Scientists: Martian gullies formed by CO2 frost, not water flows
Dry ice frost on Martian cliffs. From a 2020 post.
Click for full image.
A new analysis of the gullies found on cliffs on Mars, usually on the interior rims of craters, has concluded that carbon dioxide frost is the cause of the erosion, not ancient flows of water.
This conclusion eliminates the need for liquid flowing water in the Martian past, at least in conjunction with gullies. From the paper’s conclusion:
These results show that CO2 frost is capable of producing Martian gully morphologies. Since flows powered by this process are known to be ongoing and capable of transporting the necessary volume of material, it is the simplest explanation for their formation. Variations in the frequency and fluidity of flows could have occurred over time due to variations in the CO2 cycle. CO2-driven gully formation would indicate that there was not necessarily regular, recurring meltwater during high-obliquity periods. This removes a constraint on recent climate, and also addresses a paradox: if obliquity regularly exceeds the current value as generally thought, and if gullies formed via snow melting at high obliquity, the Late Amazonian Epoch should have included regular snowmelt and widespread aqueous processes. Gully formation by CO2 frost processes is consistent with a cold-desert Late Amazonian with rare or small amounts of liquid water and little aqueous weathering, consistent with the observed mineralogy.
…Gullies, one of the most-discussed lines of evidence for liquid water on Mars, may in fact have no direct connection to H2O. CO2 frost-fluidized gully formation also has broader implications for geomorphology, widening an emerging field of new landform types and processes without Earth analogs. Similar processes could occur on other worlds with erodible substrates on steep slopes and volatile ices at their frost point, although we currently lack the high-resolution images needed to test this hypothesis. Such ices include N2 on Pluto and Triton, and SO2 on Io. [emphasis mine]
In other words, though the gullies appear at first glance to our Earth eyes to have been caused by water flowing downhill, in fact the data now suggests the annual CO2 frost cycle of Mars is the prime cause, even in the distant past. No surface water was required. And since no one has yet come up with a good model for liquid surface water even existing in the Martian past (the atmosphere being too cold and thin), this conclusion helps eliminate this conflict.
The paper also notes the lack of water likely eliminates the need for any planetary protection efforts at these gullies, as the lack of water makes the likelihood of any microbiology nil.
As these conclusions are based on lab work and analysis of images, there remains great uncertainty. Nonetheless, the results help reinforce the arguments that the geological features we see on Mars were formed not by flowing liquid water but by other processes, such as glaciers of ice.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Dry ice frost on Martian cliffs. From a 2020 post.
Click for full image.
A new analysis of the gullies found on cliffs on Mars, usually on the interior rims of craters, has concluded that carbon dioxide frost is the cause of the erosion, not ancient flows of water.
This conclusion eliminates the need for liquid flowing water in the Martian past, at least in conjunction with gullies. From the paper’s conclusion:
These results show that CO2 frost is capable of producing Martian gully morphologies. Since flows powered by this process are known to be ongoing and capable of transporting the necessary volume of material, it is the simplest explanation for their formation. Variations in the frequency and fluidity of flows could have occurred over time due to variations in the CO2 cycle. CO2-driven gully formation would indicate that there was not necessarily regular, recurring meltwater during high-obliquity periods. This removes a constraint on recent climate, and also addresses a paradox: if obliquity regularly exceeds the current value as generally thought, and if gullies formed via snow melting at high obliquity, the Late Amazonian Epoch should have included regular snowmelt and widespread aqueous processes. Gully formation by CO2 frost processes is consistent with a cold-desert Late Amazonian with rare or small amounts of liquid water and little aqueous weathering, consistent with the observed mineralogy.
…Gullies, one of the most-discussed lines of evidence for liquid water on Mars, may in fact have no direct connection to H2O. CO2 frost-fluidized gully formation also has broader implications for geomorphology, widening an emerging field of new landform types and processes without Earth analogs. Similar processes could occur on other worlds with erodible substrates on steep slopes and volatile ices at their frost point, although we currently lack the high-resolution images needed to test this hypothesis. Such ices include N2 on Pluto and Triton, and SO2 on Io. [emphasis mine]
In other words, though the gullies appear at first glance to our Earth eyes to have been caused by water flowing downhill, in fact the data now suggests the annual CO2 frost cycle of Mars is the prime cause, even in the distant past. No surface water was required. And since no one has yet come up with a good model for liquid surface water even existing in the Martian past (the atmosphere being too cold and thin), this conclusion helps eliminate this conflict.
