Engineers hope the real InSight on Mars can use its robotic arm to help the mole start digging again, a test that has succeeded with replica instruments on Earth. (Credit: NASA/JPL-Caltech)

The digging instrument on NASA’s Mars InSight lander has been stuck since February 28, and engineers have been hard at work trying to get it moving again. The problem is with its Heat Flow and Physical Properties Package, or HP3, and specifically the part known as the mole, which auto-hammers its way into