Nasa to skip shuttle test before July launch

CAPE CANAVERAL, Florida - Nasa managers have decided to skip a launch pad test of the shuttle Discovery's redesigned fuel tank because of the risk the test itself could damage the tank.

"At the end of the presentations, it was a fairly straight-forward decision not to perform a tanking test," said Nasa spokesman Kyle Herring, with the Johnson Space Centre in Houston.

The test would have entailed filling the shuttle's fuel tank with cryogenic propellants and testing its systems. The fuel tank has been the focus of Nasa's shuttle safety upgrades since the 2003 Columbia accident.

A piece of foam insulation fell off Columbia's tank during launch and damaged the ship's wing. The shuttle was destroyed and its seven astronauts killed as it attempted to return to Earth for landing 16 days later. After major redesigns and safety enhancements, Nasa launched shuttle Discovery last July on the first mission since the accident. The tank still shed large pieces of foam and the fleet was grounded again for more repairs. Engineers discovered that putting the fuel tanks through several rounds of fuelling for prelaunch tests was a factor in the foam falling off during liftoff.

Filling the tanks with the super-cold fuel for testing and then allowing them to return to ambient temperature stresses the insulation, they said. Managers today decided the benefits of testing Discovery's newly remodelled tank were outranked by the potential risks, Herring said. Nasa is targeting Discovery's launch for July 1.

A final decision about whether the shuttle is safe to fly is expected next month after engineers assess the results of wind tunnel tests ordered after the second redesign of the tank.

Nasa removed two large pieces of foam that shielded critical cables and pressurisation lines that snake along the outside of the tank. "We still have to prove that the tank is safe to fly," Herring said.

Nasa last week decide to forego additional tank redesigns until after Discovery flies. Next week, the shuttle is scheduled to be moved from its processing hangar to the assembly building, where it will be attached to a fuel tank and a pair of solid rocket boosters. Roll-out to the launch pad at the Kennedy Space Centre is scheduled for May 19.

- REUTERS