Giant leap for critics as space missions fail

THE embarrassing failure of this week's shuttle mission provides fresh ammunition for the growing band of critics of multi-million-dollar space projects.

The experiment - to unreel a satellite on the end of a 12-mile tether - was ambitious and potentially dangerous, but few expected that complications with the apparently simple process of unwinding the Teflon and copper cord would scupper the mission.

On Wednesday night, the astronauts shook the jammed tether free (avoiding the need for an emergency spacewalk to unhook it), but had to abandon their hopes of extending it to its full length. They dared not risk the tether jamming again and the possibility of losing the satellite.

Nasa scientists have yet to work out whether it was a technical fault or human error that caused the jam. The Tethered Satellite System was Italian-built, but Nasa provided the tether and the satellite-deploying tower. Officials at the Italian space agency hinted yesterday that the line may have gone askew when the astronauts applied too much tension on it as they extended the launch boom from the shuttle cargo bay.

Regardless of where the blame lies, this was a dismal end to the dollars 376m (pounds 198m) experiment. Nasa put a brave face on things, saying the mission had been partially successful. The astronauts now have experience of deploying a tethered satellite and pulling it back in - dangerous manoeuvres because of the risk of the satellite crashing into the shuttle.

The experiment aimed to test a way of generating energy in space that scientists hope could one day help power satellites or permanent space stations. The full 12- mile tether was expected to generate a potential of 5,000 volts as it swung across the Earth's magnetic field at around 17,500 mph. The foreshortened version managed to produce a potential of 40 volts, even though it was only wound out to some 850ft before jamming.

Mission managers are thankful they did not have to cut the satellite free. If it lands safely inside the shuttle cargo bay tomorrow, the Italians will have a chance to try the experiment again.

Nasa was also heartened yesterday to hear that the European Space Agency had succeeded in moving its Eureca satellite into its correct position in a higher orbit. Eureca, the second satellite carried into space on the Atlantis shuttle, had been hovering 50km (31 miles) below its operational orbit, tilted at the wrong angle. The satellite will stay in space for eight months to carry out scientific experiments. A second shuttle will bring it back to Earth.

Antagonism towards expensive space missions has been growing, and the timing of this latest failure is particularly unfortunate for Nasa. The agency has only just won continued support from Congress for a dollars 30bn space station. Opponents argued forcefully that the space station will make a minimal contribution to science and that the money would be better spent on ground-based research.

Space research projects will always be expensive, and are necessarily high-risk ventures. Nevertheless, the list of failed or at best partially successful missions is becoming a litany. Most recently, Nasa tried to make a triumph out its rescue of the Intelsat-6 communications satellite. In fact, the manouevre the astronauts had rehearsed on the ground went badly wrong and they only succeeded by an impromptu space walk to grab it by hand.

The dollars 2bn Hubble space telescope, with its unforeseen myopia, was perhaps the most stinging of recent embarrassments for Nasa because it had been so furiously hyped by the agency. The dollars 500m Galileo satellite on its way to Jupiter is another. This has had problems with its main antenna, so cannot send back all the data scientists had hoped for.

Once again we have seen how difficult it is to predict what will happen to hardware in the zero gravity of space. Months of computer simulations failed to highlight the part of the tether operation that proved to be its downfall. But how many more demonstrations do we need before the balance of risk against benefit in expensive space missions tips in favour of the critical voices?