ISS Astronauts to Free Jammed Spacecraft Antenna in Spacewalk

ISS Astronauts to Free Jammed Spacecraft Antenna in Spacewalk
Russian cosmonaut Mikhail Tyurin, an Expedition 14 flight engineer, prepares a Russian-built Orlan spacesuit for spacewalk during his six-month mission.
(Image: © NASA.)

Astronautsaboard the InternationalSpace Station (ISS) are setting the stage for the spacewalk finale of theirsix-month mission Thursday to free a jammed antenna on a Russian cargo ship.

ISS Expedition14 commander MichaelLopez-Alegria and flight engineer MikhailTyurin will step outside the space station at 5:00 a.m. EST (1000 GMT) toloose a Progress23 supply ship antenna, among other tasks, during a planned six-hourspacewalk [VIDEO:Spacewalk Overview].

"The crewis in great shape and they're ready to go," Rick LaBrode, NASA's lead ISS flight director for thespacewalk, said of the upcoming extravehicular activity (EVA).

Thursday'sspacewalk will mark the fifth and final planned EVA - an ISS mission record - forthe Expedition 14 crew as well as the fourthin a series of densely-packed activities. Lopez-Alegria and Expedition 14flight engineer SunitaWilliams staged threespacewalks in nine days to overhaul the space station's cooling system.

Spacecraftmechanics

Clad inred-striped Russian Orlan spacesuits [image],Tyurin and Lopez-Alegria will chisel, hammer or cut the Progress spacecraft'santenna free from its wedged position up against an ISS handrail [image].

"That's notwhere we want it. It all should be folded down nicely," LaBrode said of thejammed antenna, which served as part of Progress 23's autonomous Kursnavigation system that guided the unmanned space freighter to the ISS. "InApril we're going to be undocking this Progress vehicle and in order to be ableto do this safely we need to get that antenna retracted and up out of the way."[VIDEO:Spacecraft Repair]

The antennafailedto retract properly when the unmanned Progress 23 cargo ship dockedat the aft-end of the space station's Russian-built Zvezdaservice module in October 2006 [image].Efforts to free it failedduring a Novemberspacewalk.

ISS flightcontrollers aren't sure how the stuck antenna will affect Progress 23's Apriljettison, station managers said. "Because of that unknown, there's majorconcern that you may have control problems," LaBrode said.

Tyurin, whowill lead Thursday's spacewalk, and Lopez-Alegria will first try to manuallyfree the Progress antenna by manhandling it loose with a chisel-like tool andhammer, and then tying it down against the cargo ship's hull. Failing that,they can use a U.S. bolt cutter-like tool to sever two of the antenna's fouraluminum struts and then fold it against the Progress 23 exterior [image].

"They'vegot a whole bag of tricks," Glenda Laws, NASA's Expedition 14 lead EVA officer,said of the ISS spacewalkers.

Tyurin andLopez-Alegria could even cut all four of the antenna's cylindrical struts anddump the entire assembly overboard if it remains stubbornly in place afterother attempts, mission managers said.

"Everyoneis pretty confident," Laws said, adding that the spacewalkers have a goodchance of freeing Progress 23's antenna without resorting to the cutting tool.

Othertasks

Tyurin andLopez-Alegria have a number of other maintenance tasks on tap for Thursday'sspacewalk.

The astronauts plan to perform a seriesof photographic surveys of a Russian satellite navigation antenna, a German-builtRockviss robotic experiment, and a docking target for the EuropeanSpace Agency's Automated Transfer Vehicle - an unpiloted cargo ship slatedto make its first flight to the ISS later this year.

Tyurin andLopez-Alegria are also due to swap out a Russian materials exposure experiment,inspect the station's Russian-built Strela crane, mate bolts and connectors forother ISS hardware.

Laws saidThursday's EVA will mark the 81st spacewalk dedicated to ISSassembly or maintenance. Tyurin will make his fifth career spacewalk during theactivity while Lopez-Alegria is poised to make his 10th and set a new NASArecord, she added.

NASAwill provide a live broadcast of the ISS Expedition 14 crew's spacewalk on NASATV beginning at 4:00 a.m. EST (0900 GMT).

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