CAPE CANAVERAL, Florida â€"  Space station astronauts floated into the Dragon on Saturday, a day after its heralded arrival as the world's first commercial supply ship.

NASA astronaut Donald Pettit, the first one inside the docked capsule, said the Dragon looks like it carries about as much cargo as his pickup truck back home in Houston. It has the smell of a brand new car, he added.

"I spent quite a bit of time poking around in here this morning, just looking at the engineering and the layout, and I'm very pleased," Pettit said from the brilliant white compartment.

To protect against possible debris, Pettit wore goggles, a mask and a caver's light as he slid open the hatch of the newest addition to the International Space Station. The complex sailed 250 miles above the Tasman Sea, just west of New Zealand, as he and his crewmates made their grand entrance. The atmosphere was clean; no dirt or other particles were floating around.

"This event isn't just a simple door opening between two spacecraft -- it opens the door to a future in which U.S. industry can and will deliver huge benefits for U.S. space exploration," the Space Frontier Foundation, an advocacy group, said in a statement.

The California-based SpaceX -- formally Space Exploration Technologies Corp. -- is the first private company to send a vessel to the space station. It's run by Elon Musk, a billionaire who helped create PayPal and founded the electric car company Tesla Motors.

Now that the space shuttles are retired, NASA is handing over orbital delivery work to American business in order to focus on bigger and better objectives, such as getting astronauts to asteroids and Mars. The space agency hopes astronaut ferry trips will follow soon; SpaceX contends its Dragons could be carrying space station astronauts up and down within three or four years.

Flight controllers were ecstatic to be at the cusp of this new commercial era.

"It's great to see you guys inside Dragon. It looks great," Mission Control radioed.

The six space station residents have until the middle of next week to unload Dragon's groceries and refill the capsule with science experiments and equipment for return to Earth. Unlike all the other cargo ships that fly to the orbiting lab, the Dragon is designed for safe re-entry. It will be freed on Thursday and aim for a Pacific splashdown.

The Dragon contains 1,000 pounds (450 kilogram)s of food, clothes, batteries and other provisions. It will bring back 1,400 pounds' (635 kilograms')worth of gear.

Until now, only major governments have launched cargo ships to the space station. Russia, Japan and Europe will keep providing supplies, and Russia will continue to sell rocket rides to U.S. astronauts until SpaceX or other companies are ready to take over. Several American enterprises are competing for the honor.

Pettit noted that the Dragon -- 19 feet (5.7 meters) tall and 12 feet (3.6 meters) wide -- is roomier than the Russian Soyuz spacecraft he rode up in.

"Flying up in a human-rated Dragon is not going to be an issue," he assured reporters during a news conference.

The unmanned bell-shaped Dragon capsule was launched Tuesday from Cape Canaveral aboard a SpaceX Falcon 9 rocket. Pettit used the space station's robot arm Friday to snare the craft.

During Saturday's news conference, Pettit played down his role in the historic event. He noted that the completion of the Transcontinental Railroad, which opened up America's Western frontier, was commemorated by the pounding of a golden spike in 1869.

"This is kind of the equivalent of the golden spike," he said. "And one other interesting detail -- nobody remembers who pounded that golden spike in. The important thing is to remember that the railroad was completed and was now open for use."

Success or failure of the new commercial space effort -- the cornerstone of President Barack Obama's vision for NASA -- does not hinge on a single mission but rather many missions over many years, Pettit stressed.

"Commercial spaceflight will blossom due to its own merits," he said.