http://hiroc.lpl.arizona.edu/images/PSP/release_0027.php
Ustrax - finally - you have what you asked for
http://hiroc.lpl.arizona.edu/images/PSP/diafotizo.php?ID=PSP_003647_1745
http://hiroc.lpl.arizona.edu/images/2007/details/cut/PSP_3647_1745_cut_b.jpg
THAT...is an abyss.
Doug
Well, just look at that great big hole in the ground !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
It's obvious that's an Acme Portable Hole that Wile E. Coyote left behind....
http://video.google.com/videoplay?docid=-569080467828405640
Wow!!!
Is that the entrance or exit?
..okay, THIS made my jaw drop! Why so circular? Almost looks like a meteor punched right through a thin surface crust & into a deep dark chamber (undoubtedly making the patented Wile E. Coyote as he goes off a cliff "bomb dropping" whistle all the way down in the thin Martian air...)
Either that, or we finally found the ejection end of the linear accelerator that launched H.G. Wells' invading cylinders...
The imagination runs wild. If these things are really deep, you could have some interestingly high atmospheric pressure down there...
Well - unless its many many km's - then there are other places which will have higher atmos.press at 'ground' level. But it's still a very very exciting and interesting feature
Doug
Looks to me like one of Kim Stanley Robinson's Mars moholes.
Alternatively, we could extrapolate wildly from Titan and assume that anything that dark and featureless has to be liquidish, sort-of. Or not.
I wonder what IR will show us, especially at night. I don't think we'll be able to look down the hole directly, unless MRO's orbit is modified, right? Maybe we need to wait for a nice, strong dust storm to kick up the tau, so that more light is sent down the hole from all around. Pretty amazing that it is pitch black!
I'm sure it's possible with to make an estimate of the minimum size and depth of the cavern based on that. Maybe we'll get lucky and something interesting will show up on IR, like the extent of the roof over the cavern. Do either of the radars on Mars have the resolution to check this out?
I don't quite understand why the incidence angle != angle of the sun above the horizon; only thing I can think of is that we're looking at a slope.
Anyone locate a wider context shot of that location? I couldn't see any lava-tube features, but the whole image might be one.
EDIT: Looks like this is Jeanne:
http://themis-data.asu.edu/img/browse/V18315002?band=3&stretch=S2
Took me a bit to convince myself it's the same location.
Can someone less lazy than I do the calculations on this? If we know the angle of the sun and the angle of this photo it should be easy to calculate a minimum depth for this chasm if we assume that sunlight illuminating the bottom of this hole would be visible in the image. Since nothing is visible, the depth must exceed that minimum.
See this topic for more information and links to context images from Odyssey:
http://www.unmannedspaceflight.com/index.php?showtopic=4036
--Emily
Given this image's location on Mars, I would presume this is a skylight of an old lava tube. Very interesting though.
Yes, but it must be a very large tube since the hole is more than 100 meters across. I can't remember ever seeing a window into a lava tube that big on Earth. I wonder if lava tubes scale with gravity somehow.
The former; maybe he's tight enough with the latter to persuade him to follow suit? </wishful thinking mode>
38 degrees. Call it 130m across - sohcahtoa and all that - 101 metres is the cutoff at which we wouldn't see light at the bottom.
Doug
According to the caption on the image, though, HiRISE should be able to see deeper than that:
Just for grins, I went to HRSCview and located the http://www.geoinf.fu-berlin.de/cgi-bin/ion-p?page=product.ion&code=81675006&image=0968_0000. Here's a crop from that:
Nice find, Emily! Seems like it's right in line with that (apparent) collapsed lava tube to the upper right...
Ahh, they finally released this picture. The one's got all of the scientists perplexed, we've come to a conclusion it's likely an overhanging of some kind, meaning that the lava tube is really big... I think we've figured it must be at least 200 m deep as well. Still, it's certainly quite a mystery.
Oh, for those of you wanting to overlay MOLA data, it's already been tried, without any luck.
