Ancient Martian Lake: NASA’s Perseverance rover, equipped with ground-penetrating radar, has definitively established the presence of an ancient lake in the Jezero Crater on Mars—a crater formed by a meteor impact near the Martian equator. The confirmation comes as a result of the rover’s meticulous exploration of the crater, unveiling the remnants of a vast lake and river delta through sediment deposits and erosion over millennia.
Detailed in a recent publication in the journal Science Advances, researchers from UCLA and The University of Oslo reveal that the Jezero Crater once held water, with sediment layers accumulating on the crater floor. Subsequently, the lake receded, giving rise to a massive delta formed by sediments transported by the feeding river.
Over the course of extensive environmental changes spanning eons, the radar data collected by Perseverance underscores the accuracy of previous inferences about the crater’s geological history derived from orbital images of Mars. David Paige, a UCLA professor and the paper’s first author, emphasized the significance of the rover’s ability to probe below the surface, providing insights into the formation processes that shaped the Martian landscape.
Perseverance, roughly the size of a car and armed with seven scientific instruments, has been diligently examining the 30-mile-wide Jezero Crater since 2021. The rover’s mission includes studying the crater’s geology and atmosphere and, crucially, collecting samples of soil and rocks that may hold evidence of past life on Mars. These samples are slated to be brought back to Earth for thorough analysis in a future expedition.
Between May and December 2022, Perseverance traversed from the crater floor onto the expansive delta, composed of 3-billion-year-old sediments reminiscent of Earth’s river deltas when observed from orbit. Utilizing the Radar Imager for Mars’ Subsurface Experiment (RIMFAX), the rover sent radar waves into the Martian depths, revealing subsurface layers and providing a unique glimpse of the buried crater floor’s top surface.
RIMFAX’s imaging disclosed distinct periods of sediment deposition interspersed with erosion, indicating significant changes in the Martian environment over time. The irregularities observed in the crater floor beneath the delta suggest an earlier erosion phase before the deposition of lake sediments. The regular and horizontal nature of these sediments mirrors patterns seen in terrestrial lake deposits.
While previous studies had hinted at the existence of lake sediments, the latest research serves as conclusive evidence. The ability of ground-penetrating radar, exemplified by RIMFAX, has enabled scientists to delve beneath the Martian surface, revealing a geological history that speaks to the dynamic environmental transformations within the confines of the Jezero Crater.