NASA's InSight lander was supposed be digging a hole so a probe (above) could measure the heat escaping from Mars' interior, but it hasn't made much progress since work got started in February -- it hadn't even finished burying itself. At last, it's making some headway. The agency has revealed that the probe, nicknamed "the mole," is finally digging in earnest thanks to a new strategy. The arm had been stymied by unusually rough soil, but the team found it could get the necessary friction by having InSight press its robotic arm against the probe.