SpaceX's unmanned Dragon cargo ship blasted off Tuesday toward the International Space Station, carrying a load of food and supplies for the astronauts living in orbit.
The California-based company's Falcon 9 rocket launched from Cape Canaveral, Florida at 4:10 pm (2010 GMT), and was to be followed minutes later by an attempt at guiding the first stage of the rocket to land upright on an ocean platform.
SpaceX chief Elon Musk said the chance of the rocket landing intact on the port in the Atlantic Ocean was about 50 percent.
The last bid to recycle the rocket, in January, ended in failure. The rocket collided with the ocean platform and broke into pieces.
Recycling the rocket is signficant because it would potentially save huge amounts of money.
However, the cargo missions have gone much more smoothly for SpaceX.
The cargo ship separated from the second stage of the rocket about 10 minutes into the flight, as planned, and carried on toward the ISS.
Tuesday's cargo mission is the sixth official journey that SpaceX has contracted with NASA as part of a $1.6 billion deal for 12 such trips.
The supply is on track to arrive at the orbiting outpost on Friday, when it will be grabbed by the space station's robotic arm—operated by European Space Agency astronaut Samantha Cristoforetti—and guided in for berthing.
NASA television coverage of the arrival will begin at 1100 GMT.
The Dragon is carrying around two tonnes of food and supplies, including scientific experiments and an espresso machine.
The reusable cargo craft will stay in space for about five weeks, as astronauts reload it with equipment to return to Earth.
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