International Space Station

International Space Station

International Space Station photographed following
separation from the Space Shuttle Discovery, August 7, 2005

International Space Station insignia

ISS Statistics

Crew:

As of
August 21, 2005

Perigee:

352.8 km

Apogee:

354.2 km

Orbital period:

91.61 minutes

Inclination:

51.64 degrees

Orbits per day:

15.72

Days in orbit:

2,473

August 28, 2005

Days occupied:

1,759

Total orbits:

38,694

Distance traveled:

≈1,400,000,000 km

June 17, 2005

Average speed:

27,685.7 km/h

Mass:

183,283 kg

August 28, 2005

Living volume:

425 m³

International Space Station

International Space Station elements as of 23-July-2004.
Click to enlarge.

ISS Diagram

Cosmonaut Sergei Krikalev inside the Zvezda Service Module, November 2000

The International Space Station (ISS) is a joint project of five space agencies:

National Aeronautics and Space Administration ( United States)
Russian Federal Space Agency (Russian Federation)
Japan Aerospace Exploration Agency (Japan)
Canadian Space Agency (Canada)
European Space Agency (15 of its member states are currently participating; Austria, United Kingdom, Ireland, Portugal, and Finland chose not to participate; Greece and Luxembourg joined ESA later).

The Brazilian Space Agency (Brazil) participates through separate contract with NASA.The Italian Space Agency similary has separate contracts for various activities, that are not done in the framework of ESA ISS works (where Italy also fully participates).

The space station is located in orbit around the Earth at an altitude of approximately 360 km (220 miles), a type of orbit usually termed low Earth orbit (The actual height varies over time by several kilometres due to atmospheric drag and reboosts ). It orbits Earth in a period of about 92 minutes; by June 2005 it had completed more than 37,500 orbits since launch of the Zarya module on November 20, 1998.

In many ways the ISS represents a merger of previously planned independent space stations: Russia's Mir 2, United States' Space Station Freedom and the planned European Columbus and Japanese Experiment Module. Today it represents a permanent human presence in space, as it has been manned with a crew of at least two since November 2, 2000 (see #ISS Expeditions).

It is serviced primarily by the Space Shuttle, Soyuz and Progress spacecraft units. It is still being built, but is home to some experimentation already. At present, the station has a capacity for a crew of three. So far, all members of the expedition crews have come from the Russian or United States space programs. The ISS has however been visited by many more astronauts, a number of them from other countries (and by three space tourists).

History

Initially planned as a NASA " Space Station Freedom" and promoted by President Reagan, it was found to be too expensive. After the end of the Cold War, it was taken up again as a joint project of NASA and Russia's Rosaviakosmos. On December 1, 1987, NASA announced the names of four U.S. companies who were awarded contracts to help manufacture the US-built parts of the Space Station: Boeing Aerospace, General Electric's Astro-Space Division, McDonnell Douglas, and the Rocketdyne Division of Rockwell.

The first section, the Zarya Functional Cargo Block, was put in orbit in November 1998. Two further pieces (the Unity Module and Zvezda service module) were added before the first crew, Expedition 1, was sent. Expedition 1 docked to the ISS on November 2, 2000 and consisted of US astronaut William Shepherd and two Russian cosmonauts, Yuri Gidzenko and Sergei Krikalev.

To construct the station, the large components are almost entirely completed on Earth, so that when they are launched into orbit the amount of installation required by the astronauts on the ISS is minimal. The components are usually launched in the large cargo bay of the NASA Space Shuttle. Currently the assembly sequence is just under half complete. As of 2006 the station is only able to accommodate three permanent crew members, compared to the expected seven that the completed station will hold.

The ISS has been far more expensive than originally anticipated by NASA. Its construction is also behind schedule, largely due to the halting of all NASA Shuttle flights following the Columbia disaster in early 2003. For the two and a half years that the NASA Space Shuttle fleet was grounded, crew rotation continued on the station through the use of the Russian Soyuz spacecrafts, although the science conducted aboard was very limited.

