International Space Station

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International Space Station

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

International Space Station insignia

ISS Statistics
Crew: 2 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
File:NASA-Krikalev-inside-ISS.jpg
Cosmonaut Sergei Krikalev inside the Zvezda Service Module, November 2000

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

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 [1]). 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. 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).

Name

The name "International Space Station" (abbreviated MKS in Russian) represents a neutral compromise ending a disagreement about a proper name for the station. The initially proposed name "Space Station Alpha" was rejected by Russia, since it would have implied that the station was something fundamentally new, whereas the Soviet Union already had operated eight orbital stations long before the ISS launch (see Space station). The Russian proposal to name the space station "Atlant" was in turn rejected by the US, which was worried about that name's similarity to "Atlantis", the name of a legendary continent that sank into the ocean. The use of "Atlantis" would also have caused confusion with the US shuttle Atlantis.

Radio call sign

It should be noted that, although the space station's name is "International Space Station", the station's call sign is Alpha. The callsign was requested immediately upon the embarkation of Expedition 1, the first ISS crew. A clearly stunned NASA Administrator Dan Goldin gave "preliminary permission" (which eventually became permanent). As a result, the ISS is not named as such when hailed. "Discovery, Alpha" is thus a common call during Station-Shuttle docking procedures. Note: there is a ham radio aboard the station that gives reports to an Earth-bound station.

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 2005 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.

Building the ISS

Building the ISS will require more than 50 assembly and utilization flights. Of these flights, 39 are 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.

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 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 23,2002 13.7 3.9 12,598

Launched on periodic resupply missions

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

Scheduled for launch by Proton rocket

Cancelled elements

Visiting spacecrafts

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

Purpose 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. There are many critics of space exploration in general, who argue that the $100 billion USD would be better spent on problems on Earth.

Advocates of space exploration hold that such criticisms are at the very least short-sighted, and perhaps deceptive. Advocates of manned space research and exploration claim that these efforts have indeed produced billions of dollars of tangible benefits to people on Earth. In some estimates, it has been held that the indirect economic benefit, made from commercialization of technologies developed during manned space exploration, has returned more than seven times the initial investment to the economy (some conservative estimates put the amount at three times the initial investment). Whether the ISS, as distinct from the wider space program, will be a major contributor in this sense is, however, a subject of strong 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.

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

File:Shuttle approaching ISS.jpg
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. Whilst 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.

File:NASA-Foale-Spacewalk.jpg
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 March 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 ~190
Expedition 12 William McArthur - U.S.A.
Valery Tokarev - Russia
October 1, 2005
03:54:00 UTC
Soyuz TMA-7
Planned: April 1 2006 Soyuz TMA-7 ~182
Expedition 13 Pavel Vinogradov - Russia
Dmitri Kondratyiev - Russia
Daniel Tani - U.S.A.
Scheduled AprilOctober 2006
Expedition 14 Jeffery Williams - U.S.A.
Clayton Anderson - U.S.A.
Aleksandr Lazutkin - Russia
Scheduled for October 2006March 2007
Expedition 15 Fyodor Yurchikin - Russia
Oleg Kotov - Russia
John Grunsfeld - U.S.A
Scheduled for MarchSeptember 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).

See also

ISS-related articles

Other

References

File:ISS altitude.gif
^  A graph of the altitude of the ISS since launch

External links

Template:International Space Station

Template:US manned space programs

Template:Russian manned space programs

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