SpaceX — short for Space Exploration Technologies Corp. — has made four cargo runs to the giant orbiting outpost some 200 miles above Earth. Just last month, its Dragon capsule splashed into the Pacific, returning nearly 2 tons of science experiments and old equipment.
Companies competing for the right to ferry station astronauts need to design a spacecraft that can seat a crew of four or more and be equipped with life support systems and an escape hatch in case of emergency. SpaceX has said it's designing a seven-seat spacecraft.
SpaceX and longtime NASA contractor Boeing Co. are "more or less neck and neck" in the competition, but there's a long way to go before astronauts can rocket out of the atmosphere on private spacecraft, said John Logsdon, professor emeritus of political science and international affairs at George Washington University.
Logsdon said progress by private companies is slower than anticipated mainly because Congress has not fully funded NASA's budget request for the effort. He said it's important for the U.S. to wean its reliance on Russia given the political tension over the annexation of Crimea.
"It's essential to have our own capability to transport people to space," he said. "This is an important step in that direction."