CAPE CANAVERAL, Fla
Story first posted December 4, 2000, 12:18 p.m.
CAPE CANAVERAL, Fla. Endeavours astronauts got a tentative go-ahead to unfurl a second solar wing at the International Space Station (ISS) Monday after mission managers approved a slow, step-by-step plan for the crucial deployment.
If all goes well, the massive blue-and-gold array will begin rolling out of a beam-shaped blanket box about 6:23 p.m. Eastern Standard Time (23:23 GMT) as the combined shuttle-station complex soars some 235 miles (376 kilometers) above Earth.
Shuttle Endeavour's astronauts spread a giant solar wing at Space Station Alpha (ISS) late Sunday, Dec. 3.
"It is in the plan for the crew," NASA flight commentator James Hartsfield said from the agencys Mission Control Center at Johnson Space Center in Houston.
But flight controllers first must prepare associated electronics and batteries for the deployment, a job that is expected to take several hours.
A power converter that supplies electricity to the wing from the shuttle short-circuited early Monday, forcing flight controllers to reset electronics and make certain associated batteries are charged properly before proceeding with the deployment.
The tentatively scheduled deployment had been set for 4:51 p.m. EST (21:51 GMT) but battery charging operations were taking longer than anticipated.
NASA mission managers delayed the deployment of the second wing late Sunday after minor problems cropped up during the unfurling of an identical array.
The first solar wing fully unfurled during a 14-minute deployment sequence but a bit of slack was noticed in one of the two solar blankets that make up the array.
Engineers poring over video footage also noted that the suspect blanket rippled back and forth during the deployment, bunching up and popping free as the wings telescoping mast pulled it from its storage box.
The result was that the array which otherwise is working well and generating electricity is not stretched out as tightly as expected.
NASA would prefer the array to be completely taut to make certain the fragile wing is secure enough to withstand forces put upon it when U.S. space shuttles not to mention Russian crew transport vehicles and cargo carriers dock with the station.
The planned unfurling of the second wing will be broadcast live on SPACE.com. Look for the deployment, however, to come off in fits and starts.
With shuttle skipper Brent Jett sending commands from a laptop computer, the second solar wing will be unfurled in deliberate stages. Jett will start and stop the deployment several times to make certain the blankets stretch out tightly.
"It could make the deploy take an hour or longer to complete," Hartsfield said.
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Attached to a $600 million electrical power tower that was mounted atop the station during a seven-hour, 33-minute spacewalk Sunday, the two solar wings are designed to stretch 240 feet (73 meters) from tip to tip, generating enough electricity to power 30 homes.
That power is critical to the $60 billion station construction project, which is a joint effort of 16 nations and 100,000 workers on four continents.
Existing electrical supplies are so sparse that one of the stations three pressurized work areas remains off-limits to the stations first full-time crew, which took up residence at the complex in early November.
The extra electrical power also is a must before NASA and its international partners can expand the station during a series of almost 40 more U.S. shuttle and Russian rocket missions.
The P-6 module is raised above Endeavour's cargo bay on Dec. 2, 2000 following the shuttle's docking at Space Station during STS-97.
Two more spacewalks, meanwhile, still are planned during the shuttles stay at the station.
Astronauts Carlos Noriega and Joe Tanner are scheduled to begin a second spacewalk about 1 p.m. EST (18:00 GMT) Tuesday. The job at hand: Wiring the new solar wings to the station and repositioning a key communications antenna.
The third spacewalk which is set to begin just after noon EST (17:00 GMT) Thursday will involve mounting a device designed to determine whether the solar wings might create a shock hazard to astronauts working outside the station.
Both of those spacewalks will be broadcast live on SPACE.com.
Endeavour and its crew which also includes pilot Mike Bloomfield are scheduled to land at Kennedy Space Center at 6:19 p.m. EST (23:19 GMT) Dec. 11.
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