Atlantis is due home Thursday -- the shuttle's final flight. Today, the crew hung a small American flag on the door to the space station. That flag traveled on the first shuttle, back in 1981. It will stay at the space station for a few years, until a private firm sends astronauts up to get it.
And, as CBS News correspondent Mark Strassmann reports, there's a fierce competition among companies hoping to build America's next spaceship.
Beneath the blue skies of Boulder, Colo., what's happening inside a makeshift garage could re-launch America's manned space program.
This is where Dream Chaser comes in. It would be 1/40th the shuttle's size --a sort of space taxi, designed to carry up to seven astronauts, dock with the space station, and then return to Earth.
Jim Voss heads the space exploration team at Sierra Nevada Corporation, one of four privately-owned companies in a NASA-supervised competition to design and build a successor to the space shuttle. NASA is helping fund the companies and Sierra Nevada got $100 million in seed money.
"It's very much like the shuttle, but much, much, much smaller," Voss said of Dream Chaser.
A former NASA astronaut, Voss went on five space missions. Now he's helping Sierra Nevada develop a reusable winged spaceship that he said would do a better job of returning experiments to Earth.
"After six months on the space station, landing gently is much better than landing hard in a capsule. And for science return, if we return them to the Earth and it's not a gentle landing, we could destroy the science and it's of no use," said Voss.
But Dream Chaser's competitors took a very different approach: they're all 1960's-style crew capsule. Boeing, SpaceX and Blue Origin are also getting development money from NASA.
Stokes McMillan, who also left NASA's shuttle program to work on Dream Chaser, said compared to government projects, the private space business moves at the speed of light.
"We do things a lot quicker," he said.
When Strassman said that to be nimble is part of being competitive, McMillan responded: "To be nimble is to survive. You've got to be nimble. And I think that's one - one good thing about commercial companies doing space."
But some critics worry private firms could put profits ahead of safety and compromise on things like rigorous testing of all systems.
"Yes, the risk is going to be higher," said space flight veteran Peggy Whitson, who runs NASA's astronaut office. "They're not going to have the flight test history, so there will be some unknown risk that we are taking."
But Voss argues his company would never build an unsafe spacecraft. "I lost 14 friends on the Columbia and Challenger accidents. I know what can happen when a space flight goes wrong. We care about it just like the NASA people do."
Next spring, NASA expects to pick two finalists with plans to launch astronauts on the first commercial flight to the space station in 2015.