Massive Cave Found on Mars

mrcgran writes "Space.com is reporting a very deep hole found on Mars: 'The geological oddity measures some 330 feet (100 meters) across and is located on an otherwise bright dusty lava plain to the northeast of Arsia Mons, one of the four giant Tharsis volcanoes on the red planet. The Mars Reconnaissance Orbiter (MRO) used its High Resolution Imaging Science Experiment (HiRISE) instrument to draw a bead on the apparent deep hole — a feature that may cause more scientists to ponder about potential subsurface biology on Mars. Because the spot lacks a raised rim or tossed out material called ejecta, researchers have ruled out the pit being an impact crater. No walls or other details can be seen inside the hole, and so any possible walls might be perfectly vertical and extremely dark or — more likely — overhanging.' The original image and its cutout at full resolution can be found in the HiRISE site."

Comments

Purity

[BWJones]

That's no cave! It a giant pool of Purity.

Seriously though, the absolute absence of albedo in the visible spectrum is stunning. I wonder if there are multi-spectral images of this site? I expect this location will be of intense study in the future as there is little more than a complete absence of something to stir the human imagination.

However, I have to disagree with the analysis in that you can see shallow walls at the very edges of the crater if you stretch the image some and examine the profiles. It also appears to match the brightness of the elevation changes from one rim of the hole to the other which should give some idea for how tall the lip of the hole is to where the "blackness" starts presuming they know the angle of the sun and lat and long. Depending upon how far up the sun can get in the sky at a different season, there may be a possibility of seeing further into the hole, presuming of course it is not a giant pool of Purity.... :-)

Re:Purity

[lanswitch]

It reminds me of a certain website...

Re:Purity

[carld]

Has anyone looked on the opposite side of the planet?

Re:Purity

[3vi1]

Oddly enough, this hole is on exactly the opposite side as the "face".

Re:Purity

[dubbreak]

Has anyone looked on the opposite side of the planet?

Yeah, but all the found was a small hill. They named it Mons Pubis.

Next up: massive cave found on...

[smartbei]

"A very dark spot on [Uranus] could be an entrance to a deep hole or cavern, according to scientists studying imagery taken by NASA's a...ss Orbiter. The geological oddity measures some 330 feet (100 meters) across... The hole might be the sort of place that could support life or serve as a habitat... Must be deep..."

Re:Next up: massive cave found on...

[gfxguy]

We need to change the name of that planet to stop these stupid jokes. I nominate "Urectum".

already a known and cataloged feature

[rubycodez]

[Time Lapse. They reach a cliff and look over the edge.]

Zapp: Behold: The Great Stone Face of Mars.

Fry: Hm.

Zapp: The only known entrance to the Martian reservation.

Leela: What about the Great Stone Ass of Mars?

Zapp: Well, yeah, but it's way over the other side of the planet.

    -- Futurama, Where the buggalo roam

We're doomed I tell you.

[geoff lane]

NO one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinised and studied, perhaps almost as narrowly as a man with a microscope might scrutinise the transient creatures that swarm and multiply in a drop of water. With infinite complacency men went to and fro over this globe about their little affairs, serene in their assurance of their empire over matter. It is possible that the infusoria under the microscope do the same. No one gave a thought to the older worlds of space as sources of human danger, or thought of them only to dismiss the idea of life upon them as impossible or improbable. It is curious to recall some of the mental habits of those departed days. At most terrestrial men fancied there might be other men upon Mars, perhaps inferior to themselves and ready to welcome a missionary enterprise. Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us. And early in the twentieth century came the great disillusionment.

Yeah, yeah.

[spungo]

$10 says it's a bug on the lens.

Re:My god!

[kEnder242]

"My dog! It's full of Rats!" - 2001: A Dyslexic Odyssey

shamelessly ripped from someones sig

War of the Worlds

[HTH NE1]

It's the subsurface cannon barrel they used to fire their cylinders to invade Earth in 1898, 1938, and 1953. They may be readying for another attempt! When is the next opposition?

That's No Cave!

[Stanistani]

It's Dick Cheney's soul, placed in a blind trust for the duration of his public service.

Weird

[GreggBz]

There is so much to know about Mars that we don't.

No light is reflected back, which is kind of spooky. What can be inferred about the depth? How deep would it have to be for the HiRES camera stop sensing the light that is reflected?

