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Mars 2020 Rover will visit the perfect place to find signs of life

An engineer conducts tests on NASA's Mars 2020 rover.

On some sunny next summer, in front of a crowd at the Kennedy Space Center, a rocket carrying NASA's next and best hope of finding life on Mars will be launched into the sky.

Seven months later, the car-sized Mars 2020 spacecraft will land near the Jezero Crater, a dry lake in the northern hemisphere of Mars. With its six wheels and high-tech instrument cluster, it will scour the surrounding rocks for evidence that alien microbes have lived on the Red Planet.

Decades of Mars research with probes, landings and orbiting vehicles have revealed that the planet has once harbored a thick atmosphere and water on its surface. Researchers have even found traces of complex organic molecules – possible components for living cells.

Now two new studies offer a tantalizing suggestion that Mars 2020 may find even stronger evidence of Martian life – if it ever existed.

The rocks around Jezero show evidence of carbonate and hydrated silica – known molecules on Earth that help preserve microscopic fossils for billions of years.

"It's a big blatant sign saying" Look here, look here, "" said Briony Horgan, planetary scientist at Purdue University and lead author of a study in Icarus magazine that reported carbonate detection. "The Jezero Crater is an incredibly mineralogically diverse place with many paths to follow to look for biosignatures, which means we have a good chance of understanding exactly what has happened to the history of life here."

But what would Mars 2020 have to find in order for scientists to be sure that there were Martians?

Both studies published this week featured the Compact Image Recognition Spectrometer (CRISM), an orbiting camera capable of scanning the Martian surface in infrared and visible light. At 250 miles high, CRISM produces color maps of minerals on the Red Planet.

Carbonates, which form when carbon dioxide interacts with rocks and water, have been found throughout the Jezero Crater. But CRISM showed a particularly high concentration of the mineral along the inner rim of the crater, exactly where the lake shore would have been more than 3 billion years ago.

For Horgan, this suggests that they could have been left behind by waves crashing into the rock. She compared the deposits to the slag line that forms where water meets the sides of a bathtub (scientists even called the region a "bathtub ring").

"What makes it so exciting is [carbonate] imprisons everything that precipitates, "said Horgan." It mimics the structures of microbes to get preserved textures. . . but it also retains the organic material there. "

If the microbes lived on the shore of Jezero Lake, there is a decent chance that carbonate caught them.

Some of the oldest fossils on earth were buried in carbonate. Scientists have discovered stromatolites – layered structures formed from blankets of carbonate-encased bacteria – dating to 3.7 billion years.

Jesse Tarnas, a planetary scientist at Brown University, also relied on CRISM maps for his research. His article, published in the journal Geophysical Research Letters, describes hydrated silica near the Jezero Delta, where water from a river has long been introduced into the old crater lake.

Hydrated silica, better known as opal, can form in volcanic eruptions and on the banks of hot springs. But when it is created from sediments depositing on the sea floor, it can form strong and resilient crystals that are exceptionally effective at preserving signs of life. On Earth, scientists found samples of hydrated silica containing ancient organic material and even fossilized cells.

Since Martian hydrated silica is so close to a delta, it may contain material from the river system. And if the rivers of Mars once harbored life, remnants of ancient organisms may still be trapped within these crystals.


An artistic version of NASA's Mars 2020 rover studying its surroundings.

Hydrated silica "is not something that has been found before," said Katie Stack Morgan of the Jet Propulsion Laboratory, assistant project scientist for the 2020 mission. Morgan, who did not participate in the Tarnas research, said the mineral probably will be the rover's main target when it lands.

"It's really exciting to think that there are deposits in Jezero like we have on Earth," she said. "Let's think of ways to get as close to them as possible."

The 2020 spacecraft will be armed with a wide variety of tools to examine these minerals. Cameras can capture stromatolite images, if any. Molecular lasers and sniffers known as spectrometers will map the rock composition to an elemental level.

"It will be able to do the kind of astrobiological research we have wanted to do on Mars for decades," Horgan said.

The Curiosity spacecraft, which has been around Gale Crater since 2012, can only measure "bulk" molecules, Morgan said. Although it has found organic molecules, it cannot locate them in certain rock layers or associate them with microscopic structures.

"With 2020, we can go there and say that we are seeing an element or mineral concentration associated with this very specific fine-scale texture," Stack said. "These very subtle textural differences are what people are looking for, and they kind of squinted at defending biosignatures."

But even in the scientists' dream scenario – the one where life on Mars and its remains were preserved, and the 2020 rover can find the fossils – it is unlikely that only the mission will prove if the Martians once existed.

The discovery of life beyond the earth is such an extraordinary statement, as Carl Sagan would say, requires extraordinary evidence – evidence that only a human being can deliver.

"What we are really trying to do with this spacecraft is to look for 'potential biosignatures'," said Horgan. But only if "we check here with all our amazing laboratory equipment," she continued, "can we turn a potential" biosignature "into a" biosignature "."

The 2020 mission is only the first step of a proposed four-part program. After identifying the most attractive rocks around the Jezero crater, the spacecraft will use a specially developed drill bit to collect and cache samples of the material.

Someday (if all goes according to plan), scientists will launch follow-up missions to retrieve the samples and take them home. Finally, in an ultra-secure facility that has not yet been built, they will analyze the rocks on an elementary scale to definitively determine if they contain evidence of life.

The whole process will take years, if not decades. It can never happen. The necessary follow-up missions have not yet been approved, much less funded and developed. And travel to Mars is notoriously difficult: about 50 percent of all attempts to reach the Red Planet have failed.

"There is tempting evidence that perhaps [life] it was there, but you won't know until you get the samples back, "said Tarnas." And you really need to have patience and courage to endure. "

(Except for the title, this story was not edited by the NDTV team and is published from a syndicated feed.)

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