Construction of the station was scheduled to resume in 2006, following a few 'Return to Flight' missions, like STS-114. Unfortunately, the reappearance of the foam debris problem on the STS-114 mission in July 2005, (the same that doomed Columbia) has again delayed the launch sequence, and has even called into question the future of the space station. Further aggravating the construction of the ISS, the plant where the space shuttle's external fuel tank is made, is located near New Orleans, Louisiana, and was damaged by Hurricane Katrina.

Building the ISS

ISS assembly sequence

Building the ISS requires more than 50 assembly and utilization flights. Of these flights, 39 are planned to be Space Shuttle flights. In addition to the assembly and utilization flights, approximately 30 Progress spacecraft flights are required to provide logistics. When assembly is complete, the ISS will have a pressurized volume of 1,200 cubic meters, a mass of 419,000 kilograms, 110 kilowatts of power output, a truss 108.4 meters long, modules 74 meters long, and a crew of six.

As of the end of 2005 many changes have been made to the originally planned ISS, modules and other structures have been cancelled or replaced and the number of remaining Shuttle flights to the ISS has been reduced to now 18 during the years 2006-2010.

The station consists of several modules and elements:

Element	Flight	Launch Vehicle	Launch date	Length (m)	Diameter (m)	Mass (kg)
Zarya FGB	1A/R	Proton rocket	November 20, 1998	12.6	4.1	19,323
Unity Node 1	2A - STS-88	Endeavour	December 4, 1998	5.49	4.57	11,612
Zvezda Service Module	1R	Proton rocket	July 12, 2000	13.1	4.15	19,050
Z1 Truss	3A - STS-92	Discovery	October 11, 2000	4.9	4.2	8,755
P6 Truss - Solar Array	4A - STS-97	Endeavour	November 30, 2000	73.2	10.7	15,900
Destiny	5A - STS-98	Atlantis	February 7, 2001	8.53	4.27	14,515
Canadarm2	6A - STS-100	Endeavour	April 19, 2001	17.6	0.35	4,899
Joint Airlock - Quest Airlock	7A - STS-104	Atlantis	July 12, 2001	5.5	4.0	6,064
Docking Compartment - Pirs Airlock	4R	Progress M	August 14, 2001	4.1	2.6	3,900
S0 Truss	8A - STS-110	Atlantis	April 8, 2002	13.4	4.6	13,970
Mobile Base System for Canadarm2	UF-2 - STS-111	Endeavour	June 5, 2002	5.7	2.9	1,450
S1 Truss	9A - STS-112	Atlantis	October 7, 2002	13.7	3.9	12,598
P1 Truss	11A - STS-113	Endeavour	November 24, 2002	13.7	3.9	12,598
External Stowage Platform (ESP-2)	LF1 - STS-114	Discovery	July 26, 2005	?	?	?

Launched on periodic resupply missions

Multi-Purpose Logistics Module (MPLM)

Scheduled for launch by Shuttle after return to flight
(listed in order of planned launch sequence)

4 Truss segments (two port and two starboard)
Node 2 (launch ~2007)
Columbus Laboratory (launch ~2007/08)
Japanese Experiment Module (JEM), aka KIBO (launch ~2007/08)
Cupola - (launch ~2009)

Scheduled for launch by Proton rocket

Multipurpose Laboratory Module FGB-2 based - (launch ~2007)
European Robotic Arm (ERA) (launch ~2007 together with MLM)
Russian Research Module reduced to 1 (launch ~2009)

Cancelled elements

Node 3 - cancelled
Centrifuge Accommodations Module cancelled (would have been attached to Node 2)
Universal Docking Module - cancelled, replaced by (MLM - FGB2)
Docking and Stowage Module - cancelled
Habitation Module - cancelled
Crew Return Vehicle (CRV) - cancelled
Interim Control Module - cancelled, no need to replace Zvezda
ISS Propulsion Module - cancelled, no need to replace Zvezda

Uncertain elements

Science Power Platform planned to be launched by a Shuttle flight, now more likely to be launched by a Proton

Visiting spacecrafts

Soyuz spacecraft for crew rotation and emergency evacuation, replaced every 6 months
Progress spacecraft - resupply vehicle
European (ESA) Automated Transfer Vehicle (ATV) ISS resupply spacecraft
Japanese (JAXA) H-II Transfer Vehicle (HTV) resupply vehicle for KIBO module

There is also a large unpressurized truss system partially in place that will eventually support the prominent solar arrays.

