InSight’s Heat Probe Partially Backs Out of Hole: This GIF shows NASA InSight’s heat probe, or “mole,” digging about a centimeter (half an inch) below the surface last week. Credit: NASA/JPL-Caltech.

NASA’s latest Mars lander is having problems with one of its main instruments — a self-hammering probe that just can’t seem to hammer itself into the interplanetary dirt. Over the weekend, the probe was attempting to dig itself into the Martian soil when it popped out of the ground unexpectedly. Now, NASA engineers are trying to troubleshoot to see if they can get this instrument to burrow underneath Mars’ surface as intended.

InSight’s second main instrument is the heat probe — nicknamed the mole. It’s supposed to hammer down into the ground just next to InSight and take Mars’ temperature. If it works as planned, it could give scientists more information about how much heat is leaving the planet’s interior. But the mole hasn’t had as much luck as the seismometer. In fact, it pretty much started having problems as soon as InSight got to the Red Planet. Since it started digging at the end of February, it hasn’t been able to travel more than 14 inches (35 centimeters), even though it’s designed to dig up to 16 feet (5 meters).

The InSight team thinks that the soil surrounding the mole may be to blame. While it digs, the mole needs the soil to fall around the probe uniformly, providing friction that allows the instrument to hammer farther underground. Otherwise, it’d just bob up and down in one place, according to NASA. But testing has indicated that the soil in this particular spot is unlike soil encountered by previous landers on Mars. It’s clumping around the probe and not providing any friction. That may explain the slow movement.