Saturday's launch of the Curiosity rover was just the prologue of the $2.5 billion mission, and officials will spend the next eight months readying for the craft's untried descent to the surface of Mars.

An Atlas 5 booster rocketed away from Cape Canaveral at 10:02 a.m. EST Saturday. Credit: Pat Corkery/United Launch Alliance

The rover soared into space at 10:02 a.m. EST (1502 GMT) Saturday on top of an Atlas 5 rocket. Its mission at Mars will be to detect organic molecules, the building blocks of life, and determine if the planet could have ever harbored life, past or present.

Forty-four minutes later, the probe separated from the Atlas rocket's Centaur upper stage on a trajectory to escape Earth. Officials reported the craft was in good health.

"We all recognize this is the prologue for the mission, necessary but not sufficient," said Peter Theisinger, project manager for the Mars Science Laboratory. "We all have our work cut out for us over the next eight-and-a-half months to prepare for the surface mission and do the final 'I-dotting' and 'T-crossing' for [entry, descent and landing]."

All the hardware necessary for the make-or-break landing went up Saturday, but software engineers are still writing and testing programming for Curiosity's arrival at Mars and its two-year mission on the surface.

After entering the Martian atmosphere shielded by an ablative carbon-based thermal protection system, Curiosity will deploy a parachute, jettison its heat shield and will be lowered to the surface hanging on nylong tethers underneath a rocket pack.

Six course correction thruster firings are planned through Aug. 6, 2012, when Curiosity will reach Mars.

Controllers will uplink the final version of Curiosity's landing software in May, followed in June by the transmission of software for the rover's surface operations, according to Theisinger.

The Mars Science Laboratory spacecraft separated from the Atlas 5's upper stage 44 minutes after liftoff. Credit: NASA TV/Spaceflight Now

"The rover already has software to do individual tasks," Theisinger said. "What we're adding is a level of efficiency so we can tell it to do something and then it can execute a whole block of activities in one go."

The in-flight delivery of software is not unusual for NASA's Mars missions. Theisinger, who led development of the Spirit and Opportunity rovers, said controllers uplinked operations software to those vehicles as they cruised to the Red Planet.

Opportunity has received subsequent software upgrades since its 2004 landing, allowing the robot more autonomy and independence on drives and scientific investigations.

NASA ordered the Curiosity team to concentrate its efforts on preparing the spacecraft for launch this year. The rover had three weeks to blast off to reach Mars in 2012, or else wait another two years.

With the rover safely on its way to Mars, engineers have little time to breathe easy.

"As soon as we launch, we will start what call robustness testing, where we actually try to break the software," said Doug McCuistion, head of NASA's Mars exploration program. "We've tested the hardware enough where we know the hardware works. The software ties it all together. We're going to try to break it. We're going to, at a minimum, test the corners of the envelope of where its performance limits are."

Artist's concept of the Curiosity rover on the surface of Mars. Credit: NASA/JPL-Caltech

A series of week-long simulations are also planned to prepare the Curiosity operations team for what's to come.

Linking a mock-up of the rover with the science team and control room, officials will test command sequences, check software and verify other procedures.

"In these simulations, the science team gets to practice, for example, how you would do triage the amount of data that's available, the amount of power that's available and the mount of time that's available, basically the three fundamental resources that allow us to do the science experiments," said John Grotzinger, MSL's project scientist.

Scientists plan 10 of the simulations, called operational readiness tests, on the voyage to Mars.