|Volume: 05, Issue: 13||06/13/2007|
Mission STS-117: AtlantisThe STS-117 Atlantis mission to the International Space Station includes the tasks of installing a new truss segment, unfurling new solar arrays, and folding up an old one. The crew includes commander Rick Sturckow, pilot Lee Archambault, and mission specialists Patrick Forrester, Steven Swanson, John “Danny” Olivas, Jim Reilly, and Clay Anderson. Anderson will remain on the station to begin a long-duration flight. Expedition 15 flight engineer Suni Williams, who has been aboard the station since December 2006, will return home on Atlantis.
In addition to the crew, a small piece of early American history is traveling aboard Atlantis. A nearly 400-year-old metal cargo tag bearing the words “Yames Towne” and some commemorative mementoes are packed in Atlantis’ middeck floor cargo space for the roundtrip flight to the International Space Station. Their hitchhike through the galaxy honors this year’s 400th anniversary of Jamestown, Virginia, the first permanent English settlement in North America. NASA has teamed with Jamestown 2007 to promote the spirit of exploration then, now, and in the future.
The shuttle launched June 8 and docked to the International Space Station on Day 3 of the mission after performing the Rendezvous Pitch Maneuver safety test. This test includes turning onto its back to reveal any damage the underside of the shuttle may have sustained.
On Day 4, a truss segment including a set of solar arrays was installed by the station’s robot arm, and mission specialists Reilly and Olivas made the first spacewalk to begin connecting the segment and unfurling the arrays. The new solar arrays on the starboard side of the station are a mirror image of those installed on the port side in September 2006. Like the crew that installed the port arrays, the STS-117 crew unfolded the arrays and prepared them to track the sun and generate power. Unfortunately, things didn’t go quite as intended the first time a set of solar arrays was unfolded in space in 2000. The array panels stuck together, allowing cables meant to pull the arrays taut to come off their pulleys and leave the array slack.
The crew was able to fix the problem, but to avoid it altogether in the future the unfolding technique was changed when the second set of arrays was launched on STS-115. By unfolding more slowly and during periods of sunlight, the arrays were deployed without a hitch.
Crew members also want to learn from a problem their predecessors experienced in September 2006. A 10-foot wide rotary joint turns the solar arrays, allowing them to track the movement of the sun. Before that can happen, the bolts that keep the joint from shifting during launch in the shuttle’s cargo bay have to be removed. That’s where the STS-115 crew ran into trouble – the bolts were screwed in more tightly than expected. It took more than 20 minutes and two astronauts to loosen one of them. The STS-117 now has a tool onboard that will give their elbow grease a little more oomph.
“We have a torque multiplier that we’re bringing up that they didn’t have,” Sturckow said. “So if we do encounter the same difficulty with high torques that they had, we’ll break out this tool. And we’ll apply whatever torque it takes to break the bolt or back it out at the higher torque settings. So I don’t have any doubt that we’ll be able to remove those launch restraints.”
Like the solar arrays activated in December 2006, the new arrays won’t be able to rotate and track the sun until another set of arrays is retracted. If STS-116 is any indication, the assignment won’t be easy. It took more than 71 attempts and an extra spacewalk to neatly fold the array back into its box during that mission. The original plan was for the arrays to be folded by ground command while all the astronauts were inside the station. However flight controllers developed a plan that has Swanson and Forrester assisting with the folding during the second spacewalk of the mission so that the arrays can be relocated. This walk began on Day 6 and will also involve continuing work on the newly unfurled solar arrays.
Two further spacewalks are being prepared before the shuttle undocks from the Space Station and returns for landing on Day 12.
For more information about STS-117, please visit: http://www.nasa.gov/mission_pages/shuttle/main/index.html.
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