What happened to early Mars' atmosphere? New study eliminates one theory

September 2, 2015, Jet Propulsion Laboratory
This view combines information from two instruments on a NASA Mars orbiter to map color-coded composition over the shape of the ground within the Nili Fossae plains region of Mars. Credit: NASA/JPL-Caltech/JHUAPL/Univ. of Arizona

Scientists may be closer to solving the mystery of how Mars changed from a world with surface water billions of years ago to the arid Red Planet of today.

A new analysis of the largest known deposit of carbonate minerals on Mars suggests that the original Martian atmosphere may have already lost most of its carbon dioxide by the era of valley network formation.

"The biggest carbonate deposit on Mars has, at most, twice as much carbon in it as the current Mars atmosphere," said Bethany Ehlmann of the California Institute of Technology and NASA Jet Propulsion Laboratory, both in Pasadena. "Even if you combined all known carbon reservoirs together, it is still nowhere near enough to sequester the thick atmosphere that has been proposed for the time when there were rivers flowing on the Martian surface."

Carbon dioxide makes up most of the Martian atmosphere. That gas can be pulled out of the air and sequestered or pulled into the ground by chemical reactions with rocks to form carbonate minerals. Years before the series of successful Mars missions, many scientists expected to find large Martian deposits of carbonates holding much of the carbon from the planet's original atmosphere. Instead, these missions have found low concentrations of carbonate distributed widely, and only a few concentrated deposits. By far the largest known carbonate-rich deposit on Mars covers an area at least the size of Delaware, and maybe as large as Arizona, in a region called Nili Fossae.

Christopher Edwards, a former Caltech researcher now with the U.S. Geological Survey in Flagstaff, Arizona, and Ehlmann reported the findings and analysis in a paper posted online by the journal Geology. Their estimate of how much carbon is locked into the Nili Fossae carbonate deposit uses observations from numerous Mars missions, including the Thermal Emission Spectrometer (TES) on NASA's Mars Global Surveyor orbiter, the mineral-mapping Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and two telescopic cameras on NASA's Mars Reconnaissance Orbiter, and the Thermal Emission Imaging System (THEMIS) on NASA's Mars Odyssey orbiter.

Researchers estimating the amount of carbon held in the ground at the largest known carbonate deposit on Mars used data from five instruments on three NASA Mars orbiters, including physical properties from THEMIS (left) and mineral information from CRISM (right). NASA/JPL-Caltech/ASU/JHUAPL

Edwards and Ehlmann compare their tally of sequestered carbon at Nili Fossae to what would be needed to account for an early Mars atmosphere dense enough to sustain surface waters during the period when flowing rivers left their mark by cutting extensive river-valley networks. By their estimate, it would require more than 35 carbonate deposits the size of the one examined at Nili Fossae. They deem it unlikely that so many large deposits have been overlooked in numerous detailed orbiter surveys of the planet. While deposits from an even earlier time in Mars history could be deeper and better hidden, they don't help solve the thin-atmosphere conundrum at the time the river-cut valleys formed.

The modern Martian atmosphere is too tenuous for liquid water to persist on the surface. A denser atmosphere on ancient Mars could have kept water from immediately evaporating. It could also have allowed parts of the planet to be warm enough to keep liquid water from freezing. But if the atmosphere was once thicker, what happened to it? One possible explanation is that Mars did have a much denser atmosphere during its flowing-rivers period, and then lost most of it to outer space from the top of the atmosphere, rather than by sequestration in minerals.

"Maybe the atmosphere wasn't so thick by the time of valley network formation," Edwards said. "Instead of Mars that was wet and warm, maybe it was cold and wet with an atmosphere that had already thinned. How warm would it need to have been for the valleys to form? Not very. In most locations, you could have had snow and ice instead of rain. You just have to nudge above the freezing point to get water to thaw and flow occasionally, and that doesn't require very much atmosphere."

NASA's Curiosity Mars rover mission has found evidence of ancient top-of-atmosphere loss, based on the modern Mars atmosphere's ratio of heavier carbon to lighter carbon. Uncertainty remains about how much of that loss occurred before the period of valley formation; much may have happened earlier. NASA's MAVEN orbiter, examining the outer of Mars since late 2014, may help reduce that uncertainty.

