Nasa pledged to press ahead with its troubled space shuttle programme on Thursday night after its decision to ground the ageing fleet over safety fears raised new questions about the agency’s future direction.
Shuttle managers admit they may never be able to solve the debris problem that doomed the Columbia shuttle two years ago and occurred again during Tuesday’s launch of Discovery. They were unable to say when they might return to space once the current 12-day mission is over.
But, as Discovery docked serenely with the International Space Station, managers said there was no question of scrapping the final five years of shuttle flights, which it says are essential to the completion of the $100-billion station, as well as to plans of returning man to the moon and making a Mars landing.
”We have to face reality,” said John Shannon, the space shuttle’s flight operations manager. ”We have a significant problem, but nobody is folding their tents, no one is down in the mouth and all I see from the team is determination to fix the problem.
”The shuttle is an amazing vehicle that can do things in space nothing else can do. With the work we are doing, we think we can get it in good shape to fly again.”
What should have been a triumphant week for Nasa, with the launch of the first manned spaceflight since the Columbia disaster killed seven astronauts in February 2003, quickly turned sour when video pictures were released showing a chunk of foam 33 inches wide breaking off the fuel tank two minutes into Discovery‘s ascent.
It did not strike the orbiter and there is no danger to its astronauts. But there was dismay at Nasa that two and half years’ work on safety improvements, at a cost of about $1,4-billion, had failed to prevent a repeat of exactly the same problem that afflicted Columbia.
On that occasion, a briefcase-sized slab of foam struck the left wing, leaving a hole that allowed deadly hot gasses to seep in on re-entry.
”We thought we had fixed the problem but we were wrong,” said Bill Parsons, the space shuttle programme manager, who added that none of the agency’s three orbiters — Discovery, Atlantis and Endeavour — all scheduled for retirement in 2010, could be launched again until Nasa engineers had found a solution.
One option under consideration is to replace the part of the fuel tank from which the foam broke away with bolted or welded metal, which would eliminate the need for cladding.
”We will never be able to get the amount of debris shed by the tank down to zero,” said Nasa administrator Mike Griffin, adding that Discovery‘s mission is largely a test flight to assess safety improvements made since the Columbia accident.
”We are trying to get it down to the level that cannot damage the orbiter.”
Meanwhile, experts have criticised Nasa’s continuing reliance on the shuttle’s ageing technology rather than diverting resources to developing its long-awaited successor, which is provisionally called the Crew Exploration Vehicle (CEV). The replacement craft remains on the drawing board.
”The shuttle is costing a hell of a lot of money and we’ve got to get on to the CEV,” said Sherwood Boehlert, chairperson of the committee on science in the US House of Representatives. Nasa is asking Congress for $34,7-billion over the next two years, a quarter of which would be earmarked for manned space exploration.
The former astronaut Tony England, a space expert at the University of Michigan who flew on the shuttle Challenger in 1985, also expressed concern. ”I’m not completely sympathetic to the new Nasa,” he said. ”But the problem is they haven’t been able to maintain the shuttle, develop a new vehicle and do all the other tasks they are expected to do.”
The debris debate continues to overshadow the successes of Commander Eileen Collins and her six fellow astronauts aboard Discovery. The shuttle docked with the International Space Station 195km above Chile on Thursday, and will stay connected until it returns to Earth on August 7. – Guardian Unlimited Â