The first company to fly to the International Space Station has begun its first mission to deliver cargo to the orbiting lab as part of a $1.6 billion contract with the U.S. space agency NASA.

The Falcon9 rocket built by California-based SpaceX lifted off from Cape Canaveral in the southeastern U.S. state of Florida late Sunday, carrying the company's Dragon capsule for a planned docking with the space station early Wednesday. The capsule entered its target orbit shortly after launch.

The Dragon is carrying 455 kilograms of supplies to the orbiting lab and is expected to carry almost double that amount of cargo back to Earth. The return cargo will include biological samples that have been collected and stored in the space station's freezers until they can be analyzed on the ground.

ISS manager Michael Suffredini said Sunday the Dragon's mission is “critical” to the astronauts' research because it has the capacity to return large amounts of samples to the ground. Russia's Soyuz capsule is the only other spacecraft that returns anything to Earth from the station, and has little room for cargo because it is used for astronaut transport.

SpaceX successfully completed a test delivery to the ISS in May, the first by any private company. The current mission is the first of 12 supply flights to the orbiting lab under the NASA contract. The Dragon capsule is expected to return to Earth October 28.