Author: Robert Zimmerman

Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on October 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a cluster of craters filled with ripple dunes.

The color strip tells us something [pdf] about the surface materials here. The reddish-orange in the craters is thought to be dust. The greenish terrain above the craters is likely coarse rock or bedrock, covered with a veneer of dust.

There is no ice here, just dust that over time has become trapped in the craters and cannot escape. And though there is also dust on the surrounding terrain, there is not that much. The craters themselves are likely very ancient, based on their shape and the eroded condition of their rims.

» Read more

Click for full image.

Today’s cool image to the right, rotated, cropped, reduced, and sharpened to post here, not only gives us another example of a Martian geological feature that is unique to Mars and whose origins are not yet understood, it also shows what appears to have once been a lake-filled crater that over time drained out to the east through a gap.

This picture was taken on October 14, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The inexplicable geology is called brain terrain, and it fills the floor of the crater on the picture’s left side. The rim shows a gap, from which a meandering channel continues downhill to the east. The lake inside the crater might not have been liquid water, but ice. The channel might not have been formed by flowing water, but by a glacial flow downhill.

What makes this glacial evidence especially interesting is that it is located in a very different part of the Martian mid-latitudes.
» Read more

Click for full image.

In a cool image post last week, I noted that the near surface “ice sheets in the northern lowland plains are never … smooth, even if well protected.” The picture to the right, cropped, reduced, and sharpened to post here, provides an excellent example. It was taken on November 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

It is winter, and the sunlight is coming from the southwest, only 27 degrees above the horizon. The mound on the left is soft, while the depression on the upper right appears to have sand dune ripples sitting on top of a flat glacial mound. This depression may be an eroded crater (no upraised rim) or it could be a sink caused by the sublimation of the near surface ice.

Everywhere else the flat plains are stippled with small knobs.

The overview map below provides more context.
» Read more

Click for full image.

Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 12. 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Dubbed simply as a a “terrain sample” by the science team, the picture was not taken as part of any specific research project, but instead to fill a gap in the orbiter’s shooting schedule so as to maintain the camera’s proper temperature. When MRO’s science team does this, they try to pick something in the area below that might be interesting. Sometimes they succeed, but often the features in the picture are nondescript.

The white line delineates the rim of a faint and very eroded small crater. Are the depressions that are mostly concentrated just to its south and east sinks or past impact craters? I haven’t the faintest idea. The overview map below helps to answer this question, but only partly.
» Read more