The paper also notes the lack of water likely eliminates the need for any planetary protection efforts at these gullies, as the lack of water makes the likelihood of any microbiology nil.
As these conclusions are based on lab work and analysis of images, there remains great uncertainty. Nonetheless, the results help reinforce the arguments that the geological features we see on Mars were formed not by flowing liquid water but by other processes, such as glaciers of ice.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Interesting, dry ice answers some questions, but creates more. There is so much we do not yet know. Even with the abundance of rovers on the surface, we’ve learned very little. As you say, the uncertainty of Science.
The reporter on the radio was discussing last night the admission of most scientist that the erosion they see on Mars surface could not of happened without the presence of liquid water. They just don’t see a way around it. (again with the possibility of life scenario)
I did not locate the recent article he was speaking of, but I did find an older one that has 114 references to other studies that they draw from.
https://www.nature.com/articles/s41561-023-01349-2
In essence, 3 billion years ago, mars had a thicker atmosphere with weather. All blown away now by the solar wind, due to low gravity allowing the atmosphere to extend beyond its gravitational containment.
It’s good to see that someone is thinking outside the box on other possible scenarios for the erosion. I look forward to Mars occupation with core samples and definitive results.
My personal hypothesis is that Mars once looked like Europa, covered in ice a mile or more thick. (The ice on the poles is all that remains above ground)
Possibly deposited by the Local Fluff in a supernova event cloud that passed through our solar system, converting most of earths thick oxygen atmosphere into water, killing the dinosaurs and putting us into an Ice Age.
The same event darkened our Sun for hundreds of years, depositing material on all of the planets and their moons.
So what created all be erosion and canyons on Mars? The astroid that created Helenas basin was violent enough to create the super volcanoes with the bulge on the planet on the far side. A heating event under the ice containing the pressure and liquid to run violently in places, with escaping water and gas refreezing to the surface adding to glacier movement that pushed mountain ranges out of place. Add to that the ejects from the impact and all the volcanic dust thickening the atmosphere covering the planet depositing on the ice with material hundreds of feet thick.
This seems like a one size fits all scenario, but how do you get the largest canyon in the solar system without a lake or ocean with shoreline on it’s far end? Did a void open up and 2 miles of material just drop? Not likely, but the erosion in this area is unlike anything on earth.
I love a mystery.
Max, you lost me here: “Possibly deposited by the Local Fluff in a supernova event cloud that passed through our solar system, converting most of earths thick oxygen atmosphere into water, killing the dinosaurs and putting us into an Ice Age.” – for a number of reasons.
The nonavian dinosaurs’ extinction correlates too well with the Chicxulub impact, which was last I heard a C-type chondrite. Also a cloud of ionic hydrogen would have to be thick indeed to interact effectively with Earth’s oxygen and rain it out. How does it even get into the 1 AU range of our star?
To be the annoying replyguy, I do want to add some context, partly to Max’s comment but mostly to the OP.
We are, for this post, talking about the recent gullies: not the vast dry streambeds held over from Mars’ ancient times.
Mars’ proposed wet era is (aptly) named the Noachian, lasting 4.1Gya – 3.7Gya. Then, Hesperian, 3.7-3Gya. The paper mentions only the “Amazonian” which Mars is still in, presumably until the Sun gets warm enough some billion or two years in our Sun’s future.
In fact the paper concentrates just in the last few million years. So the “distant past” and the “ancient flows” remain in play for Noachian and probably also Hesperian.
David Ross: Point taken. Thanks for adding the important time element.
Regardless, I think Mars’ researchers are too inclined to apply Earth-familiar processes to Mars in their long term theories about the geological processes that formed its surface. There is more here than meets the eye, and the evidence suggests strongly that ice-glacier processes might have played a major if not entire part in creating those “vast dry streambeds” from the Noachian and Hesperian.