズダの打ち上げ成功により不要となった

• 米国推進モジュール - 米、キャンセル
• 米国居住モジュール - 米、キャンセル
• セントリフュージ環境モジュール (CAM) - 米、キャンセル
• X-38乗員帰還機 (CRV) - 米、キャンセル

現在はソユーズ宇宙船で代替 将来は有人型ドラゴンV2とCST-100に交代する方針

他の主要なシステム

• アメリカ 太陽電池パドル - S4, S6, P4, P6トラスに設置
• アメリカ ドラゴン宇宙船 - 無人補給船
• カナダ モービルベースシステム（カナダアーム2のベース部）
• ロシア ソユーズ宇宙船 - 乗員交代及び緊急避難用、6か月ごとに交換
• ロシア プログレス補給船 - 無人補給船
• ヨーロッパ (ESA) 欧州補給機 (ATV) - 無人補給船
• 日本 (JAXA) 宇宙ステーション補給機 (H-II Transfer Vehicle: HTV) - 無人補給船

基本構造

総体積は約935立方メートル、総重量は約420トン。

ISSは大きく3つの部分から構成されている。まず、全体を与圧モジュールとトラスに、与圧モジュールはアメリカ側とロシア側に区分することができる。ISSの中央部には、進行方向に与圧モジュールが直列に連結しており、さらに枝状にもモジュールが取り付けられている。これと直交して、左右方向にトラス構造物が取り付けられている。与圧モジュールとトラスの交点は、それぞれデスティニーとS0トラスで、両者は金具で強固に結合されており、ここ以外に与圧モジュールとトラスの結合部はない。

与圧モジュール

滞在する宇宙飛行士の居住と作業の空間で、内部は地球上と同じ1気圧の空気で満たされている。温度、湿度、成分が調節され、乗員は地上と変わらない軽装で活動することができる。生活に必要な生命維持システムや居住のための装置、ISSの目的である様々な実験装置のほか、ISSの運用に必要なシステム機器なども設置されており、多くの機器はモジュール内でメンテナンスや交換が可能である。

基本的な機能を有するモジュールは、列車のように1列に連結されている。先頭からハーモニー、デスティニー、ユニティ、ザーリャ、ズヴェズダの順である。これらのモジュールのうち、ズヴェズダ以外はアメリカの資金で製造され、アメリカが所有権を有しているが、ザーリャはロシアに開発、製造、運用を委託している。ズヴェズダはロシアのモジュールである。一般に、ユニティより前側を「アメリカ側」、後側を「ロシア側」と呼ぶ。

アメリカ側モジュールとロシア側モジュールは、設計が全く異なっている。ユニティとザーリャは直接結合することができないため、与圧結合アダプタ (PMA-1) を介して接続されている。電力や通信も、PMA-1を通じて接続されている。

アメリカ側モジュール

代表的なアメリカ側モジュール、デスティニー。

ユニティより前方のモジュールは、フリーダム計画から流用されたもので、NASAの標準設計や安全基準を適用しているため、一般に「アメリカ側」と呼ばれる。日欧の実験モジュールも、アメリカ側に含まれる。これらのモジュールはいずれも直径4.4メートルの円筒形だが、これはスペースシャトルのペイロードベイの寸法に合わせたためである。内部は、国際標準実験ラック (ISPR) を4面に取り付ける設計で標準化されており、日米欧のモジュール間でラックを移設できる互換性を備えている。

モジュール同士の結合には共通結合機構 (CBM) を用いているため、本来とは異なる場所にモジュールを仮設したり、移設することもできる。また、HTVやドラゴン宇宙船もCBMを使用して結合する。CBMは大型で高機能の結合機構だが、自動ドッキングには対応しておらず、ロボットアームを使用して丁寧に接触させたあと、電動の結合装置でしっかりと結合する構造である。

なお、アメリカ側でもスペースシャトルのドッキングだけは、ロシアが開発したアンドロジナスドッキング機構を使用しているため、ユニティ(ノード3「トランクウィリテイー」設置後はトランクウィリテイーに移設された。2015年にはハーモニーに移設予定)とハーモニーにスペースシャトル用のPMAが設置されており、現在はハーモニーのPMA-2のみを使用している。このPMA-2にはISSからスペースシャトルに電力を供給する配線が施されており、ISS係留中のスペースシャトルの電力を節約することができた。

アメリカ側モジュールは、個々の機能を備えたユニットとして設計されており、ロシア側のモジュールのようには単体では機能できない。スペースシャトルで輸送されてISSのシステムに組み入れられて初めて、稼働することができる。

ロシア側モジュール

ロシア側を主体とした、組立初期のISS。

ザーリャより後方のモジュールは、ミール2計画から流用されたもので、ロシアの標準設計や安全基準を適用しているため、一般に「ロシア側」と呼ばれる。アメリカが所有するザーリャのほか、ロシアが独自資金で設置するズヴェズダ等のモジュールも、当然ロシア側である。ロシアセグメントの開発にはESAも協力しており、ズヴェズダのコンピュータや、欧州ロボットアーム(ERA)を開発している。日本はロシア側モジュールも実験に利用しているが、基本的にはアメリカ側に含まれるきぼうを使用する。

ロシア側の特徴は、主要なモジュールが単独で宇宙船としての機能を備えていることである。それぞれのモジュールにエンジンや自動操縦装置、通信システム、太陽電池パネルを備えており、単独で飛行して、自力でドッキングすることができる。これは、ロシアの宇宙ステーションの伝統的な手法である。このため、相当の規模まで組み立てなければ「自立」できないアメリカ側に先立って、まずロシア側を打ち上げて単独の宇宙ステーション（事実上はミール2そのもの）を稼働させ、そこにアメリカ側を増設する手法をとることで、ISS初期の費用削減に貢献した。

ザーリャとズヴェズダは段階的にアメリカ側モジュールのものに機能を譲り、ザーリャは通路兼、荷物置き場になった。しかし、ズヴェズダの方は、ISSの軌道高度や姿勢を維持する役割を担っているほか、米国と分担して環境制御の役割も担っている。

ロシア側モジュールのドッキングには、アンドロジナスと呼ばれるドッキング装置を使用する。アンドロジナスはCBMより小型だが、鉄道車両のように「衝突」させるだけでドッキング可能であり、自動ドッキングするロシア側モジュールには欠かせない装置である。また、緊急時の退避に使用されるソユーズ宇宙船や、ロシアのプログレス補給船、ESAのATVも、アンドロジナスを使用してロシア側にドッキングする。

ロシア側にも、単独の太陽電池パネル（科学電力プラットフォーム）を増設する計画があったが、費用削減のため中止になった。不足する電力は、アメリカ側の太陽電池から供給されている。

トラス

トラスと船外活動中の宇宙飛行士。

詳細は「トラス (ISS)」を参照

フリーダム計画では船外作業の基盤として大規模なものが計画されていたが、縮小を重ねた結果、ISSのインフラ機能を担う船外機器の設置場所として使用されている。主要な機能は、太陽電池パドルをはじめとする電源機器、ラジエーターなど廃熱システム、姿勢制御のためのコントロールモーメントジャイロ、アンテナなどの通信機器の設置場所である。フリーダム計画では軌道維持のためのエンジンも設置する予定だったが、この機能はロシア側に移されたため、エンジンを備える予定だったトラスは欠番 (S2, P2) になった。

トラスはISSのなかでも大きな寸法を占めるため、初期には折り畳んだ状態で打ち上げて、軌道上で展開することが検討されていた。しかし、展開したトラスに各種機器を取り付ける手間を考えれば、地上で機器や配管、配線を完成させた状態のトラスを打ち上げた方が効率がよいことがわかり、そのような設計に落ち着いた。

なお、長大なトラス上で作業をする際、宇宙飛行士やカナダアーム2が移動する拠点として、トラス上にはモバイルベースシステム (MBS) と呼ばれる車両とそのレールが設置されている。これは、人類史上最初の「宇宙鉄道」である。

トラス上には、船外機器の予備品や、故障して取り外された機器の保管スペースもあり、これを船外実験に利用することもできる。しかし、排熱用の冷媒を供給することはできないため、小型の実験にしか使われない(例外的にAMS-02は大型であるが、独自の熱制御系を有している)。本格的な船外実験装置や宇宙観測装置を設置できるのは、日本のきぼう船外実験プラットフォームだけである。また、ヨーロッパのコロンバスにも、小型の実験装置を設置する機能が設置されているが、きぼうよりは簡易である。

主要なシステム

2001年、夜のグライダーモードで飛行するISS。

電力供給

ISSの電力源は、太陽光を電気に変換する太陽電池である。組立フライト4A（2000年11月30日のSTS-97）以前は、ザーリャとズヴェズダに装備されたロシアの太陽電池が唯一の電源だった。ISSのロシアの部分は、スペースシャトルと同じ28ボルトの直流電力を使用する。ISSの他の部分には、トラスに設置された太陽電池から、130 - 180ボルトの直流電力が供給される。電力は直流160ボルトに安定化されて分配され、さらにユーザーが必要とする124ボルトの直流に変換される。電力はコンバータによってISSの米露のセグメントに分配される。ロシアの科学電力プラットフォームがキャンセルされ、ロシア区画もアメリカが設置した太陽電池の電力供給に依存することになったため、この電力分配機構は重要である。

ISSのアメリカ区画では、高圧（130-160ボルト）配電を行うことで電流を小さくし、電線をより細くすることができて、軽量化できた。

太陽電池パドルは、太陽エネルギーを最大にするために、常に太陽を追尾する。パドルは、面積375平方メートル、長さ58メートル。完全に完成した構成では、太陽電池パドルはS3とP3トラスに装備されたアルファジンバル (SARJ) を軌道1周回にあわせて1回転させることによって太陽を追跡する。ベータジンバル (BGA) は軌道面と太陽の角度に合わせて角度を調整するもので、このアルファ軸とベータ軸の2軸の動きを組み合わせることで発生電力を最適化している(発生電力が多すぎる場合も角度を調節することで対処)。米国セグメントの太陽電池による最大発電電力は約120kW。

しかし、主要なトラス構造が打ち上げられるまで、パドルは最終的な設置場所とは垂直な位置であったP6トラスのみに設置されていた。この構成では、右上の写真で示すように、太陽追尾にはベータジンバルしか使えなかった。「夜のグライダー」モードと呼ばれる方法は、夜間は使い道のない太陽電池パドルを進行方向に水平に向けて調整することで、空気抵抗を減らすことができ、高度の低下を抑える事が出来た。

生命維持

環境制御・生命維持システム (ECLSS)

ISSの環境制御・生命維持システム (ECLSS) は、気圧、酸素・二酸化炭素の濃度、水、火災消火、その他の要素を提供もしくは制御する。

生命維持に関して常に注意が払われるのはISS内の空気である。酸素の供給は、ロシアのエレクトロンと米国のOGS (Oxygen Generation System) で行われている。水を電気分解して酸素を作るエレクトロンやOGSが故障したり、交代時に宇宙飛行士が増えたりすると「キャンドル」と呼ばれる円筒形のSFOG（Solid Fuel Oxygen Generator、固体燃料酸素発生装置）を使用する。これらの装置の他にもロシアのプログレスやESAのATVによって酸素や空気が運ばれる。2015年初めでATVは退役するため、2014年10月(このシグナス補給船3号機は打ち上げに失敗したため、次のドラゴン5号機から運搬開始)からは商業補給船でも運搬できるNORS(Nitrogen/Oxygen Recharge System)が利用されるようになった。 二酸化炭素の除去は、一度ゼオライトに吸着させてから船外に放出することで再生を繰り返すロシアの「ヴォズドーク」(Vozdoch) と呼ばれる装置と米国の「シードラ」(CDRA)によって行われる。また、一時的に宇宙飛行士が増えた場合や装置の故障時には、水酸化リチウムの入った缶に基地内の空気を通して二酸化炭素を除去する、スペースシャトルと同じしくみの予備の装置も使うことができる。

次に重要なのは乗員が体内から排出したり洗浄などで使用した水や装置由来の水など、水の収集と再生処理である。水はこれまでロシアの「エスエルベーカー」(SRVK)と呼ばれる装置で基地の空気中の湿気を凝結させて回収されていて、スペースシャトルの燃料電池が生む水、最大11キログラム/時間を加えても飲料用や酸素発生装置用で不足する分は、従来年間約6800キログラムが地上から補給されていた。これを改善するためにSTS-126で運ばれた米国の水再生システム (Water Recovery System, WRS) は、空気中の凝結水だけでなく尿からも水を再生することで、地上からの水の補給をほとんど必要としなくなった。有害物質や臭いを除去するには、主に活性炭フィルタを使用しておりロシアのBMPと米国のTCCSが使われている。

姿勢制御

ISSの姿勢（方向）は、2つのメカニズム(推進式と非推進式)で維持される。通常は、Z1トラスに設置されている米国のコントロール・モーメント・ジャイロ (CMG) 4基を使ってISSを正しい方向、すなわちデスティニーをユニティの前方に、P(ポート側の)トラスを左舷側に、ピアースを地球側（底側）に向ける。CMGシステムが飽和すると、ISSの姿勢をコントロールすることができなくなってしまうため、その場合は、ロシアの姿勢制御システムが自動的に(外乱が加わる方向と反対方向に)スラスタを噴射して、CMGの飽和をクリアできるように制御しているほか、CMGが使用できない期間のISSの姿勢制御も担当する。 スペースシャトルオービタがISSにドッキングしていた時は、主にオービタのスラスタ（とCMG）が姿勢制御に使われていた。

高度制御

ISS高度の推移グラフ。

ISSの軌道は最低高度278 km、最高高度460 kmの範囲に維持される。最高高度制限は、ソユーズ宇宙船のランデブーが可能な425 kmであり、最低高度は、リブースト等の制御が出来なくなった状態でも一定期間落下を防いで対応する時間を稼ぐための高度で設定される（このため太陽活動に伴って最低高度制限も変動する）。ISSの高度は大気の抵抗によって絶えず低下しているので、毎年数回、より高い高度に上昇させる（リブースト）必要がある。高度のグラフは、毎月約2.5 kmずつ徐々に低下することを示している（注：高度低下率は、太陽活動による大気層の膨張の度合いにより変化するため変動する。また高度が低いほど低下率は増える）。リブーストはズヴェズダ後方の2基のエンジン、ドッキング中のスペースシャトル・プログレス補給船・あるいはESAのATVで実行することができる。高度の上昇は、今後の飛行計画や、デブリの接近状況などを考慮して実施される。このため、まれにではあるが高度を若干下げる事も行っている。ISSの組み立て段階では、スペースシャトルができるだけ多くのペイロードをISSへ運べるように、高度は比較的低く抑えられていたがシャトル退役後はおおむね高度400km以上で運用されるようになった。

装甲・放射線防護

大型のデブリは常に地上から監視されており、衝突の可能性がある場合は前述の高度制御により回避することができる。しかしながら監視されていない小規模なデブリと衝突する可能性はあるので、対策としてモジュールには装甲が施されている。装甲はアルミニウムによる空間装甲と、衝突により発生した破片を受け止めるためのケブラー繊維製内張りで構成される。

放射線に対しても多少考慮はされている。新しい居住区画は被曝量が少なくなるようにそれまでよりも緩衝材が厚くなっている。太陽フレアのように放射線量が増すと判っている場合には、ロシア側のドッキングポートが最も壁が厚いためにここに避難することになっている。

輸送機

「国際宇宙ステーションへの有人宇宙飛行の一覧」および「国際宇宙ステーションへの無人宇宙飛行の一覧」も参照

スペースシャトル退役まで

当初のNASAの宇宙ステーション建設構想は、スペースシャトルの全面的な利用を想定していた。このため、モジュールや機材の多くはスペースシャトルでの輸送を前提として設計されている。しかし予算上の理由からロシアが参加することになり、人員輸送には緊急脱出用を兼ねてソユーズ宇宙船を、貨物輸送にはプログレス補給船を合わせて利用することになった。ロシアの建設資材は、大半がロシア独自で打ち上げられる。ロシアは与圧モジュールを独立の宇宙船として設計しており、プロトンロケットで打ち上げられるとモジュール自体の機能でISSに自動ドッキングする。一部の小型モジュール（ピアースなど）は、プログレス補給船のペイロードとして輸送される。

