Tag Archives: caves

Cave pits in the Martian northern lowlands

Essays And Commentaries

New pits in Hephaestus Planitia

I could call this my monthly Martian Pit update. Since November 2018 I have each month found from two to five new and interesting cave pits in the monthly download of new images from the high resolution camera on Mars Reconnaissance Orbiter (MRO). My previous posts:

All except the last August 12 post were for pits on the flanks of Arsia Mons, the southernmost in the line of three giant volcanoes to the southeast of Olympus Mons, and were thus almost certainly resulting from lava flows.

The August 12 post instead showed pits found in Utopia Planitia, one of the large plains that comprise the Martian northern lowlands where scientists think an intermittent ocean might have once existed. All of these pits are found in a region of meandering canyons dubbed Hephaestus Fossae.

In the most recent MRO release scientists once again focused on the pits in or near Hephaetus, imaging four pits, two of which have been imaged previously, as shown in my August post and labeled #2 and #4 in this article, and two (here and here) that appear new. The image on the right, cropped to post here, shows the two new pits, dubbed #1 and #3. In the full image of #1, it is clear that this pit lines up nicely with some other less prominent depressions, suggesting an underground cave. Pit #3 however is more puzzling. In the full image, this pit actually runs perpendicular to a long depression to the west. There are also no other related features around it.

What makes all four of these pits intriguing is their relationship to Hephaestus Fossae and a neighboring rill-like canyon dubbed Hebrus Valles, as shown in the overview map below.
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Test drone maps ice cave in Iceland

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Engineers have tested a prototype lidar-equipped drone by flying it through a lava tube in Iceland and using it to automatically map the tube.

While a cave-exploring drone on Earth may use propellers, free-flying spacecraft exploring caves on the Moon, where there is practically no atmosphere, or in the thin air of high altitude lava tubes on Mars’ giant volcanoes, would have to use small thrusters. The mission of the terrestrial drone deployed at the Lofthellir Ice Cave focused on validating the idea of using a drone-equipped LiDAR to safely navigate and accurately map rock and ice inside a dark lava tube in the absence of GPS or any prior map.

Under a research contract with NASA, Astrobotic has developed a custom navigation software product, known as AstroNav, to give drones and small free-flying spacecraft the ability to autonomously explore and map subterranean environments. AstroNav employs both stereo vision and LiDAR, works without GPS or previously stored maps, and can operate in real-time while a novel environment is explored at a high rate of speed.

…”The Astrobotic drone and LiDAR performed exactly as we had hoped, and was able to help us map the Lofthellir Lava Tube in 3D within minutes” says Lee. “We now have a highly accurate model of the shape and dimensions of the cave, and of the configuration of its many rocky and icy features, such as rock falls, ice columns, and micro-glaciers.”

The concept is an excellent one, especially for exploring the caves and pits of Mars. This test however only checked out the lidar. A drone that could do this on either Mars or the Moon does not yet exist.

I have posted their video of the flight below the fold.

Note: Thanks to reader Eddie Willers for noting that I mistakenly located this research in Greenland, not Iceland. Post now corrected.
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The location for a future Martian colony?

Essays And Commentaries

Pit draining into Kasei Valles

Regular readers of this webpage will know that I am a caver, and am fascinated with the pits and caves that have so far been identified on Mars, as illustrated by an essay I wrote only last week.

Some of the cave research I have cited has being led by planetary scientist Glen Cushing of the U.S. Geological Survey. Two weeks ago Dr. Cushing sent me a slew of pictures of caves/pits that he has accumulated over the years, many of which he has not yet been able to highlight in a paper. At least two were images that I had already featured on Behind the Black, here and here.

One pit image however I had never seen. A cropped and reduced close-up is shown on the right, with the full photograph viewable by clicking on the image. In many ways this pit is reminiscent of many pits on Mars. Its northern rim appears to be an overhang several hundred feet deep that might have an underground passage continuing to the north. The southern lip is inviting in that its slope appears to be very accessible for vehicles, meaning this pit/cave might be a good location to build a first colony.

