The SpaceX Dragon cargo ship has completed a historic journey to the International Space Station, splashing down in the Pacific Ocean after becoming the first commercially operated vehicle to travel to the orbiting outpost.

The Dragon arrived back on Earth Thursday, after its successful demonstration flight.

The International Space Station crew released the Dragon capsule early Thursday from the station's long robotic arm to begin the final leg of its flight. The unmanned ship re-entered Earth's atmosphere and splashed down in the Pacific Ocean southwest of the California coast at midday Thursday.

The Dragon departed the ISS less than a week after becoming the first private spacecraft to deliver supplies to the station. The U.S. space agency NASA has reached deals with a number of private companies to take over the duties of the retired space shuttle fleet to deliver cargo and, eventually, astronauts to the ISS.

The Dragon flight is the first under a $1.6 billion contract that California-based Space Exploration Technologies, or SpaceX, has signed with NASA to deliver supplies to the ISS. Another commercial venture, Virginia-based Orbital Sciences Corporation, is scheduled to make its maiden voyage later this year.

The United States has had to rely on Russia, Japan and the European Space Agency to ferry cargo to the International Space Station since retiring the shuttle fleet last year.