The International Space Station modules and systems

Launched periodically: Multi-Purpose Logistics Module

Scheduled for Proton: Multipurpose Laboratory Module | European Robotic Arm | Russian Research Module

Other subsystems: Truss | Solar Arrays | Canadarm2

Criticism of the ISS

There are many critics of NASA who view the project as a waste of time and money, inhibiting progress on more useful projects: for instance, the estimated $100 billion USD lifetime cost could pay for dozens of unmanned scientific missions or could be used for space exploration in general or be better spent on problems on Earth. Critics complain that very little high-quality scientific research has been done on the ISS, and that if the station's scientific program had had to compete with other scientific research in the normal process of peer review and grant applications, it would have never been funded. The recent problems of the shuttle program have put the ISS in a precarious position, in which its inhabitants spend most of their time trying to survive, rather than doing scientific research.

So far the costs have been $26 billion, of which the US' share consists mainly of costs related to the Space Shuttle, not expenses NASA incurred by building elements or maintaining the ISS. However, critics say that the main justification for the shuttle program is to service the ISS, while the main justification for the ISS is to give the shuttle somewhere to go. With the cancellation of parts of the ISS, such as the Centrifuge Accommodations Module or Node 3 and the shift of the European Robotic Arm and the Science Power Platform to a launch by a Russian Proton rocket NASA's ISS expenses excluding Shuttle assembly flight costs are expected to be much lower than the $100 billion figure that is often used in the media.

Advocates of space exploration say that criticism of the ISS project is short-sighted, and that manned space research and exploration have produced billions of dollars of tangible benefits to people on Earth. By some estimates, the indirect economic benefits made from commercialization of technologies developed during manned space exploration have returned many times the initial investment to the economy. However, there is no consensus among economists on how to make such an estimate, since it requires speculation as to what the tax money would have accomplished had it remained in the economy. Whether the ISS, as distinct from the wider space program, will be a major contributor in this sense is, thus a subject of debate. More cynical advocates have pointed out that even if its scientific value is nil, it would have still served to force international cooperation at a time of tough international politics.

Two technical aspects of the ISS's design have been heavily criticized: (1) it requires too much maintenance, and in particular too much maintence through risky, expensive EVAs; (2) its orbit is too highly inclined, making it difficult to reach from the Earth's surface in an economical way. The latter decision arose from the political realities of the US's desire to keep Russia involved in the program.

Space Tourism, weddings and the ISS

The ISS has seen the first space tourist, Dennis Tito, who spent 20 million USD to fly aboard a Russian supply mission and the first space wedding when Yuri Malenchenko on the station married Ekaterina Dmitriev who was in Texas.

Present status of the ISS

The Space Shuttle Discovery is seen here approaching the International Space Station

After the breakup of Columbia on February 1, 2003, and the subsequent two and a half year suspension of the US Space program, followed by problems with resuming flight operations in 2005, there remains some uncertainty over the future of the ISS.

Due to weight restrictions and design constraints, payloads intended for the Shuttle - even if ready to fly - cannot be launched to the station on any other available launcher. In addition, assembly work is manpower-intensive, making it difficult to do without the assistance of EVA teams brought up by the Shuttle.

In the meantime, crew exchange has been carried out using the Russian Soyuz spacecraft. Starting with Expedition 7, two-astronaut caretaker crews have been launched, instead of the previous crews of three. However, Soyuz lacks the raw cargo space of the shuttle, and cannot carry a significant amount of material back to earth; because the ISS had not been visited by a shuttle for an extended period, a large amount of waste accumulated which temporarily hindered station operations.

The Space Shuttle Program resumed flight on 26 July 2005 with STS-114, the Return to Flight mission of Discovery. This mission to the ISS was intended to both test new safety measures implemented since the Columbia disaster, and to deliver supplies to the station. Although the mission succeeded safely, it was not without risk; foam was shed by the external tank, leading NASA to announce future missions would be grounded until this issue was resolved.

Astronaut Michael Foale on a construction EVA outside the ISS in February 2004

The second Return to Flight mission, STS-121 was planned for September 2005, but has been delayed until at least May 2006.

