Tag: Mars

Terby Crater and its drainages into Mars’ basement

1:59 pm

Channels in Terby Crater on Mars
Click for full image.

Cool image time! Over the past few years, in my endless rummaging through the archive of high resolution images from Mars Reconnaissance Orbiter (MRO) I have posted a lot of photos of meandering channels of all kinds, most of which evoke to Earth eyes canyons eroded by flowing water. (This September 2020 cool image is just one of the more recent examples.)

Today’s cool image is another example, but in this case it is only a very small part of a very large drainage basin that is more than a hundred miles across and extends at least that far southward into the basement of Mars, Hellas Basin, the place on Mars with the lowest elevation.

The photo to the right, rotated and reduced to post here, was taken on September 12, 2020 by the high resolution camera on MRO. I normally wouldn’t post the whole image, but to crop it would mean you wouldn’t get the sense of extensive nature of this drainage. Downhill is to the south. The channel apparently passes through three or four stages. First, its northernmost section is in a wide canyon, the floor of which resembles glacial debris (though with a latitude of 27 degrees south this is a bit too close to the equator for ice). More likely we are looking at wind-blown sand and dunes being pulled downhill in the floor of the canyon.

This first canyon is also actually a gap in the rim of a 13-mile-wide unnamed crater. See this MRO context camera image for a wider view.

Next, the drainage becomes a series of meandering small interweaving channels, resembling the channels often seen in beach mud as the tide goes out.

Finally, the channels head into a gap to fall over a sloping cliff into lower terrain.

Nor these stages entirely linked. The first glacial-like stage exiting the gap in the crater appears to drain to the southeast, while the second seems to emanate from what appears to be a very faint small crater now partly buried. Both head south toward the gap, but the path of the eastward drainage appears less obvious. Some of it flowed westward to join the meandering channels but some also appears to work its way south more to the east.

This one image shows a lot of channels, but it is only a very small slice of this whole drainage system. In fact, we are looking here at only one strip of the interior slope of the northern rim of 108-mile-wide Terby Crater.

The overview map below gives the larger context. Terby Crater sits on the northern border of Hellas Basin, which in itself extends another 1,500 miles to the south. From this point the drop in elevation into Hellas is almost four miles.
» Read more

0 comments

Ice-filled crater on Mars?

12:13 pm

Crater in southern mid-latitudes
Click for full image.

Time for another of the many cool images from Mars that suggest the presence of buried glacial ice. The photo to the right, rotated, cropped, and reduced to post here, shows an unnamed crater in the cratered southern highlands of Mars at about 44 degrees south latitude. Taken on October 2, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the crater sits at the very southernmost point of the Tharsis Bulge where the Red Planet’s four more distinctive giant volcanoes are located.

The crater is also in the middle of the 30 to 60 degree mid-latitude bands where scientists have detected many features that suggest glaciers, including a large number of craters that appear to have ice filling their interior.

Does the material in this crater’s floor suggest eroding and sublimating ice to you? It does to me. The second image below zooms in at full resolution at the north-south trench and the strange patterned terrain to its east.
» Read more

0 comments

Aram Chaos: Illustrating the puzzle of Mars

11:20 am

Aram Chaos
Click for full image.

The geological history of Mars is incredibly complex, and we really don’t know much about it. What we do know right now is based on a limited number of tiny fragments of a much larger story, with those fragments allowing scientists to only make educated guesses on how they fit together.

Many of those guesses will certainly turn out right. Just as many will turn out wrong. At this moment in our exploration of the Red Planet we can only grasp at straws while always keeping an open mind, as later data is surely going to change any conclusions we presently have.

The photo to the right is a good illustration of this struggle. Rotated, cropped, and reduced to post here, it was taken on September 27, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what at first glance looks like a stream of white frost or ice descending down a canyon to the south.

That first impression however is entirely wrong. When I asked Chris Okubo of the U.S. Geological Survey, who requested this image from MRO, what it was, he explained,

The white material is not frost. Instead, these are sedimentary rocks comprised primarily of sulfates. The texture to me suggests these are lithified dunes.

Lithified merely means that the dunes have hardened into rock. Sulfates are a salt formed from sulfuric acid, and are on Mars often linked to some complex mineralogy. If you stood there the colors would be white and red, quite beautiful. As Okubo explained,

The sulfates are white to tan in color, but there would also be a lot of red/brown Mars dust on top of it. It would be similar to walking around some of the playas in the desert southwest.

Though these white sulfate deposits have their root in sulfuric acid, Okubo added that they “are in the form of minerals similar to gypsum and so they would be safe to touch.”

What is going on here? As is usually the case, we need to first take a wider view to get some context.
» Read more

0 comments

Sagging cliffs on Mars

11:20 am

Sagging escarpment on Mars
Click for full image.

Cool image time! On Mars things change, but not like on Earth because the atmosphere is not as thick and there is no flowing water. The photo to the right, rotated, cropped, reduced, and annotated to post here, gives a good example of that slow change. The image was taken on August 29, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows the high escarpment that in this one place separates the planet’s southern cratered highlands from the transition zone down to northern lowland plains.

