NASA has revealed that the Mars InSight lander’s Heat Flow and Physical Properties Package probe is once again operational. The probe is designed to measure heat escaping the planet’s interior, which could reveal unique information about the planet’s geologic past.

The Heat Flow and Physical Properties Package, commonly referred to as the “Mole” began drilling into the surface of Mars on February 29, 2019. The probe was expected to reach a depth of 5 meters (16 feet) over a period of two months. However, on March 7, it paused drilling after it encountered harder than expected soil.







Following several months of testing on Earth, engineers discovered that the mole requires friction from surrounding soil in order to operate optimally. Without it, the probe simply bounces in place. In order to provide the additional force required to dig, the engineers devised a technique that uses a scoop attached to the lander’s robotic arm to apply pressure to the top of the probe.

The new technique called “pinning” has enabled the probe to resume progress. In an October 17 NASA press release, the agency revealed that it has progressed nearly 2 centimeters (¾ of an inch) over the past week.

“The mole still has a way to go, but we’re all thrilled to see it digging again,” said Troy Hudson, an engineer at JPL who has led the probe’s 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.”

Although the probe has continued to burrow into the Martian soil, JPL engineers are concerned that progress may once again come to halt when the probe sinks below the reach of the robotic arm. As a result, testing on techniques to counter this has already begun with several options currently being considered.