Tarnas’s team sifted through data collected by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on NASA’s Mars Reconnaissance Orbiter, launched in 2005 to monitor Mars and study its surface in high detail. He and his colleagues developed and applied a new analytical technique that detects weak electromagnetic signals emitted by minerals on the surface. They found two outcrops of silica deposits situated in Jezero (some at low layers where fossils are more likely to be preserved).

The other paper, published in Icarus on November 12, also used CRISM data to identify deposits of carbonates sitting along the inner rim of Jezero. Carbonates are extremely hardy minerals most often associated with preserving terrestrial fossils of seashells, coral, and stromatolites along shorelines. Concentrated in a “bathtub ring” around Jezero, these newly discovered carbonates may have been deposited by an ancient lake—and could be home to the preserved remains of microbial Martian life.

Briony Horgan, a planetary scientist at Purdue University and the lead author of the new study, is especially hopeful the findings might help us find stromatolites, which are macroscopic mounds made of layers of carbonates and microbes. "These are big enough that they would make a clear target for the rover," she says.

No one is completely sure how the carbonates or the silica deposits got here, but the Mars 2020 rover should be able to easily determine how, when, and where they initially formed. Its SHERLOC instrument, specifically designed to look for signs of extraterrestrial life, is a Raman spectrometer that uses UV laser light to identify organic chemicals. Over its first two years, the rover should be able to explore and study samples of both minerals at their respective locations.

Better yet, even if the rover runs into any walls (literal or otherwise) and fails to determine whether these minerals are associated with ancient Martian life forms, the mission will secure samples for laboratory analysis back on Earth. The silica and carbonate deposits will surely be near the top of the “must return” list.