It's the pits on Mars

Posted: Wednesday, August 29, 2007 6:12 PM by Alan Boyle

NASA / JPL / Univ. of Ariz.

Sunlight is reflected off the wall of a Martian pit.

Fresh imagery from NASA's Mars Reconnaissance Orbiter shows that the strange holes detected in earlier pictures of the Red Planet's surface are most likely vertical pits rather than openings to underground cave networks, as some had previously speculated.

Here's the latest from the imaging team for the MRO's high-resolution camera, or HiRISE, posted today on its Web site:

"Dark pits on some of the Martian volcanoes have been speculated to be entrances into caves. A previous HiRISE image, looking essentially straight down, saw only darkness in this pit.

"This time the pit was imaged from the west. Since the picture was taken at about 2:30 p.m. local (Mars) time, the sun was also shining from the west. We can now see the eastern wall of the pit catching the sunlight.

"This confirms that this pit is essentially a vertical shaft cut through the lava flows on the flank of the volcano. Such pits form on similar volcanoes in Hawaii and are called 'pit craters.' They generally do not connect to long open caverns but are the result of deep underground collapse. From the shadow of the rim cast onto the wall of the pit we can calculate that the pit is at least 78 meters (255 feet) deep. The pit is 150 by 157 meters (492 by 515 feet) across."

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Comments

Whether a giant cavern system or an individual deep pit, these sites deserve a look-see, for future use as settlement site. How useful would it be to (relatively) easily cover such a pit, seal it against the thin Martian atmosphere, and live in it? Look at the volume you would gain use of! At least as deep as a 15 story building, as big as four city blocks, this one alone is simply massive

David Stever, Cochituate, Massachusetts (Sent Thursday, August 30, 2007 8:25 AM)

is it me or does the wall of the pit stop (and open to a larger space) about 70 meters down?

Pete, DC (Sent Thursday, August 30, 2007 11:14 AM)

LOL...two days in a row of good headlines "alcohol claims go flat" and now this..Good job Alan

Bilal Mujahid, Homewood, Illinois (Sent Thursday, August 30, 2007 12:38 PM)

I agree, David. Pop on a geodesic dome about the size of a football stadium, add solar panels for power and you've got Martianton. It's close to the equator and the valley system. And, although there is a faint image of an incline toward the bottom of the picture, The wall seems top extend straight toward the top of the pit openeing, so it could be even bigger than their estimates.

Dennis Ridgley (Sent Thursday, August 30, 2007 12:43 PM)

I'm glad to see these images! I think these are the first I've seen from the Recon orbiter. I've yet to see the gullies or the hot spot noted on the South Pole.

Chris Eldridge (Sent Thursday, August 30, 2007 12:52 PM)

Pete - I'm scratching my head on this one too... this image looks much more like a skylight than a pit crater. I'd love to hear a detailed analysis. We're guaranteed to see future science reports that go into far more detail, so I'll hold my questions until then.

Brian, Boulder, CO (Sent Thursday, August 30, 2007 1:09 PM)

Nice try with the disinfo campaign Alan, but I recognize a Flying Saucer launch platform when I see'em! ;-)

red pill junkie, Mexico city (Sent Thursday, August 30, 2007 2:43 PM)

I think that the analysis that they are pits is based on circumstantial geological evidence. These formations are being compared to sheild volcanoes on Earth, under the assumption that whatever these are, they probably resemble something we've encountered here before.

The tricky part of this whole situation, is that there simply isn't enough light coming out of them to really know for sure whats down there.

Joseph Basile, Worcester, MA (Sent Thursday, August 30, 2007 5:39 PM)

"Easily" cover a pit? Not very easy at all, I'm afraid. If the pit is 152 m circular, then the area is about 18000 m2. Pressurize that to one atmosphere, and the upward force on the cover is P x A, or about 1.8 E9 newtons. At mars surface gravity, it would take about 480,000 tons of dirt to hold down that cover. The cover and the anchors would be many thousands of tons, and if they fail, everyone not inside a smaller pressure hull dies dramatically.

Alternately, if you put dirt on top of the cover, it would take around 10 meters to balance the air pressure.

For any habitat in a vacuum or near-vacuum like Mars, the problem isn't holding the roof up, it's holding it _down_.