2003年2月1日に別ミッションで飛行中のスペースシャトル「コロンビア」が大気圏再突入後に空中分解で失われる事故が発生し、運行の安全が確認されるまでスペースシャトルの打ち上げが無期限停止となったため、ISSの組み立て作業は、2002年11月に行われた「STS-113/ISS組立ミッション11A」を最後に一時停止した。これによりISSへの輸送力が大幅に低下したため、ISSにおける宇宙飛行士の3人の常駐体制が一時的に2人に減らされた。2005年7月26日午後11時39分（日本時間）に、事故後初となるディスカバリー (STS-114) の打ち上げが行われ、ISS組立再開ミッションとなる「ミッション/LF-1」が行われた。このミッションには日本から野口聡一飛行士が参加した。

2008年には欧州のESAが欧州補給機 (ATV) の運用を開始し、2009年には日本のJAXAが宇宙ステーション補給機 (HTV) の運用を開始した。スペースシャトルによる宇宙飛行士の交代は2009年11月で終了し、以後の宇宙飛行士の交代には専らソユーズ宇宙船が使われるようになった。

2010年にはNASAがスペースシャトルを退役させることを決定した。ISSのロシア以外の建設資材は、大半がスペースシャトルでの打ち上げを前提に設計されており代替輸送は困難であるため、仮にスペースシャトルの運航が遅れれば全ての資材を打ち上げることなくISSの建設を打ち切る可能性もあると懸念された。また、スペースシャトル退役以後はコンステレーション計画の一環として、スペースシャトルの後継となるアレスロケットとオリオン宇宙船によってISSに人員や貨物を輸送する計画があったが、2010年にバラク・オバマ政権によりコンステレーション計画の中止が決定された。アメリカはスペースシャトルの退役によりドラゴン宇宙船の運用開始までの間、ISSへの独自の輸送手段を一時的に失うことになった。

スペースシャトル退役以降

無人宇宙補給機の比較。左からプログレス、ATV、HTV、ドラゴン標準型と拡張型、シグナス標準型と拡張型。赤が与圧区画、橙が非与圧区画、青が燃料区画。

2011年7月にスペースシャトルが退役した後しばらくは、ISSへの人員輸送にはソユーズ宇宙船、貨物輸送にはプログレス補給船、欧州補給機 (ATV)、宇宙ステーション補給機 (HTV) のみが使用されていたが、プログレス補給船、ATV、HTVには貨物回収能力はなく、ソユーズはわずか60kgの手荷物しか回収できないため、ISSから地球へ貨物を持ち帰る能力が最小となった。

スペースシャトル退役後のアメリカのISSへの人員・貨物輸送手段としては、商業軌道輸送サービス (COTS) により開発された、民間企業スペースX社のファルコン9とドラゴン補給機、オービタル・サイエンシズ社のアンタレスとシグナス補給機を使用した商業補給サービス (CRS) を活用する。ドラゴン宇宙船は2012年5月26日に民間宇宙船として初めてISSにドッキングして補給に成功し、5月31日 (UTC) に太平洋に着水し帰還した。これによりISSからの貨物の回収が再び可能となった。10月10日には初の商業補給サービス (CRS) ミッションに成功した。

NASAは2011年5月に、コンステレーション計画で使用される予定だったオリオン宇宙船の設計を流用した新たなオリオン宇宙船 (Orion Multi-Purpose Crew Vehicle, MPCV) の開発を発表した。新たなオリオン宇宙船の無人テスト機EFT-1は2014年12月にデルタIV Heavyロケットで打ち上げられた。また2011年9月に、スペースシャトルの後継としてオリオン宇宙船も打ち上げることになるNASA独自の打ち上げロケットとして、サターンVロケットを超える規模のスペース・ローンチ・システムの開発が発表された。しかし、オリオン宇宙船によるISSへの宇宙飛行士の輸送任務はその後キャンセルされ、商業クルー輸送機（有人型ドラゴン宇宙船とボーイング社のCST-100）に任せることになり、オリオン宇宙船は有人での深宇宙探査と商業クルー輸送計画が上手くいかなかった時のバックアップの位置づけとなっている。

2015年2月、欧州補給機（ATV）の5号機が大気圏に再突入し、欧州補給機全機の運用を終了した。

運用中の輸送機

ロシア

• ソユーズ宇宙船

詳細は「ソユーズ」を参照

ロシアが運用中の3人乗り有人宇宙船である。ISSに非常事態が起きた際の脱出用救命ボートの役割を果たしている。この用途に対しては、アメリカが乗員帰還機 (X-38 CRV) を開発して置き換える計画だったが、こちらは中止された。2009年5月までは、ISS長期滞在クルーは3名体制だったので、ソユーズが常時1機備え付けられていたが、2009年5月からは6名体制に拡張されたため、ソユーズも2機常備されることになった。緊急時に利用しやすいよう、ISSの中央に近いザーリャ前方の地球側にドッキングするが、2機に増えた場合はさらにズヴェズダ前方（に結合しているピアース）も利用する。ズヴェズダの後方はISSの末端にあたるので、プログレス、ATVの結合を優先するため出来るだけ避けてはいるが、ズヴェズダ後方も必要に応じて使用することもある。なお、2010年1月からは、MRM-2のドッキングポートも利用できるようになる。

ソユーズの軌道上での寿命は6ヵ月なので、6ヵ月ごとに新しいソユーズを打ち上げて交換する。この際、滞在3名中2名から3名がソユーズとともに交代するが、ソユーズは3人乗りなので、ロシア人用の1人分の空席が空く場合もある、その場合はISSへの短期訪問（新しいソユーズでISSへ向かい、古いソユーズで帰還する）に利用される。このような便乗者をタクシークルーと呼び、ロシアが利用権を販売している。私的宇宙旅行でのISS訪問や、マレーシアや韓国によるISS訪問はこの枠を利用したものである。ただし、シャトルでのクルーの交代2009年11月のSTS-129を最後になくなり、滞在人数も6名に増加したため、タクシークルーの搭乗機会はなくなった。

• プログレス補給船

詳細は「プログレス補給船」および「#高度制御」を参照

ロシアが運用中の無人貨物船。与圧貨物として食料、衣類、実験機材、補修用部品などを輸送するほか、酸素や水、液体推進剤をISSに補給するタンクとパイプも装備している。プログレスはズヴェズダの後方にドッキングすることが多い（その他、ザーリャとピアースにもドッキングする）。ここはISSの後方端にあたるので、プログレスは自身のエンジンを使用してISSを推進（リブースト）し、高度を上げることができる。スペースシャトルが事故の影響で運用不能に陥っていた際には、強力なピンチヒッター役を務め、ISSを維持した。スペースシャトル復帰後も物資輸送に活躍しているが、後述のATVとHTVの運用が開始されてからは役割を分担することになった。

日本

• 宇宙ステーション補給機

詳細は「宇宙ステーション補給機」を参照

宇宙ステーション補給機 (HTV)、愛称「こうのとり」はJAXAが2009年に運用を開始した無人貨物船。プログレスやATVと異なり、ISSの先頭にあたるハーモニーに結合するため、リブーストに用いることはできない。しかし、MPLMと同様にサイズが大きい共通結合機構 (CBM) で結合するため、ISPRを丸ごと搭載するなど、大型の貨物を輸送することができる。また非与圧部があり、ISSの船外に装着されるバッテリーなども輸送することができる。スペースシャトル退役後、後述の民間機の運用が開始されるまでは、これらの物資を輸送可能な輸送機はHTVのみだった。

アメリカ合衆国

2014年10月のアンタレス（シグナス）、2015年6月のファルコン9（ドラゴン）の打ち上げ失敗により、アメリカ合衆国側の輸送機計画に影響が出る可能性がある。

• ドラゴン

詳細は「ドラゴン (宇宙船)」を参照

商業軌道輸送サービス (COTS) 計画で開発された初の民間無人宇宙補給機。ドラゴンはファルコン9により打ち上げられ、2010年12月に初めて地球低軌道を周回し大気圏に再突入して太平洋に着水し、2012年5月に初めてISSのドッキングに成功して補給を成功させた。

• シグナス

詳細は「シグナス (宇宙船)」を参照

シグナスはドラゴンと同じくCOTS計画で開発された民間無人宇宙補給機。シグナスはアンタレスにより打ち上げられ、2013年9月に初めてISSとのドッキングに成功して補給を成功させた。

過去に運用された輸送機

スペースシャトル

トラスを輸送中のスペースシャトル。

詳細は「スペースシャトル」を参照

2011年7月に退役するまでNASAがISSへの人員と建設資材と補給物資の輸送のために運用していた輸送機。ISS建設資材の大半を輸送したほか、7名の人員とロボットアームを搭載でき、特に建設初期段階では作業基地の役割も果たした。人員交代にも使われるが、ソユーズ宇宙船を6箇月ごとに交換する際に人員交代も行えるため、補助的な役割にとどまった。

日米欧の実験モジュールなど、ロシア以外の与圧モジュールはスペースシャトルで輸送された。このため、これらのモジュールは全てスペースシャトルのペイロードベイに合わせた寸法、形状、重量になっている。ただし、スペースシャトルの度重なる改良（主に安全性向上）により搭載可能な重量は計画当初より減少しているため、一部の大型モジュール（デスティニー、きぼう船内実験室）は船内機器の一部を別便で輸送せざるを得なくなった。

補給には、大きく分けて4つの方法を用いた。ひとつは、スペースシャトルの船内に補給品を搭載し、ドッキング装置を通して運搬する方法である。ドッキング装置の通路は直径60センチメートル程度と狭く、船内スペースを使用するため輸送力は小さいが、補助的に毎回使われていた方法である。

2つめは、ペイロードベイにスペースハブ輸送モジュールを搭載する方法である。船内より多くの補給品を搭載できるが、やはり大きな物資は輸送できない。次のMPLMが導入されると使われなくなった。

3つめは、ペイロードベイに多目的補給モジュール (MPLM) を搭載する方法である。MPLMはペイロードベイから取り出され、ユニティまたはハーモニーに直接結合される。サイズが大きい共通結合機構 (CBM) を使うため、ISPRなど大型の機材を輸送できるほか、小型物資も広い通路を利用して効率よく搬入できた。作業終了後のMPLMはペイロードベイに戻されて持ち帰られた（詳しくはMPLMを参照）。

4つめは、ペイロードベイ内に露出した形で輸送する方法である。ISSの外部に設置するバッテリーやタンクなどの部品を交換する際には、アダプターを使用して搭載した。

欧州補給機

詳細は「欧州補給機」を参照

欧州補給機 (ATV) はESAが2008年から2015年まで運用した無人貨物船。機能や利用方法はプログレスとほぼ同じで、ロシア側のドッキング装置を使用し、補給用のタンクやパイプも装備している。大型のアリアンVロケットで打ち上げられるためプログレスよりもかなり大型で、リブースト用推進剤を含む輸送力はプログレスの約3倍である。ただし、ドッキング装置もプログレスと同じなので大型物資の輸送はできない。

開発中の輸送機

オリオン宇宙船

詳細は「オリオン (宇宙船)」を参照

NASAは2011年5月にオリオン宇宙船 (Orion Multi-Purpose Crew Vehicle, MPCV) の開発を発表した。オリオン宇宙船の無人テスト機は2013年7月にデルタIV Heavyロケットで打ち上げられる予定である。また2011年9月に、スペースシャトル後継機のSLSの開発とオリオン宇宙船を搭載した初号機を2017年に打ち上げることが発表された。

当初のオリオン宇宙船は、NASAがコンステレーション計画に使用するために2014年運用開始を目標に開発していたが、2010年にコンステレーション計画が中止されると計画が現在のものに変更された。コンステレーション計画においては、6名が搭乗可能で、ソユーズを置き換えて緊急帰還船としても使われる模様であった。また、詳細は発表されていないが無人貨物船型の開発も予定されており、有人型と同様の物資回収カプセルを備えた型と、HTVのような非回収カプセル（大気圏再突入廃棄物処理など）を備えた型のイラストが公表されていた。まずISSに対応した型（ブロック1）が開発され、続いて月飛行に使用可能なブロック2、火星や小惑星への飛行に使用可能なブロック3を開発する予定であった。

PPTS

詳細は「PPTS (宇宙船)」を参照

ロシアが2018年の有人飛行を目標に開発中のソユーズ代替有人宇宙船。ISSへ6人輸送することが可能である他、無人輸送機としての運用も考慮されており、2tの貨物をISSへ輸送し500kgの貨物を地上に持ち帰ることが可能となる予定である。RKKエネルギアが開発を担当する。

開発検討中の輸送機

HTV発展型

詳細は「宇宙ステーション補給機#回収機能付加型宇宙ステーション補給機 (HTV-R)」および「宇宙ステーション補給機#発展型の展望」を参照

JAXAが開発を検討中の宇宙船で、当面は貨物回収カプセルを搭載した無人回収機の開発を見込んでいる。打ち上げにはH-IIBを用いる。有人型についても検討は開始しているが、開発可否の判断は2015年以降（未定）に行うとされている。

計画中止になった輸送機

X-38 CRV

詳細は「X-38 (航空機)」を参照

乗員帰還機 (CRV) としてNASAが開発を進めていた宇宙船である。X-24実験機に似たリフティングボディ形状の機体であり、6名が搭乗することができる予定だった。大気圏内での滑空実験などが行われたが、コロンビア号事故後の計画見直しで2002年に開発がキャンセルされた。

クリーペル

詳細は「クリーペル」を参照

ロシアが開発を検討していた有人宇宙船でソユーズを代替する予定だった。釣り鐘型のカプセルだが小さな翼を取り付けた案もあった。エンジン部分は宇宙にとどまって繰り返し使われ、打ち上げにはソユーズ3ロケットを使用する予定だった。ESAやJAXAに共同開発を打診したが、2007年末にESAとの間でCSTS計画を立ち上げ、これに伴い計画は中止された。

ACTS/CSTS

ESAとロシアが開発を検討していた有人宇宙船でソユーズを代替する予定だった。有人カプセルと脱出装置、打ち上げロケットはロシアが、推進部はESAが開発し、2014年実用化を目標としていた。ESAでは、次のATV発展型とどちらが採用されるかは最終決定されず、JAXAにも共同開発を打診したが、共同開発には至らなかった。この計画は中止され、2009年初めにロシアは独自の有人宇宙船PPTSを開発することを決定した。

アレス

詳細は「アレス (ロケット)」、「アレスI」、および「アレスV」を参照

月探査計画（コンステレーション計画）用の大型貨物ロケットであるアレスロケットシリーズを、ISSに利用する案もあった。アレスVは地球低軌道に130tもの貨物を輸送可能であり、過去にサターンVでスカイラブを打ち上げたように、アルタイル着陸船を改造した軌道変更ユニットを取り付けることで大型のモジュールをISSに届けることが可能な計画だった。しかし開発は大幅に遅れ、2010年にコンステレーション計画自体の中止が決定された。

ATV発展型

詳細は「欧州補給機#提案された有人型」を参照

ESAが開発を検討していた宇宙船で、まず貨物回収カプセルを搭載した無人型を、続いて有人カプセルと脱出装置を備えた有人型を開発する計画だった。打ち上げにはアリアン5を使用。ACTS/PPTSとは異なりヨーロッパ独自の計画だが、ESAはACTS/PPTSと比較検討していた。ATVは2015年のATV-5ミッションの終了をもって退役し、ESAはオリオン宇宙船にATVのサービスモジュールの技術を派生させたESM(European Service Module)を提供する計画に変更した。

費用

2010年までの国際宇宙ステーション計画における各国の支出は、アメリカが6兆4400億円（585億ドル）、日本が7100億円、欧州が4600億円（35億ユーロ）、カナダが1400億円（17億カナダドル）である。2011年から2015年までの5年間の各国の予想支出は、アメリカが1兆8900億円（172億ドル）、日本が2000億円、欧州が2500億円（19億ユーロ）、カナダが250億円（3億カナダドル）である。（日本の支出の内訳はきぼうを参照） なお、ロシアは自国管轄部分の費用をすべて負担し、同時にその全ての利用権を所有している。

