NASA’s Perseverance rover has been busy serving as a communications base station for the “ingenious” Mars helicopter and documenting the rotorcraft’s historic flight. But the rover has also been busy focusing its science instruments on the rocks at the base of Jezero Crater.
Their findings will help scientists create a timeline of when an ancient lake formed, when it dried up, and when sediments began to accumulate in the delta where the crater formed. Understanding this timeline will help date rock samples, which may preserve a record of ancient microbes.
A camera called WATSON, located at the end of the rover’s robotic arm, has taken detailed pictures of the rocks. The Mastcam-Z imager on the “head” of the rover consists of a pair of zoomable cameras that also probe the terrain. A laser instrument called the SuperCam has detected the chemical composition of some of the rocks. These instruments and others have allowed scientists to learn more about Jezero Crater and to find areas they may want to study in greater depth.
One important question the scientists want to answer is whether the rocks are sedimentary (such as sandstone) or igneous (formed by volcanic activity). Each type of rock tells a different story. Some sedimentary rocks – formed in the presence of water in rocks and mineral fragments such as sand, silt, and clay – are better suited to preserve biological features or signs of past life. On the other hand, igneous rocks are more accurate geological clocks, allowing scientists to create an accurate timeline of how an area formed.
A complicating factor is that over time, the rocks around the Trail have been eroded by wind and covered with young sand and dust. On Earth, geologists may trek out into the field and open rock samples to better understand their origins.
“The Trailblazer has its own way of looking at the dust of the past few thousand years. When scientists find a particularly intriguing site, they can extend the rover’s arm and use a grinder to smooth the surface of a rock to reveal its internal structure and composition. Once they’ve done that, the team uses arm-mounted instruments called PIXL (Planetary X-ray Petrochemistry Instrument) and SHERLOC (Scanning the Habitable Environment with Organic and Chemical Raman Luminosity) to gather more detailed chemical and mineralogical information.
The more information the team learns, the better the samples they can eventually collect with the drills on the rover arms. The best samples will be preserved in special tubes and eventually returned to Earth for analysis.