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A Hole in Mars (nasa.gov)
400 points by jamesbritt on July 18, 2012 | hide | past | web | favorite | 110 comments

I clicked the "speculation" link thinking it would be a forum thread full of scientist debating whether it was caused by volcanism or something similar, I didn't expect to be trolled by APOD.

I was really hoping for a Hollow Mars diagram when I saw that "speculation" link.

i don't get why they do that?

Scientists are some of the world's greatest comedians.

Well, that's one way of putting it.

I always thought that in some parallel universe, Clifford Stoll has a pretty successful stand-up career. In this one he makes lovely klein bottles for people though, so we might have the better deal - http://www.kleinbottle.com/


It looks remarkably like a sinkhole. Although one could joke, "Hey guys we found your Mars Climate Explorer!"

Given the fact that its on the side of a volcano it could also be a hole in a lava tube. But whatever it is, it is really cool and damn wouldn't it be nice to have someone there we could ask to roll over and check it out?

I agree, a 115ft (35m) wide, 65ft (20m) deep sinkhole.

How far away is this from the Mars Rovers? Even having another perspective to see this would be amazing!

I think roughly 4200km from Spirit and 6400km from Opportunity:




The rovers have driven 8km and 35km respectively, so this is out of reach. :)

How far is it from the projected landing site of Curiosity?

Road trip!

Coming this summer!

An orbiter carrying tens or hundreds of small, throwaway rovers would be nice.

We have a pretty creepy looking one here on Earth too:


Pretty cool, not quite the same, since we know what it is.

But thanks for making me spend the rest of my afternoon wikipediaing around on random geological occurrences.


I love that Pingualuit crater was formerly called "Chubb Crater"

I didn't really get why he proposed to call it Chubb crater. Chubb didn't discover it or anything.

Funny I visited #1 "Meteor Crater" or Barringer Crater last year with my wife.. It's hard to understand the scale of this thing until you're on the ground walking around it. Makes you feel very small in the grand scheme of things.. :)

Oh, Canada.

10 lines of CSS makes this site slightly more pleasant to the eyes :-)


What 10 lines?

From the look of the screenshot it looks like the poster just applied the standard twitter bootstrap css style sheet to the page.

If you wanna see what it looks like for yourself (and are using chrome) you can use this chrome plugin I wrote: http://scommab.github.com/chrome-twitter-bootstrapper/

Just the link color was borrowed from Twitter Bootstrap. Rest is pretty much white background, max-width, padding between <center> elements on the page, bigger line-height :)

If you send me the CSS (by comment or email from my profile), I know a few people that work at Goddard, and might have a better shot at getting them to add it :)

Send it to them!

White background, top padding, larger line-height, max-width. Did I miss something?

It's nice, though the change is very subtle on a 1024x768 screen like the iPad.

and style change for links (color change, not underlined by default)

so, pretty simple changes.

(Shrug) The image got smaller and the text got blurrier, but maybe my eyes aren't the best optimization targets.

Your browser probably shrunk the image he linked so that it fit. Try clicking for full size.

click on the image once, then it zooms in to the actual size.

Perhaps this feature or one like it could be incorporated in to a future colony by sealing up the hole and artificially stabilizing the interior structure? I know similar ideas have been floated in the past for the conversion of lunar lava tubes into habitable space.


It's obviously the dwelling of a Sarlacc.

Even though this is an awesome topic, i must say, i laughed!

In lieu of Curiosity landing on Mars in just two weeks, I wonder if one of these is within reach for the rover to do some exploration? Although it's probably too dangerous and the rover is probably not equipped to explore something like this.

The chances of this being within single digit kms of the Opportunity rover are very very slim. Mars is a big planet. The MERs are amazing, and have outdone all expectations, but they're not magical.

Yeah, I figured it would be slim, but I'm guilty of letting my imagination run away from me. Btw, what's an MER - Mars Exploration Rover? Agreed, if yes: I wish I was more into Astronomy when Opportunity and Spirit landed, but thankfully, they lasted long enough for me to appreciate the feat, while in progress.

Yep. MER is Mars Exploration Rover.

They also drive pretty slow from what I recall.

If an exploration vehicle were to go there and check it out, how difficult or impossible would it be for it to leave afterwards?

Relevant XKCD: http://www.xkcd.com/695/

By leave you mean, exit from inside the hole? Leave the perimeter?

Exit from within the crater.

Could we put a glass roof over that and fill the interior with a breathable atmosphere?

