Sunday, April 23, 2023

3971 - LIFE - how will we detect it on exoplanets?

 

-   3971 -   LIFE  -   how will we detect it on exoplanets?    Is there life on Mars?  Been part of science fiction dramas for decades.  But, so far most of humanity’s forays into the Solar System seeking signs of life have returned only ambiguity.


----------------  3971  -  LIFE  -   how will we detect it on exoplanets?

-    NASA’s Viking 1 lander designed its suite of experiments to find any signs of life, or biosignatures, on the Martian surface, returned a mix of positive and negative results that summed to an indeterminate answer.    Scientists found no signs of life, but insufficient evidence to say there were no signs to be found.

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-   Scientists have a new tool that might make sure future astrobiology experiments return clearer answers about what they find, and what they don’t, wherever they look.

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-    A “Laser Desorption Mass Spectrometer”, or LDMS device using a cutting analysis tool first pioneered in the pharmaceutical industry uses a laser to ionize material from the surface ice of Saturn’s moon Enceladus.   The instrument can detect larger organic compounds more advanced than any of the biosignature detecting tools currently aboard NASA missions.

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-   The LDMS device is really a combination of two pieces of equipment. There is the laser system, which zaps samples of material on other worlds.

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-    Using lasers for this purpose is not entirely novel. NASA’s Perseverance rover carries a Laser Induced Breakdown Spectroscopy instrument that can zap rocks from some distance away and looks for patterns in the light based on how different geological elements absorb light or fluoresce.

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-   But the LDMS instrument is a bit different.  It is not looking at light, it is looking at mass.

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-    When you zap a bit of rock or ice with a laser, you move electrons around, giving the particles in the resulting vapor an electric charge. This allows the instrument to pull them inside using charged plates and guide them into the second part of the instrument, an analyzer known as an “orbitrap”.

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-    An orbitrap contains a central electrode that looks a bit like a football.  The charged particles oscillate around the football at speeds commensurate with their mass. Get their mass, and you know their elemental composition.  Scientists can infer what the molecule is based on the speed at which it oscillates back and forth across this electrode.

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-    An orbitrap is not the only instrument that can analyze particle masses to determine molecular makeup, but it is one of the most accurate. Some very different molecules may possess very nearly the same mass, and ,  some instruments cannot tell them apart. But the orbitrap has high enough resolution that you know exactly what the chemical formula is.

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-    The combined laser and orbitrap analyzer should be capable of detecting larger organic molecules than existing instruments such as the “Sample Analysis at Mars”, or SAM tool on NASA’s Curiosity rover. Instruments like the SAM work by heating samples of soil until volatile compounds begin evaporating.

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-   That system works well for organic compounds that easily become gas, such as methane but it can’t detect larger organic compounds like peptides, which are chains of amino acids.

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-    The LDMS instrument can detect peptides, and while finding peptides on another world wouldn’t be a sure sign of alien life, the more complex the organic molecule you find, the less likely it is to have been created through an abiotic process.

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-       NASA was still planning on sending a lander mission to Europa, the Jovian moon which scientists believe hosts a massive liquid water ocean beneath its icy crust. It’s possible there’s some form of life in those depths, and if any of that water made it to the surface of Europa, a lander sporting an LDMS instrument could detect it.

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-    There was a robotic arm that scooped ice from the surface of Europa. It dumped it into their sample handling system and it delivered to us on plates.  Then we hit the sample with our laser and we get the chemical composition.

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-   But by 2017, budget cuts led NASA to put the Europa lander concept on the back burner, and Arevalo’s LDMS instrument is now a tool awaiting a new mission.

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-     Weighing in at only eight kilograms, compared to the 40 kilograms of the SAM instrument on Curiosity, the LDMS instrument could go anywhere, from Mars to Europa, to Saturn’s moon Enceladus, another icy, ocean-hosting moon like Jupiter’s moon Europa. Jut waiting for a rocket ride!

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                   April 23, 2023     LIFE  -   how will we detect it on exoplanets?        3971                                                                                                                         

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--------------------- ---  Sunday, April 23, 2023  ---------------------------

 

 

 

 

         

 

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