Twenty-five years ago this week, NASA launched two astronauts into orbit aboard the first flight of the Columbia space shuttle.

But on April 12, 1981 when Columbia first left Earth, those two test pilots - STS-1 commander John Young and pilot Robert Crippen - carried with them the hopes of thousands of engineers, designers, flight controllers and spaceflight supporters eager for a new U.S. crewed spacecraft.

"There were literally tens of thousands of people that were involved," said Crippen as he looked back on STS-1's morning launch, which marked his first spaceflight. "John and I just got to do the best part."

Young and Crippen spent 54.5 hours orbiting Earth to test what became NASA's longest-running manned spacecraft and the world's first reusable, winged rocketship. And while space shuttle system has never managed to reach its goals of quick turnaround and lower-cost launches, the spacecraft also represented a major departure from NASA's capsule-based manned spacecraft.

"It was a totally different machine from what we were flying before," said Young, who flew aboard NASA's Gemini and Apollo vehicles before STS-1, in an interview. "We had about 23 guys in the Astronaut Office and they would have all killed to be on that first flight."

Since Columbia's STS-1 flight, NASA has launched 113 space shuttle missions with its orbiter fleet filled out by the Challenger, Atlantis, Discovery and Endeavour vehicles. NASA honored its STS-1 astronauts by renaming the launch firing room used for their flight the Young Crippen Firing Room on Thursday.

Image Gallery: NASA's First Shuttle Flight VIDEO: STS-1 Commander John Young Remembers Columbia's Debut

"It's still a risky business," Young said. "The shuttle has a proven one in 57 failure rate."

Building Columbia

During the 1970s, NASA tapped Rockwell International - now part of Boeing - as primary contractor for the orbiter system, where engineers worked feverishly to ready the spacecraft for flight.

"It was an extremely busy time," said Dwight Woolhouse, Boeing's associate program director for orbiter development, who served as aerosurfaces subsystem manager for Columbia's first flight. "Even up to a couple of months before that first flight we were still immersed in hardware tests. And yet, everybody really had this attitude that we were going to find a way to make this work."

Columbia was heavier than its younger shuttle brethren, each of which weigh about 100 tons, by about 5,000 pounds (2,267kilograms) since designers had yet to learn where other weight savings could be made, its builders said.

The push to use the spacecraft not only to launch astronauts and large satellites or other cargo in its school bus-sized payload bay, as well as the thousands of ceramic tiles that protected the orbiter from the intense heat of reentry, led to an increasing complexity that not only required everything to work properly for a safe flight, but also lengthened shuttle turnaround for future missions.

"There's something like 43 independent major subsystems that must work perfectly for a flight," said Bo Bejmuk, Boeing's current orbiter program director who watched Columbia launch on its STS-1 mission as a freshly-appointed system integration manager. "I was a much younger guy then. And you sit there and you see the countdown and you see John Young's face during the traditional [pre-launch] breakfast and you say 'My God, I hope we were exactly right.'"

For Bejmuk, watching Columbia rocket into orbit in 1981 gave more than just a sense of accomplishment of helping to fly NASA's first orbital space plane.

"I felt like NASA gave me an incredible birthday present," Bejmuk said, adding that his 41^st birthday coincided with STS-1's first flight. "I had plenty of anxiety in my stomach."

Wayne Hale, NASA's space shuttle program manager, remembers being sent home from his propulsion support post at Johnson Space Center in Houston just three hours before STS-1's launch.

"We went off console to go home and try to get some sleep, which of course was impossible," Hale, who served as a consumables analyst for the flight, told SPACE.com. "We ended up watching it on television, which just astounded me. The launch of a shuttle is so different from other vehicles. It has a lot of get up and go."

"There are a lot of us, I think, who would pay to sweep out the floors around here, because [spaceflight] is what we want to do," Hale said.

Nine minutes to space

Young and Crippen said their initial two-day shuttle flight was packed with tests after their nine-minute launch.

"During the flight, it was pretty busy, but it was still a fantastic thing," Crippen said, adding that as a first-time spaceflyer, the chance to ride with Young - who walked on the Moon during NASA's Apollo 16 mission - was a bonus. "When you're doing it for the first time, it's nice to do it with an old pro."

The STS-1 crew returned to Earth on April 14, rolling to a stop on a desert runway at Edwards Air Force Base and paving the way for 292 other astronauts and cosmonauts to join Young and Crippen in the ranks of shuttle flyers.

Planetary scientist Tom Jones, a veteran of four shuttle flights, flew aboard Columbia in 1996, using its robotic arm to deploy a pair of science satellites during the STS-80 mission.

"I got goose bumps crawling into the shuttle knowing that it was the same space ship that flew John Young and Bob Crippen on their first flight," said Jones, who also flew aboard Atlantis and Endeavour, NASA's youngest orbiter. "If you looked carefully, out of the corner of your eye, in the cockpit, you'd be able to tell you were aboard Columbia because of it had some extra panels and switches that later orbiters didn't have.

"And you'd notice the little scuffs on the walls, and the sort of touch-up paint from its long service," Jones said of Columbia, adding that the memory of the 2003 accident that destroyed the orbiter and killed seven of his fellow astronauts is still strong. "It still bothers me that that my spaceship that was lost and my friends that were lost. It's always going to leave a hole in my heart when the shuttles are retired and I go to the museum and it's not there."

Throughout its 22-year service, Columbia launched into orbit on 28 missions, all but one returned to home safely.

"I have a deep sense of gratitude," Jones said, adding that it is people - not hardware- that made Columbia first flight and all shuttle missions possible. "You never get a chance to see them and thank them for all their work."