NASA's Perseverance rover confirms ancient lake's presence on Mars
NASA's Perseverance rover has discovered ancient lake sediments in the Jezero Crater on Mars, raising hopes of getting signs of life in samples it collected. The findings, based on data from the rover's Radar Imager for Mars' Subsurface Experiment (RIMFAX) instrument, were published in Science Advances. Researchers from the University of California, Los Angeles (UCLA) and the University of Oslo led the study. Perseverance landed on Mars's 45km Jezero Crater on February 18, 2021, to explore a past water environment.
What do the findings suggest?
The latest study reveals clues about how water-deposited sediment layers formed over time on the Jezero Crater's floor. "From orbit, we can see a bunch of different deposits, but we can't tell for sure if what we're seeing is their original state or if we're seeing the conclusion of a long geological story," said David Paige, the study's first author and RIMFAX's deputy principal investigator. "To tell how these things formed, we need to see below the surface," he added.
How RIMFAX instrument provided subsurface profile
As the Perseverance rover traveled across the Martian terrain, the RIMFAX instrument sent radar waves downward in 10cm intervals, gauging reflections from depths approximately 20m below the surface. This process created a subsurface profile of the crater floor. The data acquired by RIMFAX indicates the presence of sediment, suggesting water once filled the Jezero Crater. If microbial life inhabited the crater during this period, sediment samples from this region could harbor traces of their existence.
Two distinct periods of deposition occurred
The Perseverance rover has been exploring the crater, seeking evidence of past life while also gathering and storing numerous samples, possibly for a future retrieval mission to Earth. The study has identified two distinct periods of sediment deposition, creating layers similar to Earth's strata. Changes in the lake's water levels formed a massive delta, which Perseverance crossed between May and December 2022. Radar measurements also reveal an uneven crater floor beneath the delta, likely due to erosion before sediment deposition.
Changes in Martian environment preserved in rock record
"The changes we see preserved in the rock record are driven by large-scale changes in the Martian environment," said Paige. "It's cool that we can see so much evidence of change in such a small geographic area, which allows [us] to extend our findings to the scale of the entire crater," he added. As the lake dried up, sediment layers in the Jezero Crater eroded, forming the geologic features now visible on Mars.
Perseverance's journey validates geo-biological endeavor
The study demonstrates scientists chose the right location for their Mars mission. The findings support the idea that the red planet was once warm, wet, and potentially habitable. Early core samples drilled by Perseverance showed volcanic rocks instead of sedimentary ones, but even these rocks showed signs of water exposure, as revealed in a study from 2022. The latest RIMFAX findings report erosion before and after sedimentary layer formation, indicating a complex geological history at the Jezero Crater's western edge.
