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An aerial photograph shows the remains of a delta where a water source once fed an ancient lake in Mars’ Jezero Crater. Credit: NASA/JPL-Caltech/ASU
Ground-penetrating radar reveals eons of environmental change and offers hope that soil samples contain traces of life.
- Onboard ground penetrating radar POT‘s Mars The Perseverance rover has confirmed that Jezero Crater, formed by an ancient meteorite impact just north of the Martian equator, once housed a vast lake and river delta.
- Over eons, sediment deposition and erosion within the crater shaped the geological formations visible today on the surface.
- The discovery of lake sediments bolsters hope that traces of life can be found in soil and rock samples collected by Perseverance.
Animation showing the RIMFAX instrument on NASA’s Mars Perseverance rover acquiring ground-penetrating radar measurements across the contact between the crater floor and the delta in Jezero Crater, Mars. Credit: Euibin Kim, David Paige, UCLA
If life once existed on Mars, the Perseverance rover’s verification of lake sediments at the base of Jezero Crater bolsters hope that traces can be found in the crater.
In new research published in the journal Scientific advancesa team led by UCLA and the university of oslo shows that at some point the crater filled with water, depositing layers of sediment at the bottom of the crater. Subsequently, the lake shrank and the sediments carried by the river that fed it formed a huge delta. As the lake dissipated over time, the crater’s sediments eroded, forming the geological features visible today on the surface.
Mars Perseverance Rover RIMFAX ground-penetrating radar measurements of the Hawksbill Gap region of the western delta of Jezero Crater, Mars. Carey gap. Credit: Svein-Erik Hamran, Tor Berger, David Paige, University of Oslo, UCLA, California Institute of Technology Jet Propulsion Laboratory, NASA
Periods of deposition and erosion took place over eons of environmental change, the radar indicates, confirming that inferences about the geological history of Jezero Crater based on space-based images of Mars are accurate.
“From orbit we can see a lot of different deposits, but we can’t say for sure if what we’re seeing is their original state or if we’re seeing the conclusion of a long geologic history,” said David Paige, professor of earth, planetary sciences. and space sciences at UCLA and first author of the article. “To know how these things formed, we need to look beneath the surface.”
Video interpolated by AI from NAVCAM images of NASA’s Perseverance rover as it traversed the western Jezero Delta from Cape Nukshak to the crater floor on Sol 641. Credit: Lior Rubanenko, Emily Cardarelli, Justin Maki, David Paige, UCLA , California Institute of Jet Propulsion Technology Laboratory, NASA
The rover, which is about the size of a car and carries seven scientific instruments, has been exploring the 30-mile-wide crater, studying its geology and atmosphere and collecting samples since 2021. Perseverance’s soil and rock samples will be returned to the earth. by a future expedition and studied for evidence of past lives.
Between May and December 2022, Perseverance headed from the crater floor toward the delta, a vast expanse of 3 billion-year-old sediments that, from orbit, resembles river deltas on Earth.
Mars Perseverance Rover RIMFAX ground-penetrating radar measurements of the Hawksbill Gap region of the western delta of Jezero Crater, Mars. Credit: Svein-Erik Hamran, Tor Berger, David Paige, University of Oslo, UCLA, California Institute of Technology Jet Propulsion Laboratory, NASA
As the rover moved toward the delta, PerseveranceRadar imager for the Mars subsurface experiment, The RIMFAX instrument fired radar waves downward at 10-centimeter intervals and measured reflected pulses from depths of about 20 meters below the surface. With radar, scientists can see down to the base of the sediments to reveal the upper surface of the buried crater floor.
Years of research with ground-penetrating radar and RIMFAX testing on Earth have taught scientists how to read the structure and composition of subsurface layers from their radar reflections. The resulting subsurface image shows rock layers that can be interpreted as a road cut.
“Some geologists say radar’s ability to see below the surface is like cheating,” said Paige, RIMFAX’s deputy principal investigator.
Mars Perseverance Rover RIMFAX ground-penetrating radar measurements of the Cape Nukshak region of the western delta of Jezero Crater, Mars. Credit: Svein-Erik Hamran, Tor Berger, David Paige, University of Oslo, UCLA, California Institute of Technology Jet Propulsion Laboratory, NASA
RIMFAX images revealed two distinct periods of sediment deposition sandwiched between two periods of erosion. UCLA and the University of Oslo report that the crater floor beneath the delta is not uniformly flat, suggesting that a period of erosion occurred before the deposition of lake sediments. Radar images show that the sediments are regular and horizontal, just like sediments deposited in lakes on Earth. The existence of lacustrine sediments had been suspected in previous studies, but has been confirmed by this research.
A second period of deposition occurred when fluctuations in lake level allowed the river to deposit a broad delta that once extended into the interior of the lake, but which has now eroded closer to the river’s mouth.
“The changes we see preserved in the rock record are driven by large-scale changes in the Martian environment,” Paige said. “It’s great that we can see so much evidence of change in such a small geographic area, allowing us to extend our findings to the scale of the entire crater.”
Reference: “Ground-penetrating radar observations of the contact between the western delta and the floor of Jezero Crater, Mars” by David A. Paige, Svein-Erik Hamran, Hans EF Amundsen, Tor Berger, Patrick Russell, Reva Kakaria, Michael T Mellon, Sigurd Eide, Lynn M. Carter, Titus M. Casademont, Daniel C. Nunes, Emileigh S. Shoemaker, Dirk Plettemeier, Henning Dypvik, Sanna Holm-Alwmark, and Briony HN Horgan, January 26, 2024. Scientific advances.
DOI: 10.1126/sciadv.adi8339
The research was funded by NASA, the Norwegian Research Council and the University of Oslo.