Tag: Mars Reconnaissance Orbiter

Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on September 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team titled this picture “Gullies with Terminal Ridges on Glacial Crater Fill,” a title that in one phrase encapsulates everything we see here of this unnamed 8-mile-wide crater’s western rim and interior.

The crater is located at 46 degrees south latitude inside the much larger 145-mile-wide Kepler Crater, and about 1,500 miles east of Hellas Basin in a region where a lot of glacial ice is found. A context camera image taken in July 2020 shows the entire crater floor apparently covered with glacial fill that on the edges appears to be eroding away.

Today’s high resolution photo focused on the western part of the crater, where that eroding edge was instead replaced by a meandering ridge reminiscent of a moraine. The gullies on the interior slope to the west, as well as the parallel north-south cracks, suggest that debris falling and sliding down from that rim had pushed up against this glacial ice and created that ridge.

There is a lot more to this geology however.
» 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 August 13, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is another fine example of the wind-blown sculpted terrain that one finds routinely in Mars’ largest volcanic ash field, dubbed the Medusae Fossae Formation. About the size of India, this gigantic field is thought to be the source of most of the dust on Mars.

This particular location sits on the northernmost edge of that huge field. The elongated mesas mark the field’s edge, disappearing to the north but becoming thick and extensive to the south. The prevailing southeast-to-northwest winds have acted to clean most of the ash away.

We can get an idea about how deep and pervasive that field once was at this location by the pedestal crater in the middle right. Once, the floor of that crater was below the top of the ash field. At that time, the top of the dunes marked the general ground level across this entire image. Over time, the winds blew most of this material away, but the denser packed floor of the crater resisted that erosion, and thus now stands above the surrounding terrain.

The more normal-looking craters nearby could have occurred before the ash was deposited, or after it was blown away. The impact that created the pedestal crater however occurred when the ash covered everything here.
» Read more

Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, should at first glance be one of my “What the heck!?” images. However, a little detective work quickly provides us some understanding of the inexplicable geology seen at this particular location on Mars.

The picture was taken on August 29, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and was labeled by the science team a “Lobate Debris Apron in Deuteronilus Mensae.” This mensae region is the western part of the 2,000-mile-long strip in the northern mid-latitudes of Mars that I label glacier country, since almost every high resolution picture taken in this strip shows extensive glacial features.

This picture is no different, showing what appears to be glaciers, but by itself it is still difficult to make sense of it. Glaciers flow downhill, like rivers. In this high resolution image the direction of flow is somewhat unclear.

As always, a wider view clarifies the picture.
» Read more

Click for full image.

Cool image to end the week! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken by on July 18, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the bedrock layers on one of two very large mesas that jut out into the floor of 108-mile-wide Terby Crater.

I want to focus your eye on the spoon-shaped mesa near the top right of the photo. Note how the layers can be seen on both sides, even though the top of the mesa seems to be concave. This is strange and complex geology, made even more fascinating in that the two mesas almost reach the center of the crater floor. Why are they here? Why were they not flattened during impact, like the rest of the crater floor? Or maybe the original crater floor is the mesa top, but if so, why did the rest of the crater interior get eroded away.

The overview map below provides some context, and helps fill in some details, even if it fails to answer any of these questions.
» Read more

Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on July 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “viscous flow” that has apparently carved the wide curving canyon as it slowly flows into open country to the south.

I would estimate the height of that canyon wall to be around 3,000 feet, though this is a very rough guess. I also image a trail switchbacking up the nose of that canyon wall would make for a truly stupendous hiking experience.

The flow filling the canyon floor appears very glacial, which is not surprising as this canyon is at 37 degrees north latitude, in the mid-latitude band where many glacial features are found. The overview map below provides some more detailed context.
» Read more

Click for full image.

Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on June 15, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a crater whose ejecta has been sculpted to the east into a teardrop-shaped mesa by some ancient flow, coming from the west.

The crater itself is located in one of several outflow canyons draining out from the volcanic Tharsis Bulge into the northern lowland plain of Chryse Planitia, the biggest of which is Valles Marineris. This particular canyon is one of the smaller and is dubbed Ravi Vallis.

The overview map below illustrates why many scientists think the flow that shaped this mesa came from a catastrophic flood of liquid water, billions of years ago.
» Read more

Click for full image.

Cool image time! The photo to the left, rotated, cropped, and reduced to post here, was taken on June 1, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the rim edge to a fifteen-mile-wide canyon, with many apparent layers exposed on the high plateau.

The layers are intriguing in that they suggest several things. First, they give us a glimpse into the top and youngest layers that make up the interior canyon wall. Second, they tell us that erosion has removed much of those top and youngest layers, resulting in the mesas on that plateau.

Finally, the gullies flowing down into the canyon indicate further erosion processes, eating away at the canyon wall over time.

The location of this canyon is also intriguing.
» Read more

Click for full image.

Cool image time! The photo to the right, rotated and cropped to post here, was taken on June 17, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The section highlighted is at full resolution, in order to make clear the absolutely crazy and complex terrain seen in the full image.

This terrain is not glacial, as the location is only about 1 degree south of the Martian equator. There might have been surface or near surface ice here once in the past, but there is none now.

Could we be looking at some form of lava flow? This is possible, because a close look at the context map at the image link suggests this region has been partly covered by some material, obscuring some craters to the east and west. However, there is no visible evidence anywhere in this region of a volcanic vent or caldera. If this covering material was volcanic it is very unclear where it came from.

The overview map below does not really provide any answers, but at least gives the context.
» Read more

Click for full image.

Cool image time! The photo above, rotated, cropped, and reduced to post here, was taken on May 13, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows two dramatic ancient flows of flood lava. The arrows indicate what I think is the direction of flow for each, though the direction of the flow to the north appears more certain. In a wider context camera image the bulk of the evidence suggests the southern flow is heading west (as indicated by the arrow), but there are scalloped mesas within it that suggest the opposite.

The overview map above marks the location of this picture by the white cross inside the Athabasca Valles flood lava, thought by some scientists [pdf] to be Mars’ youngest major lava event that erupted about 600 million years ago and in just a matter of a few weeks poured out enough lava to cover an area about the size of Great Britain.

The general trend of the Athabasca flow was to the south, splitting into a big western and southeastern flows. This picture captures the southern edge of that southeastern flow, which might help explain why the flow directions in the picture seem so different from the main Athabasca flow. On a large scale, the flow was to the southeast. On a small scale at the edges the flow could go in many directions as the lava looks to find its level.

The Medusa Fossae Formation is the largest volcanic ash deposit on Mars, and is thought to be the source of most of the red planet’s dust. Though the origin of the ash is not yet known, it likely came from the eruptions that formed the planet’s giant volcanoes to the east and west.