備考

• トラスの名称「S1」のSや「P1」のPは、それぞれ船の「右舷」(Starboard Side)、「左舷」(Port Side) からきている。また、「Z1トラス」のZは「天頂」(Zenith) からきている。
• 国際宇宙ステーションからアマチュア無線が運用されている。宇宙飛行士は余暇時間を使って交信を地上のアマチュア無線家と交信している。コールサインはNA1SSとRS0ISSが使用されている。また、青少年に宇宙に対して関心を持って貰うため、スクールコンタクトが実施されている。
• 2010年1月より、ISSからのインターネット直接接続が可能となった。野口聡一がISS滞在中に投稿サイト「Twitter」に1200回以上書き込み、宇宙から最も多くTwitterに投稿した飛行士とされている。
• 2011年1月28日日本のHTV-2号機「こうのとり」が国際宇宙ステーションにドッキングした。その後、2月24日に欧州補給機 (ATV) 2号機「ヨハネス・ケプラー」が、さらに2月26日にスペースシャトル「ディスカバリー」(STS-133) が国際宇宙ステーションにドッキングした。先にドッキング中のプログレス、ソユーズを加え、この時点で上記の5機種6機が一堂に会し、ISS計画に参加している各国の全宇宙船が初めて同時に国際宇宙ステーションにドッキングした状態となった。シャトルが退役することが決まっていることから、現役の宇宙機の勢ぞろいはこのSTS-133が最初で最後の機会となり、宇宙開発の国際協力を象徴するイベントとなった。またこのSTS-133ミッションでは恒久的多目的モジュール (PMM) が最後のアメリカ側モジュールとして取り付けられ、国際宇宙ステーションの与圧区画がほぼ完成状態となった。

脚注

関連項目

• 宇宙ステーション
  • スカイラブ計画
  • サリュート
  • ミール
  • 天宮（中国計画の宇宙ステーション）

外部リンク

• 宇宙航空研究開発機構 (JAXA)
  • 国際宇宙ステーションと日本の実験モジュール 開発計画の経緯、進行状況など各種の情報が提供されている。
  • 国際宇宙ステーション計画に関する宇宙機関長会議の結果について（平成18年3月8日） 計画見直しについてPDFで紹介。
• 国際宇宙ステーションをみよう 倉敷科学センター

wiki en

[Wiki en表示]

"ISS" redirects here. For other uses, see ISS (disambiguation).

International Space Station

The International Space Station on 23 May 2010 as seen from the departing Space Shuttle Atlantis during STS-132.
Station statistics
COSPAR ID	1998-067A
Call sign	Alpha, Station
Crew	Fully crewed: 6 Currently aboard: 3 (Expedition 44)
Launch	20 November 1998
Launch pad	Baikonur 1/5 and 81/23 Kennedy LC-39
Mass	Approximately 450,000 kg (990,000 lb)
Length	72.8 m (239 ft)
Width	108.5 m (356 ft)
Height	c. 20 m (c. 66 ft) nadir–zenith, arrays forward–aft (27 November 2009)
Pressurised volume	916 m3 (32,300 cu ft) (3 November 2014)
Atmospheric pressure	101.3 kPa (29.91 inHg, 1 atm)
Perigee	409 km (254 mi) AMSL
Apogee	416 km (258 mi) AMSL
Orbital inclination	51.65 degrees
Average speed	7.66 kilometres per second (27,600 km/h; 17,100 mph)
Orbital period	92.69 minutes
Orbit epoch	25 January 2015
Days in orbit	6087 (21 July)
Days occupied	5374 (21 July)
Number of orbits	92579
Orbital decay	2 km/month
Statistics as of 9 March 2011 (unless noted otherwise)
References:
Configuration
Station elements as of December 2011, but missing Pirs (exploded view)

The International Space Station (ISS) is a space station, or a habitable artificial satellite, in low Earth orbit. Its first component launched into orbit in 1998, and the ISS is now the largest artificial body in orbit and can often be seen with the naked eye from Earth. The ISS consists of pressurised modules, external trusses, solar arrays and other components. ISS components have been launched by Russian Proton and Soyuz rockets as well as American Space Shuttles.

The ISS serves as a microgravity and space environment research laboratory in which crew members conduct experiments in biology, human biology, physics, astronomy, meteorology and other fields. The station is suited for the testing of spacecraft systems and equipment required for missions to the Moon and Mars. The ISS maintains an orbit with an altitude of between 330 and 435 km (205 and 270 mi) by means of reboost manoeuvres using the engines of the Zvezda module or visiting spacecraft. It completes 15.54 orbits per day.

ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations as well as Skylab from the US. The station has been continuously occupied for 7008464331055000000♠14 years and 261 days since the arrival of Expedition 1 on 2 November 2000. This is the longest continuous human presence in space, having surpassed the previous record of 7008314841600000000♠9 years and 357 days held by Mir. The station is serviced by a variety of visiting spacecraft: Soyuz, Progress, the Automated Transfer Vehicle, the H-II Transfer Vehicle, Dragon, and Cygnus. It has been visited by astronauts and cosmonauts from 15 different nations.

After the US Space Shuttle program ended in 2011, Soyuz rockets became the only provider of transport for astronauts at the International Space Station, and Dragon became the only provider of bulk cargo-return-to-Earth services (downmass capability of Soyuz capsules is very limited).

The ISS programme is a joint project among five participating space agencies: NASA, Roscosmos, JAXA, ESA, and CSA. The ownership and use of the space station is established by intergovernmental treaties and agreements. The station is divided into two sections, the Russian Orbital Segment (ROS) and the United States Orbital Segment (USOS), which is shared by many nations. As of January 2014, the American portion of ISS was funded until 2024. Roscosmos has endorsed the continued operation of ISS through 2024, but have proposed using elements of the Russian Orbital Segment to construct a new Russian space station called OPSEK.

On March 28, 2015, Russian sources announced that Roscosmos and NASA had agreed to collaborate on the development of a replacement for the current ISS. NASA later issued a guarded statement expressing thanks for Russia's interest in future cooperation in space exploration, but fell short of confirming the Russian announcement.

Purpose

Sunrise at Zvezda

Fisheye view of several labs

According to the original Memorandum of Understanding between NASA and Rosaviakosmos, the International Space Station was intended to be a laboratory, observatory and factory in low Earth orbit. It was also planned to provide transportation, maintenance, and act as a staging base for possible future missions to the Moon, Mars and asteroids. In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic and educational purposes.

Scientific research

Main article: Scientific research on the ISS

The ISS provides a platform to conduct scientific research. Small unmanned spacecraft can provide platforms for zero gravity and exposure to space, but space stations offer a long term environment where studies can be performed potentially for decades, combined with ready access by human researchers over periods that exceed the capabilities of manned spacecraft.

The Station simplifies individual experiments by eliminating the need for separate rocket launches and research staff. The wide variety of research fields include astrobiology, astronomy, human research including space medicine and life sciences, physical sciences, materials science, space weather, and weather on Earth (meteorology). Scientists on Earth have access to the crew's data and can modify experiments or launch new ones, which are benefits generally unavailable on unmanned spacecraft. Crews fly expeditions of several months duration, providing approximately 160-man-hours per week of labour with a crew of 6.

To detect dark matter and answer other fundamental questions about our universe, engineers and scientists from all over the world built the Alpha Magnetic Spectrometer (AMS), which NASA compares to the Hubble space telescope, and says could not be accommodated on a free flying satellite platform due in part to its power requirements and data bandwidth needs. On 3 April 2013, NASA scientists reported that hints of dark matter may have been detected by the Alpha Magnetic Spectrometer. According to the scientists, "The first results from the space-borne Alpha Magnetic Spectrometer confirm an unexplained excess of high-energy positrons in Earth-bound cosmic rays."

Comet Lovejoy photographed by Expedition 30 commander Dan Burbank

Expedition 8 Commander and Science Officer Michael Foale conducts an inspection of the Microgravity Science Glovebox

The space environment is hostile to life. Unprotected presence in space is characterised by an intense radiation field (consisting primarily of protons and other subatomic charged particles from the solar wind, in addition to cosmic rays), high vacuum, extreme temperatures, and microgravity. Some simple forms of life called extremophiles, including small invertebrates called tardigrades can survive in this environment in an extremely dry state called desiccation.

Medical research improves knowledge about the effects of long-term space exposure on the human body, including muscle atrophy, bone loss, and fluid shift. This data will be used to determine whether lengthy human spaceflight and space colonisation are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars. Medical studies are conducted aboard the ISS on behalf of the National Space Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity study in which astronauts perform ultrasound scans under the guidance of remote experts. The study considers the diagnosis and treatment of medical conditions in space. Usually, there is no physician on board the ISS and diagnosis of medical conditions is a challenge. It is anticipated that remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.

Microgravity

A comparison between the combustion of a candle on Earth (left) and in a microgravity environment, such as that found on the ISS (right)

The Earth's gravity is only slightly weaker at the altitude of the ISS than at the surface, but objects in orbit are in a continuous state of freefall, resulting in an apparent state of weightlessness. This perceived weightlessness is disturbed by five separate effects:

• Drag from the residual atmosphere; when the ISS enters the Earth's shadow, the main solar panels are rotated to minimise this aerodynamic drag, helping reduce orbital decay.
• Vibration from movements of mechanical systems and the crew.
• Actuation of the on-board attitude control moment gyroscopes.
• Thruster firings for attitude or orbital changes.
• Gravity-gradient effects, also known as tidal effects. Items at different locations within the ISS would, if not attached to the station, follow slightly different orbits. Being mechanically interconnected these items experience small forces that keep the station moving as a rigid body.

ISS crew member storing samples

Researchers are investigating the effect of the station's near-weightless environment on the evolution, development, growth and internal processes of plants and animals. In response to some of this data, NASA wants to investigate microgravity's effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.

The investigation of the physics of fluids in microgravity will allow researchers to model the behaviour of fluids better. Because fluids can be almost completely combined in microgravity, physicists investigate fluids that do not mix well on Earth. In addition, an examination of reactions that are slowed by low gravity and temperatures will give scientists a deeper understanding of superconductivity.

The study of materials science is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground. Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve current knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosols, ozone, water vapour, and oxides in Earth's atmosphere, as well as cosmic rays, cosmic dust, antimatter, and dark matter in the universe.

Exploration

A 3D plan of the Russia-based MARS-500 complex, used for ground-based experiments which complement ISS-based preparations for a manned mission to Mars

The ISS provides a location in the relative safety of Low Earth Orbit to test spacecraft systems that will be required for long-duration missions to the Moon and Mars. This provides experience in operations, maintenance as well as repair and replacement activities on-orbit, which will be essential skills in operating spacecraft farther from Earth, mission risks can be reduced and the capabilities of interplanetary spacecraft advanced. Referring to the MARS-500 experiment, ESA states that "Whereas the ISS is essential for answering questions concerning the possible impact of weightlessness, radiation and other space-specific factors, aspects such as the effect of long-term isolation and confinement can be more appropriately addressed via ground-based simulations". Sergey Krasnov, the head of human space flight programmes for Russia's space agency, Roscosmos, in 2011 suggested a "shorter version" of MARS-500 may be carried out on the ISS.

In 2009, noting the value of the partnership framework itself, Sergey Krasnov wrote, "When compared with partners acting separately, partners developing complementary abilities and resources could give us much more assurance of the success and safety of space exploration. The ISS is helping further advance near-Earth space exploration and realisation of prospective programmes of research and exploration of the Solar system, including the Moon and Mars." A manned mission to Mars may be a multinational effort involving space agencies and countries outside the current ISS partnership. In 2010, ESA Director-General Jean-Jacques Dordain stated his agency was ready to propose to the other four partners that China, India and South Korea be invited to join the ISS partnership. NASA chief Charlie Bolden stated in February 2011, "Any mission to Mars is likely to be a global effort". Currently, American legislation prevents NASA co-operation with China on space projects.

Education and cultural outreach

Japan's Kounotori 4 docking

The ISS crew provides opportunities for students on Earth by running student-developed experiments, making educational demonstrations, allowing for student participation in classroom versions of ISS experiments, and directly engaging students using radio, videolink and email. ESA offers a wide range of free teaching materials that can be downloaded for use in classrooms. In one lesson, students can navigate a 3-D model of the interior and exterior of the ISS, and face spontaneous challenges to solve in real time.

JAXA aims both to "Stimulate the curiosity of children, cultivating their spirits, and encouraging their passion to pursue craftsmanship", and to "Heighten the child's awareness of the importance of life and their responsibilities in society." Through a series of education guides, a deeper understanding of the past and near-term future of manned space flight, as well as that of Earth and life, will be learned. In the JAXA Seeds in Space experiments, the mutation effects of spaceflight on plant seeds aboard the ISS is explored. Students grow sunflower seeds which flew on the ISS for about nine months as a start to 'touch the Universe'. In the first phase of Kibō utilisation from 2008 to mid-2010, researchers from more than a dozen Japanese universities conducted experiments in diverse fields.

Original Jules Verne manuscripts displayed by crew inside Jules Verne ATV

Cultural activities are another major objective. Tetsuo Tanaka, director of JAXA's Space Environment and Utilization Center, says "There is something about space that touches even people who are not interested in science."

Amateur Radio on the ISS (ARISS) is a volunteer programme which encourages students worldwide to pursue careers in science, technology, engineering and mathematics through amateur radio communications opportunities with the ISS crew. ARISS is an international working group, consisting of delegations from 9 countries including several countries in Europe as well as Japan, Russia, Canada, and the United States. In areas where radio equipment cannot be used, speakerphones connect students to ground stations which then connect the calls to the station.

First Orbit is a feature-length documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker Christopher Riley and ESA astronaut Paolo Nespoli were able to film the view that Yuri Gagarin saw on his pioneering orbital space flight. This new footage was cut together with the original Vostok 1 mission audio recordings sourced from the Russian State Archive. Nespoli, during Expedition 26/27, filmed the majority of the footage for this documentary film, and as a result is credited as its director of photography. The film was streamed through the website firstorbit.org in a global YouTube premiere in 2011, under a free license.

In May 2013, commander Chris Hadfield shot a music video of David Bowie's Space Oddity on board the station; the film was released freely on YouTube. It was the first music video ever to be filmed in space.

Assembly

Main articles: Assembly of the International Space Station and List of ISS spacewalks

Partially constructed ISS in December 2002

S3-S4 Truss Installed in 2007

Soyuz TMA-19 departs in 2010

ISS in 2007, with fewer solar arrays

The assembly of the International Space Station, a major endeavour in space architecture, began in November 1998. Russian modules launched and docked robotically, with the exception of Rassvet. All other modules were delivered by the Space Shuttle, which required installation by ISS and shuttle crewmembers using the Canadarm2 (SSRMS) and EVAs; as of 5 June 2011, they had added 159 components during more than 1,000 hours of EVA. 127 of these spacewalks originated from the station, and the remaining 32 were launched from the airlocks of docked Space Shuttles. The beta angle of the station had to be considered at all times during construction, as the station's beta angle is directly related to the percentage of its orbit that the station (as well as any docked or docking spacecraft) is exposed to the sun; the Space Shuttle would not perform optimally above a limit called the "beta cutoff".

The first module of the ISS, Zarya, was launched on 20 November 1998 on an autonomous Russian Proton rocket. It provided propulsion, attitude control, communications, electrical power, but lacked long-term life support functions. Two weeks later a passive NASA module Unity was launched aboard Space Shuttle flight STS-88 and attached to Zarya by astronauts during EVAs. This module has two Pressurized Mating Adapters (PMAs), one connects permanently to Zarya, the other allows the Space Shuttle to dock to the space station. At this time, the Russian station Mir was still inhabited. The ISS remained unmanned for two years, during which time Mir was de-orbited. On 12 July 2000 Zvezda was launched into orbit. Preprogrammed commands on board deployed its solar arrays and communications antenna. It then became the passive vehicle for a rendezvous with the Zarya and Unity. As a passive "target" vehicle, the Zvezda maintained a stationkeeping orbit as the Zarya-Unity vehicle performed the rendezvous and docking via ground control and the Russian automated rendezvous and docking system. Zarya's computer transferred control of the station to Zvezda's computer soon after docking. Zvezda added sleeping quarters, a toilet, kitchen, CO₂ scrubbers, dehumidifier, oxygen generators, exercise equipment, plus data, voice and television communications with mission control. This enabled permanent habitation of the station.

