CAPE CANAVERAL, Fla. - An unmanned Space Exploration Technologies Falcon 9 rocket blasted off from Florida on Saturday carrying a cargo capsule for the International Space Station, then turned around to attempt an unprecedented landing on earth.
While the cargo ship flies towards the space station, the rocket was expected to head back to a floating platform in the Atlantic Ocean some 200 miles (322 km) off Jacksonville, Fla., north of the Cape Canaveral Air Force Station launch site.
If successful, the test by the privately owned SpaceX firm will mark a significant step in its quest to develop rockets that can be refurbished and reflown, slashing launch costs.
The mission blasted off at 4:47 a.m. EST/0947 GMT, and it was not immediately clear if the flyback maneuver had succeeded.
Elon Musk, founder and chief executive of SpaceX has estimated the chance of a successful landing on the first try at 50 percent.
SpaceX Vice President Hans Koenigsmann told reporters before launch: "When you look at (the floating platform) on the ground, it's a very big platform, but if you look at it from 150 or so miles up ... then it looks like a very small place to land on."
The primary purpose of the flight is to deliver a Dragon cargo capsule to the space station, a $100-billion laboratory that flies about 260 miles (418 km) above Earth.
The capsule, which is loaded with more than 5,100 pounds (2,300 kg) of food, equipment and supplies, should reach the station on Monday. The cargo includes fruit flies for immune system studies and an instrument to measure clouds and aerosols in Earth's atmosphere.
SpaceX is one of two companies hired by NASA to fly cargo to the station -- a project that involves 15 nations.