Perseverance rover images reveal flash flooding before Martian lake disappeared


Jezero Crater, the rover’s exploration web site on Mars, was a quiet lake 3.7 billion years in the past. A small river fed into the lake, typically resulting in flash flooding that was so energetic, it may carry giant boulders from miles upstream and drop them into the lake. The large rocks are nonetheless there as we speak.

These findings, which have been printed Thursday within the journal Science, come from the primary scientific evaluation of rover photographs that present outcrops of rocks contained in the crater.

The new data reveals the significance of sending rovers to discover the floor of Mars. Previous photographs captured by orbiters had proven that this outcrop resembled the sort of fan-shaped river deltas now we have on Earth. Perseverance’s photographs present definitive proof of the river delta’s existence.

“It helps us understand so much more about the water cycle on Mars,” mentioned Amy Williams, research coauthor and University of Florida astrobiologist, in an announcement. “From orbital images, we knew it had to be water that formed the delta, but having these images is like reading a book instead of just looking at the cover. This is the closest I will ever get to going to Mars and doing this work in person. Seeing these rocks as I would in real life, looking up at them, is really staggering and really beautiful.”

When Perseverance landed at Jezero Crater on February 18, it was simply over a mile away from the delta. Before the rover’s wheels ever began rolling, it instantly started taking photos and sending them again to Perseverance’s science crew on Earth — like Martian postcards with excessive scientific worth.

The photographs confirmed tilted layers of sediment that have been probably created by flowing water, slightly than flat, even layers that may have been resulting from wind or different processes.

This composite image of the "Delta Scarp" in Jezero Crater shows both the base and plateau of the escarpment, including intriguing geologic features.

The high layers of the delta outcrop embrace giant boulders, some as huge as 3.2 ft (1 meter) throughout that probably weighed a number of tons. Given their location on the highest layer of sediment, they needed to have originated from outdoors the crater. The scientists imagine they originated from bedrock on the crater rim — in any other case, they got here from 40 or extra miles upstream of the lake.

Perseverance rover successfully collects first Martian sample

But flash flooding, flowing at a charge as excessive as 29.5 ft (9 meters) per second, may have carried them down.

“You need energetic flood conditions to carry rocks that big and heavy,” mentioned Benjamin Weiss, research writer and professor of planetary sciences within the Department of Earth, Atmospheric and Planetary Sciences on the Massachusetts Institute of Technology, in an announcement. “It’s a special thing that may be indicative of a fundamental change in the local hydrology or perhaps the regional climate on Mars.”

This long, steep slope is called an escarpment, or scarp, along the delta in Mars' Jezero Crater.

The incontrovertible fact that the massive boulders sit on superb layers of tilted sediment additionally illustrates that the lake was largely calm till it was hit with flash flooding occasions earlier than drying up. Then, billions of years of wind eroded away on the dry lake mattress and delta.

“The most surprising thing that’s come out of these images is the potential opportunity to catch the time when this crater transitioned from an Earth-like habitable environment, to this desolate landscape wasteland we see now,” Weiss mentioned. “These boulder beds may be records of this transition, and we haven’t seen this in other places on Mars.”

Perseverance's Martian rock samples may contain ancient water bubbles

While the reason for this shift in local weather stays unknown, the rocks may inform the story — half of a bigger story about why the Martian local weather modified from heat and moist to chilly and dry.

“If you look at these images, you’re basically staring at this epic desert landscape. It’s the most forlorn place you could ever visit,” Weiss mentioned. “There’s not a drop of water anywhere, and yet, here we have evidence of a very different past. Something very profound happened in the planet’s history.”

A key a part of Perseverance’s mission isn’t solely to discover the crater and river delta, however gather samples from intriguing rocks throughout each. Future missions will return greater than 30 of those samples to Earth by the 2030s. The samples may reveal whether or not life ever existed on historical Mars — and these new photographs can assist scientists decide the most effective rocks to pattern as they seek for proof of historical microbe fossils.

“We now have the opportunity to look for fossils,” mentioned Tanja Bosak, research coauthor and professor of geobiology at MIT, in an announcement. “It will take some time to get to the rocks that we really hope to sample for signs of life. So, it’s a marathon, with a lot of potential.”

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