The first resident crew, Expedition 1, arrived in November 2000 on Soyuz TM-31. At the end of the first day on the station, astronaut Bill Shepherd requested the use of the radio call sign "Alpha", which he and cosmonaut Krikalev preferred to the more cumbersome "International Space Station". The name "Alpha" had previously been used for the station in the early 1990s, and following the request, its use was authorised for the whole of Expedition 1. Shepherd had been advocating the use of a new name to project managers for some time. Referencing a naval tradition in a pre-launch news conference he had said: "For thousands of years, humans have been going to sea in ships. People have designed and built these vessels, launched them with a good feeling that a name will bring good fortune to the crew and success to their voyage." Yuri Semenov, the President of Russian Space Corporation Energia at the time, disapproved of the name "Alpha"; he felt that Mir was the first space station, and so he would have preferred the names "Beta" or "Mir 2" for the ISS.

Expedition 1 arrived midway between the flights of STS-92 and STS-97. These two Space Shuttle flights each added segments of the station's Integrated Truss Structure, which provided the station with Ku-band communication for US television, additional attitude support needed for the additional mass of the USOS, and substantial solar arrays supplementing the station's existing 4 solar arrays.

Over the next two years the station continued to expand. A Soyuz-U rocket delivered the Pirs docking compartment. The Space Shuttles Discovery, Atlantis, and Endeavour delivered the Destiny laboratory and Quest airlock, in addition to the station's main robot arm, the Canadarm2, and several more segments of the Integrated Truss Structure.

Aft view showing a Progress spacecraft docked to Zvezda

The expansion schedule was interrupted by the Space Shuttle Columbia disaster in 2003, with the resulting two year hiatus in the Space Shuttle programme halting station assembly. The space shuttle was grounded until 2005 with STS-114 flown by Discovery.

Assembly resumed in 2006 with the arrival of STS-115 with Atlantis, which delivered the station's second set of solar arrays. Several more truss segments and a third set of arrays were delivered on STS-116, STS-117, and STS-118. As a result of the major expansion of the station's power-generating capabilities, more pressurised modules could be accommodated, and the Harmony node and Columbus European laboratory were added. These were followed shortly after by the first two components of Kibō. In March 2009, STS-119 completed the Integrated Truss Structure with the installation of the fourth and final set of solar arrays. The final section of Kibō was delivered in July 2009 on STS-127, followed by the Russian Poisk module. The third node, Tranquility, was delivered in February 2010 during STS-130 by the Space Shuttle Endeavour, alongside the Cupola, closely followed in May 2010 by the penultimate Russian module, Rassvet. Rassvet was delivered by Space Shuttle Atlantis on STS-132 in exchange for the Russian Proton delivery of the Zarya Module in 1998 which had been funded by the United States. The last pressurised module of the USOS, Leonardo, was brought to the station by Discovery on her final flight, STS-133, followed by the Alpha Magnetic Spectrometer on STS-134, delivered by Endeavour.

The Cupola arrived in 2010

As of June 2011, the station consisted of fifteen pressurised modules and the Integrated Truss Structure. Still to be launched are the Russian Multipurpose Laboratory Module Nauka and a number of external components, including the European Robotic Arm. Assembly is expected to be completed by April 2014, by which point the station will have a mass in excess of 400 tonnes (440 short tons).

The gross mass of the station changes over time. The total launch mass of the modules on orbit is about 417,289 kg (919,965 lb) (as of 3 September 2011). The mass of experiments, spare parts, personal effects, crew, foodstuff, clothing, propellants, water supplies, gas supplies, docked spacecraft, and other items add to the total mass of the station. Hydrogen gas is constantly vented overboard by the oxygen generators.

Station structure

Russian Orbital Segment Windows

USOS International Space Station window locations

The ISS is a third generation modular space station. Modular stations can allow the mission to be changed over time and new modules can be added or removed from the existing structure, allowing greater flexibility.

Below is a diagram of major station components. The blue areas are pressurised sections accessible by the crew without using spacesuits. The station's unpressurised superstructure is indicated in red. Other unpressurised components are yellow. Note that the Unity node joins directly to the Destiny laboratory. For clarity, they are shown apart.

Russian docking port

Solar array

Zvezda DOS-8 Service Module

Solar array

Russian docking port

Poisk (MRM-2) Airlock

Pirs Airlock

Russian docking port

Nauka lab to Replace Pirs

European Robotic Arm

Solar array

Zarya FGB (first module)

Solar array

Rassvet (MRM-1)

Russian docking port

Leonardo cargo bay

PMA 1

Quest Airlock

Unity Node 1

Tranquility Node 3

PMA 3 docking port

ESP-2

Cupola

Solar array

Solar array

Heat Radiator

Heat Radiator

Solar array

Solar array

ELC 2, AMS

Z1 truss

ELC 3

S5/6 Truss

S3/S4 Truss

S1 Truss

S0 Truss

P1 Truss

P3/P4 Truss

P5/6 Truss

ELC 4, ESP 3

ELC 1

Dextre

Canadarm2

Solar array

Solar array

Solar array

Solar array

External stowage

Destiny Laboratory

Kibō logistics Cargo Bay

HTV/Dragon/Cygnus berth (docking port)

HTV/Dragon/Cygnus berth (docking port)

Kibō Robotic Arm

External Payloads

Columbus Laboratory

Harmony (Node 2)

Kibō Laboratory

Kibō External Platform

PMA 2 docking port

Pressurised modules

Zarya

Zarya as seen by Space Shuttle Endeavour during STS-88

Zarya (Russian: Заря́; lit. dawn), also known as the Functional Cargo Block or FGB (from the Russian "Функционально-грузовой блок", Funktsionalno-gruzovoy blok or ФГБ), was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly. With the launch and assembly in orbit of other modules with more specialized functionality, Zarya is now primarily used for storage, both inside the pressurized section and in the externally mounted fuel tanks. The Zarya is a descendant of the TKS spacecraft designed for the Soviet Salyut program. The name Zarya was given to the FGB because it signified the dawn of a new era of international cooperation in space. Although it was built by a Russian company, it is owned by the United States. Zarya weighs 19,300 kg (42,500 lb), is 12.55 m (41.2 ft) long and 4.1 m (13 ft) wide, discounting solar arrays.

Built from December 1994 to January 1998 in Russia at the Khrunichev State Research and Production Space Center (KhSC) in Moscow, Zarya's control system was developed by the Khartron Corp. (Kharkiv, Ukraine).

Zarya was launched on 20 November 1998, on a Russian Proton rocket from Baikonur Cosmodrome Site 81 in Kazakhstan to a 400 km (250 mi) high orbit with a designed lifetime of at least 15 years. After Zarya reached orbit, STS-88 launched on 4 December 1998, to attach the Unity Module.

Although only designed to fly autonomously for six to eight months, Zarya did so for almost two years due to delays with the Russian Service Module, Zvezda, which finally launched on 12 July 2000, and docked with Zarya on 26 July using the Russian Kurs docking system.

Unity

Unity as pictured by Space Shuttle Endeavour

Unity, or Node 1, is one of three nodes, or passive connecting modules, in the US Orbital Segment of the station. It was the first US-built component of the Station to be launched. Cylindrical in shape, with six berthing locations facilitating connections to other modules, Unity was carried into orbit by Space Shuttle Endeavour as the primary cargo of STS-88 in 1998. Essential space station resources such as fluids, environmental control and life support systems, electrical and data systems are routed through Unity to supply work and living areas of the station. More than 50,000 mechanical items, 216 lines to carry fluids and gases, and 121 internal and external electrical cables using six miles of wire were installed in the Unity node. Unity is made of aluminum. Prior to its launch aboard Endeavour, conical Pressurized Mating Adapters (PMAs) were attached to the aft and forward berthing mechanisms of Unity. Unity and the two mating adapters together weighed about 11,600 kg (25,600 lb). The adapters allow the docking systems used by the Space Shuttle and by Russian modules to attach to the node's hatches and berthing mechanisms.

Unity was carried into orbit as the primary cargo of the Space Shuttle Endeavour on STS-88, the first Space Shuttle mission dedicated to assembly of the station. On 6 December 1998, the STS-88 crew mated the aft berthing port of Unity with the forward hatch of the already orbiting Zarya module.

Zvezda

Zvezda (Russian: Звезда́, meaning "star"), also known as DOS-8, Service Module or SM (Russian: СМ). It provides all of the station's critical systems, its addition rendered the station permanently habitable for the first time, adding life support for up to six crew and living quarters for two. Zvezda's DMS-R computer handles guidance, navigation and control for the entire space station. A second computer which performs the same functions will be installed in the Nauka module, FGB-2.

The hull of Zvezda was completed in February 1985, with major internal equipment installed by October 1986. The module was launched by a Proton-K rocket from Site 81/23 at Baikonur, on 12 July 2000. Zvezda is at the rear of the station according to its normal direction of travel and orientation, its engines are used to boost the station's orbit. Alternatively Russian and European spacecraft can dock to Zvezda's aft port and use their engines to boost the station.

Destiny

Destiny interior in 2001

Destiny is the primary research facility for United States payloads aboard the ISS. In 2011, NASA solicited proposals for a not-for-profit group to manage all American science on the station which does not relate to manned exploration. The module houses 24 International Standard Payload Racks, some of which are used for environmental systems and crew daily living equipment. Destiny also serves as the mounting point for the station's Truss Structure.

Quest

Quest is the only USOS airlock, and hosts spacewalks with both United States EMU and Russian Orlan spacesuits. It consists of two segments: the equipment lock, which stores spacesuits and equipment, and the crew lock, from which astronauts can exit into space. This module has a separately controlled atmosphere. Crew sleep in this module, breathing a low nitrogen mixture the night before scheduled EVAs, to avoid decompression sickness (known as "the bends") in the low-pressure suits.

Pirs and Poisk

Pirs (Russian: Пирс, meaning "pier"), (Russian: Стыковочный отсек), "docking module", SO-1 or DC-1 (docking compartment), and Poisk (Russian: По́иск; lit. Search), also known as the Mini-Research Module 2 (MRM 2), Малый исследовательский модуль 2, or МИМ 2. Pirs and Poisk are Russian airlock modules. Each of these modules have 2 identical hatches. An outward opening hatch on the MIR space station failed after it swung open too fast after unlatching, due to a small amount of air pressure remaining in the airlock. A different entry was used, and the hatch repaired. All EVA hatches on the ISS open inwards and are pressure sealing. Pirs was used to store, service, and refurbish Russian Orlan suits and provided contingency entry for crew using the slightly bulkier American suits. The outermost docking ports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the ROS.

Harmony node in 2011

Tranquility node in 2011

Harmony

Harmony is the second of the station's node modules and the utility hub of the USOS. The module contains four racks that provide electrical power, bus electronic data, and acts as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). The European Columbus and Japanese Kibō laboratories are permanently berthed to the starboard and port radial ports respectively. The nadir and zenith ports can be used for docking visiting spacecraft including HTV, Dragon, and Cygnus, with the nadir port serving as the primary docking port. American Shuttle Orbiters docked with the ISS via PMA-2, attached to the forward port.

Tranquility

Tranquility is the third and last of the station's US nodes, it contains an additional life support system to recycle waste water for crew use and supplements oxygen generation. Two of the four berthing locations are not used. One location has the Cupola installed, one has the docking port adapter, and the third one is occupied by the Leonardo PMM.

Columbus module in 2008

Columbus

Columbus, the primary research facility for European payloads aboard the ISS, provides a generic laboratory as well as facilities specifically designed for biology, biomedical research and fluid physics. Several mounting locations are affixed to the exterior of the module, which provide power and data to external experiments such as the European Technology Exposure Facility (EuTEF), Solar Monitoring Observatory, Materials International Space Station Experiment, and Atomic Clock Ensemble in Space. A number of expansions are planned for the module to study quantum physics and cosmology. ESA's development of technologies on all the main areas of life support has been ongoing for more than 20 years and are/have been used in modules such as Columbus and the ATV. The German Aerospace Center DLR manages ground control operations for Columbus and the ATV is controlled from the French CNES Toulouse Space Center.

Kibō

Not large enough for crew using spacesuits, the airlock on Kibō has a sliding drawer for external experiments.

Kibō (Japanese: きぼう, "hope") is the largest single ISS module. This laboratory is used to carry out research in space medicine, biology, Earth observations, materials production, biotechnology, communications research, and has facilities for growing plants and fish. During August 2011, an observatory mounted on Kibō, which utilises the ISS's orbital motion to image the whole sky in the X-ray spectrum, detected for the first time the moment a star was swallowed by a black hole. The laboratory contains a total of 23 racks, including 10 experiment racks and has a dedicated airlock for experiments. In a 'shirt sleeves' environment, crew attach an experiment to the sliding drawer within the airlock, close the inner, and then open the outer hatch. By extending the drawer and removing the experiment using the dedicated robotic arm, payloads are placed on the external platform. The process can be reversed and repeated quickly, allowing access to maintain external experiments without the delays caused by EVAs.

• Pressurized Module

• Experiment Logistics Module

• Exposed Facility

• Experiment Logistics Module

• Remote Manipulator System

A smaller pressurised module is attached to the top of Kibō, serving as a cargo bay. The dedicated Interorbital communications system allows large amounts of data to be beamed from Kibō's ICS, first to the Japanese KODAMA satellite in geostationary orbit, then to Japanese ground stations. When a direct communication link is used, contact time between the ISS and a ground station is limited to approximately 10 minutes per visible pass. When KODAMA relays data between a LEO spacecraft and a ground station, real-time communications are possible in 60% of the flight path of the spacecraft. Ground staff use telepresence robotics to conduct on-orbit research without crew intervention.

Cupola

The Cupola's design has been compared to the Millennium Falcon from Star Wars.

Dmitri Kondratyev and Paolo Nespoli in the Cupola. Background left to right, Progress M-09M, Soyuz TMA-20, the Leonardo module and HTV-2.

Cupola is a seven window observatory, used to view Earth and docking spacecraft. Its name derives from the Italian word cupola, which means "dome". The Cupola project was started by NASA and Boeing, but cancelled due to budget cuts. A barter agreement between NASA and the ESA resulted in the Cupola's development being resumed in 1998 by the ESA. It was built by Thales Alenia Space in Torino, Italy. The module comes equipped with robotic workstations for operating the station's main robotic arm and shutters to protect its windows from damage caused by micrometeorites. It features 7 windows, with a 80-centimetre (31 in) round window, the largest window on the station (and the largest flown in space to date). The distinctive design has been compared to the 'turret' of the fictitious Millennium Falcon from the motion picture Star Wars; the original prop lightsaber used by actor Mark Hamill as Luke Skywalker in the 1977 film was flown to the station in 2007.

Rassvet

Rassvet (Russian: Рассве́т; lit. "dawn"), also known as the Mini-Research Module 1 (MRM-1) (Russian: Ма́лый иссле́довательский модуль, МИМ 1) and formerly known as the Docking Cargo Module (DCM), is similar in design to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking port for visiting spacecraft. It was flown to the ISS aboard NASA's Space Shuttle Atlantis on the STS-132 mission and connected in May 2010, Rassvet is the only Russian owned module launched by NASA, to repay for the launch of Zarya, which is Russian designed and built, but partially paid for by NASA. Rassvet was launched with the Russian Nauka Laboratory's Experiments airlock temporarily attached to it, and spare parts for the European Robotic Arm.

Leonardo

Leonardo installed

Leonardo Permanent Multipurpose Module (PMM) is a storage module attached to the Tranquility node. The three NASA Space Shuttle MPLM cargo containers—Leonardo, Raffaello and Donatello—were built for NASA in Turin, Italy by Alcatel Alenia Space, now Thales Alenia Space. The MPLMs were provided to NASA's ISS programme by Italy (independent of their role as a member state of ESA) and are considered to be US elements. In a bartered exchange for providing these containers, the US gave Italy research time aboard the ISS out of the US allotment in addition to that which Italy receives as a member of ESA. The Permanent Multipurpose Module was created by converting Leonardo into a module that could be permanently attached to the station.

