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The oft-stuck 'mole' on NASA's InSight Mars lander may start digging again next year

NASA's InSight Mars lander has used the scoop on the end of its robotic arm to help the mission’s burrowing heat probe, known as the "mole," get and stay underground.
NASA's InSight Mars lander has used the scoop on the end of its robotic arm to help the mission’s burrowing heat probe, known as the "mole," get and stay underground.
(Image: © NASA/JPL-Caltech)

The "mole" aboard NASA's InSight Mars lander may be ready to start digging on its own again early next year, agency officials said.

The mole — an affectionate nickname for InSight's burrowing heat probe, which is officially known as the Heat Flow and Physical Properties Package (HP3) — is designed to take temperature measurements after hammering itself at least 10 feet (3 meters) beneath the Martian surface.

But the going has been very rough for the mole since InSight touched down in November 2018. The dirt at the landing site has proven to be unexpectedly sticky. It's been clumping together as the mole hammers through it, "forming a small pit around the device instead of collapsing around it and providing the necessary friction" for digging, NASA officials wrote in an update last week.

Mars InSight in photos: NASA's mission to probe core of the Red Planet 

This unforeseen issue has kept the mole confined to the surface, or very near subsurface, during the entirety of InSight's time on Mars, despite the mission team's considerable troubleshooting efforts. Those efforts have included pushing on the mole using the scoop on InSight's robotic arm, a technique the team recently employed to help get the digger back underground after it had popped out of its shallow hole.

InSight's handlers plan to build on that success in the coming months, using the arm to scoop more dirt into the mole hole and then tamp that dirt down to provide friction for digging.

"I'm very glad we were able to recover from the unexpected 'pop-out' event we experienced and get the mole deeper than it's ever been," Troy Hudson, the scientist and engineer at NASA's Jet Propulsion Laboratory in Southern California who led the most recent work to get the mole digging, said in last week's update. 

"But we're not quite done," Hudson said. "We want to make sure there's enough soil on top of the mole to enable it to dig on its own without any assistance from the arm."

That probably won't happen until early 2021, NASA officials said in the update.

NASA's InSight retracted its robotic arm on Oct. 3, 2020, revealing where the spike-like "mole" is trying to burrow into Mars. The copper-colored ribbon attached to the mole has sensors to measure the planet's heat flow. In the coming months, the arm will scrape and tamp down soil on top of the mole to help it dig.

NASA's InSight Mars lander retracted its robotic arm on Oct. 3, 2020, revealing where the "mole" is trying to burrow. The ribbon attached to the mole has sensors to measure the planet's heat flow. In the coming months, the arm will scrape and tamp down soil on top of the mole to help it dig.  (Image credit: NASA/JPL-Caltech)

The mole is one of the two main science instruments aboard InSight. The other is a suite of supersensitive seismometers, which have picked up hundreds of marsquakes during the lander's time on the Red Planet. The seismometer data is helping the InSight team map out Mars' interior structure in unprecedented detail — the main goal of InSight's mission.

The mission team is also using the lander's communications gear to precisely track InSight's location on the Martian surface, which in turn reveals just how much the planet is wobbling around its rotational axis. This information will shed light on the size and composition of Mars' core, NASA officials have said.

InSight features extensive international collaboration: The lander's seismometers were provided by the French space agency CNES and its partners, and the mole was provided by the German Aerospace Center, which is known by its German acronym, DLR. You can read more about the recent mole work in a blog post by HP3 principal investigator Tilman Spohn in this DLR blog.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.

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