We europeans were aware of this since our childhood. :) Where had they thought Der Maus lives?


(Die Abendteuer der Maus auf dem Mars - The adventures of the mouse on the Mars)

actually the correct article for the nominative of "Maus" is "die", in the title "Die Abenteuer der Maus" "der Maus" is genitive so that's why it stands with "der" but the correct nominative is "die Maus" ("Maus" is feminine). Also note that "Abenteuer" has nothing to do with "Abend" (evening) so there's no "d" in it. SCNR.

Are the links in the APODs always this humorous?

Well, they previously talked about water on mars http://apod.nasa.gov/apod/ap050401.html

Not usually, which is why the dog thing is weirding me out.

"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"

Isn't that grasping at straws a little? I'm not a biologist, but it seems highly unlikely to me that life would develop in a hole 35 meters across.

Life wouldn't develop there, but if life used to cover the surface of Mars, and largely died over time, but was still surviving in some places, this would be one of the likely spots.

I see. It still sounds like a long shot though for life to survive for a long time in such a small space.

The caves and small places of Earth say otherwise. So do the intense environments on Earth that we've found life in. It's at least as plausible that life can hang on, sheltered in the smallest of places, as it can anywhere else. Micro organics often don't mind if you put them in a small place, with little sunlight, high or low heat, high or low oxygen, etc.

The biggest problem would be if the changes Mars underwent were too fundamentally anti-life for anything to survive whether it was in a cave or anywhere else.

In my opinion, we're going to find out on Mars that there are forms of microbes that can hang on in sedentary 'ready' state for a billion years, in extreme environments, just waiting to jump back to activity. Most of Mars will be barren, but there will be small pockets of microbes (most likely in a sheltered cave, under ice, or similar) in a form of extreme suspended animation.

They're not saying that life developed there, they're saying that if there ever were martian life, this is one of the few places on the planet that has a (relatively) less-severe environment, and therefore a higher likelihood of finding surviving specimens.

This is fascinating, especially whether the hole was created from a top impact or from the bottom such as volcanic eruption.

On another note, why are we discovering this just now? I was under the amateur impression that the entire surface of Mars was scanned and imaged by NASA at some point. But again, I may have interpreted that incorrectly.

> why are we discovering this just now? I was under the amateur impression that the entire surface of Mars was scanned and imaged by NASA at some point.

It's easy to forget just how large Mars is, as a comparison, if we scaled Mars up to the size of Earth, the hole would only end up being about 120 meters, or about %30 larger than an American football field. And when it's a feature that we pretty much need human eyes on to determine it's significance, it's easy to imagine how we've missed it. Just imagine trying to find a random football field sized thing in Google Earth, somewhere on the planet.

And to make the comparison even more valid, Mars isn't covered in water, and has a very comparable amount of land surface area as Earth does. in that case, it makes the hole only about 36 meters when scaled up to the surface are of Earth, which is likely what you'd be searching for in Google Earth.

Not to mention that I have no idea to what resolution Mars was scanned and imaged at, considering imagery I see of Earth often, the mentioned scans could easily have pixels larger then the entire size of that feature.

Hence it's easy to imagine that many more interesting features of similar size exist on the martian surface, sitting there in plain view, waiting to be discovered.

It's pretty high-contrast, though. Presumably an algorithm could find interesting high-contrast, high-symmetry structures quite easily...

This image is probably not the resolution all of Mars got imaged at, right?

I don't have the tools on this CPU to get good numbers, but if that hole is about 35 Meters, I'd estimate to resolution to be about 20 CM/Pixel. I know it's often difficult to find civilian access to Imagery at a better resolution than 5 M/Pixel for some places on Earth.

It's probably safe to assume we don't have imagery this good for the entire surface of Mars.

Edit: It seems likely that these new images are captured with this equipment: http://en.wikipedia.org/wiki/HiRISE

I wonder how far launch costs will have to drop before "Google Mars" (and/or someone else and/or other celestial bodies) is plausible...

http://www.google.com/mars/ ?

Or did you mean StreetView?

Macro-level features have been mapped for a while, but even from earth orbit (Hubble) it's not possible to resolve features at high resolution. I'm not sure what the precise limits are, but according to one photo (http://commons.wikimedia.org/wiki/File:Mars_HST_Mollweide_ma...), Hubble's imaging of Mars is at a resolution of approximately 20 km/pixel, which is several orders of magnitude too low to resolve the "hole" here, which is <100m.

