
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, May 10, 1990                   TAG: 9005100197
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A4   EDITION: METRO 
SOURCE: Associated Press
DATELINE: CAPE CANAVERAL, FLA.                                LENGTH: Medium

COLUMBIA LAUNCH DELAYED

A puzzling breakdown in Columbia's cooling system has forced NASA to delay next week's scheduled shuttle launch by an estimated two to three weeks, the space agency said Wednesday.

Columbia had been scheduled to lift off May 16 or May 17 with seven astronauts and the $100 million Astro observatory, capable of probing ultraviolet and X-ray radiation. But engineers this week spotted a problem with a valve that controls the flow of coolant in the shuttle.

"We are obviously disappointed that we are not ready to fly," said William Lenoir, head of NASA's space flight program. "However, this particular system is absolutely critical to the safety of the crew and overall mission success, so we have decided to change the component."

NASA had hoped to confirm a launch date at the end of the two-day Flight Readiness Review meeting on Wednesday afternoon, but that did not occur. Mission managers agreed that an apparently faulty valve would have to be replaced and that the work could be done at the launch pad.

"They don't understand the problem enough to feel comfortable flying with it, so they've got to go in and fix it," said Bascom Murrah, a NASA official in charge of prelaunch operations for Columbia.

"We feel we can do that at the pad, but how long that will take I really would only be guessing."

Launch teams expect to have a better idea by early next week as to how long the job will take, NASA said in a statement. The agency has never replaced a cooling valve at the launch pad.

Returning Columbia to its hangar for the valve to be replaced would have resulted in a considerably longer delay.

NASA said mission managers "decided that completing the replacement and checkout on the pad is as safe and effective" as performing the work in the shuttle's hangar.

Engineers noticed the problem Sunday when there was an unexplained change in the flow of coolant.

The valve is in one of Columbia's two Freon cooling loops beneath the payload bay liners. It controls the proportion and rate of Freon distributed between the crew cabin heat exchanger and the cooling system for payloads.

Columbia's nine- to 10-day flight will be the 36th shuttle mission, provided it goes before an Atlantis mission in July. It also will be the first Spacelab mission since 1985.

by CNB