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.

The cargo mission is the sixth official journey 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.

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.