InSight’s Heat Probe Has Bounced Back Out Of Its Hole

This is sad news. After finding what seemed like a solution to the Mole’s difficulties on Mars, engineers are stymied again. The Mole, or Heat Flow and Physical Properties Package (HP3) has bounced half-way out of its hole.

It’s like Groundhog Day on Mars. If the Mole bounces out of its hole, it means six more weeks of engineers scratching their heads to come up with a solution.

It’s been a plot full of twists and turns for the Mole. After being carefully deployed by the InSight Lander’s instrument arm, the Mole seemed to be making progress. Then only a few centimeters into the Martian ground, it stopped.

NASA and the DLR (German Aerospace Center) are partners on the InSight Lander. The DLR designed and built the Mole. At first both agencies suspected that the Heat Probe had struck a rock. They tried to find a work around here on Earth, where they have test beds and mock landers.

Eventually they realized that they had struck an unusual kind of sub-surface soil called duracrust. The Mole relies on friction with the surrounding soil to penetrate into Mars, but the duracrust wasn’t cooperating. It stubbornly refused to fall into the hole around the Mole, depriving it of the necessary friction.

Engineers tried using the scoop on the end of the instrument arm to push surface soil into the Mole’s hole, but that didn’t work. Then they tried what they called “pinning” the Mole against the side of the hole with the instrument arm scoop, to supply the needed friction. It looked like that was working, and the Mole started penetrating again.

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