Martian rectilinear ridges
Click for original image.
Today’s cool image is also a bafflement. The photo to the right, cropped, reduced, and enhanced to post here, was taken on July 25, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The ridges in this picture are labeled by the scientists “Rectilinear Ridges,” but they really do not resemble any of the Martian rectilinear ridge types outlined in this paper [pdf], all of which appear to have a much more pronounced criss-cross pattern.
These ridges however are more meandering, and instead to my eye seem more like inverted channels, ancient channels whose beds became compacted and then became ridges when the less dense surrounding material eroded away. The problem with this conclusion however is the lack of any obvious tributary pattern. If these were once channels where either liquid water or glaciers once flowed, none of them seem to exhibit any drainage pattern. The ridges go in all directions.
The context map below only increases the mystery.
The black cross marks this picture’s location, about 600 miles from the center of 17,000-foot-deep Argyre Basin, the second deepest basin on Mars, after Hellas. Though it is on the edge of glacier country, and is also located at a latitude (39 degrees south) where many glaciers are found, little in this picture suggests glacial features. Instead, everything appears to be bedrock of one sort or another, with many sand dunes (the white streaks) scattered about.
The smooth area in the lower right might be impregnated with near surface ice, but if so it looks very different than almost any near surface ice I have yet seen on Mars. For example, the impact craters on it do not have that splattered look one expects from such near-surface-ice terrain.
Still, it is possible the difference between the relatively smooth plain to the south and the ridged area to the north exists because the surface ice has sublimated away in the north, revealing the underlying topography of ridges. That the smooth surface however more resembles bedrock and not icy topsoil makes this hypothesis unlikely.
Volcanism and hardened flood lava might explain these features, but even this doesn’t work entirely. For example, the ridges could be lava upwelling from cracks, except that their meandering nature says no.
All in all, a very typical Martian geological mystery.
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:
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Click for original image.
Today’s cool image is also a bafflement. The photo to the right, cropped, reduced, and enhanced to post here, was taken on July 25, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The ridges in this picture are labeled by the scientists “Rectilinear Ridges,” but they really do not resemble any of the Martian rectilinear ridge types outlined in this paper [pdf], all of which appear to have a much more pronounced criss-cross pattern.
These ridges however are more meandering, and instead to my eye seem more like inverted channels, ancient channels whose beds became compacted and then became ridges when the less dense surrounding material eroded away. The problem with this conclusion however is the lack of any obvious tributary pattern. If these were once channels where either liquid water or glaciers once flowed, none of them seem to exhibit any drainage pattern. The ridges go in all directions.
The context map below only increases the mystery.
The black cross marks this picture’s location, about 600 miles from the center of 17,000-foot-deep Argyre Basin, the second deepest basin on Mars, after Hellas. Though it is on the edge of glacier country, and is also located at a latitude (39 degrees south) where many glaciers are found, little in this picture suggests glacial features. Instead, everything appears to be bedrock of one sort or another, with many sand dunes (the white streaks) scattered about.
The smooth area in the lower right might be impregnated with near surface ice, but if so it looks very different than almost any near surface ice I have yet seen on Mars. For example, the impact craters on it do not have that splattered look one expects from such near-surface-ice terrain.
Still, it is possible the difference between the relatively smooth plain to the south and the ridged area to the north exists because the surface ice has sublimated away in the north, revealing the underlying topography of ridges. That the smooth surface however more resembles bedrock and not icy topsoil makes this hypothesis unlikely.
Volcanism and hardened flood lava might explain these features, but even this doesn’t work entirely. For example, the ridges could be lava upwelling from cracks, except that their meandering nature says no.
All in all, a very typical Martian geological mystery.
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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