OK now I see the history of this with Odyssey. Sorry been out of the loop with assorted obligations the past few months.
Looks like a good landing site for MSL -- if it stood for the Mars Spelunking Laboratory...
-the other Doug
Martian bungee jumping anyone?
Surely this will kick off a more systematic look at the slopes of the Tharsis and Elysium volcanoes, if it isnt already happening. Who know how many of these things might turn up, and who knows how big they might be? Hmmmmm, 0.38 gravity.....
P
Actally, regardless of how deep these things are, at SOME time of the day at SOME time of the year (given their near equatorial location, around local mid day and around the equinoxes) the sun will illuminate the floors of these caverns. Being lucky enough to have an MRO overpass at one of these short periods is another matter of course...
P
MRO is in sun-synchronous orbit so the nadir point below is either early morning or late afternoon local time to provide decent shadowing for most imaging. The orbit would have to be substantially adjusted to get a fly over noon local time.
What is the range of illumination angles due to seasonal variations from axial tilt?
Excellent. ~100m across? >200m deep? What a place to dome over and start building.
Andy
Is it really impossible to dig out something from the black?
http://s148.photobucket.com/player.swf?refURL=/&file=http://vid148.photobucket.com/albums/s18/spacEurope/Filme.flv&os=1&ap=1
What I did was an attempt to enhance some features that were already visible in the image shown http://hiroc.lpl.arizona.edu/images/2007/details/cut/PSP_3647_1745_cut_b.jpg on the right but that also come out from the http://hiroc.lpl.arizona.edu/images/PSP/diafotizo.php?ID=PSP_003647_1745.
Note: I know that it has already a name but Cernunnos, the Celtic God of Fertility, Life, Wealth and the Underworld sounded just perfect for the occasion...
Yes - it really is impossible. That's not details - that's noise.
Doug
What sort of liquid at .006 bar and -80degC? Would a liquid not have specular reflection etc. Orbital images of lakes and seas on earth are not black. Do not confuse the 'black lakes' of Cassini Radar imagery with the optical wavelengths of HiRISE.
There is nothing nonsensical in the concept of overhangs. We see them on Earth - they could be even more extreme in the 1/3rd G of Mars.
Doug
I can't imagine anything else than a hole in a (lava) tube.
I don't remember the width of the path of MOLA. Somebody suggested that the depth can be find in the data. Is that possible?
Regarding that overhang:
We are told that the sun was 38 degrees above the horizon, or 52 degrees from zenith. This means that if the angle of overhang was less than 52 degrees from the vertical the sun would be directly illuminating part of the overhang wall surface underneath the visible rim. This would add significantly to the level of downward illumination inside, so my guess is it's not happening. That makes the angle of overhang quite severe and the rim quite thin. The direct sunlight entering through the skylight would then be falling on the floor of the cavern some distance down-sun. The light scattered from that bright spot would then be shining upward, illuminating the interior roof but not the part of the floor in our line of sight.
^
"Oh, for those of you wanting to overlay MOLA data, it's already been tried, without any luck."
Doug
There must be some liquids (carbon based) that absorb most /all visible light (independent of the light frequency). Is there any evidence that this hole is a hollow tube / entrance to a cave / ? Why is there no light on one of the walls?
Because the ceiling is overhanging. It's a collapse to a lava tube. We've seen other hirise images that take this to the extreme just leaving a single piece over the top of the old lava tube - itself with overhanging edges (the 'bridge' picture). The mechanism behind a formation like this is certainly not that unusual and indeed terrestrial analogues are not uncommon either.
http://www.texasbeyondhistory.net/plateaus/images/ap17.html
We're looking almost straight down it - so in actual fact it wouldn't take that much of an overhang to mean we don't see the sides even if they're lit.
That opening is 11,000 sq m . If there were 11,000 sq m of an unusual liquid - CRISM would have found it and we'd know about it. It's 8 or so Crism pixels across.
