All Wired Up: Space Station Spreads its New Solar Wings
The starboard 1A solar array extends out from the newly delivered S4 truss at the International Space Station after a successful deployment on June 12, 2007.
CREDIT: NASA TV.
This story was updated at 11:59 p.m.
HOUSTON -- The International Space Station (ISS) unfurled a shiny new set of solar wings Tuesday to increase its power supply and support future construction.
Astronauts aboard the ISS and NASA?s shuttle Atlantis watched as the new solar arrays at the tip of the station?s new Starboard 3/Starboard 4 (S3/S4) truss unfolded like window blinds as the two spacecraft flew 214 miles (344 kilometers) above Earth.
?Everything worked as expected and we ended up with two brand new solar arrays,? Atlantis astronaut Jim Reilly II said after the successful deployment.
The new solar wings are the third of four U.S.-built arrays to be installed at the ISS and were attached to the orbital laboratory during a Monday spacewalk. They will allow the orbital laboratory to power new modules and international laboratories from Europe and Japan, which are slated to launch towards the ISS later this year and in early 2008.
"So they need electricity for those new modules, and that's part of our job, to allow them to have that," said Atlantis astronaut Steven Swanson, an STS-117 mission specialist, in a NASA interview.
The solar arrays? S4 truss is designed to rotate its power-generating wings like a paddlewheel so they can track the Sun and maximize electricity production. But first, an older solar array wing extending over the new S3/S4 trusses from the station?s mast-like Port 6 (P6) truss will have to be retracted to clear the area.
That solar array retraction is planned during a Wednesday spacewalk by Swanson and fellow STS-117 astronaut Patrick Forrester. The astronauts launched towards the ISS aboard Atlantis on June 8 to deliver the new starboard solar arrays, trusses and a new crewmember to the ISS during their 13-day mission.
Slow and steady
The space station?s new solar wings began to unfold in earnest at about 4:03 a.m. EDT (0803 GMT), while the ISS and shuttle astronauts slept, when flight controllers on Earth commanded the first of the two solar wings to extend a single mast section, or bay, of its 31.5-bay length.
?It?s really good to look out and see the solar array blankets extended one bay,? STS-117 mission commander Rick Sturckow said.
By 1:58 p.m. EDT (1759 GMT), both solar arrays were fully deployed.
Each ISS solar wing is made up of two 115-foot (35-meter) panels attached to a central mast. When fully unfurled, their wingspan reaches 240 feet (73 meters) from tip to tip.
Both arrays were deployed in stages, which allowed sunlight to warm them up and avoid their paper-thin photovoltaic cells from sticking to one another too strongly -- a phenomena known as ?stiction? -- after years of being packed in a box about 20 inches (50 centimeters) deep.
When NASA deployed its first pair of U.S. solar arrays from the station?s P6 truss during the STS-97 mission in 2000, the panels encountered severe stiction and a tension line came off its spool, prompting a spacewalk repair.
Tuesday?s solar array deployment, by comparison, appeared to go smoothly.
A navigation computer issue in the station?s Russian-built segment forced the orbital laboratory to switch between its own U.S. gyroscopes and the Atlantis shuttle?s thrusters to maintain attitude control, leading to some delays in fully charging the new solar wings and impacting the power produced by their older port-side counterparts. But by late Tuesday, the system was back online and the new arrays charging properly, NASA officials said.
Meanwhile, the Atlantis astronauts had some free time Tuesday before gearing up for Wednesday?s spacewalk.
Swanson and Forrester will perform the second of four planned spacewalks for the STS-117 mission during the excursion, and will spend the night in the station?s Quest airlock to cut down on the time required to prepare their bodies for the planned 6.5-hour excursion.
NASA is broadcasting the space shuttle Atlantis' STS-117 mission live on NASA TV. Click here for mission updates and SPACE.com's video feed.
- SPACE.com Video Interplayer: Space Station Power Up with STS-117
- STS-117 Power Play: Atlantis Shuttle Crew to Deliver ISS Solar Wings
- Complete Shuttle Mission Coverage
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