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Cosmonauts Set For Return Home Aboard Soyuz

September 26, 2008

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.

 


Source: imaginova



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