Volcanic Activity on Ancient Mars May Have Produced Organic Life
By Elizabeth Howell
Even a cursory look at a global map of Mars reveals how huge its volcanoes are.
The famous Olympus Mons rises three times higher than Mt. Everest, and is just one of
several volcanoes that adorn the Red Planet's famous Tharsis ridge.
Presumably, when these volcanoes were more actively spewing gases such as carbon monoxide
and sulfur, they must have had a determining influence on the Martian atmosphere.
A new paper in the journal Icarus suggests that these volcanoes may in fact have created
an environment habitable to ancient microbes.
Specifically, a new model showing a range of volcanic eruptions shows that Mars' atmosphere
could have been made anoxic, with depleted levels of oxygen and limited oxygen-based
reactions.
"These results imply that ancient Mars should have experienced periods with anoxic and reducing
atmospheres even through the mid-Amazonian whenever volcanic outgassing was sustained
at sufficient levels," the researchers wrote.
"Reducing anoxic conditions are potentially conducive to the synthesis of prebiotic organic
compounds, such as amino acids, and are therefore relevant to the possibility of life on Mars."
"This is important from an astrobiology standpoint because these reducing anoxic conditions have
been hypothesized as being important to the origin of life on the early Earth," said lead
author Stephen Sholes, a Ph.D. candidate in earth and space sciences and astrobiology
at the University of Washington, said in an e-mail to Seeker.
He pointed out that the famous Urey-Miller experiments of the 1950s showed that electrical
pulses, in an environment with a reducing atmosphere and liquid water, produced complex
organic molecules.
By contrast, an oxidizing atmosphere would also oxidize these molecules, making them
less useful in supporting the formation of life.
While volcanism on the Red Planet has been discussed for decades, Sholes said his research
is different because it is quantifying how much volcanism is required to create reducing
atmospheres on Mars.
Specifically, his work delves into what it would take to do so, whether it is feasible,
and how it could be detected.
Another difference is the approach itself.
Other models that discuss volcano-atmosphere reactions on Mars focus on how the planet
could be warmed, Sholes said, using outgassed volcanic gasses.
"Yes, you need liquid water, but you also need appropriate conditions for life, and
here we are finding that the volcanoes should have changed the atmosphere enough to be more
conducive to forming complex bio-important molecules," he said.
If the atmosphere was anoxic, scientists may be able to see the evidence on the ground,
even billions of years later.
That's because anoxic conditions should alter the types of minerals and rocks that form,
allowing for testable predictions for future Mars missions.
Examples include minerals made of ferrous iron � such as siderite, or iron carbonate
� as well as elemental sulfur.
"Our results show that, given models for volcanic activity, during periods of sustained volcanism,
Mars� atmosphere could easily shift towards reducing and anoxic conditions, thus producing
measurable amounts of elemental sulfur deposits," Sholes said.
He added that elemental sulfur has not been found yet on Mars, but it is a difficult mineral
to study.
"The measurement techniques used could actually cause it to breakdown into smaller molecules
that could be misidentified," he said.
Two missions are specifically investigating the Martian atmosphere right now.
NASA's MAVEN (Mars Atmosphere and Volatile Evolution), which primarily examines atmospheric
loss, and the European Space Agency's TGO (Trace Gas Orbiter), which looks at minority
molecules in the Martian atmosphere.
Sholes said the atmosphere does not preserve tracers of past reducing conditions, so the
current missions would not help us learn directly about past volcanic activity.
Their measurements will help refine the atmospheric models used, however.
"Eventually we would like to update the model to test how single eruption events would change
the atmosphere and the timescales involved," he added.
"Our current model assumes constant volcanic eruptions, which wouldn�t necessarily be
the case.
If we could test individual eruptions, we could learn how big of an eruption would be
required to switch the atmosphere anoxic, and how long that atmosphere would last before
it would switch back."
For more infomation >> 聯合航空是光明會成員！(United Airlines is Illuminati) - Duration: 2:00. 
For more infomation >> Is That a Gun in Your Pocket? - Movie - Duration: 1:37:19. 
For more infomation >> What the Cross is Really About - Mark Hart #ShareJesus Lent Video 45 - Duration: 3:53. 
Không có nhận xét nào:
Đăng nhận xét