- 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?
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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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