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wduckss
1 / 5 (11) Sep 02, 2015
Send an investigative mission to another planet, not to explore but to confirm our ideas emerged on Earth. If the evidence does not agree with the concept, are not valid, seeking to continue instead: evidence say that on Mars ... , to whom wrong, to whom the right.
baudrunner
1 / 5 (7) Sep 03, 2015
First, no-one has assumed that Mars had a very thick atmosphere. Rather, it is more likely that the atmosphere was similar to that found on elevations equal to the Tibetan Plateau and higher.

Also, the article's presumption is based on the theory of natural progression, and that nothing cataclysmic and instantaneous occurred to wrest atmosphere and water from the red planet, such as a close pass by of a very large planetary object, which would also explain Joshua's long day (Joshua 10:12-14), when the sun stood still in the heavens for a full day, and which is also recorded in Chinese lore, and in pre-Incan lore, wherein the night stayed for a full extra day.

We know when this event occurred, sometime between 1355-1245 BCE. If there was life on Mars then, they would have been the Igigi, who had been banned from the Earth.
wduckss
1 / 5 (4) Sep 03, 2015
There is more than enough modern and advanced technology, so I asked for a response in the spent coffee grounds. I'm considering only "see", time belief is passed, only checking (skepticism).
Collected evidence is clear: Mars and life do not go together (at this stage of development of Mars), as well as a richer atmosphere.
FredJose
1.4 / 5 (11) Sep 04, 2015
Having read the article and relooked at the heading, I do not share the optimism that scientists will one day be able to say exactly why Mars doesn't have any water left in spite of the ground exhibiting signs of massive water or other fluid flows.

So it's real ironic that they are looking for the water that caused the floods on Mars where there isn't any but when told there was a world wide flood on earth a few thousand years ago they vehemently deny any such possibility. Even though there's enough water here to drown the planet [ if all mountains and valleys are levelled ] to a depth of about 6 kilometres.
Vietvet
5 / 5 (10) Sep 04, 2015

So it's real ironic that they are looking for the water that caused the floods on Mars where there isn't any but when told there was a world wide flood on earth a few thousand years ago they vehemently deny any such possibility. Even though there's enough water here to drown the planet [ if all mountains and valleys are levelled ] to a depth of about 6 kilometres.


@Freddytroll

There is zero, zip, nada evidence for a world wide flood. Of course young earth creationists don't need no stinkin evidence but trust in a book of myths.
Torbjorn_Larsson_OM
5 / 5 (9) Sep 04, 2015
Why do anti-scientists even bother to troll science site with claims that are rejected by the article content? And why do they always miss the interesting advances? (Yes, yes, I know, they are genuinely stupid and want to share that fact with the rest of us.. What else is new?)

wduckss
1 / 5 (6) Sep 04, 2015
It is easy to criticize without arguments and hide behind the "science". Empty stories about water and water nowhere, except in the wishes of some "scientists", which are used as hard evidence. Need be reconciled with the fact, Mars is a dry and desolate planet, which is confirmed by the results of exploration of Mars. The face on Mars, pyramids, ET, water, atmosphere vanished ... the simultaneous emergence of the fairy tales for those who believe without skepticism.
antigoracle
1 / 5 (2) Sep 04, 2015
world wide flood on earth a few thousand years ago

Was that the flood that killed the dinosaurs and covered their bones for us to find?
Captain Stumpy
5 / 5 (7) Sep 04, 2015
...Mars is a dry and desolate planet...confirmed by ...exploration of Mars
ducktroll
Jakosky, B.M.; Haberle, R.M. (1992) "The Seasonal Behavior of Water on Mars"

Carr, M.H. (1996) Water on Mars

http://adsabs.har...28..627B

http://www.nature...461.html

http://www.esa.in...uth_pole

http://onlinelibr...abstract

http://mars.jpl.n...28a.html

https://en.wikipe..._on_Mars

http://www.jpl.na...2014-065

the rest of that post is gibberish, IMHO

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