Cosmonauts Set For Return Home Aboard Soyuz
WASHINGTON - Cosmonauts aboard the International Space Station are preparing to return home next month aboard a Soyuz spacecraft, while Russian engineers believe they?ve isolated the glitch that sent the last two landings careening off-course, mission managers said Thursday.
Expedition 17 station commander Sergei Volkov and flight engineer Oleg Kononenko are due to land on Oct. 23 to end a six-month mission that included spacewalk surgery on their Soyuz TMA-12 spacecraft to help engineers understand why one of five separation explosive bolts on similar vehicles failed to fire during the recent landings.
Volkov and Kononenko removed the suspect bolt in a July spacewalk so it can be returned to Earth for analysis.
Station astronauts aboard Soyuz craft last October and April reentered the Earth?s atmosphere at a bumpy, steeper-than-normal angle because the failed explosive bolt kept their landing capsule attached to an adjoining module longer than planned. The glitch sent them on a steeper, so-called ?ballistic landing? that subjected the astronauts to higher gravitational forces and sent them hundreds of miles off-course.
Russian engineers believe electrical arcs triggered by ungrounded insulation near the bolt?s location on the Soyuz can cause the pyrotechnic device to fail, said NASA space station program manager Mike Suffredini in a mission briefing. The sparks stem from the electrical potential generated between the space station?s expansive U.S. solar arrays and the surrounding environment.
?Where it?s failed to separate each time, they?ve determined there?s been some arcing, if you will, or equalizing of voltage in this area,? Suffredini told reporters. ?This, over time, has caused the pyros to be ineffective.?
With the suspect bolt removed from Soyuz TMA-12, Russian engineers believe Volkov and Kononenko will have a smoother ride. Similar bolts on future Soyuz are also being replaced, Suffredini said.
?Given that cause, they believe they?ve made the steps necessary so that we won?t experience ballistic reentry for those reasons,? he added.
Suffredini added that while NASA engineers found it is possible that the Soyuz pyrotechnic bolts could be affected by sparks from the station?s surrounding environment, they believe a much higher electrical potential would be required to cause the arcing effect.
Crew swap ahead
While Volkov and Kononenko prepare for their return to Earth, their NASA crewmate Gregory Chamitoff is looking forward to seeing some new faces. Chamitoff joined the two cosmonauts midway through their Expedition 17 mission in June and will stay aboard the station to join the incoming Expedition 18 commander Mike Fincke, of NASA, and Russian flight engineer Yuri Lonchakov.
The Soyuz TMA-13 spacecraft carrying that new crew is slated to launch Oct. 12 from the Central Asian spaceport of Baikonur Cosmodrome in Kazakhstan.
Also launching to the station with the Expedition 18 crew will be American space tourist Richard Garriott, an American computer game developer who is paying $30 million for a 10-day spaceflight. His mission, the sixth privately paid ticket to the space station, was arranged with Russia?s Federal Space Agency by the Virginia-based firm Space Adventures.
Garriott is the son of retired NASA astronaut Owen Garriott, making him the first second-generation American astronaut when he launches into orbit next month. He has lined up a host of science experiments and educational outreach projects for the short spaceflight, and will return to Earth with Volkov and Kononenko in late October.
By coincidence, Volkov is the son of famed Russian cosmonaut Alexander Volkov, and became the world?s first second-generation spaceflyer when he launched in April.
During Expedition 18, station astronauts plan to work alongside visiting NASA space shuttle crews to install a new bathroom, sleeping quarters and life support equipment that will allow the orbital laboratory to double its crew size to six people in 2009. Chamitoff is due to return to Earth in November during the first of those shuttle missions, with two other one-person crew swaps to follow on subsequent flights.
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