Mars Cave..something suspicious?

[MeteorWayne]

But even a several km deep pit still leaves you many km above mean surface level, hence very low atmosphereic pressure.<br />Just cause it's a cave, it doesn't substantially change the fact that even a 6 km pit would still be above most of the atmosphere at the bottom.<br /><br />MW <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[yevaud]

Regardless. The atmosphere "piles up" in a narrow column like that. You see the same with a standing column of water. Similar mechanism. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[jaxtraw]

Are you saying that the cave could contain high pressure atmosphere? How would that work? What would stop the lower pressure outside just sucking it out?

 

[Boris_Badenov]

<font color="yellow"> What would stop the lower pressure outside just sucking it out? </font><br /><br />The weight of the atmosphere itself would keep a balance point below the opening. Above the opening is still pressure, in order for the atmosphere to be sucked out at the surface you would need a vacuum. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[MeteorWayne]

I still have a problem with this concept. I'll hit the physics over the weekend <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[JonClarke]

The base of the volcano is at about 11 km above datum. Datum on Mars is defined by the elevation at which liquid water is possible. So the cave would have to be at least 11 km deep for the pressure of the atmospheric column to sustain liquid water - more if the cave is high n the volcanoe's flanks.<br /><br />Unfortunately lava caves are horizontal, not vertical in extent. So I think the cnaces of liquid water in this cave is effectively ruled out. <br /><br />The place to look would be lava caves associated with some of the young, low elevation vlocanoes, such as those in Elysium. These are below datum and, if warm through residual volcanic heat, could well support liquid water.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

<i>Jon, is it possible that this hole is the product of a whack by an asteroid right on top of a lave tube?</i><br /><br />Possible, but not neccessary. Cave skylights can be circular. Caves fall in on Earth without the assistance of impacts.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[jaxtraw]

<blockquote><font class="small">In reply to:</font><hr /><p>Above the opening is still pressure, in order for the atmosphere to be sucked out at the surface you would need a vacuum.<p><hr /></p></p></blockquote><br /><br />I beg to differ. All you need is lower pressure. Take a cannister of air at greater than 1bar, make sure it's vertical, take the lid off and the air will rush out the top until the pressure equalises. I can't see any way around this.

 

[yevaud]

True, but the action of a pressure column in a tight constrained space is different.<br /><br />Although, yeah, if horizontal rather than vertical, it would put the kibosh on that. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[robnissen]

<font color="yellow">Datum on Mars is defined by the elevation at which liquid water is possible. </font><br /><br />Yes, but isn't Datum based on fresh water, not highly briney water. If the water was briney enough, I believe it could be liquid at this higher elevation.<br /><br />BTW, there is no magic to the air being in the cave. A cave 5 KMs deep, will have the EXACT same air pressure, as an outside location that was 5 KMs lower on the flanks of the mountain. For those of you who are arguing otherwise, you are just flat wrong. Now, if the cave had just been opened, it might take a little while for the pressure 5 KMs deep to equalize with air pressure outside the cave that was 5KMs below the cave entrance. But in geologic time, that is a blink of an eye.

 

[jaxtraw]

<blockquote><font class="small">In reply to:</font><hr /><p>A cave 5 KMs deep, will have the EXACT same air pressure, as an outside location that was 5 KMs lower on the flanks of the mountain. For those of you who are arguing otherwise, you are just flat wrong.<p><hr /></p></p></blockquote><br /><br />I don't think anyone's arguing that. What they're arguing AFAICS is that the bottom of a 6 km deep cave, whose mouth is 11km above the (water) datum, is 5km above that datum, which is 5km too high for water to exist in liquid form.<br /><br />And my post, personally, was answering one which seemed to imply that the air in the cave would be at <i>higher</i> pressure than air at the corresponding altitude outside i.e. the air at the bottom of the cave would be at higher pressure than outside air at 5km altitude. If I misconstrued that that was what was being suggested, I apologise.<br /><br />Is it okay to refer to Mars' atmosphere as air, or is that an entirely geocentric term? I wonder if all these geocentric terms (or heliocentric indeed, with terms like "planet") should be just generalised to other worlds. Seems a bit silly for geologists to turn into areologists, selenologists and so on <img src="/images/icons/smile.gif" />

 

[MeteorWayne]

That is what Yevaud is saying, if I understand him correctly. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[yevaud]

At the bottom of that column of atmosphere (say a lava tube), it will be still air, not bleed off easily, maintain itself quite consistently in pressure and temperature. An ideal environment.<br /><br />Sorry if I was unclear. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[h2ouniverse]

Jaxtraw,<br />You may know about "Pascal's barrel experiment" (a counter-intuitive one, dated back from 17th century): take a big barrel full of water, so at one bar; open a small aperture on its top, just enough to insert the lower end of a 10 meters long vertical pipe. If you fill the thin pipe with water, you will get 2 bars in the barrel (on Earth!). Actually the barrel generally explodes before you can fill 10 meters of water in the small tube. <br /><br />The pressure at the bottom of an open column is a function of the height of the free column of gas, and of the gravity.<br />As Jon points it, the bottom of the column may be filled with "high" pressure, but provided that it lies close enough to the center of gravity of Mars. Either by being very long, or by being located in a low-altitude area such as Vastitas Borealis. The fact that it is a 1m-wide pit, or a 1000km-wide crater does not change the bottom pressure.

