ad info




CNN.com
 MAIN PAGE
 WORLD
 U.S.
 LOCAL
 POLITICS
 WEATHER
 BUSINESS
 SPORTS
 TECHNOLOGY
* SPACE
 HEALTH
 ENTERTAINMENT
 BOOKS
 TRAVEL
 FOOD
 ARTS & STYLE
 NATURE
 IN-DEPTH
 ANALYSIS
 myCNN

 Headline News brief
 news quiz
 daily almanac

  MULTIMEDIA:
 video
 video archive
 audio
 multimedia showcase
 more services

  E-MAIL:
Subscribe to one of our news e-mail lists.
Enter your address:
Or:
Get a free e-mail account

 DISCUSSION:
 message boards
 chat
 feedback

  CNN WEB SITES:
CNN Websites
 AsiaNow
 En Español
 Em Português
 Svenska
 Norge
 Danmark
 Italian

 FASTER ACCESS:
 europe
 japan

 TIME INC. SITES:
 CNN NETWORKS:
Networks image
 more networks
 transcripts

 SITE INFO:
 help
 contents
 search
 ad info
 jobs

 WEB SERVICES:

  sci-tech > space > story pagecorner  

NASA delays shuttle launch to inspect wiring

MESSAGE BOARDS:
Space Shuttle

InteractiveINTERACTIVE
   3-D VRML
   • Control the Shuttle Discovery
   (PC only)
 

August 13, 1999
Web posted at: 11:02 a.m. EDT (1502 GMT)


In this story:

Second exposed wire prompted delay

RELATED STORIES, SITES icon



By Robin Lloyd
CNN Interactive Senior Writer

(CNN) -- The next space shuttle launch has been postponed at least three weeks to give inspectors time to remove Endeavour's massive payload and inspect dozens of miles of cables for potential short circuits like one that popped during a July shuttle launch.

The short circuit occurred five seconds after the space shuttle Columbia's July 23 launch because electricity arced between a stripped screw and an exposed wire, NASA said this week.

The possibility of a similar problem on Endeavour, which had been set for a September 16 launch for a radar mapping mission aboard, prompted NASA managers to put off the launch to no sooner than October 7 to give technicians time to inspect its wiring.

"We think it's appropriate that we take out the cargo bay and inspect the entire length of cable trays," said shuttle team supervisor and astronaut Don McMonagle.

The short circuit on Columbia was the result of a one-time incident, he said, when a technician inadvertently pressed a packet of wires against the stripped screw, rubbing off a wire's insulation. The wire and its insulation are about as thick as a paper clip.

Launch vibrations on July 23 shook the wire to the point that it made contact with the screw, causing the arc, engineers believe. The short knocked out power to two of the three engines on the shuttle, but back-up systems took over. A second short circuit would have meant a permanent loss of power to at least one engine, forcing an emergency landing in Florida or Africa and putting astronauts' lives at risk.

wires
Photo showing the worn section of shuttle wiring and burn marks from the short  

Second exposed wire prompted delay

The source of the short was discovered Saturday and Sunday. The next day, technicians inspected the rest of Columbia and another shuttle in the fleet, Atlantis. On Columbia, they found one other wire with rubbed-away insulation. No such wires were found on Atlantis, which is younger than Columbia.

Given the discovery of the second exposed wire on Columbia, managers decided it was "prudent" to inspect Endeavour as well before launch. The rest of the shuttle fleet also will be inspected.

"Because of the finding of damage of a similar nature, that led us to believe that there is at least one credible scenario that could cause us to have damage in more than this one isolated incident," McMonagle said.

Lab tests showed that the insulation on the Columbia wire that had a short circuit had worn away before launch during an isolated incident, not over time. The wire is one of several bundled in a metal tray -- like a gutter with a cover -- where the floor of the payload bay meets one of its walls, said NASA spokesman Joel Wells.

During a Thursday meeting at the Kennedy Space Center, managers, engineers and technicians decided to inspect Endeavour's wiring, rather than moving it as planned from its hangar to the Vehicle Assembly Building in preparation for launch.

Engineers think the wire was pressed against a burred screw head by a worker stepping on the wire, resting an elbow against it or bracing to move upward, Wells said.



RELATED STORIES:
NASA: Loose pin caused space shuttle hydrogen leak
July 30, 1999
NASA confirms fuel leak after shuttle landing
July 28, 1999
CNN - First female commander guides shuttle to nighttime landing
July 27, 1999

Columbia crew ready to step back on Earth
July 26, 1999

RELATED SITES:
NASA Human Spaceflight - mission STS-99
Note: Pages will open in a new browser window
External sites are not endorsed by CNN Interactive.

 LATEST HEADLINES:
SEARCH CNN.com
Enter keyword(s)   go    help

Back to the top   © 2001 Cable News Network. All Rights Reserved.
Terms under which this service is provided to you.
Read our privacy guidelines.