By Irene Mona Klotz
at the Kennedy Space Center, Florida
Nasa is looking at other options for completing the International Space Station if it is not finished by the time the shuttle retires in 2010, the head of the US space agency has said.
Nasa is looking at other options for the completion of the ISS
"The shuttle is inherently flawed. It does not have an escape system for its crew," Nasa chief Michael Griffin told a Senate oversight committee.
"We all know that since human perfection is unattainable, sooner or later there will be another shuttle accident," he said. "I want to retire it before that flight can occur."
Retiring the shuttle as scheduled will also ensure that money is available to develop a proposed replacement ship, the Crew Exploration Vehicle (CEV).
"The expense of maintaining the shuttle fleet year after year is so great that in order to move effectively ahead on the Crew Exploration Vehicle systems, we must retire the shuttle.
"We must retire it in an orderly fashion; we must fly every flight safely, but we must get it behind us," Griffin said.
The new vehicle is part of a space transportation network which, in addition to ferrying crews to and from the space station, will lay the foundation for human expeditions to the Moon and Mars.
'Have to have priorities'
The ship's first manned flight is targeted for 2014, but Griffin wants to speed development of the new vehicle to smooth the transition from shuttle to CEV.
The price for doing so, however, is likely to spark howls of protests. Griffin told senators he is prepared to use money earmarked for space station science as well as technology development programs and planetary exploration missions.
"We can't do everything on our plate," Griffin said. "We have to have priorities."
The shuttle launch has now been pushed to July
Before Nasa can even test how amenable Congress, contractors and its international space partners will be to the plan, it has to get the shuttles back in space.
The fleet has been grounded since the fatal 2003 Columbia accident.
Launch of the first mission since Columbia had been planned for this month, but was postponed for additional work on the shuttle's fuel tank.
The tank shed foam insulation during Columbia's launch. It struck and damaged the ship's wing. As the shuttle flew through the atmosphere 16 days later in preparation for landing, the wing was torn apart, dooming the ship and its seven astronauts.
In addition to redesigning parts of the foam insulation, managers want another heater installed on the tank to prevent ice from building up and possibly breaking off and striking the ship during launch.
If work proceeds smoothly, launch could occur between 13 and 31 July.
"The schedule is going to be tight," Nasa spokesman Bruce Buckingham said.
While the first two shuttle missions after Columbia are considered test flights of new equipment and procedures, both are to fly to the International Space Station to deliver critical gear.
Nasa says 18 shuttle flights are needed to complete assembly of the outpost, with another 10 flights earmarked for logistics and science requirements.
With Nasa prepared to fly its shuttle fleet about four times a year, that leaves the agency far short of what is required for station assembly and operations prior to the end of shuttle flights.
Griffin said a report outlining options for reassigning station missions to other vehicles would be presented to Congress by mid-summer.