A unmanned rocket has blasted off from Florida to begin the first commercial resupply of the International Space Station (ISS).
The SpaceX Falcon 9, launched on Sunday, will deliver a Dragon cargo capsule carrying 400kg of food, clothing, spares and equipment.
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The cargo includes equipment for scientific experiments and, at the request of the three station residents, a freezer of chocolate-vanilla swirle ice cream.
The Falcon 9 is the second of SpaceX's 12 planned missions in a $1.6bn contract with the National Aeronautics and Space Administration, NASA. A test flight was completed in May.
Officials declared the launch of the Falcon 9, which is expected to reach the ISS on Wednesday, a success, despite a problem with one of the nine first-stage engines.
The rocket put Dragon in its intended orbit, said Elon Musk, the billionaire founder and chief executive officer of SpaceX.
"It's driving its way to station, so that's just awesome," said Gwynne Shotwell, SpaceX president.
It was the second launch of a Dragon capsule to the orbiting lab by the California-based company. The first was last spring.
NASA is counting on private business to restock the space station, now that NASA's shuttles have retired to museums.
Especially exciting for NASA is the fact that the Dragon will return twice as much cargo as it took up, including a stockpile of astronauts' blood and urine samples.
The samples, nearly 500 of them, have been stashed in freezers since Atlantis made the last shuttle flight in July 2011.
The Dragon will spend close to three weeks at the space station before being released and parachuting into the Pacific at the end of October.
By then, the space station should be back up to a full crew of six.
None of the Russian, European or Japanese cargo ships can bring anything back as they are destroyed during re-entry.
The Russian Soyuz crew capsules have limited room for anything other than people.
Space Exploration Technologies Corp, or SpaceX, owned by PayPal co-founder Musk, is working to convert its unmanned Dragon capsules into vessels that could carry astronauts to the space station in three years.
Other US companies also are vying to carry crews.
Currently, US passengers must ride Russian rockets to orbit in the meantime, for a steep price.
Musk, who monitored the launch from SpaceX Mission Control in Hawthorne, California, called the capsules Dragon after the magical Puff to get back at critics who, a decade ago, considered his effort a fantasy.
The name Falcon comes from Han Solo's Millennium Falcon in the Star Wars series.
An estimated 2,400 people packed the launching centre to see the Falcon, with its Dragon, come to life for SpaceX's first official, operational supply mission.
Across the country at SpaceX headquarters, about 1,000 employees watched via TV and webcast.
"Just over a year after the retirement of the space shuttle, we have returned space station cargo resupply missions to US soil,'' said Charles Bolden Jr, NASA administrator.
SpaceX is aiming for its next supply run in January.
Another company looking to haul space station cargo, Virginia's Orbital Sciences Corp, hopes to launch a solo test flight in December and a demo mission to the station early next year.
Every time SpaceX or a competitor flies successfully, Bolden told reporters, "that gives the nonbelievers one more opportunity to get on board and root for us" and help enable commercial launches for space station astronauts.
This will further free NASA up to aim for points beyond low-Earth orbit, like Mars.
"This was a big night,'' Bolden concluded.