spaceSpace and Physics

The Martian Mole Has Finally Started Digging Again


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockOct 18 2019, 13:04 UTC

The mole being held down by InSight's robotic arm. NASA/JPL-Caltech

And the mole is back to work! One of the most peculiar instruments of NASA’s InSight mission is a digging device that will eventually measure the internal temperature of the Red Planet. Nicknamed the mole, the device has failed to dig more than 35 centimeters (14 inches) since March. However, the issue has finally been resolved and the mole is now digging down.

The actual name of the instrument is the Heat Flow and Physical Properties Package (HP3) and it is a self-hammering heat probe. It is designed to burrow itself up to 5 meters (16 feet) below the surface using the friction caused by the soil around it as a way to propel itself forward. Unfortunately, the surface soil was looser than expected and the hammer ricocheted, causing the mole to just bounce in place.


The instrument was designed by the German Aerospace Center (DLR) and the team, working with NASA's engineers, spent months planning potential solutions to this peculiar problem. The approach they've experimented with, which so far appears to be working, is very simple. The mole is being kept in place by InSight’s robotic arm.

Gif of the mole digging again. NASA/JPL-Caltech

Since October 8, the mole has hammered over 220 times over three separate occasions. It has dug through several centimeters of soil. However, it's still early days and the mole has a lot more digging to do before it reaches an operational depth.

"Seeing the mole's progress seems to indicate that there's no rock blocking our path," said HP3 Principal Investigator Tilman Spohn of the DLR in a statement. "That's great news! We're rooting for our mole to keep going."


While everyone is certainly happy that the mole is progressing, they are aware that realistically it might stop again. The NASA team at the Jet Propulsion Laboratory (JPL) has come up with some solutions in case, having dug further, the mole gets stuck once again. They might cover the mole in soil to prevent it from recoiling upwards or just use the arm to keep the mole down.

"The mole still has a way to go, but we're all thrilled to see it digging again," said the JPL's Troy Hudson, an engineer and scientist who has led the mole recovery effort. "When we first encountered this problem, it was crushing. But I thought, 'Maybe there's a chance; let's keep pressing on.' And right now, I'm feeling giddy."

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