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Arthur T Knackerbracket has found the following story:
Next year, both NASA and the European Space Agency (ESA) will send new rovers to Mars to hunt for evidence of past life.
As previous missions have discovered, Mars had a warmer and wetter past, featuring conditions that could probably sustain life. Current satellites orbiting Mars also reveal there are many places where water was once present on the surface.
The difficulty in hunting for life lies not in finding where there was water, but in identifying where the essential nutrients for life coincided with water.
For life to move into a new environment and survive, it needs essential nutrients such as carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (together known as CHNOPS), plus other trace elements. It also needs to acquire energy from the environment. Some of Earth's earliest life forms gained energy by oxidizing minerals.
Mars's crust is mostly made of intrusive and volcanic basalt (the same rock that forms from Hawaii's lavas) which is not particularly nutrient-rich. However, meteorites and micrometeorites are known to continuously provide essential nutrients to the surfaces of planets.
We modeled the heating and oxidation effects of atmospheric entry to Mars and found most particles less than about 0.1-0.2mm in diameter would not melt, depending on their composition. In terms of materials accumulating on the Martian surface, particles of this size are overwhelmingly more common than larger particles.
On Earth, about 100 times as much cosmic dust in this size range accumulates on the surface, when compared to meteorites larger than 4mm. This is despite extensive melting and evaporation during atmospheric entry to Earth.
As part of our research, we used an analogue site on the Nullarbor Plain in South Australia (which, like Mars, has wind-modified sediment sitting on cracked bedrock) to examine whether wind causes micrometeorites to accumulate at predictable locations.
We found more than 1,600 micrometeorites from a variety of sample sites.
(Score: 2) by takyon on Saturday September 07 2019, @03:33PM
If you find evidence of a large microbial ecosystem in underground lakes/oceans on Mars, Europa, Enceladus, Titan, etc., that would indicate that it probably wasn't due to spacecraft contamination, and that life is even more resilient than previously known. Even if you can't conclusively prove that the life formed independently, you expand the habitability prospects for the entire galaxy. In some cases, a planet (e.g. Venus) may start habitable, spread life around, and planets/moons further from the star could have improved conditions for life later while the origin planet burns to a crisp.
Titan is a special case since there are surface lakes to look at, possibly containing life forms based on a different chemistry.
If you want unambiguous confirmation of "independent life" (a galactic panspermia argument could still be made), you need large space telescopes. If humanity really wants the data, it could build gigantic modular space telescopes in the next few years and start looking for signs of extrasolar biospheres, including direct imaging of exoplanets with obvious surface vegetation. But we will probably have to wait decades before the space agencies make the right moves.
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