After a series of delays, NASA's Aura satellite was launched into orbit early Thursday on a $785 million mission to study Earth's atmosphere.

A two-stage Boeing Delta II rocket carrying the satellite roared off the launchpad just before 3:02 a.m. The satellite separated from the rocket an hour later and entered orbit 438 miles above Earth.

"Everything went well. We did get initial orbit, and it seems to be right on," said Chuck Dovale, launch manager.

The liftoff was scrubbed four times in recent weeks, including twice in the past two days. Tuesday's launch was postponed because of concerns about the satellite's scientific data recorder. Wednesday's launch was scratched because of a reading of low current from a battery system on the rocket's second stage.

Dovale said three or four problems cropped up in the 45 minutes before the launch, but they were worked out without delaying the liftoff. NASA had said there was only a 60 percent chance of launching because of concerns that the remnants of Tropical Storm Blas off Mexico might prevent the flight of a support aircraft. However, skies cleared enough for observers at the launchpad to follow the rocket on its long trajectory.

Aura's six-year mission is intended to determine the composition of Earth's atmosphere in unprecedented detail.