March 26, 2013 at 2:00 PM ET
SpaceX said its robotic Dragon capsule splashed down in the Pacific Ocean on Tuesday, bringing back more than a ton of cargo from the International Space Station.
"Welcome home!" the California-based company said in a Twitter update, heralding the Dragon's return to Earth after more than three weeks in space. SpaceX said its recovery crew watched the spacecraft descend to the sea at the end of its parachutes, and a ship headed to the site to haul the capsule aboard and bring it back to port.
"Time to go fishing!" the Canadian Space Agency said in a congratulatory tweet.
The on-time splashdown came at 12:34 p.m. ET, five and a half hours after the Dragon was released from the grip of the space station's robotic arm. "It looks both beautiful and nominal from here," Canadian astronaut Chris Hadfield, the station's commander, reported as the orbital outpost flew 256 miles (411 kilometers) above the Pacific.
NASA astronaut Tom Marshburn said he was "sad to see the Dragon go. ... Performed her job beautifully, heading back to her lair."
This marks the third time that SpaceX's commercial cargo craft has made a round trip to the space station. The first visit, in May 2012, showed NASA that the California-based company could deliver payloads safely. Last October, another Dragon took on the first of 12 cargo runs under the terms of a $1.6 billion contract with the space agency. This latest mission launched on March 1, carrying 1,200 pounds (544 kilograms) of supplies and equipment.
SpaceX had to cope with a post-launch glitch involving the Dragon's thruster system, but the mission went swimmingly after that. Astronauts unloaded the cargo soon after its was brought in for its berthing at the station, and then refilled it with 2,600 pounds (1,180 kilograms) of payload items due to be returned to Earth — including scientific experiments, station hardware and trash. Packaging brought the total weight past the 3,000-pound (1,360-kilogram) mark, SpaceX said.
NASA said the plant samples that were brought back from the station could help scientists enhance crop production on Earth and develop food production systems for future space missions. Other experiments carried by the Dragon could help in the development of more efficient solar cells, detergents and electronics.
The returned cargo also included 13 sets of Lego toy blocks that went up to the station two years ago aboard the shuttle Endeavour. The blocks were used by the astronauts in educational videos to demonstrate how machines work in weightlessness. One of the kits, a 3-foot-long (meter-long) scale model of the space station, was so bulky that it would have collapsed under its own weight in Earth's gravity.
Dragon's return was originally scheduled for Monday, but "fairly aggressive" seas at the intended splashdown zone forced a one-day postponement, NASA spokesman Josh Byerly said. The weather was better on Tuesday, and the splashdown target was a couple of hundred miles nearer to shore, at a point in the Pacific 214 miles (344 kilometers) west of Baja California.
SpaceX's billionaire founder, Elon Musk, said the capsule was secured aboard its recovery ship without incident. "Cargo looks A ok," he reported in a Twitter update.
The ship is due to make a 30-hour voyage back to the port of Los Angeles, where time-sensitive biological samples will be offloaded. Then the Dragon and its remaining cargo will be trucked to SpaceX's facility in McGregor, Texas.
The next SpaceX cargo run is scheduled at the end of September. Another company, Virginia-based Orbital Sciences Corp., is working on a second commercial delivery system that's due for its first test launch next month. But only the Dragon is capable of bringing significant amounts of cargo back to Earth.
NASA selected SpaceX and Orbital to help fill the gap left by the retirement of the space shuttle fleet in 2011. Russian, European and Japanese cargo craft also service the space station. For now, Russia's Soyuz capsules are the only spacecraft that transport people to and from the station, but NASA intends to have U.S.-built commercial spaceships — perhaps including an upgraded version of the Dragon — carrying astronauts within five years.
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Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.