Because of that accessible southern lip, I decided to do more digging about this particular pit. I was quickly able to find the uncaptioned release of complete image by doing a quick search through the image catalog of Mars Reconnaissance Orbiter’s (MRO) high resolution camera. That image, reduced and cropped to post here, is shown below, on the right.
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The many pits/caves of Mars

Essays And Commentaries

Sinkhole in Martian northern lowlands with dark seep

Time for many cool images! Over the years I have written frequently about the pits/caves on Mars, in both magazine articles and the many posts here at Behind the Black. The following posts are the most significant, with the June 9, 2015 providing the best geological background to many of these pits, especially the many located near the giant volcanoes of Mars.

As I wrote in that June 9, 2015 post:
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Another skylight entrance pit found on Mars

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Pit in Hephaestus Fossae

Cool image time! In my routine monthly review of the hundreds of new images released from the high resolution camera on Mars Reconnaissance Orbiter (MRO), I came across another most intriguing geological feature, the image of which is posted to the right, after cropping.

As the scale shows, the pit is about 300 feet across. Calculating the pit’s depth would require someone with better math skills than I. The website provides information about the sun angle, which can be used to extrapolate the shadows and then roughly calculate the depth.

The most fascinating aspect of this pit is the impression of incredible thinness for the pit’s overhung edges. All of the pit’s edges appear significantly overhung, and the thickness of the overhang seems incredibly paper-thin. This thinness is likely only an illusion, though in Mars’s light gravity it is perfectly possible for the overhang to be far thinner and more extended than anything you would find on Earth.

The image itself is in color, though the only color visible is within the pit itself. In that blueness at the base it seems to me that there is a pile of dust/debris, but once again, that conclusion should not be taken very seriously.

If you take a look at the full image, what is impressive is the bland flatness of the surrounding terrain. There is no hint that there might be underground passages hidden here. While most of the scattered craters are probably impact craters, many (especially those with unsymmetrical shapes) could be collapse features indicating the presence of underground voids. None however is very deep. Nor is there any other pits visible.

Below is a global map of Mars with the location of this pit indicated by a black cross. It is just on the edge of the transition zone between the lower northern plains and the southern highlands, where the shoreline of an intermittent sea is thought by some scientists to have once existed. This is also an area where not a lot of high resolution images have been taken, mostly because of its apparent blandness as seen in previous imagery.

This image demonstrates however that Mars is going to have interesting geology everywhere, and that we won’t really know it well until we have explored it all.
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Another intriguing pit on Mars

Essays And Commentaries

pit on Mars

Cool image time! In the June release of images from the high resolution camera on Mars Reconnaissance Orbiter, I came across the image on the right, cropped slightly to post here, of a pit in a region dubbed Hephaestus Fossae that is located just at the margin of Mars’s vast northern plains.

Below and to the right is an annotated second image showing the area around this pit. If you click on it you can see the full resolution image, uncropped, and unannotated.

wider view of pit

The scale bar is based on the 25 centimeter per pixel scale provided at the image link. Based on this, this pit is only about ten to fifteen meters across, or 30 to 50 feet wide. The image webpage says the sun was 39 degrees above the horizon, with what they call a sun angle of 51 degrees. Based on these angles, the shadow on the floor of the pit suggests it is about the same depth, 30 to 50 feet.

The shadows suggest overhung walls. This, plus the presence of nearby aligned sinks, strongly suggests that there are extensive underground passages leading away from this pit.

For a caver on Earth to drop into a pit 30 to 50 feet deep is nowadays a trivial thing. You rig a rope (properly), put on your vertical system, and rappel in. When you want to leave you use that same vertical system to climb the rope, using mechanical cams that slide up the rope but will not slide down.

On Mars such a climb would be both easier and harder. The gravity is only one third that of Earth, but the lack of atmosphere means you must wear some form of spacesuit. Moreover, this system is not great for getting large amounts of gear up and down. Usually, people only bring what they can carry in a pack. To use this Martian pit as a habitat will require easier access, preferable by a wheeled vehicle that can drive in.