It's nice and round, that's unusual. There is no crater ejecta so I'm guessing nothing hit it. I'm not a geologist, but aren't giant round holes in otherwise homogeneous flat terrain a bit uncommon?

Is there any radar in orbit with enough resolution to bounce a signal down one of these? I'm just so full of questions and awe.

I'll be checking unmanned spaceflight for theories to these questions. Awesome site.

Re:Weird

[SpaceLifeForm]

No. Sinkholes exhibit that feature, for example, in Florida.

Floor seen on one image

[dwarmstr]

If you read the preprint (PDF), you'd note that luckily, one of the caves actually was imaged with the floor sunlit, giving the authors the ability to calculate the depth of that particular cave. This was covered on May 23rd on the Planetary Society blog.

Re:Floor seen on one image

[FiloEleven]

And for those interested in the depth of that cave, it is estimated to be ~130 meters. Additionally, temperatures inside these openings (of which there are seven) appear to be more stable than on the surface.

Upon closer inspection, scientists find ...

[Lucas123]

There's a log in the hole in the bottom of Mars There's a log in the hole in the bottom of Mars There's a log, there's a log There's a log in the hole in the bottom of Mars. There's a branch on the log in the hole in the bottom of Mars There's a branch on the log in the hole in the bottom of Mars There's a branch, there's a branch There's a branch on the log in the hole in the bottom of Mars.

At last!

[niceone]

At last we have the answer to the burning question: Is there a hole on mars?

I'm confused

[palewook]

Does this mean men are from Venus and women are from Mars?

Martian Mordor

[Kythe]

I guess that's what happens when you leave the door to Mount Doom unlocked :)

Low Gravity Base Jumping

[TheLazySci-FiAuthor]

To me this is exciting. Imagine, hundreds of years from now this cavern may be visited by our descendants, and they will probably be just as crazy as we are today and thus will do things like this.

Ah, the future. I really want to stick around to see as much of it as possible!

I feel they're missing at least one obvious option

[Anonymous Coward]

The article says that the lack of ejected material rules out an impact, but it certainly does not rule out an impact into the roof of a dome (likely a lava-formed dome given the material)... whether from space or from a volcano (any within several miles?). There'd be little to no kick-back of debris if it simply punhced through.

It could be a structural collapse, but it's awfuly round.

Re:I don't buy it.

[Smidge204]

From the summary: "No walls or other details can be seen inside the hole, and so any possible walls might be perfectly vertical and extremely dark or -- more likely -- overhanging."

If you look at the image more carefully, you can clearly see shades and highlights that suggest the terrain slopes into the hole all around. That pretty much excludes equipment faults. One possible theory is that the cavern is conical in shape, getting wider as it goes down, which would certainly explain why it's so dark.

Also remember this picture is taken from a satellite. I'm sure they'll be taking more as soon as they get an opportunity.
=Smidge=

Re:Oh man

[PFI_Optix]

Y'know, if the UAC would follow a few simply rules of planetary colonization, they wouldn't have such problems.

1) When your life depends on the structural integrity of your base/space station, keep it well lit. Dark corners and unlit passageways invite unobserved problems and make excellent hiding places for demonic hordes.

2) Emergency lighting is your friend. Self-contained lights that can run off batteries for days have existed since the 20th century. USE THEM.

3) Teach your space marines how to use a pistol and flashlight at the same time. Television actors pretending to be cops can do it, so can they.

4) Keep hidden compartments, passageways, and crawlspaces to a minimum. This will drastically reduce construction and maintenance costs by keeping the design simple, and make it far easier for a lone marine to save all of humanity.

5) Develop lockdown procedures. They're useful in the event of a sudden loss of pressure to prevent your entire base from leaking air out a single fracture. They can also come in handy when your absurd experiments fail and you find yourself surrounded by blood-thirsty monsters. Seal all the doors. Combine this with #4 so that they can't simply bypass the doors by crawling through unnecessarily large ventilation shafts or open ceilings.

Lava Tube

[jnaujok]

Given the fact that it's on the side of a volcano, and the fact that it's in the middle of a lava field, the most likely answer is that it opens into a lava tube. Most likely a small meteorite hit the center of the circle and caused a circular fracture that fell into the underlying tube.

Re:Lava Tube

[jnaujok]

1. the opening would be elongated along the axis of the tube

Possibly, but only if the size of the hole is similar to the size of the tube. If this is a shot through the "ceiling" and doesn't come close to the walls, (and if the Dena guess of 130m for the diameter of the cave is close) then this could easily be just a punched "skylight". If the tube is, in fact, even larger, then it might very well be possible to see no difference in the edges. Lava tubes, at least from the data I've seen, tend to have mostly flat ceilings and are not purely cylindrical.

