Tag: geology

Flooding from crater lakes on Mars

9:36 am

Loire Valley on Mars

According to a new paper published today, scientists estimate that flooding from crater lakes on Mars — caused by sudden breaches in the crater rims — could have created as much as 25% of the volume of the valley networks that have been identified there.

Mars’ surface hosted large lakes about 3.5 billion years ago. Some of these lakes overtopped their rims, resulting in massive floods that rapidly formed deep canyons. Similar lake breach floods occurred in the northwest United States and central Asia at the end of the last glacial period over 15,000 years ago.

“We found that at least a quarter of the total eroded volume of Martian valley networks were carved by lake breach floods. This high number is particularly striking considering that valleys formed by lake breach floods make up just 3% of Mars’ total valley length,” Morgan said. “This discrepancy is accounted for by the fact that outlet canyons are significantly deeper than other valleys. These floods would have shaped the overall Martian topography, affecting the flow paths of other valleys. Our results don’t negate the importance of precipitation-fed runoff on early Mars. On the contrary, liquid water had to be stable for long enough for lakes to fill from inlet rivers.” [emphasis mine]

The map above shows in white the Loire Valles on Mars, located at about 20 degrees south latitude in transition zone between the northern lowland plains and southern cratered highlands. The paper cites this valley as a typical example of a flood valley caused by a crater rim breach.

This research only makes the geological and climate history of Mars more puzzling. Though the geological evidence strongly suggests lakes and liquid water once existed on Mars, and this research strengthens that conclusion (as indicated by the highlighted sentence above), no model of the planet’s climate has ever satisfactorily created a situation where that was possible. Either there are factors about Mars’ ancient history we have not yet identified (likely) and don’t yet understand (very likely), or the planet’s geology was formed by processes alien to Earth and thus not yet recognized by us.

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Rivulets in Martian lava

2:14 pm

Overview map

Today’s cool image is another example of scientists finding cool things hidden within distant pictures. The small white rectangle on the overview map to the right shows us where we are heading, to the severely eroded lava plains to the southwest of Mars’ largest volcano, Olympus Mons.

The white spot is about 500 miles from the caldera of Olympus Mons. In elevation it sits about 58,000 feet below that caldera, more than twice the height of Mt. Everest. Yet, despite these great distances, the material at that white rectangle was almost certainly laid down during an eruption from Olympus Mons, thus illustrating the gigantic scale of volcanic events on Mars. Because of the red planet’s light gravity, about 38% of Earth’s, not only can lava flow farther, it does so much faster.

The second image below is a wide angle photo taken by the context camera on Mars Reconnaissance Orbiter (MRO) in January, 2012, rotated, cropped, expanded, and enhanced to post here.
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Glaciers in the Martian south latitudes

1:12 pm

Glaciers in Mars' southern hemisphere
Click for full image.

Most of the glacier cool images I have posted in the past few years from the high resolution camera on Mars Reconnaissance Orbiter (MRO) have shown the obvious glacial features found in the northern hemisphere in that 2,000 mile long strip of chaos terrain at about 40 degrees latitude I dub “Glacier Country.”

Today’s glacier image to the right, cropped and reduced to post here, takes us instead to the southern hemisphere, into Hellas Basin, the death valley of Mars. The picture was taken on April 8, 2021, and in the full picture gives us a myriad of examples of glacial features. The section featured to the right focuses in on what appears to be an ice covered south facing slope, which in the southern hemisphere will get the least sunlight.

Think of the last bits of snow that refuse to melt after a big blizzard. They are always found in shadowed areas, which in the southern hemisphere would be this south-facing slope.

The overview map below shows how this location, marked by the small white rectangle, is inside Hellas Basin, at a low altitude comparable to the northern lowland plains. The feature is also a comparable latitude, 43 degrees south, to the glacier country of the north.
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InSight detects the three more large quakes on Mars, the most powerful measured so far

8:40 am

In the past month InSight’s seismometer has detected the three most powerful earthquakes so far measured on Mars, with one located in a region where no quakes had as yet been seen.

InSight spotted 4.2- and 4.1-magnitude temblors on Aug. 25, then picked up another roughly 4.2-magnitude quake on Sept. 18 that lasted for nearly 90 minutes, NASA officials announced on Wednesday (Sept. 22).

The previous record holder, which InSight measured in 2019, clocked in at magnitude 3.7 — about five times less powerful than a 4.2-magnitude quake.

