Imaginative drawing of a huge lake that would have formed in Jezero Crater on Mars [사진 = NASA]
NASA’s Perseverance probe, which is exploring a large crater on Mars, has discovered that there was once a huge lake and delta in the basin, CNN and other media reported on the 15th (local time), citing NASA’s announcement.
Since landing on Mars in February 2021, the Perseverance rover has been steadily collecting samples and searching for traces of life on Mars.
Perseverance has spent the past three years exploring the 28-mile-wide Jezero crater, which was formed by an asteroid impact nearly 4 billion years ago. In the process, the probe discovered evidence that this huge crater was once a lake.
“We chose Jezero Crater as the landing site because we captured the delta in orbital images. “This is clear evidence that a large lake once formed in this crater.”
Perseverance project scientist Ken Farley explained this in a NASA press release on the 12th:
“This lake is an environment where life could have existed, and the delta rocks are a good environment to hold traces of ancient life as fossils.”
He added:
“After thorough exploration, we were able to trace the geological history of the crater and chart the stages of lake and river formation from beginning to end,” said researcher Farley.
Scientists were able to create a timeline of the lake’s formation history, dividing it into three distinct periods.
During the first period, fine sand and mud were pushed into the crater, preserving microorganisms in fossil form.
In the next stage, the lake expanded, forming a layer of sediment 22 miles wide and 100 feet deep. Finally, ‘high-energy rivers’ formed that transported rock across the Martian surface.
“We can get a rough idea of the long history of lake formation with examples from orbital images, but we need Perseverance’s detailed exploration to understand the exact timeline,” said Libby Ives, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory. He explained.
Perseverance rover active in Jezero Crater on Mars [사진 = NASA]
During its 1,000 days on Mars, the Perseverance rover collected 23 rock samples from Jezero Crater. The probe drilled a hole in the ground and removed a chunk of rock about the size of chalk. The samples were then stored in specially designed metal tubes.
According to NASA, some of these samples showed signs that the lake may have been colonized by microorganisms.
“Scientists have identified evidence that water transported clay minerals from the surrounding area into the crater lake.”
The NASA website explains it this way:
“Microbial life may have been present during these wet periods. If so, traces of it may be found in lake bottoms or lake sediments. “Scientists will study how the region formed and evolved, search for traces of past life, and collect samples of Martian rocks and soil that may have preserved these traces.”
Perseverance has so far collected two samples that could prove the existence of ancient life on Mars. One of them contains notable amounts of silica, which is also found in fossils on Earth.
And in the second sample, large amounts of phosphate, an important component of life on Earth, were detected. Phosphate is a component of DNA and is found in cell membranes.
Perseverance also found that the crater floor is composed of igneous rock formed by underground magma or volcanic activity.
Sandstone and mudstone layers are formed on top of the igneous rock, which is a sign that a river flowing into the lake was formed. The mudstone is rich in salt and also shows traces of the lake’s evaporation.
The rover can use special tools onboard to determine the composition of rocks. The tool can detect both microscopic fossil-like structures and chemical changes left behind by ancient microorganisms, but so far it has not captured these signs of life.
Nevertheless, NASA scientists remain hopeful that evidence will emerge.
“We have adequate perseverance to detect hospitable silicon dioxide, as well as carbonates and phosphates that indicate water and signs of life,” said Morgan Cable, a research scientist at the Jet Propulsion Laboratory.
[위키리크스한국 = 최석진 기자]
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