Written by Will Dunham
WASHINGTON (Reuters) – Core samples excavated by NASA’s Mars rover have revealed the geology of a crater that scientists suspect contained microbial life billions of years ago, including surprises about the nature of the rocks there.
The samples, obtained by the car-sized six-wheeled robotic rover and stored for future transport back to Earth for further study, showed that the rocks from four locations within Jezero crater are igneous—formed by cooling magma. The rocks also carried evidence of change through exposure to water, another sign that the cold, dry planet Mars has long been warm and humid.
Scientists had thought that the rock, which formed nearly 3.5 billion years ago, may have been sedimentary, formed as mud and sand deposited at the bottom of a lake.
“In fact, we found no evidence of sedimentary rocks where the rover explored the crater floor, despite the fact that we know the crater contained a lake and that sediments were deposited,” said Kenneth, a geochemist at Caltech. Sedimentary has eroded.” Farley, lead author of one of four studies published in the journals Science and Science Advances describing the geology of the crater.
Perseverance reached Mars in February 2021 and has been busy working at Jezero crater ever since, using an array of instruments, as scientists investigate whether Earth’s closest neighbors possess conditions favorable to life.
It collects rock samples, the size of blackboard chalk, in small tubes that are scheduled to be retrieved by a spacecraft in 2033 and bring them to Earth for further examination including biomarkers – indicators of life.
Jezero Crater is 28 miles (45 km) wide and is located north of the Martian equator. The area appears to have once been abundant in water and home to a river delta, with river channels extending over the crater wall to form a large lake. Scientists suspect the crater may have harbored microbial life, with evidence possibly in the lake bed or beach rocks.
Perseverance is now collecting samples in the delta region.
Igneous rocks were found in the crater of the volcano to react with water, resulting in the formation of new minerals and the deposition of salts, although this water appears to have been either low in abundance or non-existent for a long time – likely groundwater. The presence of water suggests that this may have been a habitable environment at the time, the researchers said.
“We collected the samples that will be returned to Earth, and they should provide important evidence of what species, if any, organisms that inhabited the terrestrial rocks of Jezero crater when it interacted with the water,” said Yang Liu, a planetary sampler at NASA. JPL and lead author of one of the studies.
The four samples were excavated from two areas, one called Sita and the other Moaz. Sittah rock appears to have formed underground by the slow cooling of a thick plate of magma. The Maaz rocks may have cooled relatively more quickly in the upper layer of subterranean magma or after the eruption of the volcanic surface. Either way, any bedrock that covered these areas has since been eroded, either by water or wind.
The setah samples were coarse-grained igneous rocks containing the mineral olivine, Liu said, noting that three Martian meteorites found on Earth have the same composition.
Examination of samples found on Earth may reveal the history of the rock’s formation and give a more definitive answer as to whether there was liquid water on Mars. Liquid water is an essential element for life.
“Understanding when, and for how long, climatic conditions on Mars allowed liquid water to settle is central to the larger questions we’re trying to address through this mission and sample return — about whether and when life can once and for all, geochemist and study co-author David said. Schuster of the University of California, Berkeley: “It was on Mars very early, billions of years ago.”
(Reporting by Will Dunhamk; Editing by Rosalba O’Brien)
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