In this spot that escarpment, approximately 4,000 feet high, shows signs of avalanches and sagging. In the upper steep section, I point to what looks like a dust avalanche that wiped the slope clear of rough terrain as it rolled downhill. At the bottom of the cliff a large section has separated away. Since this cliff is located at 28 degrees north latitude and is in the midst of the chaos terrain regions I like to dub glacier country, it is very possible that this large section is actually buried glacial ice that in shifting down slope cracked, separating the lower section from the upper.

This particular location is east of an area dubbed Nilosyrtis Mensae (where there is a lot of evidence of glaciers and frozen ice), and about 650 miles north of Jezero Crater, where the rover Perseverance will land on February 18, 2021.

0 comments

A spray of Martian meteorites

12:27 pm

A spray of small secondary impacts
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on October 26, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is what the camera team calls a “terrain sample,” meaning it was not specifically requested by a researcher but was instead chosen by the camera team because they need to regularly take images to maintain the camera’s temperature. When they do this, they try to pick a location that hasn’t been photographed in high resolution previously, and that might have some interesting features. Sometimes the photo is boring. Sometimes they hit pay dirt.

In this case, the photo captured an small impact crater, about 1,300 feet across, surrounded by a spray of secondary impacts. The color portion of the image shows what I suspect are dust devil tracks cutting across a surface that, because of its blue tint, is either rough or has frost or ice within it. At 48 degrees north latitude, the possibility of the latter is high, especially because this location is northwest of the Erebus mountains, where SpaceX has its prime Starship candidate landing zone and where scientists suspect ice is readily available very close to the surface. The overview map below shows this context.
» Read more

2 comments

A place on Mars where lakes, snowfall, and rivers once existed

2:19 pm

Inverted channels near Juventae Chasma
Click for full image.

Cool image time! The photo to the right, cropped and enhanced to post here, attracted my immediate interest when I was going through the November image dump from Mars Reconnaissance Orbiter (MRO) because of its meandering sharp ridges, estimated to be about sixty feet high on average. While I have previously posted MRO images of inverted channels such as these, their particular sharpness, plus their large number in this localized single image, aroused my curiosity. What is their history? Does this illustrate an particularly interesting place on Mars?

The picture itself was taken was on September 29, 2020 by MRO’s high resolution camera. The blue areas in the color strip probably indicate coarser-grained surface. This makes sense, as these ridges are believed to have been initially carved as channels by flowing water or ice, which compressed their riverbed and thus made it resistant to erosion. Over time, the surrounding terrain eroded away, leaving that channel behind now as a upstanding ridge. The surrounding eroded terrain should thus be expected to be rougher.

Where did the water for these rivers come from, however? As always, the overview maps below give the context, and a possible explanation.
» Read more

2 comments

Eroded and possibly wet Lohse Crater

2:51 pm

Gully flow near central peak of Lohse Crater on Mars
Click for full image.

Cool image time! Today we take a look at one particular 100-mile-wide crater, Lohse Crater, located in the southern cratered highlands on Mars. The photo to the right, cropped and reduced to post here, focuses in on one of the many eroding gullies found in the mountainous region surrounding the crater’s central peak. Taken on August 20, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the full image is centered on that central peak, just off the south edge of this cropped section. This new image is part of a long monitoring campaign, begun in 2007, of this central peak region. For more than six Martian years, scientists have been tracking the numerous gullies found throughout the central peak region to see if there have been any changes.

I focused on this specific gully because I think it illustrates well why planetary scientists are monitoring these gullies. Whatever flowed down from the cliff on the left hit the material on the right hard enough and fast enough to imprint a curve into the material on the crater floor. Moreover, it does not appear to have simply been a landslide, for several reasons. First, the cliff does not appear cut back at the flow’s head, as you would expect if a section had broken off. Second, the material in the flow does not look like debris from an avalanche. In fact, there does not appear to be very much debris in the gully at all.

Third, and most important, the flow appears to originate at the cliff base, kind of what you’d expect if there was seepage coming out of a layer in that cliff face. Kind of what you’d expect on Earth, at a spring!

Was that flow water? This is the big question. Lohse Crater is significant in that it was one of the first locations on Mars [pdf] spotted by Mars Global Surveyor in the late 1990s where gullies were found suggesting some form of regular erosion possibly caused by flowing water. As this 2005 paper then concluded,
» Read more

3 comments

Giant wind eddies in the sands of Mars

12:13 pm

Wind eddies on Mars
Click for full image.

Cool image time! The image to the right, cropped and reduced to post here, was photographed by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on August 5, 2020. It shows a cluster of the crescent-shaped gullies, apparently carved from desert sand by the prevailing winds.

Those prevailing winds here are from the southwest to the northeast. As the wind blows the sand to the east, it hits a more solid object, such as a mountain buried in the sand, which forces the wind and the blown sand to go around, much as water passes a boulder in river rapids. That solid object also causes an eddy to form at its face, the wind forced downward and then around and up, carving out the gullies by lifting the sand at the base of that solid object. The result are these crescent gullies, dubbed blow-outs.

