No Quick Fix Spacewalk for Disabled ISS Gyroscope

No Quick Fix Spacewalk for Disabled ISS Gyroscope
NASA engineers and technicians lower a control moment gyroscope - a replacement part to be installed at the International Space Station during an STS-114 spacewalk - into a carrier. The gyroscope is part of Discovery's cargo during NASA's first return to flight mission. (Image credit: NASA/KSC.)

The currentcrew of the International Space Station (ISS) will not make a special effort to replace a faulty circuit breaker that hobbled one of threegyroscopes used for orientation this week, NASA's ISS program manager saidThursday.

Instead,ISS Expedition 10 commander Leroy Chiao and flight engineer Salizhan Sharipovwill go ahead as planned with a March 28 spacewalk to install antennas andother equipment to the exterior of the space station.

"It willnot impact [the spacewalk] at all," said NASA ISS program manager BillGerstenmaier of the circuit breaker glitch during a teleconference withreporters. "We're perfectly fine with using two control moment gyroscopes forthat EVA."

The spacestation requires a minimum of two functional U.S.-built gyroscopes to maintainits position in space without switching to propellant-driven Russian thrusters.

Gerstenmaiersaid that a known fault with a single transistor within the circuit breaker,known as a Remote Power Control Module (RPCM), apparently caused a power lossan ISS gyroscope Wednesday. The fault is identical to an earlier glitchthat forced Expedition 9 astronauts to make an unplanned spacewalkrepair last year.

"When wemade the change out we knew the transistor had a fault in it and we assumed it couldshow up again [and] we were hoping it wouldn't be the case," Gerstenmaier said."But it looks like it is."

Spacestation officials said they will continue to examine other ISS systems to makesure the circuit breaker is the only failure.

Aspacewalk for another day

ISSmanagers said the earliest the RPCM could be replaced could be during the nextspace shuttle flight, STS-114, aboard Discovery, since a two astronauts on thatmission are already planning to replace a broken gyroscope. If that fallsthrough, the spacewalk repair could be reset for later this summer, they added.

"Itcertainly is possible and doable," said NASA astronaut Michael Fincke, whospent six months as ISS flight engineer during the Expedition 9 mission andhelped make the initial RPCM fix. "It should go even smoother and faster them."

The RPCMglitch is one of several currently afflicting the space station and its crew,ranging from broken exterior lights to a finicky Russian oxygen generator and abroken toilet, both of which were repaired earlier today by Sharipov.

"The thingsthat are going on at the space station are normal," Fincke said, adding thatExpedition 10's Chiao and Sharipov are doing a fine job of balancing thedemands of maintenance and science aboard the ISS.

Also today,NASA officials released their Implementation Plan for the International SpaceStation Continuing Flight, a 210-page document addressing ISS-related issuesfor the agency's shuttle return-to-flight effort.

"We triedto be as thorough and creative with these things, to look at what's going on atthe station, to keep it operational," Gerstenmaier said.

  • Complete Coverage: ISS Expedition 10

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Tariq Malik

Tariq is the Editor-in-Chief of and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. In October 2022, Tariq received the Harry Kolcum Award for excellence in space reporting from the National Space Club Florida Committee. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. You can find Tariq at and as the co-host to the This Week In Space podcast with space historian Rod Pyle on the TWiT network. To see his latest project, you can follow Tariq on Twitter @tariqjmalik.