APOD: A Hole in Mars (2020 Mar 01)

[APOD Robot]

A Hole in Mars

Explanation: What created this unusual hole in Mars? The hole was discovered by chance in 2011 on images of the dusty slopes of Mars' Pavonis Mons volcano taken by the HiRISE instrument aboard the robotic Mars Reconnaissance Orbiter currently circling Mars. The hole, shown in representative color, appears to be an opening to an underground cavern, partly illuminated on the image right. Analysis of this and follow-up images revealed the opening to be about 35 meters across, while the interior shadow angle indicates that the underlying cavern is roughly 20 meters deep. Why there is a circular crater surrounding this hole remains a topic of speculation, as is the full extent of the underlying cavern. Holes such as this are of particular interest because their interior caves are relatively protected from the harsh surface of Mars, making them relatively good candidates to contain Martian life. These pits are therefore prime targets for possible future spacecraft, robots, and even human interplanetary explorers.

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[Guest0301]

THEM!

[wildespace]

Very cool. I think the "crater" is the result of a collapse. Here's a zoomed in view, with some enhancement of the dark part; seems like there's a pile of sand or soil at the bottom of the hole.

[MadCat-75]

The home of the giant ant lions... xD

The question arises as to how the cavern under the surface of Mars was formed.

-Erosion, as in karst areas?
-River channels of lava flows?

Is there a photo of the immediate vicinity?

EDIT:

ok, it's a volcano, so the latter is most likely not the reason.

[neufer]

Staring into a Pit

---

<<This observation was meant to examine a pit identified in a Context Camera image to see if HiRISE could resolve any details inside. In this cutout, we see the “normal” view of the HiRISE image on the left, while the right shows what happens when we try to “enhance” the brightness of the pixels in the pit.

Fortunately, HiRISE is sensitive enough to actually see things in this otherwise dark pit. Since HiRISE turned by almost 30 degrees to capture this image, we can see the rough eastern wall of the pit. The floor of the pit appears to be smooth sand and slopes down to the southeast. The hope was to determine if this was an isolated pit, or if it was a skylight into a tunnel, much like skylights in the lava tubes of Hawai’i. We can’t obviously see any tunnels in the visible walls, but they could be in the other walls that aren’t visible.>>

[SpaceCadet]

How is martian life a possibility when there isn't any atmosphere to speak of?

[smitty]

Have any other similar holes been found on Mars? If so, how many?

[orin stepanek]

It's so perfect; almost made rather than created by natural
causes! A volcano cone; or a sinkhole?

[Chris Peterson]

How is martian life a possibility when there isn't any atmosphere to speak of?

Simple life doesn't require an atmosphere. Just occasionally liquid water and a source of energy.

[saturno2]

This hole is strange

[wildespace]

How is martian life a possibility when there isn't any atmosphere to speak of?

Some forms of like don't require oxygen (or any atmosphere really). Thermal vents, even solid rocks. There are organisms feeding off chemical composition.

[SteveH]

My speculation is that being on a volcano, the cavern is a lava tube. The hole is located in a place where the ceiling of the tube was very near the ground surface and, as mentioned before, there was a collapse. The circular crater is what was left after the sandy surface drained into the tube.

There may be others like this hole in this or other volcanoe's plumbing system systems. They may or may not be visible from the surface. Presumably, they could be hidden from view where there was enough sand to pile up from the floor to the ceiling and close the hole. Subsequent dust storms could then have hid the feature from being visible on the surface.

[HellCat]

I'll upvote SteveH on the lava tube skylight hypothesis.
It might be that we don't see any other skylights because they:
1) Happen infrequently, especially so the more time passes from their formation, and
2) Once open, they are filled in from above. (instantaneously in geologic time frames)

[Astronymus]

The home of the giant ant lions... xD

Hehe, had the same thought. Now I'd like to see those giant Mars ants.

[Chris Peterson]

The home of the giant ant lions... xD

Hehe, had the same thought. Now I'd like to see those giant Mars ants. :lol2:

I remember this old movie I saw on TV when I was a kid, where martian invaders kidnapped people by somehow making the sand under them open up and swallow them. A really hokey movie, but there was something terrifying about the way people just got sucked into the ground. Thought about that for years when I was on sand!

(The movie, creatively enough, was called Invaders from Mars.)
_

Click to play embedded YouTube video.

[Ann]

The home of the giant ant lions... xD

Hehe, had the same thought. Now I'd like to see those giant Mars ants.

I remember this old movie I saw on TV when I was a kid, where martian invaders kidnapped people by somehow making the sand under them open up and swallow them. A really hokey movie, but there was something terrifying about the way people just got sucked into the ground. Thought about that for years when I was on sand!

(The movie, creatively enough, was called Invaders from Mars.)
_

Click to play embedded YouTube video.

