spaceSpace and Physics

NASA’s Latest Approach To Getting Its Martian Mole Working Is To Give It A Push


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockFeb 24 2020, 17:40 UTC

This test using an engineering model of the InSight lander here on Earth shows how the spacecraft on Mars will use its robotic arm to press on a digging device, called the "mole." NASA/JPL-Caltech

Currently, on Mars there is a very sophisticated instrument that doesn’t seem to work, so NASA has resolved taking some desperate measures to get it going again.

The instrument in question is the Heat Flow and Physical Properties Package, or HP3, but better known as "the mole". Its job is to dig down into the Martian soil and begin to measure the internal temperature of the Red Planet. Unfortunately, since February 28, 2019, it's not been doing much digging.


The heat probe is self-hammering, so it drills through the soil by jumping up and down. To work it needs friction, which is best given by loose, sand-like soil. However, the soil where the NASA mission landed is different from the soil in previously studied locations, and it's not providing the friction it needs.

The mole is attached to the lander InSight, and over the past year engineers from both sides of the Atlantic have been looking at solutions to get the mole back in its hole. After some issues in October last year, the solution that had the most success was the “pinning” approach. The team used InSight’s robotic arm to push against the side of the heat probe, providing enough friction to hammer through the top layer of soil. It did get digging again, but unfortunately, the mole popped back out on two occasions likely due to a soil buildup during the self-hammering process. Hence the need now for drastic measures.

NASA InSight recently moved its robotic arm closer to the "mole," in preparation to push on its top, or back cap.Credit: NASA/JPL-Caltech

The robotic arm will now be placed on top of the mole so it can push the probe down deeper and deeper into the ground; hopefully, deep enough for it to get a grip (literally and figuratively) and continue by itself. Despite its simplicity, this is a risky move. The back of HP3 is where the delicate science tether that links the mole to the lander is found.

Over the next few weeks, the team will test this approach. They will gently place the robotic arm scoop on the mole's back cap and allow the mole to do a short hammering session. They will also use the scoop to cover the hole around the mole with more soil, hopefully producing more friction for it.


Hopefully, HP3 will be soon known as the little mole that could and (finally) start to uncover the mysteries of Mars' interior.

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