Darkened craters on Mars
Click for full image.
It’s time for the first cool image of 2020! The photo to the right, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on October 10, 2019. It shows a handful of darkened craters on the vast volcanic Elysium Planitia plain between the giant volcanoes Olympus Mons to the east and Elysium Mons to the north.
My first thought was that these dark craters were recent crater impacts, possibly a set of secondary impacts from a larger nearby impact. However, in looking at the archive of MRO’s high resolution camera at this location (Latitude 5.925° norther; Longitude 164.965°) I found that almost no high resolution images have been taken in this region, as shown by the overview map below to the right.
The black cross indicates the location of the image above. The red rectangles indicate where MRO has taken other high resolution images. As you can see, this area, about a hundred square miles plus in size, is largely untouched by high resolution images. The nearest other image, to the south, also showed the same features, a generally featureless plain with a few scattered small craters, some of which are darkened in their interior.
That not all the craters are darkened strengthens the hypothesis that the darkened craters are recent impacts, all occurring at the same time. However, for an impact to have created so many secondaries suggests that it was relatively large, and though I could find some research that found recent impacts in this region (here, here, and here [pdf]), no impact seemed large or close enough to account for all these darkened craters.
Then again, maybe this area was not hit by one large impact with secondaries, but by a rubble pile asteroid like Bennu, that broke up upon entering the Martian atmosphere and splattered a scattering of rocks across a wide area. That could account for the many recent small impacts.
Or maybe wind is removing dust to reveal the darker basalt volcanic material below, as seen in the dark splotches on the lower western flanks of Olympus Mons. The problem with this theory is that it is difficult to explain why only some craters are attracting wind, and why the wind removal is only happening in craters. Some of the same theories that explain the Olympus Mons splotches might apply (these craters happened to be thermally warmer for any number of reasons, thereby attracting dust devils). Somehow this explanation does not promote enthusiasm.
So what do we have? We have another cool image, and another Martian geological mystery that likely cannot be solved until people are actually roaming about on the surface of Mars.
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.
Click for full image.
It’s time for the first cool image of 2020! The photo to the right, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on October 10, 2019. It shows a handful of darkened craters on the vast volcanic Elysium Planitia plain between the giant volcanoes Olympus Mons to the east and Elysium Mons to the north.
My first thought was that these dark craters were recent crater impacts, possibly a set of secondary impacts from a larger nearby impact. However, in looking at the archive of MRO’s high resolution camera at this location (Latitude 5.925° norther; Longitude 164.965°) I found that almost no high resolution images have been taken in this region, as shown by the overview map below to the right.
The black cross indicates the location of the image above. The red rectangles indicate where MRO has taken other high resolution images. As you can see, this area, about a hundred square miles plus in size, is largely untouched by high resolution images. The nearest other image, to the south, also showed the same features, a generally featureless plain with a few scattered small craters, some of which are darkened in their interior.
That not all the craters are darkened strengthens the hypothesis that the darkened craters are recent impacts, all occurring at the same time. However, for an impact to have created so many secondaries suggests that it was relatively large, and though I could find some research that found recent impacts in this region (here, here, and here [pdf]), no impact seemed large or close enough to account for all these darkened craters.
Then again, maybe this area was not hit by one large impact with secondaries, but by a rubble pile asteroid like Bennu, that broke up upon entering the Martian atmosphere and splattered a scattering of rocks across a wide area. That could account for the many recent small impacts.
Or maybe wind is removing dust to reveal the darker basalt volcanic material below, as seen in the dark splotches on the lower western flanks of Olympus Mons. The problem with this theory is that it is difficult to explain why only some craters are attracting wind, and why the wind removal is only happening in craters. Some of the same theories that explain the Olympus Mons splotches might apply (these craters happened to be thermally warmer for any number of reasons, thereby attracting dust devils). Somehow this explanation does not promote enthusiasm.
So what do we have? We have another cool image, and another Martian geological mystery that likely cannot be solved until people are actually roaming about on the surface of Mars.
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.
Has anyone done any research on the effects of the Martian atmosphere on meteorites? I remember reading ( a long time ago!) Of the threat that micro meteorites pose to potential moon colonies, but I wonder if like Earth, Mars has enough atmosphere to burn up the majority of incoming space rocks?
And regarding the theory of wind clearing the craters… Dust devils did a good job of clearing spirit and opportunities solar panels, so perhaps the same, localised effect is in play here?
I note that the large craters are clustered together improbably. Why might this be? Were the large craters the result of a single meteorite that had broken up?