Orbiting 350 kilometres above Earth, the International Space Station is celebrating its 10th anniversary. Manuel Mitternacht asks if it’s worth the massive expense.

The multinational effort to establish a permanently manned space station is epic in its scope. It’s also mind-bogglingly expensive. A consortium of 16 nations will spend $US100billion ($142billion) building and maintaining the largest spacecraft ever built.

It costs about $64 for every kilometre travelled and moves at more than 27,740 kmh.

The station is designed to conduct experiments in microgravity to learn more about the long- term effects of human space travel, preparing the way for possible future settlements on other planets.

Critics have described the ISS as an “orbital turkey”, soaking up taxpayers’ money from member countries while failing to deliver on promised research breakthroughs.

In the 10 years since the first section of the ISS was transported into orbit, 79 rockets and shuttles have lifted off from the Kennedy Space Centre in Florida and the Baikonur Cosmodrome in Kazakhstan to build, man and supply the giant station.

So far, 161 astronauts and six space tourists – who paid about $US20million each – have visited the ISS.

Crews of three usually spend about six months in the labyrinth of modules, segments and airlocks that hold more than 700 cubic metres of living and working space – about the size of a five-bedroom house.

To keep the human outpost functioning, the ISS is supported by more than 100,000 scientists, engineers, specialists and administrators on Earth provided by the 16-member nations – US, Russia, Japan, Canada, Brazil and 11 European countries.

Supporters say it is producing outstanding scientific data while promoting multinational collaboration to the benefit of all mankind.

The water and energy efficiency on board has been pushed to levels that makes long haul flights to other planets viable. Its power supply is produced by high-tech solar panels mounted in 58-metre-long arrays that track the path of the sun.

The Environmental Control and Life Support System, recycles waste water from the sink, toilet and shower into drinking water.

NASA sees the ISS as a potential gateway station for a manned mission to Mars and an eventual return of humans to the moon.

“The ISS is now a stepping stone on the way, rather than being the end of the line,” NASA administrator Michael D. Griffin said.

But some scientists have become increasingly doubtful at the need to have a human presence in space.

Nobel Prize winning astrophysicist Steven Weinberg, of the University of Texas, dubbed the ISS an “orbital turkey”. “No important science has come out of it. I could almost say no science has come out of it,” he said during a speech at a scientific workshop on dark energy in Baltimore last year.

“Human beings don’t serve any useful function in space,” he said.

“They radiate heat, they’re very expensive to keep alive, and unlike robotic missions they have a natural desire to come back, so that anything involving human beings is enormously expensive.”

So far, the heaviest cost incurred was on February 1, 2003 when the space shuttle Columbia disintegrated upon its return to Earth from the ISS, killing all seven of the shuttle’s crew.

The US community organisation, Citizens Against Government Waste is a major critic of the project.

“The ISS is expected to be finished 16 years behind schedule, $92billion over budget, with perhaps one-eighth of the capability that engineers had hoped,” the organisation says on its website.

But the ISS consortium points to the station’s value as a giant science laboratory; it hosts 19 research facilities ranging from biomedical research to quantum physics.

The focus, however, is on the long-term effects of space travel on humans and animals. The station’s labs are filled with containers of flora and fauna. Insects, fish and plants are examined for their behaviour and reproduction capabilities in space. Also on board is an animal enclosure module that serves as a self-contained home for rodents that provides living space, food and water and even features an internal waste management system.

The most observed species on board, however, are humans. Bodily functions, blood composition and even the mental and emotional state of the crew are monitored around the clock. The station’s biomedical research programs seek to avoid muscle atrophy and bone loss caused by the lack of gravity.

Historically, space stations seem to have served political purposes rather than scientific objectives. The establishment of manned stations can be seen as an extension of competing nations’ race to the moon.

In April, 1971, Russia launched its first space station program, Salyut.

In 1973, the US launched its first space station program, Skylab, which was to later crash-land over Western Australia in 1979.

Russia then launched the Mir space station, module-by-module, between 1986 and 1996.

But the demise of the Soviet Union and Mir’s controlled crash-landing to Earth in 2001 marked the end of the era of Soviet space stations.

In 1993, Russia and the US announced plans to build and operate a common station. The Shuttle-Mir program consisted of space shuttle visits to the Mir station and was the forerunner of the ISS.

The US-Russian mission was considered by many as a symbol of a new world order and a promising sign for a peaceful future between the two nations.

On November 20, 1998 the Russian-built and US-financed Proton-K rocket launched the first ISS module – Zarya – into orbit.

But 10 years on, it seems technology and policies have changed.

NASA’s Space Shuttle program is set to end in 2011 while the new Ares1 rocket and the Orion spacecraft will not be operational until late 2014.

Meantime, the US will have to rely on Russia’s rockets and spacecraft to send NASA missions to the ISS.

The recent Russian military engagement in South Ossetia and the planned US missile defence shield on the Russian border, however, has strained the relationship between the two countries.

A leaked email from NASA boss Griffin to senior management seems to confirm fears that the US will find it difficult to get their astronauts to the ISS once the space shuttle is out of service, at least for a while.

“Retiring the shuttle is a jihad rather than an engineering and program management decision,” the email reads. “My guess is that there is going to be a lengthy period with no US crew on ISS after 2011”.

But some remain hopeful that the potential of the space station will be fulfilled. Current ISS commander Mike Fincke said: “With the ISS, we have learned so many things – and we’re going to take that knowledge and apply it to flying to the moon and Mars.”