The drying out of Mars’ tropics
Click for original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 26, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team calls the features surrounding these small 20 to 60 foot high hills “polygon features,” an apt description and a geological feature that is seen in many places on Mars.
When these features are found in the icy higher latitudes, it is believed they are formed in connection to the freeze-thaw cycle that causes cracks in the near surface ice. When found in the dry equatorial regions, where these polygons are located, they are usually thought to be ancient evidence of past standing water that left behind these cracks, much like the cracks seen in mud after the water has evaporated away on Earth.
The formation of these tiny hills is a bit more complex.
The red dot on the overmap to the right marks the location of these polygons, inside 85-mile wide Galilaei Crater. Scientists believe catastrophic floods coming down from Valles Marineris filled the crater with a lake, as well as leaving behind the nearby inland sea noted in blue on the map. Later that lake drained out through a breach in the crater’s southwestern wall, leaving behind its cracked floor with many of these strange little hills in its southern half.
These cracks have been here for a long while, but it is also possible that during the wide swings in Mars’ rotational tilt, from 11 to 60 degrees the Martian tropics might have seen many cycles of wetter weather, even after those catastrophic floods were long gone. The polygons here might thus not be from those floods, but from later cycles.
And of course, there is always the question of whether these features were caused by liquid water or ice, since the existence of running liquid water on the surface of Mars at any time in the past remains unproven. Based on the known data the climate has apparently always been too cold and the atmosphere too thin.
Readers!
Every February I run a fund-raising drive during my birthday month. This year I celebrate my 72nd birthday, and hope and plan to continue writing and posting on Behind the Black for as long as I am able.
I hope my readers will support this effort. As I did in my November fund-raising drive, I am offering autographed copies of my books for large donations. Donate $250 and you can have a choice of the hardback of either Genesis: the Story of Apollo 8 or Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space. Donate $200 and you can get an autographed paperback copy of either.
Please consider supporting my work here at Behind the Black. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID 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. Every one of those 2020 conclusions has turned out right.
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.
Click for original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 26, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team calls the features surrounding these small 20 to 60 foot high hills “polygon features,” an apt description and a geological feature that is seen in many places on Mars.
When these features are found in the icy higher latitudes, it is believed they are formed in connection to the freeze-thaw cycle that causes cracks in the near surface ice. When found in the dry equatorial regions, where these polygons are located, they are usually thought to be ancient evidence of past standing water that left behind these cracks, much like the cracks seen in mud after the water has evaporated away on Earth.
The formation of these tiny hills is a bit more complex.
The red dot on the overmap to the right marks the location of these polygons, inside 85-mile wide Galilaei Crater. Scientists believe catastrophic floods coming down from Valles Marineris filled the crater with a lake, as well as leaving behind the nearby inland sea noted in blue on the map. Later that lake drained out through a breach in the crater’s southwestern wall, leaving behind its cracked floor with many of these strange little hills in its southern half.
These cracks have been here for a long while, but it is also possible that during the wide swings in Mars’ rotational tilt, from 11 to 60 degrees the Martian tropics might have seen many cycles of wetter weather, even after those catastrophic floods were long gone. The polygons here might thus not be from those floods, but from later cycles.
And of course, there is always the question of whether these features were caused by liquid water or ice, since the existence of running liquid water on the surface of Mars at any time in the past remains unproven. Based on the known data the climate has apparently always been too cold and the atmosphere too thin.
Readers!
Every February I run a fund-raising drive during my birthday month. This year I celebrate my 72nd birthday, and hope and plan to continue writing and posting on Behind the Black for as long as I am able.
I hope my readers will support this effort. As I did in my November fund-raising drive, I am offering autographed copies of my books for large donations. Donate $250 and you can have a choice of the hardback of either Genesis: the Story of Apollo 8 or Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space. Donate $200 and you can get an autographed paperback copy of either.
Please consider supporting my work here at Behind the Black. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID 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. Every one of those 2020 conclusions has turned out right.
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.
Readers: the rules for commenting!
No registration is required. I welcome all opinions, even those that strongly criticize my commentary.
However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.
Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.