We used to have a English Listening Comprehension exercise at my school, where a stuntman and a stunt coordinator were interviewed. The stunt coordinator explained how he created a stunt where a woman really had to be swallowed up by the ground. They dug a deep hole, filled it with peat moss and water, fitted it with an oxygen tank and a lift, and had the stuntwoman step on it and be swallowed up by the ground.

Yes, she survived and was unhurt, too. Well, the stuntwoman survived, not her character in the TV show.

Ann

[neufer]

My speculation is that being on a volcano, the cavern is a lava tube. The hole is located in a place where the ceiling of the tube was very near the ground surface and, as mentioned before, there was a collapse. The circular crater is what was left after the sandy surface drained into the tube.

My only question is whether the ceiling of these tubes collapsed all on their own
or is their a meteorite or two down there somewhere!.

<<Following the identification of Heat Shield Rock as a meteorite, five similar iron meteorites were discovered by Opportunity (informally named "Block Island", "Ireland" "Mackinac Island", "Oileán Ruaidh" and "Shelter island"). Two nickel-iron meteorites were identified by the Spirit rover (informally named "Allan Hills" and "Zhong Shan"). One nickel-iron meteorite has been identified by the Curiosity rover, tagged "Lebanon." In addition, several candidate stony meteorites have also been identified on Mars.>>

<<Worried that their young twin boys had developed extreme personalities --
one was a total pessimist, the other a total optimist -- their parents took them to a psychiatrist.

First the psychiatrist treated the pessimist. Trying to brighten his outlook, the psychiatrist took him to a room piled to the ceiling with brand-new toys. But instead of yelping with delight, the little boy burst into tears. "What's the matter?" the psychiatrist asked, baffled. "Don't you want to play with any of the toys?" "Yes," the little boy bawled, "but if I did I'd only break them."

Next the psychiatrist treated the optimist. Trying to dampen his out look, the psychiatrist took him to a room piled to the ceiling with horse manure. But instead of wrinkling his nose in disgust, the optimist emitted just the yelp of delight the psychiatrist had been hoping to hear from his brother, the pessimist. Then he clambered to the top of the pile, dropped to his knees, and began gleefully digging out scoop after scoop with his bare hands. "What do you think you're doing?" the psychiatrist asked, just as baffled by the optimist as he had been by the pessimist. "With all this manure," the little boy replied, beaming, "there must be a pony in here somewhere!">>

[Raymond Kenneth Petry]

Neat circle, no rim-pucker, slightly-left-off-centered ragged bottom hole, no ejecta on the periphery, except a short spillover to its right, 8% rim bevel...suggests a single meteor impact into damp sand-stone (mud volcano shield), removing 17% of the crater, from just-right-off-vertical (back-bounce overspilling), no atmosphere (at-that-time), meteor-shaped-charge penetrating to a sublevel watertable which subsequently evaporated-down (not long ago)...

[neufer]

Neat circle, no rim-pucker, slightly-left-off-centered ragged bottom hole, no ejecta on the periphery, except a short spillover to its right, 8% rim bevel...suggests a single meteor impact into damp sand-stone (mud volcano shield), removing 17% of the crater, from just-right-off-vertical (back-bounce overspilling), no atmosphere (at-that-time), meteor-shaped-charge penetrating to a sublevel watertable which subsequently evaporated-down (not long ago)...

This little boy replied, beaming, "there must be a Petry in here somewhere!"

[mickwilson200]

Tongue in cheek: it's obviously ant lions, and those chappies look like something Khan put in Checkov's ears.

[smitty]

Anybody know whether other, similar holes have been found on Mars, and if so how many?

[Chris Peterson]

Anybody know whether other, similar holes have been found on Mars, and if so how many?

Yes, I believe there are others. A half dozen or more. IIRC, a few are not imaged well enough to be certain, but show as dark spots that are suspected to be holes.

[SpaceCadet]

How is martian life a possibility when there isn't any atmosphere to speak of?

Some forms of like don't require oxygen (or any atmosphere really). Thermal vents, even solid rocks. There are organisms feeding off chemical composition.

But wouldn't the lifeform need protection from the solar elements,like radiation? An atmosphere isn't just about providing possible nutrition or an energy source.

[Chris Peterson]

How is martian life a possibility when there isn't any atmosphere to speak of?

Some forms of like don't require oxygen (or any atmosphere really). Thermal vents, even solid rocks. There are organisms feeding off chemical composition.

But wouldn't the lifeform need protection from the solar elements,like radiation? An atmosphere isn't just about providing possible nutrition or an energy source.

You're assuming it lives on the surface. It could be under rock, under ice, underwater. It could also be very tolerant of radiation.

[smitty]

Regarding SpaceCadet's question about life surviving on Mars, it might be helpful to explore what we know about the world of extremophiles: https://en.wikipedia.org/wiki/Extremophile .