(AP) -- The astronauts headed to the international space station include a Twittering skipper, a classically trained musician who named her son after one of Columbia's fallen astronauts, and a former Navy SEAL who went into Afghanistan two weeks after the Sept. 11, 2001, terrorist attacks.
Space shuttle Endeavour's motley crew of seven is scheduled to blast off Saturday. When they join the six residents at the space station, it will be the first time so many have been in orbit together. A brief look at each:
Commander Mark Polansky is about to become only the second astronaut to tweet from space.
Polansky - known as Astro-127 because of the mission number - has been posting Twitter updates for more than a month. He's also seen on YouTube, making a pitch for questions he can answer during the flight.
He follows Michael Massimino, who provided brief Twitter messages during the May shuttle flight.
"I'll be the first to admit that I didn't know a tweet from a Twitter from a Facebook from MySpace before I got into this. But as I've done it, I've learned that there's a whole community of people who love this stuff," said Polansky, 53, a former Air Force pilot. "I hope that we draw a lot of people in."
Polansky, who's from Edison, N.J., will be making his third trip to the space station. He's been an astronaut since 1996. Before that, he was an engineer and research pilot for NASA.
He and wife Lisa, who used to work with flight crew equipment, have a 4-year-old daughter and a son who will turn 2 while his father is in orbit.
Pilot Douglas Hurley helped strap in the seven astronauts who died aboard Columbia in 2003.
Now it's his turn to climb aboard a space shuttle for liftoff.
"It's a risk business, that's just part of the job," the space rookie said. "I had to come to grips with that many, many, many years ago flying fighters and flying off aircraft carriers."
Following the accident, Hurley served on the Columbia reconstruction team. He said he never considered quitting NASA. Rather, his objective was "what can I do to make this business as safe as it can be."
Hurley, 42, a Marine lieutenant colonel with the customary crewcut, flew F/A-18s throughout the 1990s. "From there, it was kind of like, 'OK, what else can I fly?' " He became an astronaut in 2000.
He is from Endicott, N.Y., and likes to point out that three other astronauts are from the same 60-mile stretch of Route 17. "Must be something in the water up there," he joked.
Hurley is a huge NASCAR fan. His cousin is married to Greg Zipadelli, crew chief for the No. 20 Home Depot team.
Dr. David Wolf is an electrical engineer, physician, competitive aerobatic pilot, one-time NASA inventor of the year, and chief of the astronaut spacewalking branch.
So it's no surprise he's the lead spacewalker on this mission. He will venture out on three of the five spacewalks.
"I guess I've never wanted to do anything else more than be an astronaut and fly in space," he said. "To me, it's the most fulfilling spot on the team and it gets more fulfilling every day, every flight."
Wolf, 52, who's from Indianapolis, joined Johnson Space Center in Houston in 1983, working on medical equipment for space travel. He became an astronaut in 1990. But he unwittingly got caught up in an FBI kickback and bribery sting at Johnson in 1992 and 1993, and although he did nothing wrong, apologized on national TV. He spent four months on Russia's old Mir space station in 1997, supposedly as penance.
When he got called into the boss' office 1 1/2 years ago, he had no idea he was about to be offered a fourth spaceflight. "I thought I was in trouble," he said.
Army Col. Timothy Kopra will move into the space station and stay until August, then hitch a ride back on another shuttle.
When Kopra was growing up in Austin, Texas, in the 1960s and 1970s, NASA was landing men on the moon and "at least every boy wanted to be a fireman, a policeman or an astronaut." He recalls staying up late to watch the moon landings on TV.
"That sense of adventure and the excitement from that experience stuck with me," he said.
Kopra, 46, a former Army aviator and platoon leader, served in Operations Desert Shield and Desert Storm in the early 1990s and went on to test pilot school. He was assigned to Johnson Space Center in 1998 as an engineer, working in the space station program, and became an astronaut two years later.
This will be his first spaceflight. He will perform one spacewalk before settling into his space station duties. He's packed several biographies and audio books about early American history, for leisure.
He and wife Dawn have a 13-year-old daughter and 12-year-old son.
Christopher Cassidy has been in some pretty scary situations as a Navy SEAL, especially in Afghanistan in the wake of the Sept. 11, 2001, terrorist attacks.
Cassidy acknowledged space has its own dangers, but noted: "There won't be people shooting at me."
"In spaceflight, I think the risk is all of the unknown things that we don't know are looming out there to trip us up," he said. His biggest fear? "I just don't want to screw up."
Cassidy, 39, a Navy commander from York, Maine, was awarded the bronze star and a presidential citation for leading a nine-day operation at a cave complex on the Afghan-Pakistan border. He picked up another bronze star a few years later.
His resume reads like James Bond's. As a 10-year member of the SEALS, Cassidy was skilled in building assaults, ship boardings, desert reconnaissance, combat diving, underwater explosives, parachuting and rappelling.
"I like a little bit of a thrill," he explained with a chuckle.
NASA picked him as an astronaut in 2004. This is his first spaceflight. By virtue of his seating on the shuttle, he will become the 500th person to fly in space, and he will perform three spacewalks.
He and wife Julie have two daughters, one 14 and one who turns 12 this week, and a 10-year-old son.
Dr. Thomas Marshburn, a former emergency room doctor and preacher's son, has been fascinated with space ever since he was 6 - as old as his daughter is now.
He read every book about space he could find at the school library while growing up in Statesville, N.C., and Atlanta, and ordered every space film.
He didn't realize his passion, back then, was obvious to everyone else until recently. "I remember you talking about that in 10th grade," he said classmates told him.
Marshburn "fell madly in love with medicine" and worked in emergency rooms around the country before becoming a NASA flight surgeon in 1994. He worked with U.S. astronauts aboard the Russian Mir space station and later shuttle and international space station crews. He joined their ranks in 2004.
This is his first spaceflight. He will perform three spacewalks.
Marshburn, who is married, is the youngest of seven children. All his brothers and sisters will be at the launch.
An interesting tidbit: Marshburn backpacked from Canada to Mexico in 1980, covering 2,600 miles.
For Canadian astronaut Julie Payette, space is addictive. That's why she's returning for a second shot after 10 years.
She will join fellow Canadian Bob Thirsk at the international space station. It will be the first time two Canadians are in orbit at the same time, something Payette downplays.
"Maybe in some distant future, we're going to look back and stop counting that kind of thing because it will be normal for human beings to be in space," said Payette, 45, an engineer from Montreal.
Payette said she feels guiltier now about space fatality statistics than she did when she flew in 1999 to the orbiting outpost. That's because she now has a family.
Her son, Laurier, is named after friend Laurel Clark, who died aboard Columbia in 2003. He was born 4 1/2 months after the accident, and will turn 6 while his mother is in space. Her husband is a test pilot for Lockheed Martin Corp. She also has a teenage stepson.
A Canadian Space Agency astronaut since 1992, Payette is flying a drop of water from the three oceans surrounding Canada and all five Great Lakes for a water awareness exhibit.
She plays the piano and has sung with orchestras in Canada and Switzerland.
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