NASA's InSight lander still has a big problem, and nobody is quite sure how to fix it

One of NASA's most exciting ongoing missions is that of the InSight lander that currently calls Mars home. The robotic lander has the potential to teach scientists a great deal about the Red Planet and its history, but first NASA has to figure out what to do with one of its important, but underperforming, instruments. The tool, which is described as a "self-hammering mole" is designed to dig several meters into the planet in order to take temperature readings and paint a more complete picture of...