NASA’s InSight lander is busy deploying its Heat Flow and Physical Properties Package (HP3) into the Martian soil and has encountered some resistance. The German Aerospace Center (DLR), who designed and built the HP3 as part of the InSight mission, has announced that the instrument has hit not one, but two rocks in the sub-surface. For now the HP3 is in a resting phase, and it’s not clear what will happen next.

The HP3 is designed to measure the heat coming from Mars’ interior and to tell us something about the source of that heat. The basic idea is to determine how Mars formed, and if it formed the same way Earth did. It’ll also tell us something about how rocky planets in general form and evolve. But to do that, it has to get underground.

The HP3 uses a hammer system to pound itself into the ground. It works in phases, spending about four hours at a time hammering into the surface. But all that hammering creates a lot of friction and heat, so the HP3 rests for a couple days while things cool down. Then it measures the heat before continuing the cycle.

Martian hourly weather data for Saturday, Sunday, and Monday. Note the kinks in the air pressure curve at 07:00 and 19:00 daily.

There’s a new meteorologist on Mars. Although NASA’s InSight spacecraft landed on the red planet late in 2018 to measure the planet’s geology—primarily by listening for Mars quakes—it also brought some sophisticated meteorology equipment with it.

The space agency has set up a website to share that information, which includes not only daily high and low temperatures but also unprecedented hourly data on wind speed, direction, and air pressure for InSight’s location near the equator in Elysium Planitia. “We thought it was something that people might have some fun with,” Cornell University’s Don Banfield, who leads InSight’s weather science, told Ars.

Other spacecraft have brought comparable temperature and wind sensors to Mars before, but none have carried such a precise air pressure sensor. The new sensor is 10 times more sensitive than any previous instrument because InSight needs to detect slight movements in the Martian ground, and from such movements infer details about the red planet’s interior. For this, weather matters.

The Martian atmosphere may be very thin—typically it varies between 700 and 740 pascals at the surface, less than one percent of Earth’s surface pressure—but it nonetheless can induce slight tilts in the Martian surface. The air pressure sensor will therefore help scientists calibrate the lander’s seismometer so that any tilting due to higher or lower air pressure can be filtered out of the data. It’s actually pretty amazing that even so thin an atmosphere can have a slight effect on the Martian surface and that InSight’s seismometer is sensitive enough to detect it.

NASA’s InSight spacecraft flipped open the lens cover on its Instrument Context Camera (ICC) on Nov. 30, 2018, and captured this view of Mars. Located below the deck of the InSight lander, the ICC has a fisheye view, creating a curved horizon. Some clumps of dust are still visible on the camera’s lens. One of the spacecraft’s footpads can be seen in the lower right corner. The seismometer’s tether box is in the upper left corner. Image credit: NASA/JPL-Caltech

With InSight safely on the surface of Mars, the mission team at NASA’s Jet Propulsion Laboratory in Pasadena, California, is busy learning more about the spacecraft’s landing site. They knew when InSight landed on Nov. 26 that the spacecraft had touched down on target, a lava plain named Elysium Planitia. Now they’ve determined that the vehicle sits slightly tilted (about 4 degrees) in a shallow dust- and sand-filled impact crater known as a “hollow.” InSight has been engineered to operate on a surface with an inclination up to 15 degrees.

“The science team had been hoping to land in a sandy area with few rocks since we chose the landing site, so we couldn’t be happier,” said InSight project manager Tom Hoffman of JPL. “There are no landing pads or runways on Mars, so coming down in an area that is basically a large sandbox without any large rocks should make instrument deployment easier and provide a great place for our mole to start burrowing.”

Rockiness and slope grade factor into landing safety and are also important in determining whether InSight can succeed in its mission after landing. Rocks and slopes could affect InSight’s ability to place its heat-flow probe – also known as “the mole,” or HP3 – and ultra-sensitive seismometer, known as SEIS, on the surface of Mars.