Scheduled additional modules

Nauka

Nauka (Russian: Нау́ка; lit. "science"), also known as the Multipurpose Laboratory Module (MLM) or FGB-2 (Russian: Многофункциональный лабораторный модуль, МЛМ), is the major Russian laboratory module. It was scheduled to arrive at the station in 2014, docking to the port that was occupied by the Pirs module. The date has been postponed to February 2017. Prior to the arrival of the Nauka module, a Progress spacecraft was used to remove Pirs from the station, deorbiting it to reenter over the Pacific Ocean. Nauka contains an additional set of life support systems and attitude control. Originally it would have routed power from the single Science-and-Power Platform, but that single module design changed over the first ten years of the ISS mission, and the two science modules, which attach to Nauka via the Uzlovoy Module, or Russian node, each incorporate their own large solar arrays to power Russian science experiments in the ROS.

Nauka's mission has changed over time. During the mid-1990s, it was intended as a backup for the FGB, and later as a universal docking module (UDM); its docking ports will be able to support automatic docking of both spacecraft, additional modules and fuel transfer. Nauka has its own engines. Smaller Russian modules such as Pirs and Poisk were delivered by modified Progress spacecraft, and the larger modules; Zvezda, Zarya, and Nauka, were launched by Proton rockets. Russia plans to separate Nauka, along with the rest of the Russian Orbital Segment, before the ISS is deorbited, to form the OPSEK space station.

Uzlovoy Module

The Uzlovoy Module (UM), or Node Module is a 4 metric ton ball shaped module that will support the docking of two scientific and power modules during the final stage of the station assembly and provide the Russian segment additional docking ports to receive Soyuz TMA and Progress M spacecraft. UM is to be incorporated into the ISS in 2016. It will be integrated with a special version of the Progress cargo ship and launched by a standard Soyuz rocket. The Progress would use its own propulsion and flight control system to deliver and dock the Node Module to the nadir (Earth-facing) docking port of the Nauka MLM/FGB-2 module. One port is equipped with an active hybrid docking port, which enables docking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuz and Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems. The node module was conceived to serve as the only permanent element of the future Russian successor to the ISS, OPSEK. Equipped with six docking ports, the Node Module would serve as a single permanent core of the future station with all other modules coming and going as their life span and mission required. This would be a progression beyond the ISS and Russia's modular MIR space station, which are in turn more advanced than early monolithic first generation stations such as Skylab, and early Salyut and Almaz stations.

Science Power Modules 1 & 2 (NEM-1, NEM-2) (Russian: Нау́чно-Энергетический Модуль-1 и -2)

Bigelow Expandable Activity Module

On 16 January 2013, Bigelow Aerospace was contracted by NASA to provide a Bigelow Expandable Activity Module (BEAM), scheduled to arrive at the space station in 2015 for a two-year technology demonstration. BEAM is an inflatable module that will be attached to the aft hatch of the port-side Tranquility module of the International Space Station. During its two-year test run, instruments will measure its structural integrity and leak rate, along with temperature and radiation levels. The hatch leading into the module will remain mostly closed except for periodic visits by space station crew members for inspections and data collection. Following the test run, the module will be detached and jettisoned from the station.

The cancelled Habitation module under construction in 1997

Cancelled components

Several modules planned for the station have been cancelled over the course of the ISS programme, whether for budgetary reasons, because the modules became unnecessary, or following a redesign of the station after the 2003 Columbia disaster. The US Centrifuge Accommodations Module was intended to host science experiments in varying levels of artificial gravity. The US Habitation Module would have served as the station's living quarters. Instead, the sleep stations are now spread throughout the station. The US Interim Control Module and ISS Propulsion Module were intended to replace functions of Zvezda in case of a launch failure. The Russian Universal Docking Module, to which the cancelled Russian Research modules and spacecraft would have docked. The Russian Science Power Platform would have provided the Russian Orbital Segment with a power supply independent of the ITS solar arrays, and two Russian Research Modules that were planned to be used for scientific research.

Unpressurised elements

ISS Truss Components breakdown showing Trusses and all ORUs in situ

The ISS features a large number of external components that do not require pressurisation. The largest such component is the Integrated Truss Structure (ITS), to which the station's main solar arrays and thermal radiators are mounted. The ITS consists of ten separate segments forming a structure 108.5 m (356 ft) long.

The station in its complete form has several smaller external components, such as the six robotic arms, the three External Stowage Platforms (ESPs) and four ExPRESS Logistics Carriers (ELCs). Whilst these platforms allow experiments (including MISSE, the STP-H3 and the Robotic Refueling Mission) to be deployed and conducted in the vacuum of space by providing electricity and processing experimental data locally, the platforms' primary function is to store Orbital Replacement Units (ORUs). ORUs are spare parts that can be replaced when the item either passes its design life or fails. Examples of ORUs include pumps, storage tanks, antennas and battery units. Such units are replaced either by astronauts during EVA or by robotic arms. Spare parts were routinely transported to and from the station via Space Shuttle resupply missions, with a heavy emphasis on ORU transport once the NASA Shuttle approached retirement. Several shuttle missions were dedicated to the delivery of ORUs, including STS-129, STS-133 and STS-134. As of January 2011, only one other mode of transportation of ORUs had been utilised – the Japanese cargo vessel HTV-2 – which delivered an FHRC and CTC-2 via its Exposed Pallet (EP).

Construction of the Integrated Truss Structure over New Zealand.

There are also smaller exposure facilities mounted directly to laboratory modules; the JEM Exposed Facility serves as an external 'porch' for the Japanese Experiment Module complex, and a facility on the European Columbus laboratory provides power and data connections for experiments such as the European Technology Exposure Facility and the Atomic Clock Ensemble in Space. A remote sensing instrument, SAGE III-ISS, is due to be delivered to the station in 2014 aboard a Dragon capsule, and the NICER experiment in 2016. The largest such scientific payload externally mounted to the ISS is the Alpha Magnetic Spectrometer (AMS), a particle physics experiment launched on STS-134 in May 2011, and mounted externally on the ITS. The AMS measures cosmic rays to look for evidence of dark matter and antimatter.

Robotic arms and cargo cranes

Commander Volkov stands on Pirs with his back to the Soyuz whilst operating the manual Strela crane holding photographer Kononenko. Zarya is seen to the left and Zvezda across the bottom of the image.

Dextre, like many of the station's experiments and robotic arms, can be operated from Earth and perform tasks while the crew sleeps.

The Integrated Truss Structure serves as a base for the station's primary remote manipulator system, called the Mobile Servicing System (MSS), which is composed of three main components. Canadarm2, the largest robotic arm on the ISS, has a mass of 1,800 kilograms (4,000 lb) and is used to dock and manipulate spacecraft and modules on the USOS, hold crew members and equipment in place during EVAs and move Dextre around to perform tasks. Dextre is a 1,560 kg (3,440 lb) robotic manipulator with two arms, a rotating torso and has power tools, lights and video for replacing orbital replacement units (ORUs) and performing other tasks requiring fine control. The Mobile Base System (MBS) is a platform which rides on rails along the length of the station's main truss. It serves as a mobile base for Canadarm2 and Dextre, allowing the robotic arms to reach all parts of the USOS. To gain access to the Russian Segment a grapple fixture was added to Zarya on STS-134, so that Canadarm2 can inchworm itself onto the ROS. Also installed during STS-134 was the 15 m (50 ft) Orbiter Boom Sensor System (OBSS), which had been used to inspect head shield tiles on Space Shuttle missions and can be used on station to increase the reach of the MSS. Staff on Earth or the station can operate the MSS components via remote control, performing work outside the station without space walks.

Japan's Remote Manipulator System, which services the JEM Exposed Facility, was launched on STS-124 and is attached to the JEM Pressurised Module. The arm is similar to the Space Shuttle arm as it is permanently attached at one end and has a latching end effector for standard grapple fixtures at the other.

The European Robotic Arm, which will service the Russian Orbital Segment, will be launched alongside the Multipurpose Laboratory Module in 2017. The ROS does not require spacecraft or modules to be manipulated, as all spacecraft and modules dock automatically and may be discarded the same way. Crew use the two Strela (Russian: Стрела́; lit. Arrow) cargo cranes during EVAs for moving crew and equipment around the ROS. Each Strela crane has a mass of 45 kg (99 lb).

Comparison

The ISS follows Salyut and Almaz series, Cosmos 557, Skylab, and Mir as the 11th space station launched, as the Genesis prototypes were never intended to be manned. Other examples of modular station projects include the Soviet/Russian Mir and the planned Russian OPSEK and Chinese space station. The first space station, Salyut 1, and other one-piece or 'monolithic' first generation space stations, such as Salyut 2,3,4,5, DOS 2, Kosmos 557, Almaz and NASA's Skylab stations were not designed for re-supply. Generally, each crew had to depart the station to free the only docking port for the next crew to arrive, Skylab had more than one docking port but was not designed for resupply. Salyut 6 and 7 had more than one docking port and were designed to be resupplied routinely during crewed operation.

Station systems

Life support

Main articles: ISS ECLSS and Chemical oxygen generator

The critical systems are the atmosphere control system, the water supply system, the food supply facilities, the sanitation and hygiene equipment, and fire detection and suppression equipment. The Russian Orbital Segment's life support systems are contained in the Service Module Zvezda. Some of these systems are supplemented by equipment in the USOS. The MLM Nauka laboratory has a complete set of life support systems.

Atmospheric control systems

The interactions between the components of the ISS Environmental Control and Life Support System (ECLSS)

The atmosphere on board the ISS is similar to the Earth's. Normal air pressure on the ISS is 101.3 kPa (14.7 psi); the same as at sea level on Earth. An Earth-like atmosphere offers benefits for crew comfort, and is much safer than the alternative, a pure oxygen atmosphere, because of the increased risk of a fire such as that responsible for the deaths of the Apollo 1 crew. Earth-like atmospheric conditions have been maintained on all Russian and Soviet spacecraft.

The Elektron system aboard Zvezda and a similar system in Destiny generate oxygen aboard the station. The crew has a backup option in the form of bottled oxygen and Solid Fuel Oxygen Generation (SFOG) canisters, a chemical oxygen generator system. Carbon dioxide is removed from the air by the Vozdukh system in Zvezda. Other by-products of human metabolism, such as methane from the intestines and ammonia from sweat, are removed by activated charcoal filters.

Part of the ROS atmosphere control system is the oxygen supply, triple-redundancy is provided by the Elektron unit, solid fuel generators, and stored oxygen. The Elektron unit is the primary oxygen supply, O
2 and H
2 are produced by electrolysis, with the H
2 being vented overboard. The 1 kW system uses approximately 1 litre of water per crew member per day from stored water from Earth, or water recycled from other systems. MIR was the first spacecraft to use recycled water for oxygen production. The secondary oxygen supply is provided by burning O
2-producing Vika cartridges (see also ISS ECLSS). Each 'candle' takes 5–20 minutes to decompose at 450–500 °C, producing 600 litres of O
2. This unit is manually operated.

The US Orbital Segment has redundant supplies of oxygen, from a pressurised storage tank on the Quest airlock module delivered in 2001, supplemented ten years later by ESA built Advanced Closed-Loop System (ACLS) in the Tranquility module (Node 3), which produces O
2 by electrolysis. Hydrogen produced is combined with carbon dioxide from the cabin atmosphere and converted to water and methane.

Power and thermal control

Main articles: Electrical system of the International Space Station and External Active Thermal Control System

Russian solar arrays, backlit by sunset.

One of the eight truss mounted pairs of USOS solar arrays

Double-sided solar, or Photovoltaic arrays, provide electrical power for the ISS. These bifacial cells are more efficient and operate at a lower temperature than single-sided cells commonly used on Earth, by collecting sunlight on one side and light reflected off the Earth on the other.

The Russian segment of the station, like the Space Shuttle and most spacecraft, uses 28 volt DC from four rotating solar arrays mounted on Zarya and Zvezda. The USOS uses 130–180 V DC from the USOS PV array, power is stabilised and distributed at 160 V DC and converted to the user-required 124 V DC. The higher distribution voltage allows smaller, lighter conductors, at the expense of crew safety. The ROS uses low voltage. The two station segments share power with converters.

The USOS solar arrays are arranged as four wing pairs, with each wing producing nearly 32.8 kW. These arrays normally track the sun to maximise power generation. Each array is about 375 m² (450 yd²) in area and 58 metres (63 yd) long. In the complete configuration, the solar arrays track the sun by rotating the alpha gimbal once per orbit; the beta gimbal follows slower changes in the angle of the sun to the orbital plane. The Night Glider mode aligns the solar arrays parallel to the ground at night to reduce the significant aerodynamic drag at the station's relatively low orbital altitude.

The station uses rechargeable nickel-hydrogen batteries (NiH₂) for continuous power during the 35 minutes of every 90-minute orbit that it is eclipsed by the Earth. The batteries are recharged on the day side of the Earth. They have a 6.5-year lifetime (over 37,000 charge/discharge cycles) and will be regularly replaced over the anticipated 20-year life of the station.

The station's large solar panels generate a high potential voltage difference between the station and the ionosphere. This could cause arcing through insulating surfaces and sputtering of conductive surfaces as ions are accelerated by the spacecraft plasma sheath. To mitigate this, plasma contactor units (PCU)s create current paths between the station and the ambient plasma field.

ISS External Active Thermal Control System (EATCS) diagram

The large amount of electrical power consumed by the station's systems and experiments is turned almost entirely into heat. The heat which can be dissipated through the walls of the stations modules is insufficient to keep the internal ambient temperature within comfortable, workable limits. Ammonia is continuously pumped through pipework throughout the station to collect heat, then into external radiators exposed to the cold of space, and back into the station.

The International Space Station (ISS) External Active Thermal Control System (EATCS) maintains an equilibrium when the ISS environment or heat loads exceed the capabilities of the Passive Thermal Control System (PTCS). Note Elements of the PTCS are external surface materials, insulation such as MLI, or Heat Pipes. The EATCS provides heat rejection capabilities for all the US pressurised modules, including the JEM and COF as well as the main power distribution electronics of the S0, S1 and P1 Trusses. The EATCS consists an internal, non-toxic, water coolant loop used to cool and dehumidify the atmosphere, which transfers collected heat into an external liquid ammonia loop capable of withstanding the much lower temperature of space, which is then circulated through radiators to remove the heat. The EATCS is capable of rejecting up to 70 kW, and provides a substantial upgrade in heat rejection capacity from the 14 kW capability of the Early External Active Thermal Control System (EEATCS) via the Early Ammonia Servicer (EAS), which was launched on STS-105 and installed onto the P6 Truss.

Communications and computers

Main articles: Tracking and Data Relay Satellite and Luch (satellite)

See also: ThinkPad use in space

The communications systems used by the ISS

• Luch satellite not currently in use

Radio communications provide telemetry and scientific data links between the station and Mission Control Centres. Radio links are also used during rendezvous and docking procedures and for audio and video communication between crewmembers, flight controllers and family members. As a result, the ISS is equipped with internal and external communication systems used for different purposes.

The Russian Orbital Segment communicates directly with the ground via the Lira antenna mounted to Zvezda. The Lira antenna also has the capability to use the Luch data relay satellite system. This system, used for communications with Mir, fell into disrepair during the 1990s, and as a result is no longer in use, although two new Luch satellites—Luch-5A and Luch-5B—were launched in 2011 and 2012 respectively to restore the operational capability of the system. Another Russian communications system is the Voskhod-M, which enables internal telephone communications between Zvezda, Zarya, Pirs, Poisk and the USOS, and also provides a VHF radio link to ground control centres via antennas on Zvezda‍‍ '​‍s exterior.