2. it should be more cracked and irregular since there would be little surface erosion to smooth things out

Actually, I'd expect that with only gravity to do it's work, and if it was caused by a meteor impact, that the shape would be almost perfectly circular, with any further cracks being either covered by the pervasive Martian dust (see the Spirit and Opportunity data.) Also, impacts in stone tend not to make many cracks (see this image for an example of how cement breaks. Admittedly volcanic basalt is not concrete, but the idea is similar. Also, how long has this cave been here? A thousand years, a million, a billion? It could be just about any of the above.

3. lava tubes tend to be fairly shallow so the bottom should be visible

Lava tubes tend to be shallow on Earth. However the Ape Cave lava tube in Washington is clearly at least as deep as it is wide [See here], and since we can't see walls on a 100m wide image, we can assume (and I know all about that word) that it might easily be 100m deep. Also, seeing the bottom depends on lots of factors. What is the angle of the sun (hard to tell from the lack of shadows) and the resulting angle to the spacecraft. There's a lot of ways to get near zero light, even given a cave only 50 meters deep.

4. lava tubes tend to be curved and smooth inside, so you'd expect more reflection

Lava tubes on Earth. Which are a few thousand years old. Look at Ape Cave in the above image and show me "smooth and shiny." I see bumpy and cracked. What happens when you expose basalt to ionizing radiation? Mars, lacking in a major magnetic field, allows a lot of radiation to impact the surface. What does that do to basalt? On the moon it makes it dark and bumpy. (see regolith)

5. the walls would be visible on two sides and at least one of them should be getting sunlight

Again, only if this hole spanned the width of the tube because of natural collapse. Lower gravity on Mars means you can have much larger air-supported structures. Lack of water or an erosion cycle means that the tube is less likely to collapse on its own. As some one else stated, these structures could act totally differently on Mars than on Earth. Perhaps on Mars, the thin, cold atmosphere leads to near immediate radiative cooling of the surface and almost all lava flows were under the surface. Once you form an insulating skin that prevents outgassing to proceed to the surface, it could be possible that a large gap would form between the ceiling of the flow and the current lava flow even without a noticable down-slope flow pool. Maybe the entire lava field is just the surface of one big bubble.

It's always dangerous to extrapolate Earth features to other planets and expect there to be no difference. This is a fascinating feature that deserves further study.

Either that, or the Martians are cloaking their secret base. One of the two...

Vacated worm home

[Shabbs]

Clearly it's the vacated home of the Asteroid Worm in Star Wars: Episode V. He couldn't afford the rent anymore.

Cheers.

Doh

[buswolley]

Stop Dreaming Homer. Its Not A Donut.

Massive?

[Sgt O]

How can a hole in the ground be 'massive'?

One song deserves another

[jd]

There's a hole in my planet, dear NASA, dear NASA,
There's a hole in my planet, dear NASA, a hole.

Then fill it, dear Martian, dear Martian,
Then fill it, dear Martion, fill it.

With what shall I fill it, dear NASA, dear NASA,
With what shall I fill it, dear NASA, with what?

With crashed space probes, dear Martian, dear Martian,
With crashed space probes, dear Martian, space probes.

Could be lots of things.

[jd]

As another poster noted, a sink hole would be a perfectly good explanation. Erosion can also produce some amazing results - the Giant's Causeway is a series of pillars that stretch from Ireland to Scotland that formed because of intrusion into softer rock. This could be some weird reverse of that. It might not really be a hole, per-se, but merely something transparent at the frequency of observation that again has intruded a-la the Giant's Causeway. Maybe this was a gigantic geyser in a time when surface water was more common. As with the "face" on Mars, maybe this is an artifact of the camera, the angle, or the lighting.

At this point, as far as I can tell, there are a huge number of possibilities and no information to distinguish between them.

Cenote?

[Hoi Polloi]

My first though was that it looked like a cenote. They are built from limestone though so it would have to be by a different mechanism. My other thought was it might be a lava tube or a volcanic neck where the magma settled back out. I'm surprised that it hasn't been filled in by millennia of blowing sand so it must be rather young or constantly kept clear somehow. Maybe it is an alien portal and the hollow earth people got it right but for the wrong planet.