Since 2006, there's been a high-resolution camera platform orbiting Mars (http://en.wikipedia.org/wiki/HiRISE), and it's doing this high-res imaging, at up to 30cm/pixel (!), for the first time. Though Wikipedia says that as of 2010, it's only mapped 1% of Mars's surface to that degree.

One of the links goes to an earlier APOD from 2007 of other holes in Mars: http://apod.nasa.gov/apod/ap070528.html

Strange few days ago I made this free Android App that takes info from APOD and NASA https://play.google.com/store/apps/details?id=nasa.project.v... and today we have unusual picture of Mars on HN.

If we had one of the surplus Hubble-diameter Naval Reconnaissance Office mirrors orbiting Mars with a suitable camera, would we have better pictures than this?

And could one of those mirrors be mounted in the trunk of a SpaceX Dragon spacecraft?

Has anyone ever spent any time over at: http://marsanomalyresearch.com/ ? Thoughts?

Sounds like the opening to a pretty cool scifi movie.

Why isn't it red?

My guess would be that it's simply not a color image.

Pretty sure Mars looks red because of the atmosphere. The surface isn't actually red. Could be wrong.

I think you're underselling the video. That is a fascinating presentation on aerial mars exploration.

It was linked to elsewhere in this thread. I'm just citing it to answer this one misconception.

I think it's pretty obvious what this is.



Vacant Sarlacc pit?

A meteorite could have crashed through a thinner portion of the surface and created the hole.

Actually, because it is circular the chance of it being a meteorite is slim. This is because the ejecta of a meteor crater is related to the angle at which the meteor hits, the more oblique the angle, the more oval the crater. A circular crater would suggest a perpendicular collision. That would suggest a very slow or very fast meteor, the latter would have caused a bigger crater. The third challenge with the meteor hypothesis is that the 'hole' suggests a cavern, and the cavern would have undergone a lot of compressive stress when struck. One would have to figure out how the meteor went through the top of the cavern without collapsing it (the shock wave from the impact would have pushed all along the top).

So its not impossible that it was a meteorite but it is improbable.

You sound convincing, but then I look at high resolution pictures [1] of the Moon and have my doubts. I don't think those are sinkholes.

That said, it does look like a sinkhole in this case.

1. http://www.nasa.gov/centers/goddard/images/content/238403mai...

To be clear, I wouldn't rule out a meteorite, I'm just saying that in order for it to be a meteorite some things need to be understood. The sinkhole hypothesis fits the picture precisely, but requires that someone explain how the top of the cavern got opened in the first place.

In a traditional research setting the next thing we would be doing is coming up with ideas that would rule out a hypothesis in order to give us higher confidence in the ones that remain. To that end, you've added data which doesn't help us rule out either of our hypotheses so it doesn't advance us toward our goal of understanding.

Finding a circular meteor crater on the moon with a cavern underneath it would be useful.

Another useful thing is to look at the sides of the hole. If the material was removed by pushing outwards, the sides will have one shape, if it was removed by 'draining' into the hole in the center they will have another shape. A good experiment you could run on earth to think about that would be a put some sand over a hole and drain it, take that shape. And then to take the same setup, cover the hole lightly, and blow on it with a directed stream of air until you punch through the thin covering on the hole and then take that shape.

If we can figure out the probable way in which the material was removed, that too can inform our hypothesis. I encourage you to keep coming up with ways to figure this out.

I wonder how we'd explore it. I guess land a probe with a transmitting station near it and have a rover on a wire go fall in?

Could we get a flying drone down there?

What does it take to make flight happen on Mars? The air is thinner, so would more force be required for airplanes and helicopters to fly? How well would hot-air or helium inflatables work, compared to Earth?

Yes, there is work going on to achieve that. Airplanes can fly quite well in thinner air, they just have to fly faster or have bigger wings. I don't know about helicopters or balloons, but there is a project which aims to bring a solar-powered airplane to Mars. The main problem are the batteries as they have to hold enough energy to fly trough the night.

See e.g.:

Noth A., Engel W., Siegwart R. Recent Progresses on the Martian Solar Airplane Project Sky-Sailor In Proceedings of the 9th ESA Workshop on Advanced Space Technologies for Robotics (ASTRA 2006), Noordwick, Netherland, 2006. [http://www.sky-sailor.ethz.ch/docs/Sky-Sailor-ASTRA2006_Noth...]