Doug
I'm not saying that you're not pulling out three different shades from an 8 bit greyscale image, for which some photons from the bottom my be responsible. I'm saying it's impossible to say "that's the bottom". Lest we forget, similar techniques turned a black dunefield into all sorts of things.
I'm not sure that HiRISE can take longer exposures - 4x4 binning might help but of course we can do that with the image on the ground already
Doug
Binning done in the electronics before AD transformation is a lot more effective than in software, and I think this is what they talk about when some Hirise image is 2x2 binned etc.
Increasing is exposure time is of course problematic because Hirise has a scanning type detector. It will be interesting to see what the future plan is.
Will we have to wait until there is a laser altimeter or radar that can look to the bottom? How soon
can that be? I'm guessing a camera sensitive enough to see down there would not be worth it.
It's not an abyss, it's a martian oubliette!
And when we finally get illumination down there we'll find both Mars Polar Lander and Beagle 2 at the bottom!
( "My God, I see stars....")
[This image has totally tickled me pink. Aside from it's sheer image impact, a collapsed lava tube is a great way to get a peek at relatively protected Martian basalt.]
-Mike
MRO flight rules limit the off-NADIR pointing to 30 degrees. But that's only 24 degrees difference, it might allow one to see the bottom of the cave. It would almost certainly allow seeing the wall of the cave. Still, this is turning to be a highly unusual feature.
Oh, SHARAD might be able to find the depth of the cave, I'm just guessing though.
Also, you might be interested in knowing that the HiRISE team talked about the cave in a HiOPs meeting last Monday, we were joking that MSL should repel down into the cave, and then we thought, well, it can already repel, skycrane... Hmmm...
Regarding the "work" I've done with the image, Alfred McEwen told me that it may be "scattered light", "the camera optics are excellent but not perfect."
But, might I add, the closest to perfection I have ever seen...
Thinking about the possible pattern of illumination in the cavern made me think again of that wonderful Pantheon photo. The patch of sunlight in this case might be falling on a horizontal floor, but more likely somewhere part way up one sloping side of the tunnel, thus preferentially illuminating the opposite side with scattered light. I have a sketch of the geometry which could produce the apparent slight grading in interior illumination that may be showing on that image, but unfortunately no easy way of posting it here.
I've made a http://s148.photobucket.com/player.swf?file=http://vid148.photobucket.com/albums/s18/spacEurope/Cernunnos2.flv&os=1&ap=1 focusing on the top-right quadrant.
Noise? Scattered light?
I just love the way the appearing features, layers-like, matching so nicely with the rim, seem to belong there...
Perhaps they could rotate the spacecraft to compensate for motion, allowing longer exposure times (same principle as CPROTO with MOC, but using the reduced speed at which the surface goes by for longer exposure time per line instead of higher resolution. Would be difficult, but worth trying once if at all possible.
I had a quick look in the MOC Gallery for similar features around the Arsia flanks and happened to find these. The first one is clearly Dena, from http://www.msss.com/moc_gallery/r03_r09/images/R08/R0800159.html. The second one is from http://www.msss.com/moc_gallery/s05_s10/images/S09/S0901483.html (lower right of the narrow angle img), and AFAIK it has not been referred previously. Both images are full size crops from the gif files, so I think the sizes are ~about~ proportional. The second one certainly could be an artefact, but it is very similar to the other ones anyway. A thorough search in the MOC imagery could reveal more.
Wait a minute, ustrax...are you sure that's not actually their home?
Marswiggle,
The image of Dena that you posted has much better resolution and lighting than the image published in the Cushing, et al. paper (http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371.pdf).
Are we actually seeing the bottom of the pit in that one?
While I don't know, let them answer, in that very report:
Thanks.
I should do more than look at the pictures.
130 meters deep, that is really something for a lava tube. I've tried to find out what the maximum diameter of lava tubes on Earth is and the largest figures I have found is about 40 meters. However I remember seeing a considerably larger collapsed tube on Iceland so very likely it is the high gravity that limits the diameter.
