Nasa was facing fresh questions about the future of its shuttle programme on Wednesday night after it was forced to ground the fleet because the problem with falling debris that doomed Columbia two years ago had struck again during the launch of Discovery.
Officials stressed that the current 12-day mission, and the seven astronauts on board Discovery, were not jeopardised by the incident on Tuesday, when a 83cm chunk of foam cladding fell from the external fuel tank two minutes after lift-off.
But managers said it was a problem that must be eliminated before shuttles could be launched again.
”Until we fix this, we are not ready to go fly again,” said Bill Parsons, the space shuttle programme manager.
Further inspections of Discovery are planned to check that there are no ill-effects from the foam episode.
Columbia broke apart during re-entry in 2003 because a briefcase-sized chunk of foam from the fuel tank had sliced a hole in its wing during its lift-off 16 days earlier. Engineers have spent two and a half years, and $1-billion, trying to prevent the same thing recurring.
”We decided it was safe to fly as is. Obviously with the amount [of foam] we had, we were wrong,” Parsons said. ”It didn’t cause any damage to the orbiter … but it does give us pause. I don’t know if it [the grounding] is a month, I don’t know if it’s three months. You have to admit when you are wrong, and we were wrong.”
It is a major blow to Nasa’s triumphant return to flight, and means that the scheduled launch of Atlantis in September is likely to be delayed.
Further delays to a programme already curtailed by the long and expensive research prompted by the Columbia disaster will further reduce the 30-odd launches tentatively scheduled before the three shuttles are retired in 2010.
The seven astronauts on Discovery are preparing for a critical stage of their mission on Thursday, when the shuttle is to dock with the International Space Station. This will allow the ISS crew to take close-up pictures of the shuttle’s underside.
The crew, led by Commander Eileen Collins, spent their first full day in orbit on Wednesday conducting a comprehensive seven-hour review of the shuttle’s thermal protection shield using laser sensors attached to a 50ft robotic arm extension.
Hill said that the pictures revealed no obvious signs of damage and that the orbiter was working ”flawlessly”.
But there is some residual concern about damage to a small area of heat-resistant tiling near the shuttle’s forward landing gear. Technicians have also studied video footage of a bird striking the external fuel tank at lift-off.
”The last flight ended in catastrophe and we lost seven friends of ours because of damage. So even if we have damage that is clearly within our capabilities, we’re going to get concerned about it,” said Paul Hill, Nasa’s leading flight director. But he added: ”We have landed with a whole heck of a lot of damage in the 21 years we’ve been flying this thing [Discovery].”
The assessment of new safety procedures is one of two main aims of this first shuttle flight since the Columbia disaster, and the mission specialists Soichi Noguchi and Steve Robinson, will do three spacewalks to test tile repair techniques. The other objective is to deliver equipment and supplies to the ISS and to remove to Earth 13 tonnes of rubbish built up since the last visit in November 2002. – Guardian Unlimited Â