While the Mars Curiosity rover is the most complex machine NASA has ever sent to another planet, the computer that runs it is no more powerful than the one in your smartphone.

The robotic rover, which landed in the Gale Crater on Mars early Monday morning, now is being put through a series of tests to make sure all of its systems are functioning properly after its more than 350-million-mile journey from Earth. It may be several weeks before the SUV-sized robotic rover is ready to begin its trek across the Martian surface.

Curiosity is on what scientists hope will be a two-year mission to find out if the planet has or ever has had what it takes to support life, even in a microbial form. The rover also will look for signs that humans could one day live on Mars.

While Curiosity is on a major scientific mission, the rover itself is something of an engineering marvel, too, according to the men and women who built it.

The Mars rover Curiosity has two computers, four chips and software designed to last throughout its two-year mission. (Artist concept: NASA)

The rover not only has to be sturdy enough to survive a more than eight-month journey through outer space to reach Mars, once there, it has to be able to work in brutal temperature extremes for years.

"This is the most complex system that we've every sent to another planet," Devin Kipp, an operations lead on NASA's Curiosity team, told Computerworld. "The entry and landing system was the most complex system we've ever attempted. And now that it's on the ground, it's incredibly capable. The amount of state-of-the-art scientific instruments is really impressive."

Curiosity, which weighs nearly 2,000 pounds and carries 17 cameras and 10 scientific instruments, only has two computers and four processors.

Jonathan Grinblat, an avionics systems engineer with the Jet Propulsion Laboratory, said the rover used one Sun Microsystems Sparc processor to run the craft's thrusters and descent-stage motors as it moved through the Martian atmosphere. With the rover on the ground, that processor's job is done.

After the landing, a PowerPC processor, which was originally developed by the Apple-IBM-Motorola alliance, known as AIM, has taken over. This main processor, which has a redundant backup processor, runs all of the main software on the rover, handling "pretty much everything the rover will do," according to Grinblat.

The fourth chip, which also is a Sparc processor, is in Curiosity's motor controller box. Grinblat explained that the main processor sends it commands and this one handles the logistics of getting the motors to move.

All of the processors are single-core. Grinblat noted that Curiosity will be one of the last generations of NASA spacecraft that will have single-core chips.