International Space Station remains a shuttle legacy

By Anne K Walters Jul 19, 2011, 6:38 GMT

Washington - The space shuttle Atlantis might have flown off from the International Space Station for the last time early Tuesday, but the flying laboratory will remain as an orbiting reminder of the shuttle programme for at least the next decade.

The ISS could not have been built without the shuttle and its ability to carry large components into space, and the last decade of the fleet's 30-year history has been devoted largely to making the laboratory a reality - 300 kilometres above Earth.

Atlantis' final visit was focussed on stocking up the station's reserves before the shuttle's heavy-lift capability is lost for good. Atlantis brought more than 4 metric tons of cargo and spare parts to outfit the ISS for a year.

The shuttle is the only spacecraft big enough to haul such heavy, bulky loads into orbit, though Russian, European and Japanese craft can bring smaller cargo to the station.

'Thanks for leaving the ISS ready to go for the rest of the decade,' US astronaut Ron Garan said as the ISS and Atlantis crews bade each other farewell before Monday's final closing of the hatch.

The station itself has many years of life left, and current plans call for it to operate until at least 2020.

'Today the space station is a legacy of the shuttle,' notes Scott Pace of the Space Policy Institute at the George Washington University in Washington.

Building the station from parts manufactured on the ground by different nations and successfully assembling them in space has been a triumph of both engineering and diplomacy.

'There is probably no other international partnership that is as big, as expansive and as long lasting,' Pace said.

The project was born out of the death of the Cold War, as the US and Russia began cooperating, and US astronauts first visited Russia's Mir space station. The first ISS component, Russia's Zarya module, was launched in 1998.

For that reason, the ISS came to symbolize a 'post-Soviet relationship with Russia,' Pace said, helping to bring the Russian space programme into alignment with US efforts and providing a role for other partners, including Europe and Japan.

The first residents, a US astronaut and two Russian cosmonauts, moved in on November 2, 2000. In the intervening decade, more than 200 people have spent time on board, 15 countries have helped build the ISS, and more than 600 experiments have been conducted.

'It is truly an international project,' Pace said.

Now that the shuttle is being retired, more focus will be placed on the recently completed station itself.

In fact, keeping the station running was taken into account in the decision to retire the shuttle.

Safety concerns after the shuttle Columbia disintegrated on re-entry in early 2003 led some to call for a halt to the shuttle programme, but the need to complete the station and keep promises to the space partners proved compelling enough for the United States to keep the programme going until now.

'The shuttle was absolutely necessary to complete the space station,' said Pace.

But now that it is completed, the argument for keeping the complex, ageing spacecraft operating diminished.

'Once we're done with (building the station), we need to build a safer generation of vehicles,' Pace said.

As with all political decisions, cost was key in the decision to retire the shuttle. Running the station and the shuttle while also developing a next-generation spacecraft would just have been too expensive.

US lawmakers last year approved support for the ISS through at least 2020, much to the relief of its international partners. It had earlier been scheduled to be de-funded and then de-orbited in 2015.

'Now that the space station is up and going, we may be moving into the third era of (human spaceflight), which will be the era of establishing a permanent presence in space and really doing the fundamental research,' said Valerie Neal, a curator at the Smithsonian Institution's National Air and Space Museum in Washington.

'It is going to be the era of science in space.'

But even as the curtain falls on the shuttle and the station takes centre stage, the two will remain forever linked.

'If the shuttle had been designed to only carry satellites, it would have died an early death,' Neal said. 'If it had not had the capability to make possible space station, it probably would have died an early death. If the space station had not been approved, it probably would have ended after 20 years.'