Broadcast: Feb 2, 2003

Officials of the U.S. space agency, NASA, probing the loss of the space shuttle Columbia are paying close attention to the orbiter's heat-resistant outer tiles, some of which may have been damaged when the shuttle was launched more than two weeks ago.

Columbia disintegrated as it hurtled through Earth's upper atmosphere already at 18 times the speed of sound while subjected to furnace-like temperatures. NASA spokesman George Diller says the shuttle's protective tiles are more than capable of dissipating intense heat so long as they remain intact. But, he added, the tiles are not infallible. "They are ²⁾fragile in the context that, if they are broken, if something strikes them like a foreign object or debris, they can be damaged," he said. "They do not lose a lot of that heat-dissipation quality if they have minor damage. If they have major damage, that's something else."

Attention has been focused on the tiles as a possible factor in the shuttle tragedy since, shortly after lift-off on January 16, a chunk of insulating foam was seen to peel off the orbiter's external fuel tank and strike the spacecraft's left wing. Video footage from the launch did not reveal the extent to which any tiles may have been damaged by the debris. But NASA officials say they cannot dismiss the possibility of a connection between the incident and Saturday's break-up of the shuttle over Texas.

Columbia was the oldest of the shuttles. But NASA spokesman George Diller says the spacecraft was by no means too aged for service. "We think we know what the life span is: it's a hundred flights. Columbia was on its 28," he said. "So it still had a lot of life time left. Columbia was the first orbiter; it's the oldest spaceship (among shuttles). But in fact, it had just come out of an orbiter modification period when we had received the new glass ³⁾cockpit and a number of structural improvements. So, it was fresh back on the line after being upgraded."

Mr. Diller says no one should expect immediate answers to the Columbia mystery. He says the current investigation will likely prove more difficult than that of the space shuttle Challenger, which exploded shortly after lift-off in 1986. "In the Challenger accident, after looking at the launch video, we got a pretty good idea from one of the ⁴⁾optical cameras what had probably happened, though not why. In this case, we do not know what [went wrong] or why. There is no obvious smoking gun [telltale clue] " he said.

Mr. Diller says, while crews gather debris from the shuttle Columbia in Texas, officials at Cape Canaveral will review all procedures prior to the ⁵⁾orbiter's launch. The NASA spokesman says they will look for clues as to what went wrong and how to correct any problems that may be uncovered. Until there are answers, he says, future shuttle launches are on hold.

Michael Bowman, VOA news, in Kennedy space center Cape Canaveral, Florida.

1)    NASA  国家航空与宇宙航行局

2)    fragile[5frAdVail]adj. 易碎的, 脆的

3)    cockpit[5kCkpit]n. 驾驶员座舱, 战场

4)    optical[5CptikEl]adj. 视力的, 光学的

5)     orbiter[`R:bItE(r)]n. 盘旋物, 人造卫星