Images captured by the Mars Rover Perseverance in an area nicknamed Skrinkle Haven in Jezero Crater on Mars indicate the presence of a river that flowed into that crater in ancient times. The surprise is that the layers of sediments and pebbles that form what was called a curvilinear unit suggest that that river was deeper and more powerful than all other ancient Martian rivers identified so far. A hill nicknamed Pinestand about 450 meters from Skrinkle Haven may have been formed by a powerful river but scientists are assessing other explanations as well.
Arrived on Mars on February 18, 2021, the Mars Rover Perseverance is exploring Jezero Crater. It’s a very interesting area from a geological point of view because around 3.5 billion years ago there was a lake with various rivers flowing into it. At the time, it was an area where conditions could be favorable for the emergence of life forms, a factor connected to the field of astrobiology that contributed to choosing it as the area to study for Perseverance.
Recently, investigations focused on what in ancient times was a river at a site nicknamed Skrinkle Haven. The Mars Rover Perseverance’s Mastcam-Z photographed the area while the RIMFAX (Radar Imager for Mars’ Subsurface Experiment) instrument probed the subsurface to obtain information on its composition.
The presence of curved bands of stratified rocks led to the definition of curvilinear units for that area. The characteristics of the sediment layers and the presence of large pebbles suggest that that ancient river had a powerful flow capable of carrying a lot of debris, even large ones.
What we can see today are just the remains eroded by the wind but in the past, those debris must have been higher. On the other hand, they’re clearly visible whereas on Earth, deposits of sediments of that type are covered with vegetation. The images and the data collected by the radar will help to understand whether the sediments are the remains of the banks of the ancient river or sandbanks that formed inside it.
Another mosaic of photos taken by the Mars Rover Perseverance shows the site nicknamed Pinestand. It’s part of the curvilinear unit but is about 450 meters from Skrinkle Haven and is a hill with upwardly curved sediment layers with heights even exceeding twenty meters. River action is the most common mechanism for generating those sediment formations, but Pinestand’s are too tall for Earth’s rivers. Of course, a powerful river on a planet with a gravity far lower than Earth’s could have pushed the sediments to those heights, but scientists are exploring other possible explanations.
According to Katie Stack Morgan of JPL, Perseverance’s deputy project scientist, we entered a new phase in Jezero’s history and it’s the first time we’re seeing environments such as the one at Skrinkle Haven and Pinestand. She added that she and her colleagues are thinking about rivers on a different scale than in the past.
Ancient rivers were found in Gale Crater, where the Mars Rover Curiosity is working, but the traces indicate that the water was shallow. A deep, powerful river like the one discovered by the Mars Rover Perseverance again points to a more Earth-like environment confirming that there was a great deal of water when Mars was young.
The two rovers keep on working, adding new information every day to that collected by space probes orbiting the red planet and to that collected by other rovers and landers in missions of other space agencies. Scientists can’t tell if there has ever been life on Mars yet, so the missions continue.