Doug Jones, XCOR Rocket Plumber, Mojave, CA (Sent Thursday, August 30, 2007 6:44 PM)

It's a day later, and I finally clicked Alan's link back to the original picture, and I must say that the geology of the area is fascinating! The area around the hole is just devoid of any features- no rises, no ridges, no indication that a deep feature like this is lurking in the area, nothing that would indicate outgasing or water vapor discharges around the rim.

Are all of the pits/holes/caverns like this one? Are we flying any ground penetrating radar that could read the area for additional details from the depths?

If we ever fly the balloons/dirigibles on Mars that they talked about a few years ago, I think that this neighborhood is the place I’d want to explore with it. Imagine a balloon with an instrument package and a light bar that could be lowered into some of these caverns…

Doug- thanks for the science behind throwing a roof over pit like these. I did say relatively simple- if you're going to fly all of this gear the 50 million miles to Mars, then doing the civil engineering to anchor such a huge system would in deed be *relatively* easy by comparison!

David Stever, Cochituate, Massachusetts (Sent Friday, August 31, 2007 10:48 AM)

Where are all the canals I've heard about since I was a kid.

Geezer Kansas City, MO (Sent Friday, August 31, 2007 10:57 AM)

This is probably a dumb question from an admittedly ignorant engineer.

How old do they estimate the pit is? If it is of any significant age, why hasn't debris filled much of the pit? If it is recent, how likely is it to be of seismic origin given the fact that there are no plate tectonics and no (?) volcanic activity?

Taylor Kidd, Portland, OR (Sent Friday, August 31, 2007 3:22 PM)

The atmosphere inside must be at least 100x MArs abient air pressure, and as D.J. points out any dome would want to pop off like the cork from a champagne bottle. Any inhabitants would die immediately, probably with highly embarassed looks on their faces. In addition, regolith is very porous and even 'solid' rock contains lots of fractures etc. By no means would simply throwing a dome over the top seal this thing against leaks. Much of the cavern would also have to be sealed somehow.

Surely you're joking, RPJ. If not, I have a crop-circle I want to sell you; just 50 bucks.

Are you sure the 'hotspot' you refer to isn't the one detected on Enceladus, C.E.? I haven't heard of one on Mars...

JC, Fairbanks, AK (Sent Friday, August 31, 2007 4:01 PM)

SOLD! :-)

red pill junkie, Mexico city (Sent Saturday, September 01, 2007 11:17 PM)

OK, RPJ. There'll be a 2 million$ extraction charge, and 5 million $ shipping charge. The good news is I can throw in an angry farmer as a courtesy freebie; the shotgun with rock-salt loaded shells will be 100$ extra, though. So, your bill comes to 2 million, 150 dollars (I'm having a 'free shipping' special). If this is too much, I can sent you a clod of dirt with genuine corn stubble for just 10k$ (shipping not included...).

As far as the hole in Mars goes, I think it will require human exploration, on the ground, to ever really discover what it is. It's a point I'm willing to concede, that certain point "targets" cannot be explored by rovers. But the people who will do that are (optimistically) still in grade school, and it really needs a longer view of things than, for example, the Mars Society's "get me to Mars, NOW!" attitude before anything meaningful in that direction is going to happen. That means people like me, and some of the respondents to this forum, admitting to themselves that it won't happen during *our* lifetimes, but hoping and working for it to happen in the future, beyond our own shortish lifetimes….

JC, Fairbanks, AK (Sent Sunday, September 02, 2007 9:51 PM)

I think we should be asking our future politicians their stances on the issues of space exploration. We need to push this frontier immediately, not through hurried flight, but through global funding, testing, participation and communication. We are seeing a quarter of a billion dollars being used for a political campaign and it doesn't raise a concern within the general public that these same people are the ones who claim the earth is 6000 years old and was made in 7 days. COME ON PEOPLE! Let's kick this project in gear and really get behind it. In my opinion, our individual lives are so short, we owe it to ourselves and everyone who has ever taken part in this beautiful mystery known as life and try to find out what is really going on out there. We should establish justice, ensure domestic tranquility, provide for the common defense and then accept a global treaty to pull resources together for an organized exploration in to the farthest reaches into space. There would be, I am assuming, elligible candidates for one way space travel.

Jacob Evans Jacksonville Florida (Sent Monday, September 03, 2007 1:23 AM)

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