Unfurling solar array hits glitch

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By Michael Cabbage Sentinel Space Editor

Published in The Orlando Sentinel on December 4, 2000.

CAPE CANAVERAL -- Mechanical problems dogged efforts by shuttle Endeavour`s astronauts to unfurl a crucial $600 million solar array atop the international space station late Sunday.

Balky latches, stuck parts and computer glitches conspired to delay the objective of Endeavour`s 11-day mission.

One of two massive solar wings was deployed but not fully stretched tight. The other wing was trapped in its storage case by a stubborn retention pin. Mission managers decided to study both problems overnight before determining how to proceed today.

"There are no risks to the equipment," lead flight director Bill Reeves said. "Since we`re in a safe posture, we don`t want to rush into anything without thinking about it."

The stakes are huge. Deployment of the solar array is an essential milestone in the $95 billion, 16-nation effort to build an outpost in space by 2006. The 17-ton array will provide power needed to begin research on the station when the U.S. laboratory module Destiny arrives in January.

Installation of the array began Sunday morning when shuttle robot-arm operator Marc Garneau moved the solar mast into position above the station`s Unity module. Spacewalkers Joe Tanner and Carlos Noriega exited Endeavour`s airlock about 1:35 p.m. and climbed to a spot nearby to radio directions.

Once the pieces were carefully mated, Noriega activated a mechanical claw on the station to secure the array. The spacewalkers drove four bolts to firmly pull the pieces together.

With the array permanently attached, Noriega hooked up eight electrical cables while Tanner climbed atop the array to remove restraints and rotate into position boxes housing the twin 115-foot solar wings.

All went smoothly until spacewalkers were forced to pull the base of one wing to get it firmly locked into place. Next, a computer command was sent to unlock latches holding the boxes closed. It didn`t work. After about a half-hour of troubleshooting, the boxes` latches opened, but a pin keeping one of the arrays folded inside failed to come free.

While engineers tried to solve the problem, shuttle skipper Brent Jett sent a command ordering the other wing to extend. The massive panels had been stored accordion-style inside the 20-inch-thick boxes for more than eight months. Slowly, over the next 13 minutes, the wing unfurled.

But soon, the astronauts noticed the panels appeared not to be stretched taut. Mission managers decided to study the problem before sending further commands.

The array already was generating power, however, and flight controllers planned to begin charging the array's internal batteries today.

Later, the crew sent commands to close and reopen pins on the other array in an effort to troubleshoot it. Despite indications the stuck pin may have opened, engineers also will take some more time to look at that issue.

"It`s actually ready for deployment," station flight director John Curry said. "They`ll probably deploy it sometime [today]."

The crew had planned to have a light schedule today while ground controllers charged the array`s batteries and checked out its systems.

A second spacewalk planned for Tanner and Noriega remains scheduled for Tuesday.


-- Doris (nocents@bellsouth.net), December 04, 2000

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