M A I N   N E W S

Damage to tiles may have caused tragedy

New York, February 2
Damage to ill-fated space shuttle Columbia’s tiles, which protect the crew and vehicle from searing heat during re-entry, is emerging as the major area of investigation in the probe to determine what destroyed the shuttle.

Space agency NASA found that when Columbia blasted off 17 days ago, a piece of insulation from the fuel tank had come loose and stuck tiles on the left wing where the trouble was detected minutes before the shuttle broke up over Texas, killing all seven astronauts, including India-born Kalpana Chawla, yesterday.

After the lift-off, experts on the ground determined from the data and tapes that there was nothing to worry about on that count and that it would not affect the mission. Columbia did not carry a robot arm that could have helped to verify, with the help of a camera, whether the damage was serious.

The function of the tiles is mainly at re-entry when they reflect the excessive heat.

In a briefing, NASA said the first indication of trouble was the loss of temperature sensor readings in the left wing about seven minutes before all contact with the shuttle was lost. The tiles reflect the heat and experts say damage to them could result in exceptionally high temperatures that could damage the shuttle’s structure.

Till the failure of sensors was detected on the left wing, the mission was picture perfect and the shuttle was expected to land in a beautiful bright weather at Kennedy Space Center in Florida.

Sean O’Keefe, the NASA administrator, said damage to tiles was one possibility and would be examined. “But there could be other reasons too. Sometimes, the obvious might the real reason.

In Cape Canaveral, shuttle director Ron Dittemore said: “As we look at that (the lift-off incident) now in hindsight ... we can’t discount that there might be a connection.”

It was still unclear how much setback the Columbia tragedy would cause to the space programme. While NASA has suspended all shuttle flights pending an investigation, the International Space Station is not dependent on the US shuttle mission and can use Russian Soyuz spacecraft.

NASA has impounded computer tapes containing thousands of pieces of information for the investigators, he said.

Dittemore said “we are mobilising our forces, our engineers, our technicians, our best experts, to understand what went wrong.”

Columbia, the first shuttle to fly into space in 1981 and which did over two dozen missions, disintegrated at 200,700 feet while re-entering earth’s atmosphere, broke up into several pieces with a big bang and then its parts made a fiery entry just 15 minutes before it was due to land.

“Everything from a flight control perspective was perfect” as Columbia began descending from orbit more than 100 miles above the earth, until shortly before 9 am eastern time (1930 IST), Dittemore said.

That was when NASA controllers noticed a problem with temperature sensors in Columbia’s left wing. In Columbia’s final minutes, the readings from the sensors simply stopped coming in.

“It’s as if someone just cut the wire,” Dittemore said. Tyre pressure readings for the shuttle’s landing gear disappeared next, followed by indications of “excessive structural heating”.

The chief flight director, Milt Heflin, said one of the eight sensors sent a reading that the astronauts saw on their cockpit displays. The astronauts mentioned a problem with tyre pressure, apparently following their usual procedure in acknowledging a reading of some concern, Heflin said. Then a controller in Houston said, “We did not copy your last (message)”.

“Roger, but ...” came the reply, followed by a crackling sound and then silence, as if the astronaut had been cut off in mid-sentence. PTI