New paper: Underlying ice layer seen in Martian gullies at LOW mid-latitudes
Click to see full image.
In a paper just published, scientists are proposing that bright areas seen in the low mid-latitude gullies on Mars are the underground ice table newly exposed as surface dust is removed.
This paper is a reiteration in more detail of a previous presentation [pdf] by these same scientists at the 2019 the 50th Lunar and Planetary Science Conference in Texas and reported here in March 2019.
The image to the right, from the paper, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) in 2009, and has been cropped to post here. The white streaks are what the scientists propose is that exposed underground ice table. At 32.9 south latitude, this particular gully would be the closest to the equator that such an ice layer has been identified. All the previous ice layer discoveries have been in the ice scarps found at latitudes above 50 degrees. As the paper’s lead author, Aditya Khuller at Arizona State University, explained in to me in an email, “We believe we are seeing exposures of dusty ice that likely originated as dusty snow.” From their paper:
We suggest … that the light-toned materials are exposed H2O ice. … [T]he appearance, and then subsequent disappearance of these light-toned materials, suggests that they are some form of volatile, such as dusty ice, rather than dust alone. … [The appearance] of these light-toned materials is similar to the >100m thick, light-toned ice deposits exposed on steep mid-latitude scarps, indicating that these materials are probably also ice, with some amount of dust on, and within the ice.
The layer would have likely been laid down as snow during a time period (a long time ago) when the rotational tilt of Mars, its obliquity, was much higher than today’s 25 degrees. At that time the mid-latitudes were colder than the poles, and water was sublimating from the polar ice caps to fall as snow in the mid-latitudes.
The overview map below reveals some additional intriguing possibilities.
The white rectangle indicates the location of this particular gully. It is only about 25 miles from the abrupt end of Dao Vallis, suggesting that the ice/water that once flowed through Dao and carved it might have come out of this very ice layer at the canyon’s head.
This December 7, 2018 photo by MRO’s high resolution camera takes a look at the head of this canyon and the gullies found on its slope (its location is indicated by the red rectangle on the overview map). While there is no obvious evidence of the same bright patches and thus an ice layer, the slope wall is filled with similar gullies, all presumably formed by the same process. As the ice layer was exposed in the summer, a bit was sublimated or melted away, causing the gully to form and for the cliff to retreat slightly.
Given enough time and that retreat could form the canyon.
At this time however this is merely a hypothesis. As Khuller explained,
I have personally not seen other exposed ice at the end of Dao, but Dao does have a similar mantling layer present on much of its pole-facing walls, which are also likely to contain similar dusty ice. We are in the process of documenting more such exposures within other mid-latitude gullies.
As I noted in my March 2019 post describing this research,
As always, I think like a colonist on Mars. These cliffs now appear to me as prime real estate, places to look for easily accessible water on Mars. That they are near Hellas Basin increases their value, as the low elevation of this basin means it will have a thicker atmosphere which will ease colonization. If we can find some caves in this region, we might then have all the ingredients for building that first Martian colony.
Ironically, no one has sent or is even planning to send a rover or lander to the southern hemisphere of Mars. All research has presently been confined to either the northern lowland plains, or to the transition zone between those lowlands and the southern cratered highlands, which generally sits in the northern hemisphere or near the equator, as shown by the global map of Mars below:
If I was thinking of exploring or colonizing Mars, however, the head of Dao canyon — on the northeastern border of Hellas Basin and at only about 30 degrees south latitude — appears to be prime real estate, and certainly deserves a closer look. Who wants to go?
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Click to see full image.
In a paper just published, scientists are proposing that bright areas seen in the low mid-latitude gullies on Mars are the underground ice table newly exposed as surface dust is removed.
This paper is a reiteration in more detail of a previous presentation [pdf] by these same scientists at the 2019 the 50th Lunar and Planetary Science Conference in Texas and reported here in March 2019.
The image to the right, from the paper, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) in 2009, and has been cropped to post here. The white streaks are what the scientists propose is that exposed underground ice table. At 32.9 south latitude, this particular gully would be the closest to the equator that such an ice layer has been identified. All the previous ice layer discoveries have been in the ice scarps found at latitudes above 50 degrees. As the paper’s lead author, Aditya Khuller at Arizona State University, explained in to me in an email, “We believe we are seeing exposures of dusty ice that likely originated as dusty snow.” From their paper:
We suggest … that the light-toned materials are exposed H2O ice. … [T]he appearance, and then subsequent disappearance of these light-toned materials, suggests that they are some form of volatile, such as dusty ice, rather than dust alone. … [The appearance] of these light-toned materials is similar to the >100m thick, light-toned ice deposits exposed on steep mid-latitude scarps, indicating that these materials are probably also ice, with some amount of dust on, and within the ice.
The layer would have likely been laid down as snow during a time period (a long time ago) when the rotational tilt of Mars, its obliquity, was much higher than today’s 25 degrees. At that time the mid-latitudes were colder than the poles, and water was sublimating from the polar ice caps to fall as snow in the mid-latitudes.
The overview map below reveals some additional intriguing possibilities.
The white rectangle indicates the location of this particular gully. It is only about 25 miles from the abrupt end of Dao Vallis, suggesting that the ice/water that once flowed through Dao and carved it might have come out of this very ice layer at the canyon’s head.
This December 7, 2018 photo by MRO’s high resolution camera takes a look at the head of this canyon and the gullies found on its slope (its location is indicated by the red rectangle on the overview map). While there is no obvious evidence of the same bright patches and thus an ice layer, the slope wall is filled with similar gullies, all presumably formed by the same process. As the ice layer was exposed in the summer, a bit was sublimated or melted away, causing the gully to form and for the cliff to retreat slightly.
Given enough time and that retreat could form the canyon.
At this time however this is merely a hypothesis. As Khuller explained,
I have personally not seen other exposed ice at the end of Dao, but Dao does have a similar mantling layer present on much of its pole-facing walls, which are also likely to contain similar dusty ice. We are in the process of documenting more such exposures within other mid-latitude gullies.
As I noted in my March 2019 post describing this research,
As always, I think like a colonist on Mars. These cliffs now appear to me as prime real estate, places to look for easily accessible water on Mars. That they are near Hellas Basin increases their value, as the low elevation of this basin means it will have a thicker atmosphere which will ease colonization. If we can find some caves in this region, we might then have all the ingredients for building that first Martian colony.
Ironically, no one has sent or is even planning to send a rover or lander to the southern hemisphere of Mars. All research has presently been confined to either the northern lowland plains, or to the transition zone between those lowlands and the southern cratered highlands, which generally sits in the northern hemisphere or near the equator, as shown by the global map of Mars below:
If I was thinking of exploring or colonizing Mars, however, the head of Dao canyon — on the northeastern border of Hellas Basin and at only about 30 degrees south latitude — appears to be prime real estate, and certainly deserves a closer look. Who wants to go?
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
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