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LOS ANGELES — After a week of transmitted dramatic photos of Mars, rover Curiosity is going to have a four-day "brain transplant."

Engineers will be updating Curiosity's software, currently primed for its flight stage, to prepare it for its Martian surface operations. The update will add two crucial functions — the ability to use the geochemistry lab's sampling system, and to drive.

The update had to wait until the rover landed because its processor, built years ago to withstand the harsh environment of interplanetary space, is limited compared with today's consumer technology, said senior software engineer Ben Cichy.

"My phone has a processor that is 10 times as fast as the processor that's on Curiosity and has 16 times as much storage as Curiosity has," Cichy said. "And my phone doesn't have to land anything on Mars."

Also Friday, engineers offered their most detailed assessment of Curiosity's landing. The craft, they said, landed roughly 1.5 miles from its predicted touchdown zone — not bad, given that the site was more than 150 million miles away and the projected landing zone was an ellipse 12 miles wide.