Astronauts to Inspect Space Station Joints in Spacewalk

Astronauts to Inspect Space Station Joints in Spacewalk
NASA astronaut Peggy Whitson, Expedition 16 commander at the International Space Station, poses for a photograph while clad in a NASA spacesuit. (Image credit: NASA.)

Astronautsaboard the International Space Station (ISS) will step outside their spacecraftearly Tuesday to inspect a pair of critical joints serving the orbital lab'sstarboard solar wings.

Station commanderPeggy Whitson and flight engineer Dan Tani are due to begin the fourthspacewalk of their Expedition 16 mission no later than 6:00 a.m. EST (1100 GMT)to take an in-depth look at a large gear contaminated by metallic grit and alocked solar wing joint.

"Whatwe're providing is additional data," Whitson told reporters last week,adding that engineers on Earth will use tomorrow's inspections to draw up possiblerepair plans.

The twojoints, each on a different axis, are designed to rotate the station'swing-like solar panels to continuously face the sun and maximize energyproduction.

During alate October spacewalk, Tani discovereddamage and metal shavings inside the station's starboard Solar Alpha RotaryJoint (SARJ), a massive, 10-foot (3-meter) wide gear that turns the station'soutboard starboard solar arrays like a paddlewheel. Engineers will useTuesday's inspection to help decide whether the joint can be cleaned byspacewalking astronauts or will require a complicated repair over multiplespacewalks.

"We'restill in the throes of understanding what happened and how to moveforward," said Kirk Shireman, NASA's deputy ISS program manager, in amission briefing.

Anotherjoint, a Beta Gimbal Assembly used to pivot an individual solar wing from sideto side, was locked in place earlier this month after twopower feeds dropped out, possibly due to damage from a micrometeorite,mission managers said.

"We'lltry and figure out what's going on there as well," Whitson said.

Tuesday'sspacewalk will mark the fourth for the Expedition 16 crew and the 100thdedicated to space station construction. The astronauts were scheduled to begincamping out inside the station's Quest airlock at 2:50 p.m. EST (1950 GMT) to prepare their bodies to work in the 100 percent oxygen environment oftheir NASA-issue spacesuits.

Anorbital hunt

Whitson andTani will make a systematic inspection of the space station's starboard SARJ jointin hopes of finding the source of damage to the mechanism's large metal ring.

They willremove and peer under as many of the joint's 22 protective covers and retrieveone of 12 bearings that will be returned to Earth for study.

"Theground has data that suggests that maybe that's where the problem is,"Whitson said of the bearing, known as Trundle Bearing 5. "But if we canvisibly tell that it is a different one, we'll bring in the one we think is atroublemaker."

Whitsonsaid that, at face value, staging a series of spacewalks to repair the SARJjoint by switching it to a backup ring appears simpler than a full-scale cleanup operation, but Tuesday's inspection will help engineers decide what futuresteps to take.

Missionmanagers initially scheduled the joint inspection as an extra excursion duringNASA's planned STS-122shuttle mission to deliver the European-built Columbus laboratory to theISS earlier this month. But the spaceflight's delay to noearlier than Jan. 10 allowed its addition to the Expedition 16 mission.

"Wewere pretty set for this [spacewalk] in terms of tools and spacesuitconfiguration," Tani said of the upcoming extravehicular activity (EVA)."I don't think we're going to be losing any planned work for thisEVA."

NASAwill broadcast the Expedition 16 crew's fourth spacewalk live on NASA TVbeginning at 4:30 a.m. EST (0930 GMT). Click here for's live coverage andmission updates.

  • VIDEO: ISS Commander Peggy Whitson Takes Charge
  • IMAGES: The STS-120 Shuttle Mission from Orbit to Earth
  • Video Interplayer: NASA's STS-122: Columbus Sets Sail for ISS


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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.