Sunday, March 19, 2023

3921 - LIFE ON PLANETS - can we detect the beginning?

 

-   3921 -  LIFE  ON  PLANETS  -  can we detect the beginning? Coupled with newly detailed information about the ice composition of interstellar clouds from James Webb Telescope, scientists may finally be able to determine for sure whether amino acids formed in our solar system or in interstellar space.


---------  3921  -    LIFE  ON  PLANETS  -  can we detect the beginning?

                 -   Signs of Mars life may be too elusive for “rovers” to detect.  Sample return is likely our best bet to find Mars life, if it ever existed.  The robots exploring Mars may not be capable of detecting potential traces of life on the Red Planet.  You can't sen those heavier instruments to space.

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-   NASA's “Perseverance Mars rover” took a selfie looking down at one of 10 sample tubes deposited at the sample depot it created in an area nicknamed “Three Forks” using the “WATSON camera” on the rover’s robotic arm on January 20, 2023, the 684th Martian day, or sol, of the mission.

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-   The twin Viking orbiters NASA sent to Mars nearly a half-century ago discovered that the Red Planet possessed liquid water on its surface early in its history, about three billion to four billion years ago.

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-    Later missions have supported these findings, suggesting that organisms might once have lived there, and might still, since life is found virtually wherever there is water on Earth.

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-   However, NASA's two Viking landers detected no native organic chemicals within Martian soil, even at levels of parts per billion. Even the most recent, highly advanced instruments of NASA's later Curiosity and Perseverance rovers have found just traces of simple organic molecules in ancient Martian lakebeds and river deltas.

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-   It remains uncertain if the hunt for past or present life on Mars has fallen short because the Red Planet has always been barren or because the probes sent there are not sensitive enough to detect any life onsite.

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-   To test their capability the researchers analyzed samples from Red Stone, the remains of a river delta in the Atacama Desert of Chile, one of the oldest and driest deserts on Earth. These deposits, which formed under highly arid conditions about 100 million to 160 million years ago, strongly resemble Mars' Jezero Crater, which Perseverance is currently investigating.

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-   Red Stone regularly experiences fogs that supply water for microbes that live at the site. The state-of-the-art lab techniques the scientists used found a mixture of biochemicals from both extinct and living microorganisms there. About half of the DNA sequences detected at Red Stone came from the "dark microbiome", microbes that researchers have not yet properly described.

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-   However, the testbed versions of instruments currently on or planned for Mars, including one 10 times more sensitive than one on Curiosity, were barely able to detect these organic signs of life in Red Stone samples.

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-   These findings suggest that Mars probes will find it difficult, if not impossible, to detect the kinds of low levels of organic matter expected to be on the Red Planet today if microbial life did indeed exist there billions of years ago.

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-    The researchers suggest that future missions to Mars should aim to return samples from the Red Planet to Earth, where they can get tested by the most advanced equipment scientists have in order to help solve the puzzle of whether life ever lived on Mars. They aim to do just that, by the way, hauling material collected by Perseverance back to Earth as early as 2033.

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-   Future research can analyze the dark microbiome at Red Stone. These microbes are either so different from any known microorganisms that they defy current categories, or they are remnants of the life that used to live in the area when it had water millions of years ago that have no current relatives now that you can compare them with.

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-   However after searching planets maybe asteroids have picked up building blocks of life from interstellar clouds.  Scientists have taken a big step towards figuring out where building blocks of life such as amino acids and amines form in space.   New research has found that interstellar clouds may have played a significant role in creating the conditions that helped create the building blocks of life.

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-   Amino acids, which are a key ingredient of life, could have originally been made in interstellar molecular clouds like that from which the solar system formed, before winding up in asteroids that later crashed on Earth, bringing the amino acids with them.

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-   “Carbonaceous chondrite” meteorites are rich in amino acids and amines that are crucial components of proteins and biological cells in life on Earth. Understanding where and how amino acids formed is therefore important in better understanding the origin of life.

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-   Many studies have focused on trying to simulate the formation of amino acids in carbonaceous chondrites, which are meteorites from carbon-rich asteroids that formed at the dawn of the solar system, 4.5 billion years ago. This research takes things even farther back in time to the interstellar cloud of molecular gas and dust from which the sun and planets eventually formed.

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-    The make-up of asteroids originated from the parental interstellar molecular cloud, which was rich in organics.  While there is no direct evidence of amino acids in interstellar clouds, there is evidence of amines. The molecular cloud could have provided the amino acids in asteroids, which passed them on to meteorites.

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-    Researchers set about replicating conditions in interstellar clouds to try and form amino acids. Using ices such as ammonia, carbon dioxide, methanol and water that are commonly found in interstellar clouds, and bombarded them with high-energy protons from a Van de Graff generator to replicate the ices being irradiated in space by cosmic rays.

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-    The proton bombardment smashed the ice molecules apart, the component parts then reassembling themselves as more complex organic molecules, including amines and amino acids such as ethylamine and glycine, an "organic residue", a kind of gloopy slime.

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-   When the solar system formed from the molecular cloud, these amines and amino acids would have been transferred into carbonaceous asteroids and eventually brought to Earth through asteroid impacts and meteorite falls.

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-     Even with asteroid processing accounted for, the abundances of amines and amino acids still do not quite match the abundances found in carbonaceous chondrite meteorites. It is possible that having fallen on Earth, the meteorites have become contaminated with terrestrial organic material, altering their amino acid abundances.

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-     Scientists are eagerly awaiting the return of samples from the carbonaceous asteroid Bennu, which was visited by NASA's OSIRIS-REx mission. These samples will parachute back down to Earth in their capsule on September 24, 2023, and will represent pristine material uncontaminated by life on Earth that dates back to the birth of the solar system.

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-    Coupled with newly detailed information about the ice composition of interstellar clouds from James Webb Telescope, scientists may finally be able to determine for sure whether amino acids formed in our solar system or in interstellar space.

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-  If the former, then it is possible that life could be unique to our solar system.

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-   If the latter, then amino acids should be spread far and wide across the Milky Way galaxy, raising the potential for life on planets around other stars.

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-   Will we ever know.  How did we get here?   My typing this review is a far cry from an amino acid puddle! 

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                   March 18, 2023     LIFE  ON  PLANETS  -  can we detect the beginning?             3921                                                                                                                         

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--------------------- ---  Sunday, March 19, 2023  ---------------------------

 

 

 

 

         

 

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