The pit’s location however is intriguing. The map below shows its location on a global map of Mars. This region is part of the Utopia Basin, the place with the second lowest elevation on Mars.
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The cave dwellers of China

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Even as China tries to make them move out, the ethnic Miao villagers that have built homes and lived inside a cave for the past century or so refuse to leave.

Why? This explains it:

A cottage industry has popped up in which the cave dwellers earn extra money by renting out rooms in their homes, which over time have clustered within Zhong cave, a limestone cavern big enough to hold four American football fields. The hangar-like cave is so large that their wooden or bamboo-made residences form a small, subterranean village built along its undulating walls.

…Officials say that residents have not taken care of the cave, leaving it unsuitable for inhabitation, and that the government should oversee the village as it is listed as a protected community by the Getu River Tourism Administration, a local agency. They have offered each resident 60,000 renminbi, or approximately $9,500, to leave.

Only five families have agreed to move. The remaining 18 families have held on stubbornly to their homes inside the cave. They say that the new homes are too small, that they fear losing access to their land, and that they alone, because of their historical connection to the cave, should have the right to independently control its small tourism economy.

The Chinese government is simply not offering them enough to leave. And should they leave, I would expect the villagers to come out on the raw end of the deal, while the cave itself, no longer protected by their presence and financial self-interest to preserve it, will also suffer.

Hat tip Willi Kusche.

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Thirty mile cave on the Moon?

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A new analysis of data from Japan’s Kaguya lunar orbiter suggests that one of the cave pits it found could be an entrance to a lava tube 30 miles long.

In 2009, the Kaguya probe found a large shaft with an opening about 50 meters in diameter in the Marius Hills area. The shaft descends about 50 meters beneath the surface.

The JAXA team analyzed data obtained from a lunar radar sounder on the probe that indicated an underground structure extended west from the shaft. The study confirmed that the cavern, likely created by volcanic activity, has not collapsed, and there is the possibility of ice or water existing in rocks within the cave, the team said.

Do a search on Behind the Black using the search terms “cave” and “moon” and you will see many images of this pit, taken by Lunar Reconnaissance Orbiter as a follow-up to the Kaguya mission.

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Why I went to Belize

Essays And Commentaries

There are many reasons cavers decide to go to faraway places across the globe during their vacations. Some do it because they want to get out of the office. Some go because they like to see exotic sights and strange places well off the beaten path. Some go, like me, because they want the chance to see something new and unexplored. And we all do it because it is fun!

One doesn’t have to go to Belize to get these benefits. I could have traveled to England, Mexico, Hawaii, or any one of several dozen other countries to see the exotic, the new, and the unexplored. In fact, I have already done so in Russia, Ukraine, Germany, and Czechia (the new official name of the Czech Republic). Belize however was relatively close, the local population spoke English, I had never been there before, and most important, someone else was organizing things! When David and Eleanor Larson invited me to join their Belize project I decided this was a great opportunity to visit a strange and new place with a minimum of aggravation or planning. They had already done it, and I merely had to sign up and agree to do whatever their project needed doing. So, off I went.

Upon arrival, I soon discovered several very important additional reasons why this cave project exists. First there are the caves. They are grand and beautiful things, with very vast chambers filled with delicate and rare formations. The picture below, taken by fellow caver Laura Sangiala, shows one wall of the gigantic entrance room of one cave.
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New human species found?

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The uncertainty of science: Scientists in South Africa think they have found fossils of a new human species.

In the end, the work of more than 60 researchers yielded a picture of “a relatively tall, skinny hominid with long legs, humanlike feet, with a core and shoulder that is primitive,” Berger says. Some body parts have come into sharper focus than others. In an analysis of the remarkably complete hands, paleoanthropologist Tracy Kivell of the University of Kent in the United Kingdom found that bones in the wrist were shaped like those in modern humans, suggesting that the palm at the base of the thumb was quite stiff. That would allow forces to dissipate over a larger area of the hand than in more primitive humans—a trait associated with tool use. At the same time, H. naledi had a weird thumb and long, curving fingers, as if it still spent a lot of time climbing.

