Faulty Electrical Box Won't Delay Discovery Launch

CAPE CANAVERAL - A faultyelectronics box will be replaced on one of shuttle Discovery's solid rocket boosters,but the work won't delay NASA plans to launch its second post-Columbia flightJuly 1.

Technicianswill do the job at Kennedy Space Center's Launch Complex 39B. NASA has morethan a week of extra time in the processing schedule leading up to the openingof a window that extends through July 19.

"We'retaking weekends off. That's how well the flow is going at the pad," saidKyle Herring, a spokesman for NASA's Johnson Space Center in Houston.

Duringroutine testing last week, engineers testing the booster's power distributionsystem noted an unexpected power shift from a prime to a backup circuit. Itwasn't clear what prompted the shift.

NASAengineers now think the culprit is a faulty integrated electronics unit, adevice that serves as the primary communications link between the booster andshuttle orbiter computers.

Eachbooster is equipped with two of the electronics boxes. They provide controlelectronics for the booster during launch, ascent and separation as well asbooster splashdown and recovery.

The faultyunit will be replaced in the coming weeks while other prelaunch work continues.

Technicianshave swapped the electronics boxes during at least two previous launchcampaigns.

An STS-43launch attempt in 1991 was delayed a day to replace one of the units.

The boxeson both boosters were replaced at the pad prior to the STS-96 launch in 1999.

• NASA Clears Foam Debris Issue for Next Shuttle Flight
• STS-121 at the Pad: NASA's Discovery Shuttle Reaches Launch Site
• STS-121 Astronauts Train Hard for Shuttle Launch
• Shuttle Discovery Moves Closer Towards July Launch
• NASA Forgoes Fuel Tank Test for Next Shuttle Launch
• Return to Flight: NASA's Road to STS-121

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