The US Orbital Segment (USOS) makes use of two separate radio links mounted in the Z1 truss structure: the S band (used for audio) and K_u band (used for audio, video and data) systems. These transmissions are routed via the United States Tracking and Data Relay Satellite System (TDRSS) in geostationary orbit, which allows for almost continuous real-time communications with NASA's Mission Control Center (MCC-H) in Houston. Data channels for the Canadarm2, European Columbus laboratory and Japanese Kibō modules are routed via the S band and K_u band systems, although the European Data Relay System and a similar Japanese system will eventually complement the TDRSS in this role. Communications between modules are carried on an internal digital wireless network.

Laptop computers surround the Canadarm2 console.

UHF radio is used by astronauts and cosmonauts conducting EVAs. UHF is employed by other spacecraft that dock to or undock from the station, such as Soyuz, Progress, HTV, ATV and the Space Shuttle (except the shuttle also makes use of the S band and K_u band systems via TDRSS), to receive commands from Mission Control and ISS crewmembers. Automated spacecraft are fitted with their own communications equipment; the ATV uses a laser attached to the spacecraft and equipment attached to Zvezda, known as the Proximity Communications Equipment, to accurately dock to the station.

The ISS is equipped with approximately 100 IBM and Lenovo ThinkPad model A31 and T61P laptop computers. Each computer is a commercial off-the-shelf purchase which is then modified for safety and operation including updates to connectors, cooling and power to accommodate the station's 28V DC power system and weightless environment. Heat generated by the laptops does not rise, but stagnates surrounding the laptop, so additional forced ventilation is required. Laptops aboard the ISS are connected to the station's wireless LAN via Wi-Fi and to the ground via K_u band. This provides speeds of 10 Mbit/s to and 3 Mbit/s from the station, comparable to home DSL connection speeds.

The operating system used for key station functions is the Debian GNU/Linux distribution. The migration from Microsoft Windows was made in May 2013 for reasons of reliability, stability and flexibility.

Station operations

Expeditions and private flights

Zarya and Unity were entered for the first time on 10 December 1998.

Soyuz TM-31 being prepared to bring the first resident crew to the station in October 2000

ISS was slowly assembled over a decade of spaceflights and crews

Expeditions have included male and female crew-members from many nations

See also the list of International Space Station expeditions (professional crew), space tourism (private travellers), and the list of human spaceflights to the ISS (both).

Each permanent crew is given an expedition number. Expeditions run up to six months, from launch until undocking, an 'increment' covers the same time period, but includes cargo ships and all activities. Expeditions 1 to 6 consisted of 3 person crews, Expeditions 7 to 12 were reduced to the safe minimum of two following the destruction of the NASA Shuttle Columbia. From Expedition 13 the crew gradually increased to 6 around 2010. With the arrival of the American Commercial Crew vehicles in the middle of the 2010s, expedition size may be increased to seven crew members, the number ISS is designed for.

Sergei Krikalev, member of Expedition 1 and Commander of Expedition 11 has spent more time in space than anyone else, a total of 803 days and 9 hours and 39 minutes. His awards include the Order of Lenin, Hero of the Soviet Union, Hero of the Russian Federation, and 4 NASA medals. On 16 August 2005 at 1:44 am EDT he passed the record of 748 days held by Sergei Avdeyev, who had 'time travelled' 1/50th of a second into the future on board MIR. He participated in psychosocial experiment SFINCSS-99 (Simulation of Flight of International Crew on Space Station), which examined inter-cultural and other stress factors affecting integration of crew in preparation for the ISS spaceflights. Commander Michael Fincke has spent a total of 382 days in space – more than any other American astronaut.

Travellers who pay for their own passage into space are termed spaceflight participants by Roscosmos and NASA, and are sometimes informally referred to as space tourists, a term they generally dislike. All seven were transported to the ISS on Russian Soyuz spacecraft. When professional crews change over in numbers not divisible by the three seats in a Soyuz, and a short-stay crewmember is not sent, the spare seat is sold by MirCorp through Space Adventures. When the space shuttle retired in 2011, and the station's crew size was reduced to 6, space tourism was halted, as the partners relied on Russian transport seats for access to the station. Soyuz flight schedules increase after 2013, allowing 5 Soyuz flights (15 seats) with only two expeditions (12 seats) required. The remaining seats are sold for around US$40 million to members of the public who can pass a medical. ESA and NASA criticised private spaceflight at the beginning of the ISS, and NASA initially resisted training Dennis Tito, the first man to pay for his own passage to the ISS. Toyohiro Akiyama was flown to Mir for a week, he was classed as a business traveller, as his employer, Tokyo Broadcasting System, paid for his ticket, and he gave a daily TV broadcast from orbit.

Anousheh Ansari (Persian: انوشه انصاری‎) became the first Iranian in space and the first self-funded woman to fly to the station. Officials reported that her education and experience make her much more than a tourist, and her performance in training had been "excellent." Ansari herself dismisses the idea that she is a tourist. She did Russian and European studies involving medicine and microbiology during her 10-day stay. The documentary Space Tourists follows her journey to the station, where she fulfilled "an age-old dream of man: to leave our planet as a «normal person» and travel into outer space." In the film, some Kazakhs are shown waiting in the middle of the steppes for four rocket stages to literally fall from the sky. Film-maker Christian Frei states "Filming the work of the Kazakh scrap metal collectors was anything but easy. The Russian authorities finally gave us a film permit in principle, but they imposed crippling preconditions on our activities. The real daily routine of the scrap metal collectors could definitely not be shown. Secret service agents and military personnel dressed in overalls and helmets were willing to re-enact their work for the cameras – in an idealised way that officials in Moscow deemed to be presentable, but not at all how it takes place in reality."

Spaceflight participant Richard Garriott placed a geocache aboard the ISS during his flight. This is currently the only non-terrestrial geocache in existence.

Orbit

Graph showing the changing altitude of the ISS from November 1998 until January 2009

Play media

Animation of ISS orbit from a North American geostationary point of view (sped up 1800 times)

The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 330 km (205 mi) and a maximum of 410 km (255 mi), in the centre of the thermosphere, at an inclination of 51.6 degrees to Earth's equator, necessary to ensure that Russian Soyuz and Progress spacecraft launched from the Baikonur Cosmodrome may be safely launched to reach the station. Spent rocket stages must be dropped into uninhabited areas and this limits the directions rockets can be launched from the spaceport. The orbital inclination chosen was also low enough to allow American space shuttles launched from Florida to reach the ISS.

It travels at an average speed of 27,724 kilometres (17,227 mi) per hour, and completes 15.54 orbits per day (93 minutes per orbit). The station's altitude was allowed to fall around the time of each NASA shuttle mission. Orbital boost burns would generally be delayed until after the shuttle's departure. This allowed shuttle payloads to be lifted with the station's engines during the routine firings, rather than have the shuttle lift itself and the payload together to a higher orbit. This trade-off allowed heavier loads to be transferred to the station. After the retirement of the NASA shuttle, the nominal orbit of the space station was raised in altitude. Other, more frequent supply ships do not require this adjustment as they are substantially lighter vehicles.

Orbits of the ISS, shown in April 2013

Orbital boosting can be performed by the station's two main engines on the Zvezda service module, or Russian or European spacecraft docked to Zvezda's aft port. The ATV has been designed with the possibility of adding a second docking port to its other end, allowing it to remain at the ISS and still allow other craft to dock and boost the station. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed. In December 2008 NASA signed an agreement with the Ad Astra Rocket Company which may result in the testing on the ISS of a VASIMR plasma propulsion engine. This technology could allow station-keeping to be done more economically than at present.

The Russian Orbital Segment contains the station's engines and control bridge, which handles Guidance, Navigation and Control (ROS GNC) for the entire station. Initially, Zarya, the first module of the station, controlled the station until a short time after the Russian service module Zvezda docked and was transferred control. Zvezda contains the ESA built DMS-R Data Management System. Using two fault-tolerant computers (FTC), Zvezda computes the station's position and orbital trajectory using redundant Earth horizon sensors, Solar horizon sensors as well as Sun and star trackers. The FTCs each contain three identical processing units working in parallel and provide advanced fault-masking by majority voting. Zvezda uses gyroscopes and thrusters to turn itself around. Gyroscopes do not require propellant, rather they use electricity to 'store' momentum in flywheels by turning in the opposite direction to the station's movement. The USOS has its own computer controlled gyroscopes to handle the extra mass of that section. When gyroscopes 'saturate', reaching their maximum speed, thrusters are used to cancel out the stored momentum. During Expedition 10, an incorrect command was sent to the station's computer, using about 14 kilograms of propellant before the fault was noticed and fixed. When attitude control computers in the ROS and USOS fail to communicate properly, it can result in a rare 'force fight' where the ROS GNC computer must ignore the USOS counterpart, which has no thrusters. When an ATV, NASA Shuttle, or Soyuz is docked to the station, it can also be used to maintain station attitude such as for troubleshooting. Shuttle control was used exclusively during installation of the S3/S4 truss, which provides electrical power and data interfaces for the station's electronics.

Mission controls

The components of the ISS are operated and monitored by their respective space agencies at mission control centres across the globe, including:

• Roscosmos's Mission Control Center at Korolyov, Moscow Oblast, controls the Russian Orbital Segment which handles Guidance, Navigation & Control for the entire Station., in addition to individual Soyuz and Progress missions.
• ESA's ATV Control Centre, at the Toulouse Space Centre (CST) in Toulouse, France, controls flights of the unmanned European Automated Transfer Vehicle.
• JAXA's JEM Control Center and HTV Control Center at Tsukuba Space Center (TKSC) in Tsukuba, Japan, are responsible for operating the Japanese Experiment Module complex and all flights of the 'White Stork' HTV Cargo spacecraft, respectively.
• NASA's Mission Control Center at Lyndon B. Johnson Space Center in Houston, Texas, serves as the primary control facility for the United States segment of the ISS and also controlled the Space Shuttle missions that visited the station.
• NASA's Payload Operations and Integration Center at Marshall Space Flight Center in Huntsville, Alabama, coordinates payload operations in the USOS.
• ESA's Columbus Control Centre at the German Aerospace Centre (DLR) in Oberpfaffenhofen, Germany, manages the European Columbus research laboratory.
• CSA's MSS Control at Saint-Hubert, Quebec, Canada, controls and monitors the Mobile Servicing System, or Canadarm2.

Space centres involved with the ISS programme

Repairs

Main articles: Orbital Replacement Units and International Space Station maintenance

Orbital Replacement Units (ORUs) are spare parts that can be readily replaced when a unit either passes its design life or fails. Examples of ORUs are pumps, storage tanks, controller boxes, antennas, and battery units. Some units can be replaced using robotic arms. Many are stored outside the station, either on small pallets called ExPRESS Logistics Carriers (ELCs) or share larger platforms called External Stowage Platforms which also hold science experiments. Both kinds of pallets have electricity as many parts which could be damaged by the cold of space require heating. The larger logistics carriers also have computer local area network connections (LAN) and telemetry to connect experiments. A heavy emphasis on stocking the USOS with ORU's occurred around 2011, before the end of the NASA shuttle programme, as its commercial replacements, Cygnus and Dragon, carry one tenth to one quarter the payload.

Spare parts are called ORUs; some are externally stored on pallets called ELCs and ESPs.

Unexpected problems and failures have impacted the station's assembly time-line and work schedules leading to periods of reduced capabilities and, in some cases, could have forced abandonment of the station for safety reasons, had these problems not been resolved. During STS-120 in 2007, following the relocation of the P6 truss and solar arrays, it was noted during the redeployment of the array that it had become torn and was not deploying properly. An EVA was carried out by Scott Parazynski, assisted by Douglas Wheelock. The men took extra precautions to reduce the risk of electric shock, as the repairs were carried out with the solar array exposed to sunlight. The issues with the array were followed in the same year by problems with the starboard Solar Alpha Rotary Joint (SARJ), which rotates the arrays on the starboard side of the station. Excessive vibration and high-current spikes in the array drive motor were noted, resulting in a decision to substantially curtail motion of the starboard SARJ until the cause was understood. Inspections during EVAs on STS-120 and STS-123 showed extensive contamination from metallic shavings and debris in the large drive gear and confirmed damage to the large metallic race ring at the heart of the joint, and so the joint was locked to prevent further damage. Repairs to the joint were carried out during STS-126 with lubrication of both joints and the replacement of 11 out of 12 trundle bearings on the joint.

While anchored on the end of the OBSS, astronaut Scott Parazynski performs makeshift repairs to a US Solar array which damaged itself when unfolding, during STS-120.

2009 saw damage to the S1 radiator, one of the components of the station's cooling system. The problem was first noticed in Soyuz imagery in September 2008, but was not thought to be serious. The imagery showed that the surface of one sub-panel has peeled back from the underlying central structure, possibly due to micro-meteoroid or debris impact. It is also known that a Service Module thruster cover, jettisoned during an EVA in 2008, had struck the S1 radiator, but its effect, if any, has not been determined. On 15 May 2009 the damaged radiator panel's ammonia tubing was mechanically shut off from the rest of the cooling system by the computer-controlled closure of a valve. The same valve was used immediately afterwards to vent the ammonia from the damaged panel, eliminating the possibility of an ammonia leak from the cooling system via the damaged panel.

Early on 1 August 2010, a failure in cooling Loop A (starboard side), one of two external cooling loops, left the station with only half of its normal cooling capacity and zero redundancy in some systems. The problem appeared to be in the ammonia pump module that circulates the ammonia cooling fluid. Several subsystems, including two of the four CMGs, were shut down.

Planned operations on the ISS were interrupted through a series of EVAs to address the cooling system issue. A first EVA on 7 August 2010, to replace the failed pump module, was not fully completed due to an ammonia leak in one of four quick-disconnects. A second EVA on 11 August successfully removed the failed pump module. A third EVA was required to restore Loop A to normal functionality.

The USOS's cooling system is largely built by the American company Boeing, which is also the manufacturer of the failed pump.

An air leak from the USOS in 2004, the venting of fumes from an Elektron oxygen generator in 2006, and the failure of the computers in the ROS in 2007 during STS-117 left the station without thruster, Elektron, Vozdukh and other environmental control system operations, the root cause of which was found to be condensation inside the electrical connectors leading to a short-circuit.

In the foreground, a set of heat radiators

The four Main Bus Switching Units (MBSUs, located in the S0 truss), control the routing of power from the four solar array wings to the rest of the ISS. In late 2011 MBSU-1, while still routing power correctly, ceased responding to commands or sending data confirming its health, and was scheduled to be swapped out at the next available EVA. In each MBSU, two power channels feed 160V DC from the arrays to two DC-to-DC power converters (DDCUs) that supply the 124V power used in the station. A spare MBSU was already on board, but 30 August 2012 EVA failed to be completed when a bolt being tightened to finish installation of the spare unit jammed before electrical connection was secured. The loss of MBSU-1 limits the station to 75% of its normal power capacity, requiring minor limitations in normal operations until the problem can be addressed.

On 5 September 2012, in a second, 6 hr, EVA to replace MBSU-1, astronauts Sunita Williams and Akihiko Hoshide successfully restored the ISS to 100% power.

Mike Hopkins on his Christmas Eve spacewalk

On 24 December 2013, astronauts made a rare Christmas Eve space walk, installing a new ammonia pump for the station's cooling system. The faulty cooling system had failed earlier in the month, halting many of the station's science experiments. Astronauts had to brave a "mini blizzard" of ammonia while installing the new pump. It was only the second Christmas Eve spacewalk in NASA history.

Iss orbit with calendar of expeditions and modules

Fleet operations

See also: List of human spaceflights to the International Space Station and List of unmanned spaceflights to the International Space Station

A wide variety of manned and unmanned spacecraft have supported the station's activities. Progress M-28M (ISS-60P) was the 62nd Progress spacecraft planned to arrive at the ISS, including M-MIM2 and M-SO1 which installed modules. 35 flights of the retired NASA Space Shuttle were made to the station. TMA-16M is the 42nd Soyuz flight, and there have been 5 European ATV, 4 Japanese Kounotori 'White Stork', 8 SpaceX Dragon and 4 OSC Cygnus planned arrivals.

Currently docked/berthed

See also the list of professional crew, private travellers, both or just unmanned spaceflights.

