Evidence of Martian near-surface ice in an unusual location

Evidence of Martian near-surface ice in an unusual location
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 27, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a terrain sample, it was likely taken not as part of any specific research request, but to fill a gap in the camera’s picture-taking schedule so as to maintain its proper temperature.

The picture however shows features that help confirm earlier research into the near-surface ice believed to permeate Mars’ middle latitudes. The knobby flat terrain both inside and outside of the crater resembles what scientists have labeled “brain terrain”, an as-yet unexplained geological feature unique to Mars and usually associated with near-surface ice and the glacial features found above 30 degrees latitude.

This 1.4-mile-wide unnamed crater is located at 40 degrees north latitude, so expecting near-surface ice or glacial features here is not unreasonable. The location however is different for other reasons, that make this data more intriguing.
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The lava tubes on the western slopes of Alba Mons as potential Martian colonies

Lava tubes on western flank of Alba Mons
Click for full figure.

In a new paper detailing work they first began in 2019, scientists have now carefully mapped the extensive lava tubes that appear to radially descend westward from the caldera of Alba Mons, the volcano on Mars that has the largest surface area but with a relatively low peak.

The mapped population of 331 lava tube systems has a mean length of 36.2 km, with a total length in the western flank geologic map quadrangle of ∼12,000 km. Individual lava tube systems extend up to ∼400 km, and it is likely that some of our mapped lava tubes are connected such that the total number is actually smaller and lengths (average and maximum) longer.

The map above, figure 10 of their paper, shows volcanic ridges as yellow, collapsed lava tube segments as red, and collapsed lava tube on the volcanic ridge as maroon. The wider map below, shows where this region is located, and gives the larger context.
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Lava tubes on Alba Mons

Lava tubes on the western slope of Alba Mons

During oral presentations today at this week’s 50th Lunar and Planetary Science Conference in Texas, scientists revealed [pdf] a map showing what they believe are numerous lava tubes flowing down the western slope of the giant Martian volcano Alba Mons.

The image on the right is taken from their paper. The red lines indicate collapsed tube sections, maroon collapsed sections on a ridge, and yellow volcanic ridges, which I assume are external surface flows. From their paper:

Lava tube systems … occur throughout the western flank, are concentrated in some locations, and are generally radial in orientation to Alba Mons’ summit. Lava tubes are typically discontinuous and delineated by sinuous chains of elongate depressions, which in many cases are located along the crests of prominent sinuous ridges. Lava tube systems occur as both these ridged forms with lateral flow textures and more subtle features denoted by a central distributary feature within the flat-lying flow field surface. Significant parts of the sinuous volcanic ridges show no collapse features, indicating a distinctive topographic signature for Alba Mons’ lava tubes.

Alba Mons is in some ways the forgotten giant volcano on Mars.
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