With the Mars rover's software successfully upgraded, Curiosity is a big step closer to beginning its mission of finding out whether life has ever existed on Mars.

Curiosity, NASA's super robotic rover, has been on the surface of Mars for just over a week. Since Saturday, NASA has been working to update the software on the rover's main and backup computers, a necessary step before the Curiosity can begin roving.

Engineers jokingly dubbed the upgrade Curiosity's "brain transplant."

"I'm happy to say that we have completed the flight software transition," said Michael Watkins, a mission systems manager at NASA's Jet Propulsion Laboratory (JPL). "It came off pretty much without a hitch."

The new software was uploaded onto Curiosity during its 350-million-mile journey to Mars. While the new software sat dormant, the spacecraft used flight software optimised to direct the spacecraft through the Martian atmosphere and safely land on target in the Gale Crater on the Martian surface.

The newly activated software is optimised to drive the rover, operate the robotic arm and scoop up and analyse soil samples. With that software successfully loaded, NASA engineers are back to testing the rover's various operational and scientific instruments.

When Curiosity first landed, scientists calculated that it would take several weeks to get the rover ready to roll; they hope to have it driving by early September.

Watkins noted that today was a hectic one for the programming team, which daily sends up new software commands to the rover. Until now, however, they have been able to use pre-coded commands.

"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."

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

Ashwin Vasavada, a deputy project scientist at JPL, said during a news conference Tuesday afternoon that Curiosity is scheduled to begin taking its first 24-hour weather reading this week.

The rover also is scheduled to continue to send by high-resolution, color pictures of the Martian landscape.

Curiosity was sent to Mars with a two-year mission to gather evidence that the planet is, or has been, capable of supporting life - even in microbial form.

The car-sized, nuclear-powered robotic rover is equipped with 10 scientific instruments and offers the most advanced payload of scientific gear ever used on the surface of Mars, including chemistry instruments, environmental sensors and radiation monitors.

The payload is more than 10 times as large as those of earlier Mars rovers.