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‘Mole’ Probe on JPL’s InSight Mars Lander Disappears Into Martian Soil

Published on Monday, October 19, 2020 | 10:55 am
NASA’s InSight Mars Lander retracts its robotic arm to reveal the point where its “mole” probe is working its way into the Martian soil. Only the probe’s ribbon-shaped tether is seen protruding from the ground on Oct. 3, 2020. (Credit: NASA/JPL-Caltech)

A sensor on the Jet Propulsion Laboratory’s InSight Mars lander known as the “mole” has vanished beneath the Martian surface as it works its way deeper into the ground in order to take the Red Planet’s temperature, as seen in new images released by JPL.

Formally designated the Heat Flow and Physical Properties Package, the 16-inch long, spike-shaped science tool has made its way entirely below ground, with only its ribbon-shaped tether visible protruding from its “mole hole,” JPL representatives said in a written statement.

But it still has a long way to go before it reaches its intended ultimate depth of 10 feet, to enable it to take measurements of the subterranean temperature on Mars, officials said.

Scientists experienced some trouble with the probe last year, when it began backing out of its hole while being hammered into the soil, according to JPL.

“The team placed the small scoop at the end of the lander’s robotic arm on top of it to keep it in the ground,” the statement said. “Now that the mole is fully embedded in the soil, they will use the scoop to scrape additional soil on top of it, tamping down this soil to help provide more friction.”

It may take several months for enough soil to be packed to ensure the mole will work properly before the lander once again resumes hammering the mole downward.

“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,” according to JPL Scientist and Engineer Troy Hudson, who led the team in charge of getting the mole operational. “But we’re not quite done. 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.”

The mole was built by the German Space Agency. JPL heads the InSight mission for NASA.

More information on InSight is available online at

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