CAPE CANAVERAL, Fla. (AP) -- For the first time, a private company will launch a rocket to the International Space Station, sending it on a grocery run this weekend that could be the shape of things to come for America's space program.

If this unmanned flight and others like it succeed, commercial spacecraft could be ferrying astronauts to the orbiting outpost within five years.

It's a transition that has been in the works since the middle of the last decade, when President George W. Bush decided to retire the space shuttle and devote more of NASA's energies to venturing deeper into space.

Saturday's flight by Space Exploration Technologies Corp. is "a thoroughly exciting moment in the history of spaceflight, but is just the beginning of a new way of doing business for NASA," said President Barack Obama's chief science adviser, John Holdren.

By handing off space station launches to private business, "NASA is freeing itself up to focus on exploring beyond low Earth orbit for the first time in 40 years."

California-based Space Exploration, or SpaceX, is the first of several companies hoping to take over the space station delivery business for the U.S. The company's billionaire mastermind, Elon Musk, puts the odds of success in his favor while acknowledging the chance for mishaps.

NASA likewise cautions: This is only a test.

"We need to be careful not to assume that the success or failure of commercial spaceflight is going to hang in the balance of this single flight," said Mike Suffredini, NASA's space station program manager. "Demo flights don't always go as planned."

Once it nears the space station after a two-day flight, the SpaceX capsule, called Dragon, will spend a day of practice maneuvers before NASA signals it to move in for a linkup. Then its cargo a half-ton of food and other pantry items, all nonessential, in case the flight goes awry will be unloaded.

Up to now, flights to the space station have always been a government-only affair.

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Commercial rocket will fly to the space station