Floods on Mars: Perseverance rover confirms Red Planet witnessed flash floods as climate changed
Images received from the rover suggest that the area experienced significant flooding events in the past going as back as 3.7 billion years ago.
Even as the Perseverance rover remains parked in the desolate swathe of the Jazero crater as Earth's communication with Mars comes to a halt, the science continues to flow. A new analysis of images of the region, where the rover is trundling, confirms that the Jezero — a dry, eroded depression today — was once home to a well-fed lake.
Images received from the rover before it went dark on the rock suggest that the area experienced significant flooding events in the past going as back as 3.7 billion years ago. The rivers were flowing when Mars had an atmosphere thick enough to support water and the fan-shaped river delta experienced late-stage flooding events.
A paper published in the journal Science details how the hydrological cycle of the now-dry lake at Jezero Crater is more complicated and intriguing than originally thought. The analysis shows evidence of flash floods in the region, energetic enough to sweep up large boulders from tens of miles upstream and deposit them into the lakebed, where the massive rocks lie today.
FLASH FLOODS ON MARS
Scientists studied the images captured by the rover’s left and right Mastcam-Z cameras as well as its Remote Micro-Imager which confirmed that the outcrop was once a river delta. Analysis of sediments indicates that the river delta fed into a lake that was calm until a major climatic event-triggered flooding towards the final period of the lake.
Benjamin Weiss, professor of planetary sciences in MIT’s Department of Earth, Atmospheric and Planetary Sciences in a statement said, “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. 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."
This is the first paper to be published since Perseverance's landing in the Jazero crater on Mars in February this year. The rover team has long planned to visit the delta because of its potential for harbouring signs of ancient microbial life. Engineers have successfully scooped two samples from the surface which have been sealed in the rover to be returned to Earth via future missions.
THE FIRST GLIMPSE
The rover landed in the crater in February and remained stationary as engineers performed health checks and revved up its engine to begin exploring. During this time, the cameras clicked long-distance photos of the outcrop’s edge and a formation known as Kodiak butte. Geologists believe that Kodiak is a geological structure, which may have once been connected to the main fan-shaped outcrop but has since partially eroded.
The Jet Propulsion Laboratory (JPL), which is operating the rover on the Red Planet, said that Kodiak had been imaged only from orbit. From the surface, the rover’s Mastcam-Z and RMI images revealed for the first time the stratigraphy the order and position of rock layers, which provides information about the relative timing of geological deposits along Kodiak’s eastern face.
“Never before has such well-preserved stratigraphy been visible on Mars. This is the key observation that enables us to once and for all confirm the presence of a lake and river delta at Jezero. Getting a better understanding of the hydrology months in advance of our arrival at the delta is going to pay big dividends down the road,” Nicolas Mangold, a Perseverance scientist told JPL.
A DEEP LAKE
Geologists say that the levels of the ancient lake in the crater have been high enough to crest the crater’s eastern rim, where orbital imagery shows the remains of an outflow river channel. The paper further adds that the size of the lake fluctuated over time with "its water level rising and falling by tens of yards before the body of water eventually disappeared altogether."
While it is yet to be understood why the levels kept changing, was it climatic factors of flooding events, geologists have determined that they occurred later in the Jezero delta’s history, when lake levels were at least 100 meters below the lake’s highest level.
“A better understanding of Jezero’s delta is a key to understanding the change in hydrology for the area and it could potentially provide valuable insights into why the entire planet dried out," said Sanjeev Gupta, a Perseverance scientist from Imperial College, London, and a co-author of the paper.
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