Mars rovers may have to dig deeper to find signs of ancient life.
New research shows that certain protein-forming amino acids could be evidence of ancient life Mars are more vulnerable to radiation than scientists thought, meaning any amino acids left behind by life forms may have survived only if buried deep beneath the planet’s surface.
“Our results indicate that amino acids are destroyed cosmic rays in the rocks and regoliths of the Martian surface much faster than previously thought,” said Alexander Pavlov, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in a expression. “Current Mars rover missions drill down to about two inches. At those depths, it would take only 20 million years to completely destroy amino acids.”
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While 20 million years may seem like an incredibly long time, it is a short period in the evolution of planets and life. This is especially true when you consider that the vital signs of rovers such as e.g curiosity those searching on Mars would have existed billions of years ago when it was more like Mars Earth.
The team discovered that the presence of liquid water, which was abundant on Mars billions of years ago, and perchlorate (charged ions of a chlorine atom surrounded by four oxygen atoms) may have accelerated the destruction of amino acids. The findings came from the first experiment to mix amino acids with simulated Martian soil.
Research suggests we’re not digging deep enough beneath the surface of Mars to see signs of life. To address this problem, searches could shift their focus to locations where geological processes have brought buried rock to the surface.
“Shallow-hole missions need to look for recently exposed outcrops – e.g. B. looking for younger microcraters less than 10 million years old, or the material ejected from such craters,” Pavlov said.
How Mars lost its magnetosphere
One of the main reasons why Earth is more habitable than Mars is that it has a strong magnetic field magnetospheresurrounds our planet.
The magnetosphere protects earth atmosphere of the solar wind (charged particles from the Sun) and fragments from other stars ( cosmic rays) by causing them to travel down and behind the Earth’s magnetic field lines, much like a boat creates a bow thrust when cruising through water.
These charged particles can degrade or destroy organic molecules as they penetrate solid rock several feet high, ionizing and destroying everything in their path. radiation from the Sun can also remove a planet’s atmosphere a key factor in its ability to hold liquid water.
Billions of years ago, Mars lost its magnetic field, atmosphere, and eventually much of its life-sustaining liquid water. That means the search for lifeon Mars is to look for signs of ancient biological activity in Martian rocks using indicators such as amino acids.
To test how effective our current search is, the team of scientists mixed several types of amino acids in silica, silicic acid, or silica and perchlorate to simulate conditions in the Martian soil, and then sealed the samples under vacuum conditions in test tubes to simulate this thin Martian air.
While some of these samples were kept at temperatures similar to those on the surface of Mars, others were cooled to minus 67 degrees Fahrenheit (minus 55 degrees Celsius). All samples were exposed to high-energy gamma rays to simulate exposure to cosmic rays that rocks on the Martian surface would have experienced about 80 million years ago.
“Our work is the first comprehensive study examining the destruction (radiolysis) of a wide range of amino acids under a variety of Mars-relevant factors (temperature, water content, perchlorate abundance) and comparing radiolysis rates,” Pavlov said. “It turns out that the addition of silicates, and particularly silicates with perchlorates, greatly increases amino acid destruction rates.”
Researchers haven’t found amino acids on Mars yet, but they have found these molecules inside meteorites, including one from the Red Planet. But how these complex chemicals in the Martian meteorite RBT 04262 discovered in Antarctica in 2004 is still unclear.
Since meteorites are typically ejected at least 1 meter below the Martian surface, this new research implies that the amino acids in RBT 04262 may have been shielded from intense solar radiation and cosmic rays.
The results also show that the complex organic molecules that the Mars rover curiosity and persistencediscovered that intrigue scientists but are not indicators of life may have been altered over time by exposure to radiation.
The team’s research was published in the journal on June 26astrobiology.
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