Noth, A., Bouabdallah, S., Michaud, S., Siegwart, R. and Engel, W. SKY-SAILOR Design of an autonomous solar powered martian airplane. In Proceedings of the 8th ESA Workshop on Advanced Space Technologies for Robotics, (ASTRA 2004), Noordwick, Netherland,2004. [http://www.sky-sailor.ethz.ch/docs/Sky-Sailor-ASTRA2004_Noth...]

Noth, A., Engel, W. and Siegwart, R. Flying Solo and Solar to Mars - Global Design of a Solar Autonomous Airplane for Sustainable Flight. IEEE Robotics & Automation Magazine, Volume 13, Issue 3, pp 44-52, Sept. 2006. [http://www.sky-sailor.ethz.ch/docs/Flying_Solo_and_Solar_to_...]

See http://www.sky-sailor.ethz.ch/ as well for more.

Here's some info on using airplanes (http://mars.jpl.nasa.gov/programmissions/missions/missiontyp...) and balloons (http://mars.jpl.nasa.gov/programmissions/missions/missiontyp...) on Mars. In short: it's possible.

X-Plane had some interesting observations about the physics of flying on mars a few years back.


Wow, that's gotta be one of the most pumped things I've ever read.

Here's a great video[1] I've just seen about flying on mars courtesy of a comment sadly further down.

[1] - https://www.youtube.com/watch?v=4YQBuuhh76A&feature=play...

This 2009 TEDx talk is about flying an airplane on Mars:


The air is much thinner but they made a manned plane fly 85000 feet high at Mach 3.3 in the 70s. It wouldn't probably be that hard to make an unmanned drone capable of flying on Mars.

To transport and ensure it's operational by the time it gets there, might be a completely different matter, though.

0.4 g's...

I don't really understand how come no-one was able to see it before... I don't know how it works, but since telescopes are looking for stars and stuff much more distant that mars, I was confident that they scanned the whole surface of neighbors planets decades ago... Some explanation?

Things that could cause it to be missed:

* Angle of photography

* Time of day (direction of sunlight)

* Weather conditions

We often ignore problems that are "closer" to us. For example, the oceans on our own planet are still very much a mystery, yet we still look outward.

What specifically about our oceans are a mystery?

I'm just going to leave this right here. http://www.xkcd.com/1040/ It's a little bit of awesome.

There's a limit for how big/small an object you can see with a telescope due to diffraction. For instance, the Hubble telescope can not distinguish features on the moon that are less than approximately 100 meters. Obviously it gets much worse for Mars and the other planets.

Mars (according to Wikipedia) has a surface area of 144,798,500km^2. This thing is within an area of 35 meters^2 and I'm guessing it's not very flashy when viewed on a screen.

Needle in a haystack.

Heck, we're still finding strange things on the Moon:


Earth-based telescopes can't be used to find an Apollo lander on the moon. It's just too damn far. A crater on Mars is a notch up from that.

Some great info about just why this is so impossible: http://calgary.rasc.ca/moonscope.htm

Interesting - how is it they can accurately target the puny "lunar laser ranging retroreflector array" but not see the landers?

The laser is 6.5KM wide when it reaches the moon. http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment

Awesome! I see they lost the Soviet Lunokhod 1 array for nearly 40 years!

I'm not usually the one to complain, but really? Not just front page, but #1 of HN?

From submission guidelines:

  anything that gratifies one's intellectual curiosity
I just spent a whole day in AES encryption, specifications and code. Being reminded there is a wider world out there, quite literally, is fine by me, especially a world where the answers are not obvious or wrapped in politics - why is the surface white? Is it impact or collapse?

Edit - just neatened up

Yes, yes, I know the guidelines and I agree with you ofcourse. I'm not against discussing non CS / Startup related topics. I just felt that this particular topic isn't interesting enough for whole of HN to rank it at #1.

I also realize the absurdity of complaining about a topic that doesn't match my interest in a news aggregator, but oh well.

I suspect you might be, like me, beginning to suffer from deja-HN

I think I would like to capture the opinions of HN's best discussions, categorise them and then be able to filter on - oh look another discussion on web security best practises. Fine - does it add anything beyond what we already have filed under best-of-HN-security - no? Ok ignore.

It's what I suspect kills most forums, not really going downhill, but going round and round the same hill.

Instead of some of our more prolific members saying "I have posted on this before (a lot)" maybe they could say "look at the HNBrain on #dontdropyourdayrate "


Yes, it's easy to verify. Just look at the top slot of the front page.

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