NEW YORK — Space Exploration Technologies Corp.’s (SpaceX) Dragon cargo capsule dove through Earth’s atmosphere and splashed down in the Pacific Ocean early May 31, ending a monumental test flight to the international space station.

The unmanned Dragon capsule made a right-on-target water landing off the coast of Baja California, Mexico, at 11:42 a.m. EDT.

Dragon departed the space station at 5:49 a.m. EDT, when it was released from the outpost’s robotic arm after being plucked from a docking port on station’s Earth-facing Harmony module. The unmanned capsule began its return to Earth in earnest at 10:51 a.m. EDT with a nine minute, 50 second deorbit engine burn.

Dragon became the first private vehicle to visit the space station when it docked there May 25, three days after launching atop a SpaceX Falcon 9 rocket from Cape Canaveral, Fla. The capsule spent five days attached to the $100 billion orbiting laboratory.

Prior to undocking, Dragon was packed with 620 kilograms of crew items, used hardware and completed science experiments for its return trip.

Dragon’s Hawthorne, Calif.-based flight team was elated over the successful conclusion of the nine-day mission — and none more than company founder Elon Musk.

“The point at which the main parachutes opened and all three were working and Dragon was descending normally, that’s the point at which I really felt relieved and knew that the mission was likely to be 100 percent successful,” Musk said during a press conference following the splashdown. “I’m just overwhelmed with joy.”

When Musk saw the first high-resolution photo of the charred but intact capsule floating in the ocean, he said he thought, “‘Welcome home, baby.’ It’s really great, it’s like seeing your kid come home.” Dragon’s flight was a test run for the 12 cargo delivery flights SpaceX is expected to fly for NASA under a $1.6 billion contract awarded in 2008.

NASA has invested about $800 million in SpaceX to date, including $336.7 million in advance payment on its cargo delivery contract and all but the final $15 million of a $396 million Commercial Orbital Transportation Services agreement awarded in 2006.

Musk said the mission would not have been possible, and indeed SpaceX might not even exist, were it not for NASA.

“We would have died were it not for NASA,” Musk said.

Addressing Alan Lindenmoyer, manager of NASA’s Commercial Crew and Cargo Program, Musk said: “Thanks for placing your faith in SpaceX and making all of our dreams come true.”

“We weren’t sure exactly how it was going to end up,” Lindenmoyer admitted. “It was a bit of an experiment. Today we get to share in the joy of the success. It is a new way of doing business and the fact that we were so successful in meeting these objectives so early on, I would say absolutely that this is a model that works.”

Musk said he hoped the successful mission would also help sway critics of the plan, particularly those in Congress who doubt that privately built spaceships are safe or reliable.

“I think it really shows that commercial spaceflight can be successful,” Musk said. “This mission worked for the first time right out of the gate. It was done, obviously, in close partnership with NASA, but in a different way, and it shows that that different way works and we should reinforce that.”

The space-flown Dragon capsule will soon be unpacked and shipped to SpaceX’s facility in McGregor, Texas, for processing. But eventually it might get another taste of glory.

“I think it’d be cool to maybe do a little tour of the country and show it to people around the country, get students excited about space,” Musk said.