LOS ANGELES - NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, announced Tuesday that it has completed "brain transplant" on Mars rover Curiosity.

As its main and backup computers have been successfully upgraded with new software after a four-day effort, Curiosity is now a big step closer to begin its mission of finding out whether life has ever existed on Mars, according to JPL.

Curiosity has been on the surface of Mars for over a week since it successfully touched down on August 5.

JPL announced Friday that Curiosity would undergo a "brain transplant" for four days during the weekend to update the software on the rover's main and backup computers, a necessary step before Curiosity can begin roving.

"We have successfully completed the brain transplant," said Curiosity Mission Manager Mike Watkins at JPL.

"Now we are moving on to a new phase of functional checkouts of the science instruments and preparations for a short test drive," he added.

The first drive, possibly within a week or so, will likely include short forward and reverse segments and a turn.

Curiosity has a separate drive motor on each of its six wheels and steering motors on the four corner wheels. Preparation and testing of the motor controllers will precede the first drive, according to JPL.

After the test drive, the planning schedule has an "intermission" before a second testing phase focused on use of the rover's robotic arm.

For the intermission, the 400-member science team will have the opportunity to pick a location for Curiosity to drive to before the arm-testing weeks, JPL said.

"It's fair to say that the scientists, not to mention the rover drivers, are itching to move," said JPL's Ashwin Vasavada, deputy project scientist for Curiosity.

Scientists at JPL uploaded the new software onto Curiosity from Pasadena, which had travelled 350 million miles to reach the Mars rover.

While the new software sat dormant, the spacecraft used flight software optimized to direct the spacecraft through the Martian atmosphere and safely land on target in the Gale Crater on the Martian surface, according to JPL.

Scientists at JPL said the newly uploaded software is optimized to drive the rover, operate the robotic arm and scoop up and analyze soil samples.

With that software successfully loaded, engineers at JPL are back to testing the rover's various operational and scientific instruments, JPL said.

JPL scientists calculated that it would take several weeks to get Curiosity ready to work on Mars when it first landed and had hoped that the rover would drive by early September.

"Today, they're building their code from scratch," said Watkins.

"The first few days after landing, they had a pretty solid script. All that was on board and they activated it with small changes. Now, we're assembling all this from scratch on the ground," said Waltkins

He added that JPL is going with a light schedule of commands for the rover during the next few days to get the team practiced.

Vasavada told the press Curiosity is scheduled to begin taking its first 24-hour weather reading this week.

Curiosity is also scheduled to continue to send high resolution, color pictures of the Martian landscape in the coming days, JPL said.

Ben Cichy, chief software engineer from JPL for the Mars Laboratory mission, told reporters last Friday that they designed the mission from the start to be able to upgrade the software as needed for different phases of the mission.

A key capability in the new version is image processing to check for obstacles. This allows for longer drives by giving the rover more autonomy to identify and avoid potential hazards and drive along a safe path the rover identifies for it, according to JPL.

Other new capabilities facilitate use of the tools at the end of the rover's robotic arm.

Meanwhile, the first color image taken from orbit showing Curiosity on Mars includes details of the layered bedrock on the floor of Gale Crater that the rover is beginning to investigate, JPL announced Tuesday.

Operators of the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter added the color view to earlier observations of Curiosity descending on its parachute, and one day after landing, according to JPL.

"The rover appears as double bright spot plus shadows from this perspective, looking at its shadowed side, set in the middle of the blast pattern from the descent stage," said HiRISE Principal Investigator Alfred McEwen, of the University of Arizona.

"This image was acquired from an angle looking 30 degrees westward of straight down. We plan to get one in a few days looking more directly down, showing the rover in more detail and completing a stereo pair," McEwen said in a press release.