The AGU Fall Meeting is always a great time of year for planetary science. All these results and releases that were being held until the conference come flooding out, and we get to look at tons of neat science. As we continue on our tour of the inner solar system, we come to Mars and a certain newly arrived rover named Perseverance who is rolling around, collecting rocks, and taking samples.

And oh, how we are learning new things about Mars from this rover.

First, it turns out that the rocks under Percy’s six wheels are volcanic in nature. If we date those rocks, we can understand more about Mars’ geologic history, particularly in Jezero Crater, where Percy is exploring.

Second, the science team has found that rocks in the crater have interacted with water more than once and even contain some organic molecules.

These results come from an analysis of rocks sampled by the Planetary Instrument for X-ray Lithochemistry, or PIXL, which uses X-ray fluorescence to determine the elemental composition of the rocks. One particular rock, sampled on November 12 and nicknamed ‘Brac’, turned out to be composed of large olivine crystals surrounded by pyroxene. Project scientist Ken Farley explains why this is important: A good geology student will tell you that such a texture indicates the rock formed when crystals grew and settled in a slowly cooling magma – for example, a thick lava flow, lava lake, or magma chamber. The rock was then altered by water several times, making it a treasure trove that will allow future scientists to date events in Jezero, better understand the period in which water was more common on its surface, and reveal the early history of the planet.

Now they cannot yet tell if these rocks cooled underground or on the surface, but they have been taking samples and have four rock cores so far for that future Mars Sample Return mission to collect.

So what about those organic molecules? Before you get too excited, remember that in scientific terms, ‘organic’ here just means that the molecules contain carbon. These molecules were found by the SHERLOC instrument both in the interiors of rocks and in the dust on top of the rocks. It doesn’t mean there was once life on Mars since organic molecules come from both biological and non-biological mechanisms.

SHERLOC principal investigator Luther Beegle notes: Curiosity also discovered organics at its landing site within Gale Crater. What SHERLOC adds to the story is its capability to map the spatial distribution of organics inside rocks and relate those organics to minerals found there. This helps us understand the environment in which the organics formed. More analysis needs to be done to determine the method of production for the identified organics.

Oh, and I should note one more result from Perseverance presented at the AGU Fall Meeting. Onboard is a ground-penetrating radar called RIMFAX, which has been creating ‘radargrams’ of subsurface features to a depth of about 10 meters. So far, they have found rock formations along a ridgeline that have a visible downward tilt, and that feature continues underground as well. We’re mapping geology under the surface of another planet. How cool is that?

More Information

NASA JPL press release