The story of the discovery is interesting in that the fossils were found in a cave in a room that is very difficult to access, so difficult that the scientists themselves have never seen the site. Instead, they have sent very small cavers inside to do the fossil gathering.

There are many caveats to this story. The 15 skeletons appear different than humans, but to then create a whole human species from this single location is a bit risky.

I think the biggest mystery about this find involves its location. How the heck did these 15 individuals get trapped in this room at the back of a cave that requires you to squeeze down a vertical 100-foot chute only about 8 inches wide to enter?

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Counting bats on a Saturday evening

Essays And Commentaries

While most normal people spend their Saturday evenings going out to dinner followed by either a movie or a show, I spent this past Saturday doing something entirely different: counting bats!

There is a local cave here in the Tucson area that is a maternity colony for one species of bats. During the summer the females gather here to gossip and then give birth to their babies, after which they move on until next year. Because of a desire to help these bats, a few years ago the managers of the cave decided to close it during the summer months. This way humans wouldn’t be there to disturb the mothers during their labor.

The managers also decided to do regular bat counts of the bats leaving the cave each evening to feed, in order to get an estimate of the population size. To everyone’s delight they found the numbers rising year-to-year, following the summer closure. The total population of bats isn’t actually going up, but it appears that bats are finding this cave to be a good place to give birth, so more and more of them are making it their summer residence.

In the end the situation will contribute to an actual rise in population, as providing the maternity colony a safe haven will allow for more successful births and more babies.

In the past three years the bat count numbers over each summer would exhibit a typical bell curve, going up and then declining as the summer progressed, with the largest numbers ranging between 75 to 150 each night. However, last year there was one evening in which no bats left the cave. The bat biologist leading the bat count, Sandy Wolf, has theorized that this might be because the mothers are synchronizing their labor so that everyone gives birth at the same time and, because of that, on that night no one exits for feeding.. She knows that some species do this, but for this particular species such behavior has never been documented.

Anyway, she decided to find out. This has required that someone be at the entrance counting the bats at least every other evening. (In past years the counts were only done about once a week.) This has required more help, and thus Sandy has called for volunteers to do the work.

And that is how I and fellow caver Jerry Isaman ended up hiking up the hill to the cave with digital camera, infrared lights, and monitor this past Saturday.

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Finding caves on Mars

Essays And Commentaries

A new study of pits on Mars has isolated one particular type of pit that has all the features of an Earth-like cave entrance, with a large number located in the regions around the giant volcanoes where evidence of past glacier activity has been found. From the abstract:

These Atypical Pit Craters (APCs) generally have sharp and distinct rims, vertical or overhanging walls that extend down to their floors, surface diameters of ~50–350 m, and high depth to diameter (d/D) ratios that are usually greater than 0.3 (which is an upper range value for impacts and bowl-shaped pit craters) and can exceed values of 1.8. Observations by the Mars Odyssey Thermal Emission Imaging System (THEMIS) show that APC floor temperatures are warmer at night and fluctuate with much lower diurnal amplitudes than nearby surfaces or adjacent bowl-shaped pit craters.

In other words, these pits are deeper with steeper and overhanging walls that suggest underlying passages. They also maintain warmer temperatures at night with their day/night temperatures changing far less than the surface, similar to caves on Earth where the cave temperature remains the same year-round.

The study’s most important finding, from my perspective, was the location of these pit craters.
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Giant lava tubes possible on the Moon

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New analysis of the lunar geology combined with gravity data from GRAIL now suggests that the Moon could harbor lava tubes several miles wide.

David Blair, a graduate student in Purdue’s Department of Earth, Atmospheric and Planetary Sciences, led the study that examined whether empty lava tubes more than 1 kilometer wide could remain structurally stable on the moon. “We found that if lunar lava tubes existed with a strong arched shape like those on Earth, they would be stable at sizes up to 5,000 meters, or several miles wide, on the moon,” Blair said. “This wouldn’t be possible on Earth, but gravity is much lower on the moon and lunar rock doesn’t have to withstand the same weathering and erosion. In theory, huge lava tubes – big enough to easily house a city – could be structurally sound on the moon.”

