By Will Dunham
WASHINGTON (Reuters) – Nuclear samples drilled onto the surface of Mars by NASA’s Perseverance rover reveal the geology of a gaping crater that scientists suspect may have harbored microbial life billions of years ago, including surprises about the nature of the rock found there. is present.
The samples, obtained by the six-wheeled robot rover the size of a car and stored for future transport to Earth for further research, showed that rock from four locations in Jezero Crater is igneous – formed by cooling molten material. The rocks also showed signs of change from exposure to water, another sign that cold and dry Mars was warm and wet long ago.
The scientists had thought that the rock, formed about 3.5 billion years ago, could be sedimentary, formed as mud and sand deposited in a lake bottom.
“In fact, we found no evidence of sedimentary rock where the rover explored the crater floor, despite knowing that the crater once had a lake and sediment must have been deposited. Those sedimentary deposits must have eroded away,” said Caltech geochemist Kenneth. Farley, lead author of one of four studies published in the journals Science and Science Advances detailing the geology of the crater.
Perseverance arrived on Mars in February 2021 and has been hard at work in Jezero crater ever since, using a range of instruments, as scientists investigate whether Earth’s closest planetary neighbor has ever had conditions conducive to life.
It collects rock samples, about the size of blackboard chalk, in small tubes to be picked up by a spacecraft in 2033 and brought to Earth for further research, including for biosignatures – indicators of life.
Jezero crater is 28 miles (45 km) wide, located just north of Mars’ equator. It appears that the area was once abundant with water and was home to a river delta, with river channels running across the crater wall, forming a large lake. Scientists suspect the crater may have harbored microbial life, with evidence perhaps found in the lake bottom or shoreline.
Perseverance is now collecting monsters in the delta area.
The igneous rocks of the crater were found to interact with water, forming new minerals and depositing salts, although this water was apparently either in small amounts or not present for very long – probably groundwater. But the presence of the water suggests that this may have been a habitable environment at the time, the researchers said.
“We have collected samples that will be returned to Earth, and they should provide critical evidence of what types of organisms, if any, inhabited the rocks of the Jezero crater floor when they interacted with water,” said Yang Liu, a planetary scientist. monster scientist at NASA’s Jet Propulsion Laboratory and lead author of one of the studies.
The four monsters were drilled from two areas, one called Seitah and the other Maaz. The Seitah rock appears to have been formed underground by slow cooling of a thick layer of magma. The Maaz rocks may have cooled relatively faster in an upper layer of underground magma or after a volcanic surface eruption. Regardless, every rock layer that once covered these areas has since been eroded away, either by water or wind.
Liu said the Seitah samples were a coarse-grained igneous rock containing the mineral olivine, noting that three Mars meteorites found on Earth have a similar composition.
Examining the samples on Earth can reveal when the rock formed and provide a firmer answer to when liquid water existed on the surface of Mars. Liquid water is an important ingredient for life.
“Understanding when and for how long the climatic conditions on Mars enabled the stability of liquid water is critical to the larger questions we are trying to address with this mission and sample return — about whether and when life once existed on early Mars. , billions of years ago,” said geochemist and co-author David Shuster of the University of California, Berkeley.
(Reporting by Will Dunhamk, editing by Rosalba O’Brien)
