NASA's InSight mission is struggling to dig into Mars

(CNN)Since landing on Mars in November 2018, NASA's InSight mission has been taking selfies, providing daily Martian weather reports, detecting quakes on Mars and hearing strange sounds. But its heat probe experiment is struggling to burrow beneath the surface of the Red Planet.

While the Curiosity rover is currently exploring Gale Crater, InSight is a stationary probe permanently parked in Elysium Planitia. It's along the Martian equator, bright and warm enough to power the lander's solar array year-round.
InSight, or Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a two-year mission to explore a part of Mars that we know the least about: its deep interior.
The suite of geophysical instruments on InSight sounds like a doctor's bag, giving Mars its first "checkup" since the planet formed. Together, those instruments take measurements of Mars' vital signs, like its pulse, temperature and reflexes — which translate to internal activity like seismology and the planet's wobble as the sun and its moons tug on Mars.
    InSight's heat probe.
    But "the mole," or the self-hammering heat probe, has only dug roughly 14 inches into the surface since February 28. It was designed to reach at least 16 feet beneath the surface to record how heat escapes from the interior, according to NASA.
    The mole seems to be missing a key factor in digging: friction in the surrounding soil. Instead, the team believes that the probe is simply bouncing in place. Applying extra pressure may be a solution.
    "We're going to try pressing the side of the scoop against the mole, pinning it to the wall of its hole," said Sue Smrekar, InSight deputy principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, California. "This might increase friction enough to keep it moving forward when mole hammering resumes."