When it comes to lengths, tubes here on Earth can extend many kilometers. Interestingly the longest seem to be on Hawaii (sensu stricto) which of course is the largest shield volcano complex on Earth, so on Mars' vastly larger shield volcanos tubes might very well be hundreds of kilometers long!
A tube 200 km long and 200 meter in diameter, how about that for an underground habitat?
What's causing that lighter area to the top of the hole?
Actually, Stu, I think the lightened area looks roughly the same in terms of the extent of duning as the rest of the surrounding terrain. It looks more to me like the lightened area has seen more deposition than the surrounding terrain -- the underlying lava-flow surface is more muted and softened in the lightened area.
I think what's happening here is that the prevailing winds are coming from the bottom of the image. As they pass over the hole, the air sinks a bit, and winds strike the rim of the hole along the top arc (all directions -- top, bottom, etc. -- relate to the orientation of your posted image). So the top arc of the rim is being eroded a little more rapidly than the rest of the rim, and the erosion product (basaltic dust, most likely) has been deposited on the ground beyond the top rim arc.
It's also at least somewhat possible that winds are entering the hole, swirling around, eroding the interior of the lava tube, and blowing dust out from the cavern and onto the ground above the top rim arc. I just don't think that Martian winds are powerful enough to reach into such a deep hole and scoop dust out of it, but I could be wrong. At any rate, it's impossible to model airflow into and out of that hole without having a decent idea of the size and shape of the empty lava tube, and we really have no way of determining that...
-the other Doug
I doubt it's wind through the lava tube itself. Think of a crater - that can have a dust tail of some sort and there's no network to do that. I imagine it's just a function of prevailing wind and topography. Wind blowing over a lage flat area suddently finding a big hole is going to get chucked up a bit - you might even find that the area under the hole is at a slight negative pressure relative to the surrounding area because of it.
Another thought - given that this tube is beginning to collapse at this one obvious site and potentially many others, it's quite likely that the tube itself isn't much of a tube anymore and more like a range of adjacant chambers. Who knows...I can't imagine we will for a few decades.
Doug
Chilling yet fascinating, Stu...really captures the ominous feel/excitement of what it might be like to stand near the edge of one of these things...well done!
That. Is. Incredible.
Interesting, how this one image has completely usurped the others in the press release. It's interesting to speculate on what's it's like inside...I wonder if the floor has a thick coating of dust from (perhaps) eons of storms. Any way you slice it's, it's a beautiful image.
P.S.--Groovy poem.
It's interesting, not since the Victoria crater picture has a HiRISE picture gathered so much interest as this one. And that's the only one that I know of that has surpassed the interest in this picture of any one image we have taken. Kind of funny how that works out sometimes.
I don't know if this is news to anyone, but FWIW, after a similar amount of interest about this image on my site, I asked the MRO team for some more info, and received this reply from Nathan Bridges on the HiRISE team, via Suzanne Smrekar:
"1. Yes, HiRISE is planning to image this again. We can't do much about the Sun angle because MRO's orbit is close to 3:00 P.M. and we are near the equator. Seasonal variations mostly affect the solar azimuth at this latitude, not the angle above the surface. However, we can change the angle that MRO looks at the target. So, for our 2nd observation, we will do a large roll to the east in the hopes of seeing the west-facing wall.
2. The two prevailing hypotheses is that this feature is either a deep collapse pit or a "skylight" ( opening) into an ancient lava tube. The location is between Pavonis and Arsia Mons, two large shield volcanoes, so a volcanic origin is appealing."
http://planetary.org/radio/show/00000241/
Planetary Radio
Monday, June 18, 2007
Wow! They were able to actually get the bottom of a pit out of the dark!
http://www.universetoday.com/2009/03/19/hirise-looks-down-to-the-bottom-of-a-pit-on-mars/#more-27497
Nothing new here...done it two years ago...
http://www.unmannedspaceflight.com/index.php?s=&showtopic=4220&view=findpost&p=90761
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