Key

  Uncrewed cargoships are in light blue

  Crewed spacecraft are in light green

Spacecraft and mission			Location	Arrived (UTC)	Departure date
	Progress M-26M	Progress 58 Cargo	Zvezda aft	17 February 2015	26 August 2015
	Soyuz TMA-16M	Expedition 43/44	Poisk zenith	28 March 2015	11 September 2015
	Progress M-28M	Progress 60 Cargo	Pirs nadir	5 July 2015	19 November 2015

Scheduled launches and dockings/berthings

• All dates are UTC. Dates are the earliest possible dates and may change.
• Forward ports are at the front of the station according to its normal direction of travel and orientation (attitude). Aft is at the rear of the station, used by spacecraft boosting the station's orbit. Nadir is closest the Earth, Zenith is on top.
• Spacecraft operated by government agencies are indicated with 'Gov' and under commercial arrangements are indicated with 'Com'.

Key

  Uncrewed cargoships are in light blue colour

  Crewed spacecraft are in light green colour

  Modules are in wheat colour

Planned Missions

Launch (NET)	Launch Vehicle	Launch Site	Launch Service Provider			Payload	Spacecraft	Mission	Docking / Berthing Port	Ref.
22 July 2015	Soyuz-FG	Baikonur Site 1/5		Gov	Roscosmos	Soyuz TMA-17M	Soyuz	Expedition 44/45	Rassvet nadir
16 August 2015	H-IIB	Tanegashima LA-Y2		Gov	JAXA	HTV-5	HTV	ISS Resupply	Harmony nadir
1 September 2015	Soyuz-FG	Baikonur Site 1/5		Gov	Roscosmos	Soyuz TMA-18M	Soyuz	Expedition 45/46 including ESA Danish Astronaut Andreas Mogensen and spaceflight participant Sarah Brightman.
2 September 2015 (TBD)	Falcon 9 v1.1	Cape Canaveral SLC-40		Com	SpaceX	SpaceX CRS-8	Dragon	ISS resupply. Will deliver Bigelow Expandable Activity Module (BEAM) to the ISS.	Harmony nadir
21 September 2015	Soyuz-U	Baikonur Site 1/5		Gov	Roscosmos	Progress M-29M	Progress	ISS Resupply
21 November 2015	Soyuz-2.1a	Baikonur		Gov	Roscosmos	Progress MS-1	Progress	ISS Resupply. First launch of the new Progress-MS variant.
3 December 2015	Atlas V 401	Cape Canaveral SLC-41		Com	ULA	Cygnus CRS Orb-4	Cygnus	ISS Resupply	Harmony nadir
9 December 2015 (TBD)	Falcon 9 v1.1	Cape Canaveral		Com	SpaceX	SpaceX CRS-9	Dragon	ISS resupply. Will deliver the IDA-2 segment of the NASA Docking System to the ISS.	Harmony nadir
15 December 2015	Soyuz-FG	Baikonur Site 1/5		Gov	Roscosmos	Soyuz TMA-19M	Soyuz	Expedition 46/47

Docking

See also: Docking and berthing of spacecraft

The Progress M-14M resupply vehicle as it approaches the ISS in 2012. Over 50 unpiloted Progress spacecraft have been sent with supplies during the lifetime of the station.

All Russian spacecraft and self-propelled modules are able to rendezvous and dock to the space station without human intervention using the Kurs docking system. Radar allows these vehicles to detect and intercept ISS from over 200 kilometres away. The European ATV uses star sensors and GPS to determine its intercept course. When it catches up it then uses laser equipment to optically recognise Zvezda, along with the Kurs system for redundancy. Crew supervise these craft, but do not intervene except to send abort commands in emergencies. The Japanese H-II Transfer Vehicle parks itself in progressively closer orbits to the station, and then awaits 'approach' commands from the crew, until it is close enough for a robotic arm to grapple and berth the vehicle to the USOS. The American Space Shuttle was manually docked, and on missions with a cargo container, the container would be berthed to the Station with the use of manual robotic arms. Berthed craft can transfer International Standard Payload Racks. Japanese spacecraft berth for one to two months. Russian and European Supply craft can remain at the ISS for six months, allowing great flexibility in crew time for loading and unloading of supplies and trash. NASA Shuttles could remain docked for 11–12 days.

The American manual approach to docking allows greater initial flexibility and less complexity. The downside to this mode of operation is that each mission becomes unique and requires specialised training and planning, making the process more labour-intensive and expensive. The Russians pursued an automated methodology that used the crew in override or monitoring roles. Although the initial development costs were high, the system has become very reliable with standardisations that provide significant cost benefits in repetitive routine operations. An automated approach could allow assembly of modules orbiting other worlds prior to crew arrival.

Space Shuttle Endeavour, ATV-2, Soyuz TMA-21 and Progress M-10M docked to the ISS during STS-134, as seen from the departing Soyuz TMA-20

Soyuz spacecraft used for crew rotation also serve as lifeboats for emergency evacuation; they are replaced every six months and have been used once to remove excess crew after the Columbia disaster. Expeditions require, on average, 2 722 kg of supplies, and as of 9 March 2011, crews had consumed a total of around 22 000 meals. Soyuz crew rotation flights and Progress resupply flights visit the station on average two and three times respectively each year, with the ATV and HTV planned to visit annually from 2010 onwards. Following retirement of the NASA Shuttle Cygnus and Dragon were contracted to fly cargo to the station.

From 26 February 2011 to 7 March 2011 four of the governmental partners (United States, ESA, Japan and Russia) had their spacecraft (NASA Shuttle, ATV, HTV, Progress and Soyuz) docked at the ISS, the only time this has happened to date. On 25 May 2012, SpaceX became the world's first privately held company to send cargo, via the Dragon spacecraft, to the International Space Station.

Launch and docking windows

Prior to a ship's docking to the ISS, navigation and attitude control (GNC) is handed over to the ground control of the ships' country of origin. GNC is set to allow the station to drift in space, rather than fire its thrusters or turn using gyroscopes. The solar panels of the station are turned edge-on to the incoming ships, so residue from its thrusters does not damage the cells. When a NASA shuttle docked to the station, other ships were grounded, as the carbon wingtips, cameras, windows, and instruments aboard the shuttle were at too much risk from damage from thruster residue from other ships movements.

Approximately 30% of NASA shuttle launch delays were caused by poor weather. Occasional priority was given to the Soyuz arrivals at the station where the Soyuz carried crew with time-critical cargoes such as biological experiment materials, also causing shuttle delays. Departure of the NASA shuttle was often delayed or prioritised according to weather over its two landing sites. Whilst the Soyuz is capable of landing anywhere, anytime, its planned landing time and place is chosen to give consideration to helicopter pilots and ground recovery crew, to give acceptable flying weather and lighting conditions. Soyuz launches occur in adverse weather conditions, but the cosmodrome has been shut down on occasions when buried by snow drifts up to 6 metres in depth, hampering ground operations.

Life aboard

Crew activities

Crewmember peers out of a window

A typical day for the crew begins with a wake-up at 06:00, followed by post-sleep activities and a morning inspection of the station. The crew then eats breakfast and takes part in a daily planning conference with Mission Control before starting work at around 08:10. The first scheduled exercise of the day follows, after which the crew continues work until 13:05. Following a one-hour lunch break, the afternoon consists of more exercise and work before the crew carries out its pre-sleep activities beginning at 19:30, including dinner and a crew conference. The scheduled sleep period begins at 21:30. In general, the crew works ten hours per day on a weekday, and five hours on Saturdays, with the rest of the time their own for relaxation or work catch-up.

The time zone used on board the ISS is Coordinated Universal Time (UTC). The windows are covered at night hours to give the impression of darkness because the station experiences 16 sunrises and sunsets a day. During visiting space shuttle missions, the ISS crew will mostly follow the shuttle's Mission Elapsed Time (MET), which is a flexible time zone based on the launch time of the shuttle mission.

The station provides crew quarters for each member of the expedition's crew, with two 'sleep stations' in the Zvezda and four more installed in Harmony. The American quarters are private, approximately person-sized soundproof booths. The Russian crew quarters include a small window, but do not provide the same amount of ventilation or block the same amount of noise as their American counterparts. A crewmember can sleep in a crew quarter in a tethered sleeping bag, listen to music, use a laptop, and store personal items in a large drawer or in nets attached to the module's walls. The module also provides a reading lamp, a shelf and a desktop. Visiting crews have no allocated sleep module, and attach a sleeping bag to an available space on a wall—it is possible to sleep floating freely through the station, but this is generally avoided because of the possibility of bumping into sensitive equipment. It is important that crew accommodations be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide has formed around their heads.

See also: Christmas on the International Space Station

Food

The crews of STS-127 and Expedition 20 enjoy a meal inside Unity.

See also: Space food

Most of the food on board is vacuum sealed in plastic bags. Cans are heavy and expensive to transport, so there are not as many. The preserved food is generally not held in high regard by the crew, and when combined with the reduced sense of taste in a microgravity environment, a great deal of effort is made to make the food more palatable. More spices are used than in regular cooking, and the crew looks forward to the arrival of any ships from Earth, as they bring fresh fruit and vegetables with them. Care is taken that foods do not create crumbs. Sauces are often used to ensure station equipment is not contaminated. Each crew member has individual food packages and cooks them using the on-board galley. The galley features two food warmers, a refrigerator added in November 2008, and a water dispenser that provides both heated and unheated water. Drinks are provided in dehydrated powder form and are mixed with water before consumption. Drinks and soups are sipped from plastic bags with straws; solid food is eaten with a knife and fork, which are attached to a tray with magnets to prevent them from floating away. Any food that floats away, including crumbs, must be collected to prevent it from clogging up the station's air filters and other equipment.

Hygiene

Space toilet in the Zvezda Service Module

Showers on space stations were introduced in the early 1970s on Skylab and Salyut 3. By Salyut 6, in the early 1980s, the crew complained of the complexity of showering in space, which was a monthly activity. The ISS does not feature a shower; instead, crewmembers wash using a water jet and wet wipes, with soap dispensed from a toothpaste tube-like container. Crews are also provided with rinseless shampoo and edible toothpaste to save water.

There are two space toilets on the ISS, both of Russian design, located in Zvezda and Tranquility. These Waste and Hygiene Compartments use a fan-driven suction system similar to the Space Shuttle Waste Collection System. Astronauts first fasten themselves to the toilet seat, which is equipped with spring-loaded restraining bars to ensure a good seal. A lever operates a powerful fan and a suction hole slides open: the air stream carries the waste away. Solid waste is collected in individual bags which are stored in an aluminium container. Full containers are transferred to Progress spacecraft for disposal. Liquid waste is evacuated by a hose connected to the front of the toilet, with anatomically correct "urine funnel adapters" attached to the tube so both men and women can use the same toilet. Waste is collected and transferred to the Water Recovery System, where it is recycled back into drinking water.

Crew health and safety

Main article: Effect of spaceflight on the human body

Radiation

The ISS is partially protected from the space environment by the Earth's magnetic field. From an average distance of about 70,000 km (43,000 mi), depending on Solar activity, the magnetosphere begins to deflect solar wind around the Earth and ISS. Solar flares are still a hazard to the crew, who may receive only a few minutes warning. The crew of Expedition 10 took shelter as a precaution in 2005 in a more heavily shielded part of the ROS designed for this purpose during the initial 'proton storm' of an X-3 class solar flare, but without the limited protection of the Earth's magnetosphere, interplanetary manned missions are especially vulnerable.

Play media

Video of the Aurora Australis taken by the crew of Expedition 28 on an ascending pass from south of Madagascar to just north of Australia over the Indian Ocean.

Subatomic charged particles, primarily protons from cosmic rays and solar wind, are normally absorbed by the Earth's atmosphere. When they interact in sufficient quantity, their effect becomes visible to the naked eye in a phenomenon called an aurora. Without the protection of the Earth's atmosphere, which absorbs this radiation, crews are exposed to about 1 millisievert each day, which is about the same as someone would get in a year on Earth from natural sources. This results in a higher risk of astronauts developing cancer. Radiation can penetrate living tissue, damage DNA, and cause damage to the chromosomes of lymphocytes. These cells are central to the immune system, and so any damage to them could contribute to the lowered immunity experienced by astronauts. Radiation has also been linked to a higher incidence of cataracts in astronauts. Protective shielding and protective drugs may lower the risks to an acceptable level.

The radiation levels experienced on the ISS are about five times greater than those experienced by airline passengers and crew. The Earth's electromagnetic field provides almost the same level of protection against solar and other radiation in low Earth orbit as in the stratosphere. Airline passengers experience this level of radiation for no more than 15 hours for the longest intercontinental flights. For example, on a 12-hour flight an airline passenger would experience 0.1 millisieverts of radiation, or a rate of 0.2 millisieverts per day; only 1/5 the rate experienced by an astronaut in LEO.

See also: Coronal mass ejection and Aurora (astronomy)

Stress

Cosmonaut Nikolai Budarin at work inside Zvezda service module crew quarters

There has been considerable evidence that psychosocial stressors are among the most important impediments to optimal crew morale and performance. Cosmonaut Valery Ryumin, wrote in his journal during a particularly difficult period on board the Salyut 6 space station: "All the conditions necessary for murder are met if you shut two men in a cabin measuring 18 feet by 20 and leave them together for two months."

NASA's interest in psychological stress caused by space travel, initially studied when their manned missions began, was rekindled when astronauts joined cosmonauts on the Russian space station Mir. Common sources of stress in early American missions included maintaining high performance under public scrutiny, as well as isolation from peers and family. The latter is still often a cause of stress on the ISS, such as when the mother of NASA Astronaut Daniel Tani died in a car accident, and when Michael Fincke was forced to miss the birth of his second child.

A study of the longest spaceflight concluded that the first three weeks represent a critical period where attention is adversely affected because of the demand to adjust to the extreme change of environment. Skylab's 3 crews remained one, two, and three months respectively, long term crews on Salyut 6, Salyut 7, and the ISS last about five to six months and Mir's expeditions often lasted longer. The ISS working environment includes further stress caused by living and working in cramped conditions with people from very different cultures who speak a different language. First generation space stations had crews who spoke a single language; second and third-generation stations have crew from many cultures who speak many languages. The ISS is unique because visitors are not classed automatically into 'host' or 'guest' categories as with previous stations and spacecraft, and may not suffer from feelings of isolation in the same way. Crew members with a military pilot background and those with an academic science background or teachers and politicians may have problems understanding each other's jargon and worldview.

Medical

Astronaut Frank De Winne is attached to the TVIS treadmill with bungee cords aboard the International Space Station

Medical effects of long-term weightlessness include muscle atrophy, deterioration of the skeleton (osteopenia), fluid redistribution, a slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, and puffiness of the face.

Sleep is disturbed on the ISS regularly due to mission demands, such as incoming or departing ships. Sound levels in the station are unavoidably high; because the atmosphere is unable to thermosiphon, fans are required at all times to allow processing of the atmosphere which would stagnate in the freefall (zero-g) environment.

To prevent some of these adverse physiological effects, the station is equipped with two treadmills (including the COLBERT), and the aRED (advanced Resistive Exercise Device) which enables various weightlifting exercises which add muscle but do nothing for bone density, and a stationary bicycle; each astronaut spends at least two hours per day exercising on the equipment. Astronauts use bungee cords to strap themselves to the treadmill.

Microbiological environmental hazards

See also: Mir § Microbiological environmental hazards

Hazardous moulds which can foul air and water filters may develop aboard space stations. They can produce acids which degrade metal, glass, and rubber. They can also be harmful for the crew health. Microbiological hazards have lead into a development of the LOCAD-PTS that can identify common bacteria and moulds faster than standard methods of culturing, which may require a sample to be sent back to Earth. As of 2012, 76 types of unregulated micro-organisms have been detected on the ISS.

Reduced humidity, paint with mould killing chemical and antiseptic solutions can be used to prevent contamination in space stations. All materials used in the ISS are tested for resistance against fungi.

Threat of orbital debris

Main article: Space debris

A 7 gram object (shown in centre) shot at 7 km/s (23,000 ft/sec) (the orbital velocity of the ISS) made this 15 cm (5 7/8 in) crater in a solid block of aluminium.

