Monitoring the gullies on Mars for changes
Click for original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on March 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) as part of a long term monitoring program of the many Martian gullies scientists have found above 30 degrees north latitude on a variety of slopes.
Martian gullies are small, incised networks of narrow channels and their associated downslope sediment deposits, found on the planet of Mars. They are named for their resemblance to terrestrial gullies. First discovered on images from Mars Global Surveyor, they occur on steep slopes, especially on the walls of craters. Usually, each gully has a dendritic alcove at its head, a fan-shaped apron at its base, and a single thread of incised channel linking the two, giving the whole gully an hourglass shape. They are estimated to be relatively young because they have few, if any craters.
…Most gullies occur 30 degrees poleward in each hemisphere, with greater numbers in the southern hemisphere. Some studies have found that gullies occur on slopes that face all directions; others have found that the greater number of gullies are found on poleward facing slopes, especially from 30° to 44° S. Although thousands have been found, they appear to be restricted to only certain areas of the planet. In the northern hemisphere, they have been found in Arcadia Planitia, Tempe Terra, Acidalia Planitia, and Utopia Planitia. In the south, high concentrations are found on the northern edge of Argyre basin, in northern Noachis Terra, and along the walls of the Hellas outflow channels.
Orbital data has identified almost 5,000 gullies on Mars. Based on their shape and the Martian climate, scientists generally think these gullies were formed by some form of water flow, possibly coming from an underground aquifer at their top.
The white dot in the inset on the overview map to the right marks the location of these gullies, inside the northern interior slopes of 29-mile-wide Nier Crater. Since the first discovery of these gullies by Mars Global Surveyor in 2006, scientists have been monitoring them over and over to see if they would change seasonally due to water seepage from underground. Nier Crater itself has been photographed by MRO’s high resolution camera more than a dozen times, with the particular location above having been imaged previously in 2010 and 2019.
Few changes have been seen, however, and those have generally been attributed to a variety of rockfalls caused by the seasonal temperature shifts, not water seepage from below. It is now thought that if water caused these gullies, it did so in the past, when Mars’ changing rotational tilt made the climate different.
Nier Crater however is a good target for future exploration and research, because the floor of this crater is deeper than all but one other crater between 25 degrees south and 45 degrees north latitudes, lying about 6,500 feet below its rim. That deep elevation would provide unusual conditions for studying the Martian atmosphere.
Readers!
My annual February birthday fund-raising drive for Behind the Black is now over. Thank you to everyone who donated or subscribed. While not a record-setter, the donations were more than sufficient and slightly above average.
As I have said many times before, I can’t express what it means to me to get such support, especially as no one is required to pay anything to read my work. Thank you all again!
For those readers who like my work here at Behind the Black and haven't contributed so far, please consider donating or subscribing. 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.
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Click for original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on March 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) as part of a long term monitoring program of the many Martian gullies scientists have found above 30 degrees north latitude on a variety of slopes.
Martian gullies are small, incised networks of narrow channels and their associated downslope sediment deposits, found on the planet of Mars. They are named for their resemblance to terrestrial gullies. First discovered on images from Mars Global Surveyor, they occur on steep slopes, especially on the walls of craters. Usually, each gully has a dendritic alcove at its head, a fan-shaped apron at its base, and a single thread of incised channel linking the two, giving the whole gully an hourglass shape. They are estimated to be relatively young because they have few, if any craters.
…Most gullies occur 30 degrees poleward in each hemisphere, with greater numbers in the southern hemisphere. Some studies have found that gullies occur on slopes that face all directions; others have found that the greater number of gullies are found on poleward facing slopes, especially from 30° to 44° S. Although thousands have been found, they appear to be restricted to only certain areas of the planet. In the northern hemisphere, they have been found in Arcadia Planitia, Tempe Terra, Acidalia Planitia, and Utopia Planitia. In the south, high concentrations are found on the northern edge of Argyre basin, in northern Noachis Terra, and along the walls of the Hellas outflow channels.
Orbital data has identified almost 5,000 gullies on Mars. Based on their shape and the Martian climate, scientists generally think these gullies were formed by some form of water flow, possibly coming from an underground aquifer at their top.
The white dot in the inset on the overview map to the right marks the location of these gullies, inside the northern interior slopes of 29-mile-wide Nier Crater. Since the first discovery of these gullies by Mars Global Surveyor in 2006, scientists have been monitoring them over and over to see if they would change seasonally due to water seepage from underground. Nier Crater itself has been photographed by MRO’s high resolution camera more than a dozen times, with the particular location above having been imaged previously in 2010 and 2019.
Few changes have been seen, however, and those have generally been attributed to a variety of rockfalls caused by the seasonal temperature shifts, not water seepage from below. It is now thought that if water caused these gullies, it did so in the past, when Mars’ changing rotational tilt made the climate different.
Nier Crater however is a good target for future exploration and research, because the floor of this crater is deeper than all but one other crater between 25 degrees south and 45 degrees north latitudes, lying about 6,500 feet below its rim. That deep elevation would provide unusual conditions for studying the Martian atmosphere.
Readers!
My annual February birthday fund-raising drive for Behind the Black is now over. Thank you to everyone who donated or subscribed. While not a record-setter, the donations were more than sufficient and slightly above average.
As I have said many times before, I can’t express what it means to me to get such support, especially as no one is required to pay anything to read my work. Thank you all again!
For those readers who like my work here at Behind the Black and haven't contributed so far, please consider donating or subscribing. 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.
Here on Earth I’ve never seen a gully shaped like these that wasn’t formed by the flow of liquid; always water here on Earth. Those gullies are almost certainly a preserved water-shaped form. Glacial forms are almost always a U-shaped channel, at least here on Earth.
Thank you once again for some fascinating images.