Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on December 23, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The image shows us the north interior rim of 7-mile-wide Niquero Crater on Mars. From the high to the low points the elevation difference is about 2,500 feet, with a steep downhill slope averaging about 18 degrees. The terrain appears to show several avalanche collapses that pushed lower material out of the way, though at the bottom where that material has been pushed aside there is no obvious large debris pile.

The science team labels this image simply “volatiles and gullies”, a label that carries a host of significant information. These gullies, which were among the earliest found by Mars Global Surveyor in the late 1990s, were the first evidence that the surface of Mars had a lot of near surface ice. It is for this reason that this relatively small crater on Mars has a name. Most craters this small remain unnamed, but the gullies on Niquero’s north slopes required more study, and thus the crater was given a name.

Subsequent orbital imagery has now shown that craters like Niquero, located in latitudes higher than 30 degrees, quite often are filled with glacial debris. In fact, the material that these avalanches pushed aside at the base of the slope is that glacial material, protected by a thin layer of dust and debris. The avalanche essentially disturbed that protected layer, and thus the debris pile (made up mostly of ice) sublimated away when warmed by sunlight. Thus. no big debris pile.

The gullies tend to be on the pole-facing slopes. Scientists believe they are the remnant evidence of ancient glaciers that grew on these slopes because they were protected from sunlight. In subsequent eons, when the climate on Mars changed, those glaciers collapsed, leaving behind the gullies we see now.

The white dot on the overview map to the right marks the location, in the southern cratered highlands of Mars. The red dot in the inset shows the location of the picture itself in Niquero Crater.

Note the splash apron that surrounds Niquero. This is evidence that when the impact occurred to create the crater, the ground was impregnated with near surface ice. It melted quickly, formed the apron, then froze quickly afterward.

The global data of Mars also suggests that, based on the latitude, 39 degrees south, that ice is likely still here. Future colonists will likely find ice near the surface, protect only by a thin veneer of dust and debris, though in the apron it will likely require processing to separate the dirt from the water. Inside the crater however the ice will likely be easier to get at, as it is likely less mixed with that dirt and debris, having been deposited during later climate cycles.