NASA’s Perseverance Rover has unearthed compelling data, affirming the presence of ancient lake sediments within Mars’ colossal Jezero Crater. This revelation, backed by ground-penetrating radar observations, aligns with previous orbital imagery, suggesting that Mars once boasted extensive water bodies potentially conducive to microbial life.
Published in the journal Science Advances, a collaborative team from UCLA and The University of Oslo unveils a narrative of Mars’ geological evolution, exposing the intriguing history of Jezero Crater.
GEOLOGICAL STORYTELLING: THE RISE AND FALL OF JEZERO’S WATERS
The study unfolds a captivating tale of Jezero Crater, indicating that at a certain epoch, the crater hosted a substantial water body. This aquatic environment deposited layers of sediments on the crater floor, creating a historical record etched in Martian soil. As time elapsed, the once expansive lake diminished, and the sediments, transported by a meandering river, sculpted an immense delta. The gradual dissipation of the lake over epochs led to the erosion of crater sediments, shaping the distinctive geological features visible on the Martian surface today.
EONS OF CHANGE: RADAR INSIGHTS CONFIRM ENVIRONMENTAL SHIFTS
Ground-penetrating radar observations by Perseverance unveil the extensive periods of sediment deposition and erosion, echoing the eons-long environmental transformations within Jezero Crater. This radar data reinforces the accuracy of inferences drawn from Mars images obtained from space, providing a deeper understanding of the crater’s geological history.
David Paige, UCLA professor of Earth, planetary, and space sciences, emphasizes the necessity of exploring beneath Mars’ surface. “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 the conclusion of a long geological story,” says Paige. “To comprehend these formations, we need to delve below the surface.”
PERSEVERANCE’S SCIENTIFIC ODYSSEY: UNVEILING MARTIAN MYSTERIES
Since 2021, Perseverance, a car-sized rover equipped with seven scientific instruments, has been meticulously investigating the 30-mile-wide Jezero Crater. Its mission encompasses a comprehensive study of Martian geology and atmosphere, accompanied by the collection of crucial soil and rock samples. These invaluable samples, slated for return to Earth by a future expedition, hold the potential to reveal evidence of past life on the red planet.
Between May and December 2022, Perseverance embarked on a transformative journey, traversing from the crater floor onto the expansive delta—a landscape adorned with 3-billion-year-old sediments, reminiscent of Earth’s river deltas when viewed from orbit.
RIMFAX UNVEILS SUBSURFACE SECRETS
As Perseverance ventured onto the delta, its Radar Imager for Mars’ Subsurface Experiment (RIMFAX) instrument came into play. RIMFAX fired radar waves downward at 10-centimeter intervals, measuring pulses reflected from depths of about 20 meters below the Martian surface. This process unveiled the top surface of the buried crater floor, allowing scientists to decipher the structure and composition of subsurface layers, akin to reading a highway road cut.
David Paige, also RIMFAX’s deputy principal investigator, acknowledges the unique advantage of radar imaging. “Some geologists say that the ability of radar to see under the surface is kind of like cheating,” Paige comments, highlighting the unprecedented insights gained through this technology.
GEOLOGICAL TIME CAPSULE: TWO DISTINCT SEDIMENT PERIODS REVEALED
RIMFAX imaging exposed two distinct periods of sediment deposition separated by periods of erosion. The crater floor beneath the delta, far from being uniformly flat, displays evidence of a preceding erosion phase before the deposition of lake sediments. The regular and horizontal arrangement of sediments, akin to those found in Earth’s lakes, corroborates suspicions from previous studies, now firmly confirmed by this research.
A second phase of deposition occurred as fluctuations in the lake level facilitated the formation of a broad delta, extending far into the lake initially but subsequently eroding back closer to the river’s mouth.
“The changes preserved in the rock record are driven by large-scale changes in the Martian environment,” notes Paige. “It’s fascinating that we can observe such evidence of change in a relatively small geographic area, allowing us to extrapolate our findings to the scale of the entire crater.”