The overview map helps explain why there is so much sand here, enough apparently to bury whole mountains.
» Read more

3 comments

Glacial eddies on Mars?

12:24 pm

Glacial eddies on Mars?
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on August 15, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a truly strange bunch of blocks beside a clean flow neatly organized in almost straight parallel lines.

What is going on? This location is at 38 degrees south latitude, a latitude where scientists have found a lot of features that resemble water ice glaciers, generally protected from sublimating away by a thin layer of dust and debris.

A first guess is that the smooth glacial flow at the lower right is disturbing the glacial material next to it, causing it to rip apart and break up. At the same time, the hollowed look of these glacial blocks suggests that the ice below that protective debris layer is also slowly sublimating away, causing the surface to sink.

The wider shot below helps confirm this impression.
» Read more

0 comments

Curiosity data suggests the occurrence of mega floods in Gale Crater

3:30 pm

The uncertainty of science: Using Curiosity data a team of scientists are now suggesting that some of the features the rover has seen were created during mega flood within Gale Crater, and this data also requires a rethinking of the present theories of the crater’s geological history.

This case includes the occurrence of giant wave-shaped features in sedimentary layers of Gale crater, often called “megaripples” or antidunes that are about 30-feet high and spaced about 450 feet apart, according to lead author Ezat Heydari, a professor of physics at Jackson State University.

The antidunes are indicative of flowing megafloods at the bottom of Mars’ Gale Crater about 4 billion years ago, which are identical to the features formed by melting ice on Earth about 2 million years ago, Heydari said.

The most likely cause of the Mars flooding was the melting of ice from heat generated by a large impact, which released carbon dioxide and methane from the planet’s frozen reservoirs. The water vapor and release of gases combined to produce a short period of warm and wet conditions on the red planet.

The press release above focuses on the catastrophic floods, but the research paper itself is really much more focused on the need to rethink present hypotheses for explaining the observed geology in Gale Crater. This report notes that they are finding patches of material that could not have been laid down as seen, based on those past theories, and proposes the catastrophic flood event as a possible solution.

In reading the paper however it is evident that even this new hypothesis is based on a limited amount of data, and thus can have holes punched in it as well. This is not to say that the paper is invalid, only that it must be taken with some skepticism. The data being obtained at Gale Crater simply incomplete. Curiosity is following only one path, and has not even left the foothills of Mount Sharp. In order to gain a wider and fuller understanding geologists need to study the entire crater floor, as well as the geology on the mountain.

1 comment

Frost on a Martian hillside

3:02 pm

Frost on Martian hillside
Click for full image.

Cool image time! The image to the right, cropped to post here, was taken on August 27, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a flat-topped mesa in an enclosed canyon dubbed Sisyphi Cavi in the high southern latitudes of Mars during the spring.

Notice the white spots in the gullies on the southern-facing slopes? From what I can gather from a bit of research, these indicate the presence of carbon dioxide frost. It was spring at this location when the photo was taken. At that time, the thin seasonal mantle of dry ice that covers Mars’ the polar regions south to 60 degrees latitude in the winter is sublimating away. This would explain why the frost is only present in the south-facing slopes. Since this is in the southern hemisphere, the south-facing slopes get much less sunlight, and would sublimate away later.

The photo was taken as part of a monitoring program to study this sublimation process. According to this abstract:

Superposition of channel features over and/or through the defrosting CO2 snowpack shows that the channels are active at the present day and probably have fluid flows every spring during the annual defrosting. In itself, this is a significant observation as active fluid flows of any nature have not yet been proven on Mars. However, the ambient temperature at the time of gully activity appears to require a role for CO2 in the formation of the channels, rather than water.

In other words, the coming and going of this dry ice frost each Martian year, in conjunction with the underground water ice also found here, appears to be causing erosion that then creates of the gullies themselves. More details from the abstract in this paper:
» Read more

0 comments

ESA completes new parachute test for its 2022 Mars rover

9:58 pm

On November 9, 2020 the European Space Agency finally conducted the high altitude parachute test of the landing system for its 2022 Mars rover Rosalind Franklin that had been planned for March but had been delayed due to the Wuhan flu panic.

The timeline of the latest test, including extraction and deceleration, went exactly to plan. However, four tears in the canopy of the first main parachute and one in the second main parachute were found after recovery. The damage seemed to happen at the onset of the inflation, with the descent otherwise occurring nominally.

The team are now analysing the test data to determine further improvements for the next tests. Planning is underway for future tests in the first half of next year, to ‘qualify’ the complete parachute system ready for launch in September 2022.

Overall they consider the test a success, though the damage issues must be solved before the ’22 launch. Based on this test it also appears that the ESA made a very wise choice delaying the mission from launch this year, as its parachute system was clearly not ready.

0 comments
1 … 111 112 113 114 115 … 212