NASA expert Spawn has explained in more detail why the Mole robot’s mission to Mars was canceled.

The robot was part of the Mars mission “Insight” and was about to explore the red planet’s soil. However, the operation could not be continued as the robot could not dig further into the ground,
Explained Mission Scientific Director, Tillmann Spawn, at Deutschlandfunk (audio link). He works at the International Space Science Institute in Bern. Spawn said the exact reasons why the excavation was so difficult are not yet known.

Mars must dig itself five meters into the ground to take temperature measurements. Each stage of the device was first simulated in a laboratory on Earth. The models were positioned exactly as they were on Mars. Spawn said this test bed was equivalent to a sandpit. But the nature of the soil on Mars made various demands on the device. The robot moved only half a meter. For the researchers, only a hole three meters deep would have been sufficient. But it has also proved to be an illusion.

The message was broadcast on Deutschlandfunk on January 19, 2021.