PASADENA, Calif. (AP) — Science experiments by the NASA Mars rover Curiosity have been put on hold as engineers troubleshoot a problem with its computer.

NASA says the car-size rover is in “safe mode.” In this state, Curiosity suspends science activities but is still in contact with Earth.

Engineers discovered a problem with Curiosity’s flash memory earlier this week and switched to its backup computer.

Curiosity landed last summer in Gale Crater near the Martian equator to examine whether environmental conditions were favorable for microbes. It recently drilled into a rock and transferred a pinch of powder to its onboard laboratories to study the chemical makeup. It won’t be able to finish the analysis until its systems are back to normal.