(AP) CAPE CANAVERAL, Florida - The privately bankrolled Dragon capsule approached the International Space Station for a historic docking Friday after sailing through a practice rendezvous the day before.
The unmanned SpaceX Dragon was on track to deliver a half-ton of supplies and become the first commercial vessel to visit the space station. The achievement previously was reserved for a small, elite group of government agencies.
"It's a great view," Dutch space station astronaut Andre Kuipers said as the Dragon drew to within 900 feet (275 meters), its strobe light flashing. "The solar panels are nicely lit."
On Thursday, the capsule made a practice fly-by. It returned early Friday so Kuipers and U.S. astronaut Donald Pettit could capture it with a robot arm. First, the capsule had to go through a series of stop-and-go demonstrations to prove it was under good operating control.
As the capsule drew within 100 feet (33 meters), flight controllers told it to retreat as the SpaceX company resolved a problem with on-board tracking sensors. Stray reflections from the Japanese part of the space station were interfering with the sensors, officials said. The docking operation soon resumed.
NASA ordered extra checks of the Dragon's imagers as the capsule drew closer to the space station, putting the operation slightly behind schedule. Given that the Dragon is a new type of vehicle and this is a test flight, the space agency said it wanted to proceed cautiously.
A collision at orbital speed - 17,500 mph (28,160 kph) - could prove disastrous for the space station.
President Barack Obama is pushing commercial ventures in orbit so the U.S. space agency, NASA, can concentrate on grander destinations like asteroids and Mars. Once companies master supply runs, they hope to tackle astronaut ferry runs.
The California-based SpaceX - officially known as Space Exploration Technologies Corp. - is one of several companies vying for the chance to launch Americans from their homeland after NASA's final shuttle flight last summer. To get to the space station, NASA astronauts now must go through Russia, an expensive and embarrassing situation for the U.S. after a half-century of orbital self-sufficiency.
SpaceX's billionaire maestro, Elon Musk, who helped create PayPal, said he can have astronauts riding his Dragon capsules to orbit in three or four years. His Falcon 9 rockets lift off from Cape Canaveral, Florida.
Musk monitored Friday's operation from the company's Mission Control in California.
The space station has been relying on Russian, Japanese and European cargo ships ever since the shuttles retired. None of those, however, can bring anything of value back; they're simply loaded with trash and burn up in the atmosphere.
By contrast, the Dragon is designed to safely re-enter the atmosphere, parachuting into the ocean like the Mercury, Gemini and Apollo capsules did back in the 1960s.
Assuming all goes well Friday, the space station's six-man crew will release the Dragon next Thursday after filling it with science experiments and equipment.