NASA’s Perseverance has spent over 1,000 sols – Martian days – inside Jezero Crater. The location of an ancient impact, the crater was for a time a lake with a river carrying water into it. A prominent delta has been sculpted in the rocks and it is there that the rover has been exploring. And now, it has enough information to paint a picture of what this location has gone through over eons.
It all started 4 billion years ago. An asteroid slammed into Mars and created a large crater which we now call Jezero. The crater floor is made of igneous rock, evidence of either volcanic activity on the surface post-impact or magma formation that raised up. Hundreds of millions of years later, water came to Jezero.
Perseverance found sandstone and mudstone, indicating that water flowed into the crater that long ago. Above those rocks though, there are others. More mudstones, but these are rich in salt. From the flowing water, a shallow lake formed. It is estimated that it grew to have a diameter of 35 kilometers (22 miles) but it was at most only 30 meters (100 feet) deep. The evaporation of the lake left behind the salt.
But the watery history of the place doesn’t end there. The final chapter saw, at a later time, the flowing of fast water across the delta that Perseverance is exploring. Boulders were carried by this powerful river and they were spread over the surface of the delta.
“We picked Jezero Crater as a landing site because orbital imagery showed a delta – clear evidence that a large lake once filled the crater. A lake is a potentially habitable environment, and delta rocks are a great environment for entombing signs of ancient life as fossils in the geologic record,” Perseverance’s project scientist, Ken Farley of Caltech, said in a statement. “After thorough exploration, we’ve pieced together the crater’s geologic history, charting its lake and river phase from beginning to end.”
While the region is a prime candidate for possible ancient life, the rover has not found any signs yet. The suite of instruments on board Perseverance can detect both ancient fossil-like structures and the chemical alterations brought forth by ancient life. It has been investigating the many collected samples thoroughly but nothing so far.
The current region being explored has carbonate material indicating an ancient water environment where life might have evolved. Iron phosphates have also been found, and phosphorus is a key ingredient in life. It is also rich in silica, which is seen as an ideal substance to preserve ancient life.
“We have ideal conditions for finding signs of ancient life where we find carbonates and phosphates, which point to a watery, habitable environment, as well as silica, which is great at preservation,” added Morgan Cable, the deputy principal investigator of Pereseverance’s Planetary Instrument for X-ray Lithochemistry.
The rover is not standing still after crossing the 1,000th sol mark. It is now going to explore the rim of Jezero crater.
Source Link: The History Of An Ancient Martian Lake Has Been Revealed By Perseverance