You can read their paper here. If this is so, then the possibility of huge colonies on the Moon increases significantly, as it will be much easier to build these colonies inside these giant lava tubes.

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New images from Mangalyaan

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Arsia Mons

Indian scientists have released a new set of color images taken by their Mars orbiter, Mangalyaan.

The image on the right is of Arsia Mons, one of the three giant volcanoes to the east of Mars’ biggest volcano, Olympus Mons. Arsia Mons is important for future manned colonization, as there are known caves on its western flanks. In addition, those western flanks show solid evidence of past glaciers, which means that it is very likely that those caves will harbor significant quantities of water-ice, making settlement much easier.

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Caves on the Moon!

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Scientists have now identified more than 200 cave pits on the Moon.

The pits range in size from about 5 meters (~5 yards) across to more than 900 meters (~984 yards) in diameter, and three of them were first identified using images from the Japanese Kaguya spacecraft. Hundreds more were found using a new computer algorithm that automatically scanned thousands of high-resolution images of the lunar surface from LRO’s Narrow Angle Camera (NAC).

This work is essentially the same as that done by James Fincannon and I back in 2011 (see links here, here, here, and here) but with much greater thoroughness.

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Cave exploration in the western mountains

Essays And Commentaries

scree slope
Anthony Smith struggling up a scree mountain slope.

I have only visited Nevada twice before, and those visits had been limited to the area around Las Vegas. Thus, my impression of the state had been similar to what most other people assume: a big ostentatious urban city surrounded by boring flat deserts.

Instead what I found is that Nevada is probably one of the most beautiful states in the nation. It has many mountain ranges, interspersed with wide flat valleys, a number of which have lakes or swampy areas because the water is trapped there, draining neither to the Pacific or Atlantic.

Yet, it is desert country. The limited amount of water means that the state is lightly populated, and the few farms or ranches that you pass actually act to amplify the feeling of emptiness. This is further enhanced by the frequent mountain ranges. Every time you cross over a range, you find yourself high in the air with a spectacular view of the vast valleys below.

The Forest Service job that I was part of this past week was focused on inventorying and surveying a number of known caves covering a large area in northeastern Nevada. The work had actually started several years earlier, so that this particular week was the final wrap up, mapping the last few known caves on the list while also ridge-walking several different canyons in an effort to find some new discoveries.
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Off to Nevada

Essays And Commentaries

Nevada

For the next seven days my daytime posting is going to be spotty, as I will be in some remote areas of Nevada working on an on-going Forest Service project to inventory and survey caves in an area in the northeastern area of the state. The project is mostly over, but as I have surveyed, sketched, and done the cartography for many eastern U.S. caves, the guy running the project asked if I would be interested in participating. Interested? I was thrilled.

Though we will be in a somewhat remote area, I still hope to post periodically during the week, not only about the usual topics but also about some of the caves we will have surveyed, some of which are rarely visited. I will also try to post some pictures of the spectacular country we expect to visit. (The photo on the right was provided to me by Tom Gilleland, who is running the project.) Stay tuned.

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A 33,000-year-old dog skull found in a Siberian cave, when compared with other ancient dog remains found in a Belgium cave, suggest to scientists that the domestication of dogs took place separately in many different places.

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A 33,000-year-old dog skull found in a Siberian cave, when compared with other ancient dog remains found in a Belgium cave, suggest to scientists that the domestication of dogs took place separately in many different places.

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For as yet unexplained reasons, scientists have been finding isolated colonies of little brown bats — once the most common bat species in the region and the hardest hit by white nose syndrome — surviving and healthy.

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Hope for North America’s bats: For as yet unexplained reasons, scientists have been finding isolated colonies of little brown bats — once the most common bat species in the region and the hardest hit by white nose syndrome — surviving and healthy.

In Vermont, biologists have identified 15 colonies in the western part of the state where the numbers of little brown bats, while still far fewer than before white nose appeared, are surviving, said Vermont Fish and Wildlife Biologist Scott Darling. “We visited each and every one of those colonies and to some degree, much to our surprise, they seem to be healthy,” Darling said. “It begged the question, ‘Why are you the lucky ones?'”

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