ISS Expeditions

Expedition	Crew (commander in italics)	Launch date	Flight up	Landing date	Flight down	Duration (days)
Expedition 1	William Shepherd - U.S.A. Yuri Gidzenko - Russia Sergei Krikalev - Russia	October 31, 2000 07:52:47 UTC	Soyuz TM-31	March 21, 2001 07:33:06 UTC	STS-102	140.98
Expedition 2	Yuri Usachev - Russia Susan Helms - U.S.A. James Voss - U.S.A.	March 8, 2001 11:42:09 UTC	STS-102	August 22, 2001 19:24:06 UTC	STS-105	167.28
Expedition 3	Frank L. Culbertson - U.S.A. Vladimir N. Dezhurov - Russia Mikhail Tyurin - Russia	August 10, 2001 21:10:15 UTC	STS-105	December 17, 2001 17:56:13 UTC	STS-108	128.86
Expedition 4	Yury Onufrienko - Russia Dan Bursch - U.S.A. Carl Walz - U.S.A.	December 5, 2001 22:19:28 UTC	STS-108	June 19, 2002 09:57:41 UTC	STS-111	195.82
Expedition 5	Valery Korzun - Russia Sergei Treschev - Russia Peggy Whitson - U.S.A.	June 5, 2002 21:22:49 UTC	STS-111	December 7, 2002 19:37:12 UTC	STS-113	184.93
Expedition 6	Kenneth Bowersox - U.S.A. Nikolai Budarin - Russia Donald Pettit - U.S.A.	November 24, 2002 00:49:47 UTC	STS-113	May 4, 2003 02:04:25 UTC	Soyuz TMA-1	161.05
Expedition 7	Yuri Malenchenko - Russia Edward Lu - U.S.A.	April 26, 2003 03:53:52 UTC	Soyuz TMA-2	October 28, 2003 02:40:20 UTC	Soyuz TMA-2	184.93
Expedition 8	Michael Foale - U.S.A. Alexander Kaleri - Russia	October 18, 2003 05:38:03 UTC	Soyuz TMA-3	April 30, 2004 00:11:15 UTC	Soyuz TMA-3	194.77
Expedition 9	Gennady Padalka - Russia Michael Fincke - U.S.A.	April 19, 2004 03:19:00 UTC	Soyuz TMA-4	October 24, 2004 00:32:00 UTC	Soyuz TMA-4	185.66
Expedition 10	Leroy Chiao - U.S.A. Salizhan Sharipov - Russia	October 14, 2004 03:06 UTC	Soyuz TMA-5	April 24, 2005 22:08:00 UTC	Soyuz TMA-5	192.79
Expedition 11	Sergei Krikalev - Russia John L. Phillips - U.S.A.	April 15, 2005 00:46:00 UTC	Soyuz TMA-6	October 11, 2005 01:09:00 UTC	Soyuz TMA-6	179.02
Expedition 12	William McArthur - U.S.A. Valery Tokarev - Russia	October 1, 2005 03:54:00 UTC	Soyuz TMA-7	Planned: April 8, 2006	Soyuz TMA-7	~189
Expedition 13	Pavel Vinogradov - Russia Jeffrey Williams - U.S.A. Thomas Reiter - Germany	Scheduled March 30– September 23, 2006
Expedition 14	Michael Lopez-Alegria - U.S.A. Mikhail Tyurin - Russia Sunita Williams - U.S.A.	Scheduled for September 13, 2006–March 2007
Expedition 15	Olag Kotov - Russia Clayton Anderson - U.S.A. Fyodor Yurchikhin - Russia	Scheduled for March 9–September 2007

The International Space Station is the most-visited spacecraft in the history of space flight. As of August 28, 2005, it has had 141 (non-distinct) visitors. Mir had 137 (non-distinct) visitors (See Space station).

International Space Station
Expedition 1 \| Expedition 2 \| Expedition 3 \| Expedition 4 \| Expedition 5 \| Expedition 6 \| Expedition 7 \| Expedition 8 \| Expedition 9 \| Expedition 10 \| Expedition 11 \| Expedition 12 \| Expedition 13