Frank Morring, Jr. Washington

A journey of 1,000 parsecs begins with a single step, to paraphrase Lao Tzu. Before humans can explore the stars—or the Solar System—in person, we still must travel that first 100-km step through Earth's atmosphere.

Now that the space shuttle is a museum piece, human access to low Earth orbit is down to two spacecraft—Russia's venerable Soyuz capsule, and China's new Soyuz-derived Shenzhou. Today Shenzhou is the most modern operational human spacecraft flying, and it is likely to remain so for at least five more years.

Work is underway around the world on new ways to orbit humans and keep them alive in space. At least seven different orbital human-spaceflight vehicles are in development—most of them in the U.S.—and other longer-term work is beginning to take shape in India, Europe and elsewhere.

Not all of the vehicles in the computer-aided design (CAD) workstations today will fly, and some of those that manage to get off the ground once or twice won't be able to keep flying for lack of passengers. As it struggles to replace the shuttle, NASA has set up a competition to hold down development costs and perhaps influence the per-seat price of astronaut travel. But the U.S. agency does not plan to use all of the competing vehicles once the commercial crew capability becomes operational.

“We say 'likely one provider' in that region,” says William Gerstenmaier, who as associate administration for human exploration and operations is responsible for keeping crews on the International Space Station. “That avenue of competition up front also gives us some pretty strong benefits to help us get a good price coming out the other end, even though we may ultimately downselect to one contractor.”

Gerstenmaier is overseeing four human-vehicle developments with NASA funding, and holding the door open for at least three more. At the top end of the price list is the Orion multipurpose crew vehicle, a holdover from the defunct Constellation program that has already consumed more than $5 billion. Under NASA's post-Constellation space policy, as modified by Congress, Lockheed Martin is developing Orion for missions beyond low Earth orbit that would lift off atop the heavy-lift Space Launch System (SLS).

Also working with government funds are Boeing, Sierra Nevada Corp. and Space Exploration Technologies Inc. (SpaceX), on three different commercial crew vehicles intended to take astronauts to the ISS. Building on the George W. Bush-administration commercial cargo program that will start delivering supplies to the space station this fall, the Obama administration is using federal funds as seed money for what it hopes will one day be a low-Earth-orbit economy.