Radar-trackable objects including debris, with distinct ring of geostationary satellites

At the low altitudes at which the ISS orbits there are a variety of space debris, consisting of many different objects including entire spent rocket stages, defunct satellites, explosion fragments—including materials from anti-satellite weapon tests, paint flakes, slag from solid rocket motors, and coolant released by US-A nuclear-powered satellites. These objects, in addition to natural micrometeoroids, are a significant threat. Large objects could destroy the station, but are less of a threat as their orbits can be predicted. Objects too small to be detected by optical and radar instruments, from approximately 1 cm down to microscopic size, number in the trillions. Despite their small size, some of these objects are still a threat because of their kinetic energy and direction in relation to the station. Spacesuits of spacewalking crew could puncture, causing exposure to vacuum.

The station's shields and structure are divided between the ROS and the USOS, with completely different designs. On the USOS, a thin aluminium sheet is held apart from the hull, the sheet causes objects to shatter into a cloud before hitting the hull thereby spreading the energy of the impact. On the ROS, a carbon plastic honeycomb screen is spaced from the hull, an aluminium honeycomb screen is spaced from that, with a screen-vacuum thermal insulation covering, and glass cloth over the top. It is about 50% less likely to be punctured, and crew move to the ROS when the station is under threat. Punctures on the ROS would be contained within the panels which are 70 cm square.

Example of risk management: A NASA model showing areas at high risk from impact for the International Space Station.

Space debris objects are tracked remotely from the ground, and the station crew can be notified. This allows for a Debris Avoidance Manoeuvre (DAM) to be conducted, which uses thrusters on the Russian Orbital Segment to alter the station's orbital altitude, avoiding the debris. DAMs are not uncommon, taking place if computational models show the debris will approach within a certain threat distance. Eight DAMs had been performed prior to March 2009, the first seven between October 1999 and May 2003. Usually the orbit is raised by one or two kilometres by means of an increase in orbital velocity of the order of 1 m/s. Unusually there was a lowering of 1.7 km on 27 August 2008, the first such lowering for 8 years. There were two DAMs in 2009, on 22 March and 17 July. If a threat from orbital debris is identified too late for a DAM to be safely conducted, the station crew close all the hatches aboard the station and retreat into their Soyuz spacecraft, so that they would be able to evacuate in the event the station was seriously damaged by the debris. This partial station evacuation has occurred on 13 March 2009, 28 June 2011, 24 March 2012 and 16 June 2015. Ballistic panels, also called micrometeorite shielding, are incorporated into the station to protect pressurised sections and critical systems. The type and thickness of these panels varies depending upon their predicted exposure to damage.

End of mission

Many ISS resupply spacecraft have already undergone atmospheric re-entry, such as Jules Verne ATV

According to a 2009 report, Space Corporation Energia is considering methods to remove from the station some modules of the Russian Orbital Segment when the end of mission is reached and use them as a basis for a new station, known as the Orbital Piloted Assembly and Experiment Complex (OPSEK). The modules under consideration for removal from the current ISS include the Multipurpose Laboratory Module (MLM), currently scheduled to be launched in 2017, with other Russian modules which are currently planned to be attached to the MLM afterwards. Neither the MLM nor any additional modules attached to it would have reached the end of their useful lives in 2016 or 2020. The report presents a statement from an unnamed Russian engineer who believes that, based on the experience from Mir, a thirty-year life should be possible, except for micrometeorite damage, because the Russian modules have been built with on-orbit refurbishment in mind.

According to the Outer Space Treaty the United States and Russia are legally responsible for all modules they have launched. In ISS planning, NASA examined options including returning the station to Earth via shuttle missions (deemed too expensive, as the station (USOS) is not designed for disassembly and this would require at least 27 shuttle missions), natural orbital decay with random reentry similar to Skylab, boosting the station to a higher altitude (which would delay reentry) and a controlled targeted de-orbit to a remote ocean area.

The technical feasibility of a controlled targeted deorbit into a remote ocean was found to be possible only with Russia's assistance. The Russian Space Agency has experience from de-orbiting the Salyut 4, 5, 6, 7 and Mir space stations; NASA's first intentional controlled de-orbit of a satellite (the Compton Gamma Ray Observatory) occurred in 2000. As of late 2010, the preferred plan is to use a slightly modified Progress spacecraft to de-orbit the ISS. This plan was seen as the simplest, most cost efficient one with the highest margin. Skylab, the only space station built and launched entirely by the US, decayed from orbit slowly over 5 years, and no attempt was made to de-orbit the station using a deorbital burn. Remains of Skylab hit populated areas of Esperance, Western Australia without injuries or loss of life.

The Exploration Gateway Platform, a discussion by NASA and Boeing at the end of 2011, suggested using leftover USOS hardware and 'Zvezda 2' [sic] as a refuelling depot and servicing station located at one of the Earth Moon Lagrange points, L1 or L2. The entire USOS cannot be reused and will be discarded, but some other Russian modules are planned to be reused. Nauka, the Node module, two science power platforms and Rassvet, launched between 2010 and 2015 and joined to the ROS may be separated to form OPSEK. The Nauka module of the ISS will be used in the station, whose main goal is supporting manned deep space exploration. OPSEK will orbit at a higher inclination of 71 degrees, allowing observation to and from all of the Russian Federation.

In February 2015, Roscosmos announced that it would remain a part of the international space station program until 2024. Nine months earlier—in response to US sanctions against Russia over the conflict in the Crimea—Russian Deputy Prime Minister Dmitry Rogozin had stated that Russia would reject a US request to prolong the orbiting station's use beyond 2020, and would only supply rocket engines to the US for non-military satellite launches.

A proposed modification that would allow some of the ISS American and European segments to be reused would be to attach a VASIMR drive module to the vacated Node with its own onboard power source. It would allow long term reliability testing of the concept for less cost than building a dedicated space station from scratch.

On March 28, 2015, Russian sources announced that Roscosmos and NASA had agreed to collaborate on the development of a replacement for the current ISS. Igor Komarov, the head of Russia's Roscosmos, made the announcement with NASA administrator Charles Bolden at his side. Komarov said "Roscosmos together with NASA will work on the programme of a future orbital station," "We agreed that the group of countries taking part in the ISS project will work on the future project of a new orbital station," "The first step is that the ISS will operate until 2024," and that Roscosmos and NASA "do not rule out that the station's flight could be extended," In a statement provided to SpaceNews March 28, NASA spokesman David Weaver said the agency appreciated the Russian commitment to extending the ISS, but did not confirm any plans for a future space station.

Cost

The ISS is arguably the most expensive single item ever constructed. In 2010 the cost was expected to be $150 billion. It includes NASA's budget of $58.7 billion (inflation unadjusted) for the station from 1985 to 2015 ($72.4 billion in 2010 dollars), Russia's $12 billion, Europe's $5 billion, Japan's $5 billion, Canada's $2 billion, and the cost of 36 shuttle flights to build the station; estimated at $1.4 billion each, or $50.4 billion total. Assuming 20,000 person-days of use from 2000 to 2015 by two to six-person crews, each person-day would cost $7.5 million, less than half the inflation adjusted $19.6 million ($5.5 million before inflation) per person-day of Skylab.

International co-operation

Dated 29 January 1998

Main articles: Politics of the International Space Station and International Space Station program

Participating countries

• Canada
• Japan
• Russia
• United States
• European Space Agency
  • Austria
  • Belgium
  • Czech Republic
  • Denmark
  • Estonia
  • Finland
  • France
  • Germany
  • Greece
  • Hungary
  • Ireland
  • Italy
  • Luxembourg
  • Netherlands
  • Norway
  • Poland
  • Portugal
  • Romania
  • Spain
  • Sweden
  • Switzerland
  • United Kingdom

Sightings from Earth

Naked eye

The ISS is visible to the naked eye as a slow-moving, bright white dot due to reflected sunlight, and can be seen in the hours after sunset and before sunrise when the station remains sunlit but the ground and sky are dark. The ISS takes about ten minutes to move from one horizon to another, and will only be visible part of that time due to moving into or out of the Earth's shadow. Because of the size of its reflective surface area, the ISS is the brightest man-made object in the sky excluding flares, with an approximate maximum magnitude of −4 when overhead, similar to Venus. The ISS, like many satellites including the Iridium constellation, can also produce flares of up to 8 or 16 times the brightness of Venus as sunlight glints off reflective surfaces. The ISS is also visible during broad daylight conditions, albeit with a great deal more effort.

Tools are provided by a number of websites such as Heavens-Above (see Live viewing below) as well as smartphone applications that use the known orbital data and the observer's longitude and latitude to predict when the ISS will be visible (weather permitting), where the station will appear to rise to the observer, the altitude above the horizon it will reach and the duration of the pass before the station disappears to the observer either by setting below the horizon or entering into Earth's shadow.

The ISS and HTV photographed using a telescope-mounted camera by Ralf Vandebergh

A time exposure of a station pass

In November 2012 NASA launched its 'Spot the Station' service, which sends people text and email alerts when the station is due to fly above their town.

The station is visible from 95% of the inhabited land on Earth, but is not visible from extreme northern or southern latitudes.

Astrophotography

Using a telescope mounted camera to photograph the station is a popular hobby for astronomers, whilst using a mounted camera to photograph the Earth and stars is a popular hobby for crew. The use of a telescope or binoculars allows viewing of the ISS during daylight hours.

Parisian engineer and astrophotographer Thierry Legault, known for his photos of spaceships crossing the Sun (called occultation), travelled to Oman in 2011, to photograph the Sun, moon and space station all lined up. Legault, who received the Marius Jacquemetton award from the Société astronomique de France in 1999, and other hobbyists, use websites that predict when the ISS will pass in front of the Sun or Moon and from what location those passes will be visible.

See also

• Center for the Advancement of Science in Space - operates the US National Laboratory on the ISS
• List of space stations
• Origins of the International Space Station

Gallery

International Space Station docked with Endeavour and Johannes Kepler

Notes

References

External links

Agency ISS websites

•  Canadian Space Agency
•  European Space Agency
•  Centre national d'études spatiales (National Centre for Space Studies)
•  German Aerospace Centre
•  Italian Space Agency
•  Japan Aerospace Exploration Agency
•  S.P. Korolev Rocket and Space Corporation Energia
•  Russian Federal Space Agency
•  National Aeronautics and Space Administration

Research

• NASA: Daily ISS Reports
• NASA: Station Science
• ESA: Columbus
• RSC Energia: Science Research on ISS Russian Segment

Live viewing

See also: List of satellite pass predictors

• Live ISS webcam by NASA at uStream.tv
• Real-time position at Heavens-above.com
• Real-time position at N2YO.com
• Real-time position at WheretheISS.at

Multimedia

• Interactive reference guide at NASA.gov
• Image gallery search page at NASA.gov
• Assembly sequence animation by USA Today and NASA
• ISS tour with Sunita Williams by NASA at YouTube.com
• ISS tour with André Kuipers by ESA at YouTube.com
• The Future of Hope, Kibo module documentary by JAXA at YouTube.com
• Journey to the ISS by ESA at YouTube.com

UpToDate Contents

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• 1. 多発性骨髄腫における病期分類および予後研究 staging and prognostic studies in multiple myeloma
• 2. 特発性低身長に対する成長ホルモン治療 growth hormone treatment for idiopathic short stature
• 3. 低身長の原因 causes of short stature
• 4. 成人外傷患者における入院マネージメントの概要 overview of inpatient management in the adult trauma patient
• 5. 成人外傷患者における重症骨盤骨折 severe pelvic fracture in the adult trauma patient

English Journal

• Is the TMPM-ICD9 revolution in trauma risk-adjustment compatible with imperfect administrative coding?

• Di Bartolomeo S, Ventura C, Marino M, Chieregato A, Gambale G, Fabbri A, Volpi A, De Palma R.SourceAnaesthesia and ICU S.M.M. Hospital, Udine/Regional Health Agency of Emilia-Romagna, Viale Aldo Moro 21, 40127 Bologna, Italy.
• Accident; analysis and prevention.Accid Anal Prev.2011 Nov;43(6):1955-9. Epub 2011 Jun 8.
• BACKGROUND: TMPM-ICD9 is the latest injury-severity measure based on empirical estimation from ICD-9-CM codes. It is candidate to replace expert-based AIS measures worldwide because of easier accessibility and better predictive performances. In Italy and other countries administrative ICD coding is
• PMID 21819823

• Viscoelastic clot strength predicts coagulation-related mortality within 15 minutes.

• Pezold M, Moore EE, Wohlauer M, Sauaia A, Gonzalez E, Banerjee A, Silliman CC.SourceDepartment of Surgery, University of Colorado at Denver, Denver, CO.
• Surgery.Surgery.2011 Sep 5. [Epub ahead of print]
• BACKGROUND: Predicting refractory coagulopathy early in resuscitation of injured patients may decrease a leading cause of preventable death. We hypothesized that clot strength (G) measured by point-of-care rapid thrombelastography (r-TEG) on arrival in the emergency department can predict massive tr
• PMID 21899867

Japanese Journal

• HTV補給キャリア(与圧部,非与圧部)の開発(<特集>宇宙ステーション補給機(HTV) 第13回)

• 柴田 克司,山口 秀行
• 日本航空宇宙学会誌 59(688), 155-158, 2011-05-05
• NAID 110008594091

• Proposal of Micro-Trichroic Structures for High-Sensitivity Color Image Sensors

• Suzuki Yuta,Ozeki Yasuyuki,Yoshino Tomoki [他],Yamada Kazuhiro,Yamagata Michihiro,Tanaka Yasuhiro,Itoh Kazuyoshi
• Jpn J Appl Phys 50(4), 042201-042201-5, 2011-04-25
• … Employing such a structure on each image sensor (IS) cell can enhance the ability of color ISs. …
• NAID 150000055477

Related Links

• 国際宇宙ステーション（ISS） - 宇宙ステーション・き ...- JAXA

国際宇宙ステーション（ISS）や「きぼう」日本実験棟、宇宙飛行士の活動など有人宇宙開発の最新情報を紹介します。 ... 国際宇宙ステーションのクルー交代／ソユーズ宇宙船交換ミッション（42S）（3月30日） 国際宇宙ステーション ...

• 「きぼう」を見よう

国際宇宙ステーション（ISS）や「きぼう」日本実験棟、宇宙飛行士の活動など有人宇宙開発の最新情報を紹介します。 ... 宇宙空間の「きぼう」/国際宇宙ステーション（ISS）は、サッカー場くらいの大きさになります。条件がそろえば ...

Related Pictures

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★リンクテーブル★

リンク元	「disease burden」「外傷重要度スコア」「特発性低身長」
拡張検索	「ISSD」「SWISS-PROT」「TISS」
関連記事	「I」「IS」

「disease burden」

　　[★]

• 病気負担、疾患負荷、疾患の影響、

An International Staging System (ISS) was developed based on 10,750 previously untreated patients with myeloma from over 17 institutions worldwide. It incorporates data on the levels of serum beta-2 microglobulin (B2M) and serum albumin to divide disease burden into three stages with prognostic significance.(ISSは疾患負荷を予後の重要度で三つのステージに分けるためにβミクログロブリンと血清アルブミンのレベルのデータを組み込んだものである)

• ex.

疾病負荷, Global Burden of Diseases, GBD

disease Burdenが大きい = 発症率、罹病率、致命率、死亡者数が大きい

参考

• wiki en

http://en.wikipedia.org/wiki/Disease_burden

「外傷重要度スコア」

　　[★]

英

injury severity score、ISS

同

損傷重要度スコア

関

簡易損傷スケール

[show details]

外傷重要度スコア : 15 件
損傷重傷度スコア : 2 件

「特発性低身長」

　　[★]

英

idiopathic short stature, ISS

「ISSD」

　　[★] 乳児シアル酸蓄積病 infantile sialic acid storage disease

「SWISS-PROT」

　　[★]

スイスプロット

関

protein database

「TISS」

　　[★]

同

Therapeutic Intervention Scoring System

「I」

　　[★]

• イソロイシン isoleucine
• イノシン inosine
• 阻害剤 inhibitor
• iodine
• ヨード iodide
• I因子 factor I

　 　 　

「IS」

　　[★] 挿入配列 insertion sequence