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When NASA's shuttle Atlantis launches towards the International Space Station (ISS) Friday, the 100-ton rocket ship will ferry the high-flying laboratory's next U.S. crewmember into orbit.

Riding up to the ISS with Atlantis' STS-117 crew will be NASA spaceflyer Clayton Anderson, a late addition to the mission who will replace American astronaut Sunita Williams as part of the orbital laboratory's three-person Expedition 15 team.

"At first, you know, my expedition was relatively short," Anderson, 48, told SPACE.com, adding that he initially planned to be aboard the ISS from late June to September. "Now it's more, I would say, normal or more expected. So that's pretty cool that I'm going to do a truly long-duration mission."

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NASA mission managers plucked Anderson from the later STS-118 mission and added him to the STS-117 crew in late April in order to ensure a prompt Earth return for Williams after hail damage to the orbiter's fuel tank delayed Atlantis' launch.

Williams has lived aboard the ISS since December 2006, and faced a possible nine-month mission — rather than the traditional six-month ISS flight — if she did not return aboard Atlantis, Anderson said.

"I told her that I was her knight in shining armor come to rescue her from the throes of the space station," Anderson said with a laugh as he described his talks with Williams.

During Expedition 15, Anderson will serve as a flight engineer and NASA science officer, and looks forward to a series of spacewalks and ISS construction tasks during his flight. But he hopes to lend a hand to Atlantis' shuttle crew too.

"They are six men who are totally trained for their mission without me," Anderson said of the STS-117 astronauts. "Now they've added me so I can become, I hope, a utility infielder, and help them out wherever I'm needed."

Atlantis' STS-117 mission is slated to launch June 8 to deliver two new starboard solar arrays and massive pieces of framework to the ISS.

NASA veteran's first flight

A native of Ashland, Nebr., Anderson has spent more than two decades working at NASA's Johnson Space Center in Houston, where he started as a summer intern in 1981. So his interest in reaching space personally comes as no surprise.

"I have a little argument with my mom back in Nebraska," Anderson said in a NASA interview. "She says I was ready to be an astronaut at age 4 when she dressed me up in tinfoil and I got second place in the local parade during July. She said I was robbed — I should've gotten first."

But for Anderson, it was watching the crew of NASA's Apollo 8 mission swing behind the Moon on television in 1968 that solidified spaceflight as a goal.

"[T]he neatest thing was how scared I was when they went behind the Moon," Anderson said. "[T]hen when they came back around on the other side and I finally heard that Quindar tone, the little beep everybody hears on TV ... and I heard them start to talk again, it just gave me this really chilled feeling inside. And I thought, 'Wow, that is the coolest thing!'"

Anderson holds a bachelor's of science degree in physics from Nebraska's Hastings College and a master's of science degree in aerospace engineering.

He joined NASA full-time in 1983 to help design shuttle and ISS rendezvous and docking operations within the Mission and Planning and Analysis Division at JSC.

Anderson joined NASA's astronaut ranks in 1998, where he has trained for a long-duration spaceflight from the start. He served as a crew support astronaut for the station's Expedition 4 mission, and later as a backup crewmember for Expeditions 12, 13 and 14 for the orbital laboratory.

All in the family

Anderson's shuttle flight switch meant some late training for the ISS-bound astronaut, as well as some schedule scrambling for his family and friends who had already planned to attend the STS-118 launch in August. But his wife Susan is well-acquainted with such changes, he said.

"Sue is very adapted," said Anderson of his wife. "She worked in the shuttle-Mir station program and she is very familiar with launch slips and delays, and the requisite risk that goes with all this so she'll be able to deal with it pretty well."

With his earlier launch, Anderson now expects to spend about four months in space before returning to Earth in late October aboard a NASA shuttle during the STS-120 mission. But while he does get an extra few months in space, it comes with the drawback of more time apart from his family.

"But I do know that the sacrifice will be worth it," Anderson said in a preflight briefing. "Anybody that's done something similar to this understands that, when the times are really, really tough, if you can keep looking ahead to what the ultimate goal is, then as you look back on everything it really doesn't seem quite so bad."

Anderson has kept a meticulous log of his spaceflight training to share with his two children, son Cole and daughter Sutton Marie, along with his extended NASA family as a sort of thank you for years of support, he said.

"The neatest thing for me is the fact that everyone that's here that I know and worked with and played with and interacted with during all those 20-some years to this point can all share in this journey because they're a part of me," Anderson said. "All those people will fly with me and I think that is probably one of the most rewarding aspects of this mission."

To follow American astronaut Clayton Anderson's path to space, visit his NASA journal archive here.

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