International Space Station: Meaning (information, definition, explanation, facts)

Overview

Continuing on from the United States' Skylab and Russia's Mir, the International Space Station (ISS) represents a permanent human presence in space: it has been manned with a crew of at least two since November 2000. Each time that the crew is replaced both the old and the new crew as well as one or more visitors are present.

The ISS is a joint project of the Canadian Space Agency (CSA/ASC), European Space Agency (ESA), Japan Aerospace Exploration Agency (JAXA), Russian Federal Space Agency and the U.S.' National Aeronautics and Space Administration (NASA).

The space station is located in orbit around the Earth at an altitude of approximately 386 km, 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 at a period of about 92 minutes; on December 1, 2003 it had completed over 28,700 orbits since launch.

It is serviced primarily by the Space Shuttle, and 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 (permanent) crew 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 2 space tourists).

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 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.

ISS elements (NASA)

The station consists of several modules and elements:

• Zarya, or Functional Cargo Block (launched November 20, 1998)
• Unity Module, or Node 1 (launched December 4, 1998)
• ISS Zvezda, or Service Module (launched July 12, 2000)
• Destiny Laboratory Module (launched February 7, 2001)
• Node 2 (launch date under review)
• Columbus Orbital Facility (launch date under review)
• Japanese Experiment Module (JEM), aka KIBO (launch date under review)
• Multi-Purpose Logistics Module (MPLM)
• Joint Airlock - (Quest airlock)
• Docking Compartments - (Pirs airlock)
• Science Power Platform
• Universal Docking Module
• Docking and Stowage Module
• Cupola
• Russian Research Module
• Centrifuge Accommodations Module
• Habitation Module

Other major subsystems include

• ISS Truss girder forming a structural backbone to the station
• ISS Solar Arrays
• Mobile Servicing System (Canadarm2)
• a Soyuz module for emergency evacuation, replaced every 6 months
• European (ESA) Automated Transfer Vehicle (ATV) ISS resupply spacecraft
• Japanese (JAXA) H-II Transfer Vehicle (HTV) resupply vehicle for KIBO module

ISS major component assembly sequence

• ISS assembly sequence

As configured as of 2003, the station massed 187,016 kg and had 425 cubic meters of living space. Its extreme dimensions were 73 meters wide, 52 meters long, and 27.5 meters high. Operations had included 16 American Space Shuttle flights and 22 Russian flights. Of the Russian flights, 8 were manned and 14 were unmanned flights. Construction had required 51 spacewalks, of which 25 were shuttle-based and 26 ISS-based. Total spacewalk time at the station has been 318 hours, 37 minutes.

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 was put in orbit in 1998. Two further pieces were added before the first crew was sent. The first crew arrived on November 2, 2000 and consisted of US astronaut William Shepherd and two Russian cosmonauts, Yuri Gidzenko and Sergei Krikalev. They decided to call the space station "Alpha" but the use of that name was restricted to their mission.

The ISS has had a troubled 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. Since then, it has been far more expensive than originally anticipated by NASA, and is behind schedule. As of 2003 it is unable to yet accommodate the expected crew of seven, thus severely limiting the amount of science that can be performed on it and angering European partners in the project. In July, 2004, NASA agreed to complete the station to the level where it could support 4 crewmembers and to launch additional sections like the Japanese experiment module. NASA would continue to handle construction while Russia would continue to launch and recover the Station's crews.

There are many critics of NASA who view the project as a waste of time, 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 here 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.

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.

After the accident of the Space Shuttle Columbia on February 1, 2003, and the subsequent suspension of the US Space Shuttle program, there remains some uncertainty over the future of the ISS. Its construction is practically halted as major parts of the ISS are so heavy that they cannot be lifted to the ISS by any launcher currently in service. For example the European Space Agency's laboratory module Columbus is ready to go, but can't be delivered into orbit by currently available launchers. The Russian Energia launcher (or even the Buran shuttle) could have been brought back into service and would have easily been capable of lifting such heavier payloads for as long as the Space Shuttle remains grounded. However, this was not done, possibly for political and economical reasons. It is also unclear whether the Energia program could have been reactivated in a substantially shorter period of time than the likely delay until the expected recommencement of Space Shuttle flights. In the meantime, crew exchange is done using the Russian Soyuz spacecraft. Starting with Soyuz TMA-2, two-astronaut caretaker crews have been launched, instead of the previous crews of three.

On 27 February 2004, ISS crew Michael Foale and Alexander Kalery conducted the first spacewalk involving its entire crew (Soyuz 26 was the first involving the whole crew of a vehicle). Most of the spacewalk's goals, the installation of external equipment, were accomplished before a kinked tube in Kalery's suit caused a cooling malfunction and forced an early end.

The possibility of an extremely high-speed collision with space debris is considered a long-term threat to the International Space Station. One proposed solution is a laser broom.

• Expedition 1: William Shepherd, Yuri Gidzenko and Sergei Krikalev
• Expedition 2: Yuri Usachev, James Voss, Susan Helms
• Expedition 3: Frank L. Culbertson, Mikhail Tyurin, Vladimir N. Dezhurov
• Expedition 4: Yury Onufrienko, Carl Walz, Dan Bursch
• Expedition 5: Valery Korzun, Peggy Whitson, Sergei Treschev
• Expedition 6: Kenneth Bowersox, Donald Pettit, Nikolai Budarin
• Expedition 7: Yuri Malenchenko, Edward Lu
• Expedition 8: Michael Foale, Alexander Kaleri
• Expedition 9: Gennady Padalka, Michael Fincke
• Expedition 10: Leroy Chiao, Salizhan Sharipov (scheduled launch October 9, 2004)

The International Space Station is the most visited space craft in the history of space flight. Almost 1/4 of astronauts who have ever flown into space have been to the ISS. See the alphabetical List of International Space Station visitors.

List of ISS spacewalks performed from the ISS or visiting spacecraft.

List of manned spaceflights to the ISS. For a comprehensive chronological list of all manned spacecraft that have visited the ISS, including the spacecraft's respective crews. This list also includes the ISS' crews referenced in the previous section.

List of unmanned spaceflights to the ISS. Progress supply flights and unmanned automatic docking space station modules.