Dragon is laden with scientific gear, replacement parts for the space station, and a welcome shipment of chocolate ripple ice cream stashed in an otherwise empty lab freezer the capsule carried up.
The capsule, which launched Sunday night atop SpaceX's Falcon 9 rocket, reached the orbiting outpost about 15 minutes ahead of schedule. Using the station's robotic arm, Akihiki Hoshide, a station flight engineer, snagged Dragon at 7:56 a.m. Eastern Daylight Time. A little over an hour later, Dragon was safely docked with the station.
"Looks like we've tamed the dragon," said station commander Sunita Williams when the arm initially captured the capsule.
"We're happy she's on board with us," she said, adding a special shout-out for the ice cream.
The mission marks an important milestone for NASA along a path first set out under the Bush administration and confirmed by President Obama. After the space shuttle Columbia disaster in February 2003, NASA has pivoted to focus on sending humans beyond low-Earth orbit, while it has steered the job of ferrying supplies and astronauts to the space station to private companies.
The effort to carry astronauts to and from low-Earth orbit took a step forward in August, when NASA announced agreements worth a combined $1.1 billion to help SpaceX, Boeing, and Sierra Nevada Corporation develop such capabilities. But Dragon's arrival at the space station Wednesday – the first flight under a 12-flight, $1.6-billion contract – shows that the goal of bringing commercial carriers into the station resupply business is now being realized.
SpaceX is one of two US companies with resupply contracts. The second, Orbital Sciences Corp., is slated to test-fly its Antares booster by year's end and loft its first demonstration flight early next year.
Thursday, the station crew is schedule to open Dragon's hatch and inspect the craft's interior before unloading the cargo. Dragon will remain docked at the station until Oct. 28, when it's slated to return 1,673 pounds of hardware and experiment samples to Earth. Dragon's ability to return cargo from the space station to Earth is a unique capability among all the craft currently serving the station. Dragon will parachute to an ocean splashdown off the southern California coast, where it will be plucked out of the water and returned to an unloading facility at the Port of Los Angeles in San Pedro, Calif.
Although a key stage of Dragon's first commercial mission has been completed, the launch Sunday evening saw one of the nine engines powering the Falcon 9's first stage shut down 79 seconds after launch.
The first-stage propulsion system is designed to withstand the loss of two engines before the delivery of its primary payload is jeopardized, the company notes. Once on-board computers detected the failure, they quickly readjusted the rocket's path to keep it on course to intercept the space station.
The course correction, however, came at the expense of a second payload the Falcon 9 was carrying -- a prototype communications satellite for ORBCOMM Inc. and built by Sierra Nevada. Although the satellite is on orbit, it's hurtling around Earth at a much lower altitude than planned.
It's common for commercial launch companies to piggyback several payloads on one rocket. This was to be the first demonstration that a commercial satellite and a government station-resupply payload could share the same ride. Even with the failure of one engine on the first stage, the second stage carrying both payloads could have delivered the satellite to its proper orbit as well. But the satellite was deposited short of its goal to avoid either the second stage or the satellite coming too close to the space station as they headed higher.
SpaceX engineers are still trying to uncover the cause of the engine failure.