NASA’s InSight is the latest explorer on the Red Planet and has delivered incredible science from Mars since November 2018. Unfortunately, one of its instruments has encountered numerous snags. This is the Heat Flow and Physical Properties Package (HP3) or the “Mole”, designed to dig deep inside the Martian soil and measure the planet’s interior temperature.
But the soil around InSight has been unlike anything encountered elsewhere on Mars. The Mole is a self-hammering probe that's designed to use the friction of loose soil to dig. But the soil where it is located has been too "cement-like" to provide enough friction. After several approaches with no positive result, the team decided on a simple but risky move – they used InSight’s robotic arm to push down on the mole.
This method allowed the mole to dig all the way into the ground. Having crossed that hurdle, the team tested HP3 to see if it could dig by itself. This was the “Free Mole Test” announced in June. Unfortunately, it did not work. The team expected this result, but if it did work it would have made the next phase much easier.
“On Saturday 20 June 2020 (Sol 557 on Mars), the team completed the 'Free Mole Test' announced in my previous blog post. The result was not quite what we had optimistically hoped for, but was also not entirely a surprise. The 'Mole' started bouncing in place after making some progress without direct support from the scoop on 13 June (Sol 550),” Instrument Lead Tilman Spohn wrote on the HP3 logbook website.
The mole is fully down in the hole but given that it has performed about 9,000 hammer strokes, it has created quite a gap around it. The team plans to provide more grip by filling up the hole with sand, which will require several scrapes from the robotic arm. The team has other solutions in mind if this doesn't work, but they are taking it one hammer stroke at the time.
The robotic arm is now being used for other scientific activities, so the team and the mole will try the new approach in August.
2