At this time scientists have only been able to roughly pinpoint the location of the two August quakes, with the 4.1 quake occurring about 575 miles away, putting it in the volcanic plains where InSight sits and closer than the location of most of the previous large quakes near the long surface fissures dubbed Cerberus Fossae 1,000 miles away.

The August 4.2 quake’s is even more interesting, as its location is the farthest away of any so far detected, at an estimated distance of 5,280 miles away. The scientists presently suspect but have not yet confirmed that it may be located in the western end of Valles Marineris, Mars’ largest canyon.

The lander itself continues to fight a loss of power due to the amount of dust on its solar panels, forcing the science team to shut down practically all its other instruments so that the seismometer could continue operating.

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A clue to the Martian history of volcanic eruptions

1:00 pm

Dark layers in Medusae Fossae Formation
Click for full image.

Anyone who has taken even a single glance at a map of Mars cannot help but recognize that the red planet was once engulfed with repeated gigantic volcanic eruptions able to build numerous volcanoes larger than anything seen anywhere else in the solar system.

The cool image to the right, rotated, cropped, and enlarged to post here, provides a clue into those past eruptions, now thought to have been active for more than several billion years, with the most recent large activity ending several tens of millions of years ago. The photo was taken on May 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows just one tiny portion of the vast Medusae Fossae Formation, the largest thick volcanic ash deposit on Mars, about the size of India and what scientists think is the source of most of the planet’s dust.

What makes this picture interesting are the dark layers in the lower hollows. They indicate that this deposit was placed down in multiple eruptions, some of which produced material that appears dark blue in MRO images, and suggest that eruption was different than previous and subsequent eruptions.

The white cross on the overview map below notes the location of this picture in the Medusae Fossae Formation.
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Martian mountaintop

11:03 am

Mountains on Mars
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The outcrop top
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Cool image time! The photo to the right, cropped, reduced, and enhanced to post here, was taken on September 21, 2021 by Curiosity’s high resolution mast camera, and shows the top of that spectacular rock outcrop about 200 feet to the west of where the rover presently sits. The top image, from my September 16, 2021 post, “Curiosity: Into the Mountains!”, indicates the location of the photo with the black rectangle. The red dotted line indicates the rover’s future planned route.

I estimate the whole outcrop is about 100 feet high, which means the cliff section seen in the photo to the right is probably about 30 feet high. It would make a great challenge for any number of rock climbers I know.

What makes this image especially striking are the overhanging rocks at the peak’s top. In the Martian gravity, about one third that of Earth’s, it is possible for much more delicate rock shapes to remain structurally stable, and the sharp jagged boulders hanging out at the top of this cliff demonstrate that in a quite breath-taking way. On Earth such delicate rocks would likely have quickly fallen.

The Curiosity science team is obviously most interested in the massive layers revealed by this cliff. I am also sure they are also as enthralled by the scenery as I am.

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How to discover interesting things on Mars

2:13 pm

Overview map

Today’s cool image will do something a little different. We are going to begin in orbit, and by step-by-step zooming in we will hopefully illustrate the great challenge of finding cool geological features on the surface of Mars.

The first image to the right is an overview map of the Valles Marineris region. To its east, centered at the white dot, is a vast region of chaos terrain, endless small buttes and mesas and criss-crossing canyons. Travel in this region will always be difficult, and will likely always require some form of helicopter to get from point to point.

What is hidden in that terrain? Well, to find out you need to take a global survey from orbit with a good enough resolution to reveal some details. Below is a mosaic made from two wide angle context camera pictures taken by Mars Reconnaissance Orbiter (MRO).

Context mosaic of chaos terrain
For full images go here and here.

This mosaic, rotated, cropped, and reduced to post here, only captures a small section of the long north-south strips taken by MRO. The orbiter has taken tens of thousands of these strips, in its effort to produce a global map of Mars that shows some reasonable detail.

Do you see anything in this mosaic that looks interesting? Scientists need to pore over such images, one by one, searching for geology that is both puzzling and revealing. Sometimes the features are obvious, such as a single blobby crater in the flat relatively featureless northern lowlands.

Sometimes however the search can be slow and time-consuming because the terrain is complex, as is the example to the right. The many mesas and canyons can hide many interesting features. Since MRO can’t possibly take high resolution photos of everything, scientists have to pick and choose.

