Click for full image.
Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on June 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The left image shows what the scientists have dubbed a “lozenge-shaped depression” in the middle of an unnamed 60-mile-wide crater in the southern cratered highlands of Mars. The right image shows the same exact depression, but I have brightened the photo in order to see the details in the shadowed depression.
Though the image is inconclusive, the bottom of the darkest spot in that depression cannot be seen, suggesting it could be an entrance into a larger void below.
Even if there is no voids below, why is this depression here? What caused it? The wider view of MRO’s context camera below might give us a hint.
Click for full image.
The white box indicates the area covered by the photo above. The crater’s north and south rims can be seen at the top and bottom of the photo.
At about 28 degrees south latitude this crater is not expected to show much evidence of ice in its interior, and that generally appears to be the case, based on the visual look of the crater floor. If the crater floor had buried glacial fill, you would expect at this latitude to see more erosion features and some bedrock, as seen by a similar crater at a slightly higher latitude highlighted as a cool image in October 2020. The floor’s smoothness suggests instead that we are looking at bedrock, similar to a different crater floor featured in a cool image in August, 2021.
However, if you look closely at the two interior crater in the crater’s northern quadrant you can see what looks like a splash aprons surrounding each, the kind of apron you see often surrounding craters in the northern mid-latitudes, where there is much evidence of near surface ice.
Such aprons however could instead be impact melt and thus volcanic in nature, not the result of melting ice.
If there is buried ice here at this latitude, it would have to be underground to prevent it from sublimating in the warmer equatorial temperatures. The depression suggests that there might an ice layer below ground, and that it might even be sublimating away to leave cave voids behind. That lozenge-shaped depression on the surface could thus be a sinkhole entrance as well as the outlet in which that gas is escaping.
All guesses on my part. What reinforces my hypothesis to my eye is the look of the other small interior craters close to the depression. Though they do not appear to have aprons, they also appear to have impacted into something somewhat soft, like ice.
If this crater has a subsurface ice layer, it would be the lowest latitude such a thing has been identified, and would strengthen the possibility that future colonists will be able to find mineable underground ice practically anywhere on the Martian surface.
Any papers relating to this depression will likely be published in a year or so. Stay tuned. The data from the Martian orbiters continues to make Mars more and more enticing.
Now available in hardback and paperback as well as ebook!
From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.
Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space
, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.
does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.
“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.
All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.
Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95). Just email me at zimmerman @ nasw dot org.