In what SpaceX (News - Alert) and NASA officials called a "great day" for spaceflight, the SpaceX Dragon spacecraft departed the International Space Station (ISS) early this morning, May 31, and successfully splashed down in the Pacific Ocean southwest of Los Angeles approximately five and a half hours later at 11:42 AM ET. 

Dragon's successful rendezvous, berthing, cargo delivery and cargo return with the space station marks success both for commercial space and NASA's COTS demonstration program, opening the way for regularly scheduled supply flights to ISS by SpaceX.

NASA commercial crew and cargo manager program Alan Lindenmoyer said the mission was a 100-percent success, while the agency needed to look at the post-flight data and reports.

During a briefing today, SpaceX founder and chief designer Elon Musk expressed a mixture of happiness, thanks to NASA, and surprise that everything in the flight worked so well. He described the flight as a "grand slam" with much more success than everyone had the right to expect with a test flight, especially with such a "complex machine."

Dragon started its short journey home with about 1,000 pounds of "downmass" return cargo from ISS at about 4:07 AM ET, when it was released from the space station's bottom-side docking port and carefully moved away by robotic arm to a pre-determined release point. 

Three quick thruster firings cautiously moved Dragon out of the ISS controlled space safety zone. Once clear of the space station, joint NASA/SpaceX operations ended with control of the mission shifting back to SpaceX for reentry into earth's atmosphere and splashdown.

On a following orbit, Dragon conducted a reentry burn to slow it for atmospheric capture and released its service module to safely burn up. The Dragon capsule – like the Apollo spacecraft of decades ago – went through a fiery reentry protected by its heat shield, then popped a trip of landing parachutes to further slow its descent before splashing down at around 490 nautical miles southwest of Los Angeles. 

A trio of commercial leased ships then secured the spacecraft and hauled it onboard a barge for a two-day journey to the port of Los Angeles.

Some non-critical science experiments will be pulled out of the capsule and transferred over to NASA within 48 hours of splashdown to demonstrate SpaceX can provide a quick return capability for future missions. The capsule and its remaining contents will then be moved via truck to SpaceX's facility McGregor, Texas for processing, with the remaining equipment and cargo then transferred to NASA's Johnson Space Center in Houston.

The only apparent glitch during the mission was a problem with Dragon's LIDAR laser radar guidance sensors as the vehicle approached the station on May 25. Musk says SpaceX was able to fix the problem while Dragon was docked with the station and verified the fix during today's departure.

Today's successful landing opens the door – after NASA finishes going over all of the post-flight reports – for SpaceX to start fulfilling a $1.6 billion 12-flight order from the space agency to delivery supplies to and deliver experiments and equipment from ISS under the Commercial Resupply Services (CRS) contract. 

SpaceX hopes to make the first paying cargo to ISS by the end of the summer and get in a pair of CRS flights by the end of the year.

NASA's COTS (R&D and demonstration) and CRS (actually supply) programs originated from the retirement of the Space Shuttle, with SpaceX and Orbital Sciences (News - Alert) Corporation winning COTS demonstration missions and CRS supply missions. Some camps in Congress – egged on by legacy aerospace companies in an ugly PR campaign – questioned the ability of NASA and commercial newcomers to work together to build a successful commercial supply solution for the space station.