Preparations for the April 30 launch of the SpaceX's Dragon commercial spacecraft to the International Space Station are underway without major problems, a top NASA official said Tuesday.

"The simulations are taking place, I don't know about big drivers right now, only of what they have to do between now and launch day," said NASA Space Station manager Mike Suffredini at a news conference.

There is "a lot of work to do between now and April 30, but their schedule supports it as we see it today," he added.

Suffredini downplayed the importance of the launch, stressing the "need to be careful not to assume that the success or failure of commercial spaceflight is going to hang in the balance of a single flight."

SpaceX spokeswoman Kirstin Grantham said in a statement that NASA had not granted final approval of the launch date, but would do so only after completion of the "Flight Readiness Review, currently expected to occur on April 16."

If the commercial SpaceX team did encounter obstacles, Suffredini said it was "the kind of thing you experience in this difficult process of not only trying to launch into low Earth orbit, but do the next-hardest thing which is to try to rendezvous safely with another spacecraft in orbit."

The Dragon spacecraft launch would be the first-ever bid by a private company to dock at the orbiting lab.

The launch from Cape Canaveral, Florida had been set for February, but was postponed for technical reasons.

SpaceX -- owned by Internet entrepreneur and PayPal founder Elon Musk -- made history with its Dragon launch in December 2010, becoming the first commercial outfit to send a spacecraft into orbit and back.

SpaceX and several other companies are competing to build and operate a private capsule that could carry astronauts and cargo to the ISS, which is orbiting some 350 kilometers (220 miles) above the earth, after US space agency NASA retired its space shuttle program last year.

Other companies in the private space race include aerospace giant Boeing, the Nevada-based Sierra Nevada Corporation, and Washington state-based BlueOrigin LLC.

The main goals of SpaceX's next flight include a fly-by of the ISS at a distance of two miles (three kilometers) and a berthing operation in which the Dragon will approach the ISS and the crew aboard the orbiting outpost will use the ISS robotic arm to help it latch on.

After the test docking, the Dragon aims to detach from the station for its return to Earth and eventually splash down in the Pacific off the coast of California.