(AP) -- The six astronauts on Discovery's final flight are making space shuttle history. One never expected to be on board.
Astronaut Stephen Bowen was added to the crew just last month, replacing lead spacewalker Timothy Kopra, who was hurt in a bicycle wreck. There's never been a shuttle crew shake-up so close to flight.
Kopra helped train Bowen for a pair of spacewalks at the International Space Station.
"We're all disappointed that he's not going to be here," said commander Steven Lindsey. But if it wasn't for Kopra's assistance, "we couldn't have pulled this off in four weeks of training."
Discovery's all-veteran crew includes two former space station residents.
A brief look at the astronauts who blasted into orbit Thursday on Discovery's 39th and last mission:
Commander Steven Lindsey admits it's "really cool" being the last person to skipper Discovery. At the same time, it will be sad when it comes time for him to call "wheels stop" at the end of the flight.
He quickly ticks off all of Discovery's accomplishments: returning the shuttle fleet to flight following two disasters, delivering observatories, traveling to the space station.
"We're flying on the shoulders of thousands of people over the years, and 30 years of history with this program," he said. "We're fortunate enough to be in the cockpit, but we're representing all of them."
Lindsey, 50, a retired Air Force colonel from Temple City, Calif., is making his fifth shuttle flight and his third aboard Discovery. He flew alongside Mercury astronaut John Glenn on Discovery in 1998, then traveled twice to the space station before taking a turn as NASA's chief astronaut. He has been an astronaut since 1995 and is uncertain about his future plans.
He and wife Diane have three children ranging in age from 18 to the mid-20s.
Pilot Eric Boe considers his life part science fiction.
"I look at the space shuttle and to me, there's nothing cooler from a science fiction perspective than to see real science fiction," he said. "It's still amazing now. I look at it in wonderment."
The 46-year-old Air Force colonel would like nothing more than to fly whatever spacecraft replaces the shuttle. He's drawn to the aerospace field, in large part, because it's "where technology's going, where the planet is going."
He hopes to capture special moments during the flight in his mind so he can remember them forever.
"Trying to get that mental snapshot," he said.
This is the second shuttle mission for Boe, who's from Atlanta. He became an astronaut in 2000.
He and wife Kristen have a 12-year-old daughter and 10-year-old son.
Navy Capt. Stephen Bowen is closing out his space shuttle-flying career with an extra mission.
NASA tapped Bowen to fill in for the mission's lead spacewalker, Timothy Kopra, who had to bow out following a bicycle wreck near his Houston-area home in mid-January. Bowen was a natural choice: He'd flown to the space station on the previous shuttle mission and performed two spacewalks.
Bowen is the first astronaut to fly back-to-back shuttle missions.
He said he has "big shoes to fill," and he praised Kopra and astronaut Benjamin Alvin "Al" Drew Jr. for pulling together the spacewalks.
"I hope to be able to execute the plan as well as I can," Bowen said. "I'm sure I won't be able to fill it as well as Tim and Al could, but we'll see how this works out."
This will be the third shuttle flight for Bowen, 47, the first submarine officer to be chosen as an astronaut. His missions have unfolded in unusually rapid succession: November 2008, May 2010 and now February 2011.
He grew up in Cohasset, Mass., helping in his father's tiling business. He and wife Deborah have three teenage children.
Benjamin Alvin "Al" Drew Jr. can remember wanting to be a pilot as young as 4.
He was 5 1/2 when he asked his father whether it was a better career move to become a pilot or an astronaut. "I didn't want to give up either of them," he recalled. The elder Drew, a drug counselor, advised his son to become a pilot since most astronauts, at least back then, were pilots.
The plan worked. The Washington,D.C.-raised Drew went from flying helicopters in the Army to flying on the space shuttle.
"I was smitten with that whole idea of just being at treetop level at night in a formation of helicopters with guns," Drew, 48, said. "That was clearly not the straight-line path to being an astronaut. But it seemed like a very cool idea at the time."
Drew - a retired Air Force colonel - flew 60 combat missions over Panama in 1989, and the Persian Gulf and Iraq in the early 1990s. He became an astronaut in 2000.
On this shuttle mission, his second, he will add another skill to his repertoire when he performs a pair of spacewalks.
"What a great program, and I got to be a part of it," he said.
Dr. Michael Barratt never thought he'd ride on the space shuttle before the program ended. So he tossed his shuttle training notes into the recycling bin before leaving for Russia in 2009 to hitch a ride on a Soyuz rocket to the space station.
What a mistake. He was exercising at he space station when he learned he'd be returning to orbit. He'll help operate the station's robot arm.
"It was a huge honor to be asked to fly shuttle, and knowing that the program was coming to an end and how precious those seats were, that just raised the bar a lot," he said.
The 51-year-old physician joined NASA in 1991 to work on medical systems for NASA's original space station Freedom project. He became a flight surgeon in 1992 and assisted with the shuttle-Mir program out of Russia. He later moved to the space station program, serving as lead crew surgeon for the first crew to inhabit the orbiting lab. NASA picked him as an astronaut in 2000. He flew to and from the space station aboard a Russian Soyuz capsule, spending six months in orbit.
He and wife Michelle have five children ranging in age into the 20s. He grew up in Camas, Wash.
Nicole Stott learned via e-mail - while circling the planet - that she was getting one more shuttle ride.
She was just three weeks into her three-month stay at the space station in 2009 when her bosses informed her that she'd been assigned to Discovery's last flight. She immediately called husband Christopher, even though it was 2 in the morning for him.
"Are you willing to go for this kind of thing?" she asked. He was all for it.
He's actually in the space business. He is president and chief executive officer of Mansat Limited, a commercial space business headquartered on the Isle of Man, his homeland. They have an 8-year-old son.
Stott, 48, an engineer who grew up in Clearwater, Fla., joined NASA in 1988. She worked on shuttles at Kennedy Space Center, eventually becoming in charge of preparing Endeavour for launch and a lead engineer for Columbia. She became an astronaut in 2000. This is her second space mission; she'll help attach a cargo carrier to the space station, using a robot arm.
"I pinch myself now to think that I actually got to work that close to space shuttles every day and then now, somehow have been blessed with the opportunity to actually fly on them," she said.
Explore further: Image: Solar Electric Propulsion engine's ionizing Hall thruster