The planetary scientists who use MRO did find something here worth looking at in high resolution. Can you find it? Normally I’d provide a box to indicate it, but this time I’d thought I’d challenge my readers. Before you click below to see the feature, see if you can find it yourself in this mosaic. What would you want to photograph in high resolution?
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Landing site chosen for VIPER lunar rover

9:49 am

Overview map

NASA has now chosen the landing site for its VIPER rover, in a relatively flat area about 85 miles from the Moon’s south pole and near the western edge of Nobile Crater (pronounced No-BEEL-e).

The white rectangle on the overview map to the right shows the landing zone. The green cross on the rim of Shackleton Crater marks the South Pole. The red outlines inside craters are regions that are believed to be permanently shadowed, and thus locations that might have water ice within them. Additionally, the data suggests there are a handful of small areas inside craters within the landing zone that might also have ice.

From the press release:

The area VIPER will study in the Nobile region covers an approximate surface area of 36 square miles (93 square kilometers), 10 to 15 miles (16 to 24 km) of which VIPER is expected to traverse through during the course of its mission. During this time, the rover will visit carefully chosen areas of scientific interest that will provide further insight into a wide array of different kinds of lunar environments. The VIPER team will look to characterize ice and other resources in these areas using VIPER’s sensors and drill.

The mission’s planned lifespan is presently set at 100 days. While the Moon’s day/night is 28 days long, the rover will likely see little darkness, since at this very high latitude the Sun will simply circle the sky near the horizon.

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Glacial falls on Mars

11:01 am

A glacial falls on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on July 2, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It provides us just one more clear example of the many glaciers found in that 2,000-mile-long strip of chaos terrain at 30 to 47 degrees north latitude that runs between the northern lowland plains and the southern cratered highlands, a region I like to call Mars’ glacier country.

What makes this glacial feature interesting is that these ice-filled alcoves are south-facing, which in the northern hemisphere means they get the most sunlight. Yet, the ice here remains, well-protected by its layer of dust and debris. Think of the dirty ice slush that manages to survive the longest on city streets in the spring. The dirt acts as protection so that the ice takes more time to melt.

The overview map as always provides our context.
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Badlands on the floor of a Martian crater

1:27 pm

Badlands on the floor of a Martian crater
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, shows one small section of a 30-mile-wide unnamed crater in the cratered equatorial regions of Mars northeast of Hellas Basin. Taken on July 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the science team labeled merely as “Rocky crater fill.”

Being at 17 degrees south latitude, there shouldn’t be any ice features in this crater, and the high resolution image to the right seems to confirm this. All we see is an endless plain made up of innumerable small sharp rock ridges interspersed with small low areas filled with sand dunes. This is bed rock, and if its strange stucco-like appearance was caused by a past glacial era, that era is long gone.

Below is a mosaic showing the entire crater, created from two MRO context camera images.
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Curiosity: Into the mountains!

12:46 pm

Curiosity's path into the mountains
Click for full image.

Overview map
Click for interactive map.

Time for another cool image from Curiosity. The photo above was taken by one of the rover’s navigation cameras today, and looks south in the direction of Curiosity’s future travels. The red dotted line shows that planned route, along the cliff face to then turn west into what the science team has dubbed Maria Gordon Notch, in honor of a Scottish scientist from the early 20th century.

The map to the right gives the context as seen from above, as well as the planned travels beyond the notch. The white dotted route marks Curiosity’s actual travel route. The red dotted line marks the planned route. The yellow lines the area seen in the above picture.

At present Curiosity is paused as it performs a new drilling campaign about 200 feet from the base of that cliff face, drilling the rover’s 33rd hole on Mars.

The outcrop resembling a ship’s prow on the image’s right, which I still consider the most spectacular rock outcrop seen yet on any planetary mission anywhere, is about 100 feet high.

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Lozenge-shaped hole in Martian crater

12:15 pm

Hole in crater floor
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Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on June 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The left image shows what the scientists have dubbed a “lozenge-shaped depression” in the middle of an unnamed 60-mile-wide crater in the southern cratered highlands of Mars. The right image shows the same exact depression, but I have brightened the photo in order to see the details in the shadowed depression.

Though the image is inconclusive, the bottom of the darkest spot in that depression cannot be seen, suggesting it could be an entrance into a larger void below.

Even if there is no voids below, why is this depression here? What caused it? The wider view of MRO’s context camera below might give us a hint.
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