Shuttle Astronaut to Return to Spacewalk Duty

Shuttle Astronaut to Return to Spacewalk Duty
Astronaut Rex Walheim (left) and European Space Agency astronaut Hans Schlegel prepare to join seven other astronauts and a cosmonaut onboard the International Space Station after hatches were opened between the orbital outpost and the shuttle Atlantis on Feb. 9, 2008. (Image credit: NASA.)

HOUSTON —German astronaut Hans Schlegel will return to spacewalking duty outside theInternational Space Station (ISS) Wednesday after sitting out on an earlier excursiondue to a medical issue.

A veteranEuropean Space Agency (ESA), astronaut Schlegel will stepoutside the ISS on his first spacewalk with crewmate Rex Walheim to replacean empty nitrogen tank on the space station?s metallic backbone-like truss.

?I feelreally great right now," Schlegel told reporters from the flight deck of NASA?sshuttle Atlantis on Tuesday. ?I?m, of course, a little bit anxious becausetomorrow is going to be my first [spacewalk].?

Missionmanagers pulled Schlegel, 56, from the first spacewalk of Atlantis? STS-122mission — Monday?s excursion to help attach the station?snew European Columbus lab — due to an undisclosed illness. Officials withNASA, the ESA and Schlegel himself declined to discuss the illness in detailciting the need for medical privacy.

ButSchlegel stressed Tuesday that he supported the decision to replace him onMonday?s spacewalk to ensure Columbus, which the astronaut and crewmates openedfor business yesterday, reached the ISS successfully.

?I didn?tgo outside, but I helped from inside and that?s the most important thing,? saidSchlegel, who helped choreograph the orbital work with shuttle pilot AlanPoindexter. ?We made sure that this [spacewalk] was executed right,successfully and in a good way.?

Poindexterwill also watch over today?s spacewalk, which calls for Schlegel and Walheim tostep outside the space station?s Quest airlock at 9:35 a.m. EST (1435 GMT). Whilethe outing marks a first Schlegel, it will be Walheim?s fourth foray into theblackness of space clad only in a NASA-issue spacesuit.

The shuttleastronauts have a singular goal for today?s spacewalk: the replacement of aso-called nitrogen tank assembly used to charge up the ammonia coolant linesthat shed excess heat through the station?s port side radiators. Installed in2002, the tank has been depleted of its 80-pound (36-kg) supply of nitrogen andcannot be refilled in orbit.

?Thenitrogen tank weighs around 550 pounds (249-kg) and it is roughly the size of asmall refrigerator,? said Anna Jarvis, NASA?s lead spacewalk officer for theSTS-122 flight.

To swap outthe empty tank, Walheim will ride the space station?s Canadarm2 robotic armdown to the shuttle Atlantis? cargo bay to retrieve its replacement. An orbitalshell game will then follow to swap out the tanks before Walheim can take theolder one back to Atlantis for the return trip home.

?It seems soeasy,? Walheim said in a NASA interview.

But thework is expected to last more than 6 1/2 hours, primarily because of the needto wrestle with a series of tough bolts, detach and reattach nitrogen lines andmove the station?s robotic arm periodically to stay in position. Atlantismission specialist Leland Melvin will oversee the robotic arm work from insidethe ISS.

?[It] takesa fair amount of time, and then doing all the connections in back and doing thegymnastics of swapping them around,? Walheim said. ?These are very largecomponents.?

Schlegelwill assist Walheim during the spacewalk, which will include a few extracable-connecting chores leftover from Monday?s excursion. If they have additional time, they may also cover a set of trunnions pins aboard the Columbus lab in insulation.

?The only realdifference at the beginning,? said NASA station flight director Bob Dempsey ofthe added work. ?Otherwise the timeline is pretty much the same. ?

Commandedby veteran shuttle flyer Stephen Frick, Atlantis? seven-astronaut crew launchedFeb. 7 on what is now a 12-day mission to deliver the Columbus lab to the ISSand swap out one member of the station?s Expedition 16 crew. The shuttle isscheduled to land on Feb. 19, but could gain an extra 24 hours docked at the stationif mission managers decide later today to extend the spaceflight another day.

Today?sspacewalk will begin a 9:35 a.m. EST (1535 GMT). NASA is broadcasting Atlantis'STS-122 mission live on NASA TV. Clickhere for's shuttle mission coverage and NASA TV feed. 

  • NEW VIDEO: STS-122 Second Spacewalk Overview
  • VIDEO: ESA's New Science Laboratory
  • NEW IMAGES: STS-122 Launch Day for Shuttle Atlantis


Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at:

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.