SpaceX is due to begin regular cargo flights to the International Space Station at the end of the summer - and its Dragon spacecraft will be the only craft on the lab's roster of servicing vehicles able to return significant hardware to Earth.
Formal reviews this month after a flawless nine day test flight in May are expected to clear the way for SpaceX's first operational cargo mission sometime in September.
SpaceX's commercial Dragon spaceship made an automated pinpoint splashdown in the Pacific Ocean, completing a feat never before achieved by private industry.
The gumdrop-shaped capsule, blackened by the heat of a high-speed re-entry, splashed down in the Pacific Ocean about 560 miles west of Baja, California, at 1542 GMT.
The Dragon spacecraft became the first privately-owned vehicle to fly to the Space Station, notching that triumph May 25 at the end of a cautious laser-guided approach to the complex.
The capsule also became the first US spacecraft to reach the Space Station since the last Space Shuttle flight departed in July 2011.
With splashdown on 31 May, Dragon proved it could fill a void left after the Shuttle's retirement in returning experiment samples, broken components and other excess hardware to Earth.
The Dragon test flight launched from Florida on May 22 aboard a Falcon 9 rocket. Three days later, after a flyby to demonstrate rendezvous techniques, the spacecraft precisely flew within 30 feet of the Station, close enough for the crew inside the complex to grapple Dragon with a robotic arm.
The astronauts unloaded more than 1,000 pounds of cargo from Dragon's pressurised compartment, including food, clothing, student experiments, and computer gear. The crew installed more than 1,300 pounds of equipment back inside Dragon for return to Earth.
After six days attached to the complex, Dragon was released from the lab's robotic arm at 0935.
SpaceX flight controllers at the company's headquarters in Hawthorne, Calif., commanded the ship's thrusters to five for nearly 10 minutes a few hours later. The thrust slowed Dragon's speed by more than 200 mph, enough for its orbit to drop into the atmosphere for re-entry.
The successful conclusion of the test flight capped a triumphant mission for SpaceX, which intends to outfit the Dragon spacecraft for crewed launches and landings within three or four years. SpaceX is competing for funding from NASA to finance the effort.