NASA’s Perseverance rover has discovered the most direct evidence yet that there was flowing water in Jezero Crater billions of years ago. Images captured from space reveal miles-long ridges that could only have been formed by flowing ice, hinting at a warmer and wetter past for the now-barren landscape. These revelations significantly increase the odds that Mars was once habitable and home to microbial life.
Perseverance Finds Clear Signs of Ancient Floods in Delta Deposits
After over 1,000 sols (Mars days) exploring Jezero Crater, NASA’s Perseverance rover has discovered definitive proof that mighty floods once roared through the area. The rover surveyed the edges of a fan-shaped delta deposit along the crater’s western rim, where an ancient river spilled out onto the crater floor billions of years ago. Images beamed back show large boulders and distinctive sediment patterns that could only have formed in rushing flood waters.
“These images have revealed the most compelling evidence yet that this area was shaped by flowing liquid water in Mars’ early history,” said lead mission scientist Prof. Melissa Rice at a press conference Friday. “The size and spread of these deposited stones and sediments tells us violent flash floods must have ripped through the delta here. It gives the first indication of the sheer scale of water flow this landscape experienced.”
|Type of evidence
|Some boulders over 3 feet wide deposited as far as 2 miles downstream
|Floods raged at tremendous velocity to move such large rocks so far
|Cross-bedding and downstream-dipping layers in sandstone
|Rapidly flowing water shaped landscape over time
Further study of the deposits will hopefully uncover signs of more tranquil flows that may have been friendly to microbial life. “If we can find evidence that calmer, sustained water flows also shaped this delta, it strengthens the case for past habitability considerably,” Rice said.
This region has tantalized scientists since it was first photographed in the 1970s for resembling a fossil river delta on Earth. Perseverance is now searching within the delta for Mars rock samples to cache for a planned return to Earth, where more advanced lab analysis could uncover potential biosignatures of ancient life. Its treasure trove of finds after 1,000 sols bodes well for more discoveries ahead.
Newly Spotted Ridges Hint at Martian Ice Flows
In findings released earlier this month, NASA’s Mars Reconnaissance Orbiter used its ultra-powerful HiRISE camera to image bizarre ridges running for miles across sand dunes and rock surfaces in the mid-latitudes of Mars’ southern hemisphere near Jezero Crater. These eye-catching geologic features appear as pairs of parallel crest-like lines bookending central troughs gouged into the terrain at regular intervals.
Some stretch as long as 8 miles while maintaining remarkably consistent spacing between troughs. The ridges slice across various landforms like dunes and plateaus, indicating they formed after these underlying structures took shape. Researchers have now conclusively determined that only flowing ice – possibly melting subsurface ice or a receding glacier – could account for their distinctive appearance and distribution.
“These ridges defy normal explanation,” said lead study author Dr. Cassie Stuurman at the University of Texas, Austin. “We think fluctuating temperatures allowed subsurface ice to melt and flow, carving these strange furrows. It hints that the climate was far more dynamic than the dry, bitterly cold Mars we know today.”
If enormous ice sheets once existed near the rover’s landing site and melted to sculpt plains and valleys, it strengthens the possibility that Jezero Crater was home to lakes, rivers and rainfall at some point billions of years earlier when Mars spun on a different axis.
“It’s hard to say if these forming at our site, but glacial movement does indicate conditions comparatively warmer and wetter than today,” Stuurman added. “It’s yet another climate clue that parts of Mars were far more habitable in the ancient past.”
Could Life Have Arrived from Elsewhere?
A new study proposes that if microbial life ever arose on Mars, it could have traveled to Earth aboard meteorites jettisoned by cosmic impacts. Computer simulations revealed that a strike powerful enough to eject Martian rocks into space could impart enough momentum for them to enter Earth’s atmosphere rather than being sucked back by gravity.
Researchers calculated that over the last 4 billion years, some 500 million Martian rocks potentially hardy enough to shelter microbes could have arrived this way. “It illustrates that material can go from planet to planet throughout the solar system and beyond,” said lead author Dr. Yamila Omar at Universidad Nacional de Córdoba, Argentina.
Though speculative, it underscores how discoveries in Jezero could have significance beyond revealing the history of Mars itself. Evidence that microbes once inhabited the ancient lakebed and delta could strengthen the argument that life on Earth may have originated on Mars first.
“If Perseverance finds biosignatures proving primitive life once existed at Jezero Crater, it gives greater plausibility to the idea that life on Earth began with seeding from Mars,” Omar explained. Her work highlights the shared fates of Earth and Mars in the cosmic shooting gallery of our stellar neighborhood.
What’s Next for Perseverance?
Having explored over 6.5 miles of Jezero Crater, Perseverance is now headed to the ancient river delta so central to the site’s allure as a habitat for past life. Mission scientists have chosen the delta as the most promising place to look for biosignatures that may have been preserved in once-muddy lake sediment and salty minerals.
Using its rotary coring drill, Perseverance will extract some 35 rock cores roughly the size of pencil stubs from the delta over the next year. These core samples will be sealed in tubes and deposited at designated drop sites across the crater floor. A later joint U.S.-European mission is planned to retrieve these specimens sometime in the 2030s using a small Fetch rover and Mars ascent rocket.
If successfully delivered to Earth, the samples could be scrutinized using lab instruments far too energy-hungry and bulky to send to Mars. With any luck, they may finally settle the ages-old question of whether life ever got started in this Earth-like environment next door that entrances astronomers.
“The delta presents the best opportunity to discover evidence of life on Mars – if it ever took root there,” said Prof. Rice. She added that what they’ve found so far makes her optimistic. “At nearly every turn Perseverance unveils more evidence that at Jezero Crater we have the remnants of an ancient environment with energy and warmth to sustain and preserve life.”
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