By Irene Mona Klotz
at the Kennedy Space Center, Florida
The long-awaited finale to the US portion of the International Space Station (ISS) was to be just weeks away from launch by now, with the partner modules, including Europe's Columbus laboratory, finally at the front of the line for rides to orbit.
ISS: To be "finished" in 2010
The Columbia accident on 1 February 2003 indefinitely delayed those plans. And now, a US decision to retire the space shuttle fleet in six years has stripped away any last vestige of a clear future for the troubled ISS programme.
In announcing last week that the US would be heading back to the Moon, President George Bush said the space agency (Nasa) would fulfil its obligations to complete station assembly.
But once the complex is finished - which should occur by 2010 - the shuttles will no longer be available for station re-supply and taxi services.
Window of opportunity?
The European Space Agency's (Esa) director-general, Jean-Jacques Dordain, is trying to look on the bright side.
With Esa's space station cargo transporter, the Automated Transfer Vehicle (ATV), set for its first flight later this year, Dordain sees the US pullout from station servicing as a potential boon.
According to Dordain, it will not only benefit the 30 European companies that develop and manufacture the unmanned tugs, but also Arianespace, the French-led consortium that will launch the ATVs into space aboard Ariane 5 rockets.
Japan, which is also developing a station cargo ship, likewise could benefit.
Others are less sanguine. "I expect the partners will try to get out of the station what they can," said Joan Johnson-Freese, an international space programmes expert who teaches at the Naval War College in Newport, Rhode Island, US.
"But I think the overall lesson learned by the Europeans, the Japanese and the Russians so far in this ISS programme is that you can only afford so much US friendship.
"They probably will be reluctant to get involved in any way that gets them more dependent on the US."
Undoubtedly, the next meeting of the space station partners will reach a fever pitch as space agency representatives and members of the science community reckon with a fait accompli.
After years of negotiations, delays, broken promises and budget cuts, the partners and the science community will have to accept that crews of six or seven in orbit to run experiments will not now happen.
Short-staffed in space
Since the grounding of the shuttle fleet after the Columbia accident, Nasa trimmed the station crew from three people to two to save on water and other life-critical commodities.
Once the shuttles stop flying to the station entirely, a crew of two may become standard operating procedure, according to Dordain.
Esa's ATV will fly to the ISS this year
And while the US policy shift to return to a destination-driven, rather than a scientific, objective for its human spaceflight programme may provide new opportunities for Europe, the plan topples the space station research programme.
This will now be geared almost exclusively towards experiments to prepare astronauts for travel to the Moon and beyond.
The US does not dictate the research programmes of its station partners, but many countries, such as Italy, look to follow Nasa's lead.
Ending funding for microgravity, fluid physics and dozens of other basic science experiments has the effect of wiping collaborative projects that have been slated to fly on the station.
The day after Bush's announcement, for example, researcher Luigi Carotenuto, who heads the research and development unit of Italy's Microgravity Research and Support Center, was told the temporary suspension of research funds due to the Columbia accident and delays with the space station research programme would now become permanent.
The decision also cut Carotenuto from European-backed experiments that required matching funds from member nations.
"It was astonishing how quickly this happened," said Carotenuto, whose fluid physics experiments had been selected to fly on the station.
"It is not understandable to me that there would just be a total stopping of any funding for utilisation [of the space station] after all that has been spent to build this incredibly large and complex facility. This is such a small amount compared with what has already been spent."
Researchers are already scrambling to find other rides into space.
Swiss biologist Augusto Cogoli sees more collaboration between Europe and Russia, which will continue to fly Soyuz rockets to the space station.
Cogoli also expects Esa support to grow for sounding rocket programmes and ground-based research in machines that mimic microgravity.
"Nevertheless," said Cogoli, "the limited availability of the space shuttle and a [reduced-size] crew will have negative consequences."
The first glimpse of how Nasa plans to handle the station programme within its new initiative is expected on Thursday when managers hold a press briefing at the Johnson Space Center in Houston, Texas.