This week the space shuttle Endeavour is scheduled to blast off from Kennedy Space Centre in Florida on the 14th shuttle mission to International Space Station Alpha.
It will deliver its fifth crew, supplies and the base system for the station’s Mobile Transporter railway. After a total of at least 45 flights the biggest man-made object in space will be fully assembled, in orbit 250 miles above the Earth, in 2006.
Alpha is envisaged as a giant orbiting laboratory conducting research into a diverse range of fields, from protein crystals and tissue cultures, to flames, fluids and metals, to life in microgravity and the environment of space itself. Observations of the Earth from orbit will help scientists understand volcanoes, hurricanes and typhoons as well as the environmental changes caused by humans.
Human health could be a beneficiary. NASA hopes pure protein crystals could be grown at the station to further science’s understanding of proteins, enzymes and viruses. This knowledge could be used for the development of new drugs for cancer, diabetes, emphysema and immune system disorders.
Other experiments would involve growing living cells on the station. These, NASA claims, could be produced without the usual distortion from gravity and could be used for testing new treatments for cancer without risking patients.
There will also be the opportunity to study gravity. Long-term human exposure to reduced gravity can cause weakening of muscles, changes in how the heart, arteries and veins work and loss of bone density. NASA hopes to gain a thorough understanding of these effects and find methods of counteracting them for future long-term human solar system exploration.
A centrifuge accommodation module will be used to generate simulated gravity ranging from moon-like levels to Martian gravity of up to 2g so scientists can also study gravitational effects on plants, animals and other living cells.
The project will also teach scientists a great deal about constructing objects in space. Operating in a space suit in orbit is compared by NASA officials to trying to change a fuse in your car while wearing ski gloves and moving around on roller skates.
Dexterity is a major issue and astronauts undergo extensive training for a year in advance. A key feature of the training is to get used to using the station’s footholds and develop an idea of the problems weightlessness brings, using facilities such as the neutral buoyancy laboratory based at the Lyndon B Johnson Space Centre in Texas. This holds 23 million litres of water and replicas of sections of the station, and allows the astronauts to practise assembly procedures, including using virtual reality to learn how to operate the robotic arm that will play a vital role in assembling the station.
How much of this experimental programme will come into fruition, however, is open to debate. Arguments over funding and the fact that the project looks set to cost more than 10 times its original budget of £8bn mean that some of the planned modules for the space station may never be built. This casts doubt on how much research will actually be possible.
Originally the brainchild of Ronald Reagan, the station – then called ‘Freedom’ – was intended to be completed by 1994. Reagan envisaged it as a collaboration between the western powers, but progress was so slow in the initial years that Bill Clinton relaunched the project following the collapse of the Soviet Union, bringing in Russia and declaring the redesigned station a symbol of post-Cold War co-operation.
As well as the US, Russia and the European Space Agency member states, the project now includes Canada, Brazil and Japan. The plan was for the US to provide the core Unity module and the Russians the Zarya control module along with solar panel arrays. The Russian Space Agency would also provide a further two research modules. The main contributions from Europe and Japan would be laboratory modules: the Japan Experimental Module and ESA’s Columbus. Brazil would contribute the external platforms for experiments to be carried out on the station’s ‘hull’. Russia would also supply logistics transport vehicles and Soyuz spacecraft for crew return and transfer.
Japan and ESA are both providing additional supply vehicles; ESA has two, the Automated Transfer Vehicle, launched by the Ariane 5 rocket, and the Leonardo logistics module, which is delivered by the shuttle. Canada will provide the robotic arm, which will operate from the Mobile Transporter, a ‘railway’ mounted on an external truss forming the spine of the station.
The various nations’ precise financial contributions are not so clear. Due to what the partners call ‘bartering’ agreements, space agencies will state their share only as a ‘percentage of the overall cost’. ESA says that it is providing 8.3 per cent of the cost and will only estimate a price tag of £5bn (e8bn).
Ultimately, the international effort will require at least 45 launches over five years. With the completion of the current mission, the space station will consist of the Unity, Zarya, Zvesda (service) and Destiny (laboratory) modules, the docking compartment and the joint airlock, the first few truss segments, the Mobile Transporter, the robotic arm and solar panels. The first 15m section of the truss and track was put in place by an Atlantis shuttle in April, and it will be joined by eight more segments over the next two years.
The Mobile Transporter and the robot arm, Canadarm 2, are crucial to construction. The transporter will have a top speed of 1.7m/minute and eventually travel over 100m of track. Driven by two electric motors that generate only about 7.5W , it will carry a maximum 21 tonnes of cargo.
Tom Farrell, NASA Mobile Transporter subsystem manager at the Johnson Space Centre in Houston, says: ‘We’ve done a lot of work to make certain it can’t jump the tracks. We have to be sure it will be safe during all the station’s activities such as reboosting its orbit or during visiting vehicles’ docking procedures.’
The transporter will be held on the track with three sets of wheels, one to propel it and two in roller suspension units. These spring-loaded units will have rollers on both sides of the track to ensure the transporter can’t float loose. The railcar will have 10 stops at specific work sites where it can be locked down, allowing the robotic arm to manoeuvre cargo safely. Although it can be driven from the station, the transporter will usually be controlled from Mission Control in Houston.
The robot arm can lift loads of up to 116 tonnes and move modules, nodes and truss segments. Also attached to the arm is the smaller ‘special-purpose dextrous manipulator’, or Canada Hand. At about 4m long, it can move 590kg and has interchangeable tools for precise work using small parts.
One of the key questions facing the project is crewing. While Alpha currently has a crew of only three, the original plan was that this would be expanded to six or seven. Some reports have suggested that, because of budget overruns at NASA, the crew habitation module and crew return vehicle (CRV) – to allow six or seven astronauts to escape back to Earth in an emergency – will never be built. This would limit the crew to three, who can leave in a Russian Soyuz capsule docked at the station. But this smaller crew would then be unable to cope with the workload of all the planned experiments.
Not so, according to an ESA spokeswoman: the habitation module isn’t even necessary. ‘Without the ‘hab’ it would be less comfortable but there still could be a crew of six or seven. The current configuration still includes the hab module but even if it were deleted it would still be possible.’
At present the hab is still part of the NASA assembly plan and is due to go up in 2005, but ESA says the status of the CRV is less definite. NASA has stopped work on the return vehicle but says it has not yet officially been dropped: ‘It is still under discussion, along with the two other options: the use of the Soyuz capsule or the idea that there would be a secure part of the station for the crew to move to, where they would wait to be rescued.’
The final decision on which option will be taken is expected this autumn, and on this hangs the number of astronauts.
Whatever the outcome NASA, ESA and the other international partners can be pleased that so far, despite serious delays in production of some of the Russian modules, assembly has gone smoothly. Public relations have not been quite so problem free.
Fights in the US Congress over budgets and whether or not various parts are cancelled or not continue to dog the station. Over its expected 10-15 year life ESA estimates that the construction and operating costs will be £62bn (e100bn).
The US government’s auditor, the General Accounting Office, estimates £72bn ($106bn) for 20 years, while NASA gives a cost just for its design and terrestrial build of £17bn ($25bn). There have been suggestions that the vast cost of the project is crippling NASA, draining resources from all its other activities, but that it has gone too far to stop.
But Alpha is up there. Whether or not these cost estimates hold true there is still much in the space station to be admired as a feat of engineering. It is destined to go down as a milestone in the history of space research.