The SpaceX Falcon 9 rocket is due for launch on Wednesday from Cape Canaveral Air Force Station in Florida.
Space Exploration Technologies is readying its Falcon 9 rocket for the first launch of the Dragon capsule, a spacecraft that NASA plans to use to resupply the International Space Station after the space shuttle fleet's retirement.
The two-stage Falcon 9 was successfully tested in June, but that flight merely carried a test capsule into orbit. This time around, NASA wants to see how the Dragon will perform -- and whether it can be returned safely back to Earth after making up to four orbits. If the flight is fully successful, SpaceX will become the first commercial company to launch a spacecraft and have it re-enter the atmosphere from Earth orbit.
SpaceX's millionaire founder, Elon Musk, has gauged the chances of complete success at 60 percent.
Today's launch was delayed for 24 hours due to concerns about cracks in one of the Falcon's rocket engines. The first launch opportunity comes at 9:06 a.m. ET, with two more five- to six-minute launch windows opening at 10:38 a.m. and 12:16 p.m.
California-based SpaceX is receiving $278 million from NASA to develop the Falcon and Dragon, and the company has already received a $1.6 billion contract for station resupply flights through 2016. The gumdrop-shaped craft, which is bigger than the Apollo command and service module used for NASA's moonshots four decades ago, is designed to rendezvous with the station and be grappled by a robotic arm for docking.
If NASA gives the go-ahead, the Dragon could be used to fly astronauts as well as cargo to and from the station.