 

[franontanaya]

Mmh, what about those lava tubes and calderas that didn't break yet?<br /><br />Would they hold a pressurized atmosphere? What kind of gasses would them contain, how much pressure could them hold, and for how long? I guess it wouldn't be anything very breathable, though.<br /><br />Could those caves capture some of the ancient Mars atmosphere?<br /><br />And what kind of traces could the release of the trapped air leave? <div class="Discussion_UserSignature"> </div>

 

[exoscientist]

This free program can decode the highest resolution JP2 images:<br /><br />HiRISE: ENVI/IAS Viewing Tools. <br />http://hirise.lpl.arizona.edu/iasclient/<br /><br /> Try it on the image of the "cave":<br /><br />HiRISE | Candidate Cavern Entrance Northeast of Arsia Mons (PSP_003647_1745). <br />http://hirise.lpl.arizona.edu/PSP_003647_1745<br /><br />There are options in the program for varying the contrast in the image.<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>

 

[3488]

Hi FranOntanaya.<br /><br />If there are any sealed volcanic features, they will hold volcanic gasses, probably CO2, Chlorine, <br />Sulphur Dioxide, etc.<br /><br />This is probably more representative of Mars's early atmosphere. <br /><br />The cave entrance, if that is what it is, is more likely a hole in the roof of a giant lava tube, <br />emanating from Arsia Mons.<br /><br />As I said earlier, I would love to see the inside, with a lander that could drop inside with <br />powerful lighting, showing lava stalactites, hanging from the roof, lava flow <br />features inside, etc.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[3488]

Hi Bob,<br /><br />I tried it & it crashed my new computer!!!!!!<br /><br />Must be a huge program.<br /><br />Hopefully I can get it sorted & will try it again.<br /><br />Have you tried it with the Arsia Mons 'cave'.<br /><br />If so, did it reveal anything??????<br /><br />I for one would just love to know if anything can be seen of the floor or walls.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[aspurgeon]

I'm looking at the hole ( http://hirise.lpl.arizona.edu/PSP_003647_1745 ) with with the IAS Viewer. What has me curious is that at the top of the hole is what I like to call islands in the dark. Then when you look at the right hand side of the hole you can see the top of the wall is bright and remains so until midway then it turns a dark grey until it meets black. Its like, for lack of better word, a grey water line. The line is fairly consistent around the perimiter of the hole. Note how the islands stick up out of it.<br /><br />Could this hole be filled with some gas or fog? Note when looking at the image zoomed fairly far out that the top of the hole and onto the surface appears hazy as if diffused. As a firefighter we use thermal imagers and there are some things that the imager shows as black like water and glass. Could the camera have spectral limitations in relation to whatever is filling the hole?

 

[3488]

Volcanic emissions??????????<br /><br />I hope so, very exciting.<br /><br />Anyway I'm knackered & going to bed now.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[franontanaya]

Enhanced gamma from the full res image. You can see the glow near the borders (optics artifact?) and a zone <br />of darkness near the center or so it seems: <div class="Discussion_UserSignature"> </div>

 

[phaze]

I'm having a hard time wrapping my mind around how the features along the "north" edge of the hole would present themselves in reality - assuming the steep slopes or overhanging walls that have been mentioned. they don't seem to fit patterns of collapse that my brain can come up with.<br /><br />anyone care to help me out?

 

[3488]

Holey Moley!!!!!<br /><br />Perhaps its time a Holistic approach was taken of this whole debate!!<br /><br />Maybe the Tharsis rise is religious & is trying to be Holey?!?!?! <img src="/images/icons/laugh.gif" /> . <br /><br />Perhaps I should give up & stick with my day job??? <img src="/images/icons/rolleyes.gif" /><br /><br />More seriously,<br /><br />AFAIK, this hole is actually slightly to the north east of Arsia Mons,<br />towards Pavonis Mons.<br /><br />This means that it in on the top of the Tharsis Rise, absolute bear minimum of,<br />9,000 metres above the Datum Line.<br /><br />IMO this rules out liquid water by any measure.<br /><br />The atmospheric pressure is perhaps 3 millibars (0ne threehundredth or 0.3% of<br />average air pressure at sea level on Earth) at the very most here.<br /><br />The position of this collapse is interesting too. <br /><br />Are Arsia Mons & Pavonis Mons connected????<br /><br />Have they a common origin, despite being 700 KM apart??<br /><br />Thanks FranOntanaya for your enhancement.<br /><br />I think the 'grey' area is just bleed over from the brightly lit lava surround.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[aspurgeon]

Maybe a tiny singularity is slowly eating the planet away. Cool!<br /><br />Ok bit more seriously..<br /><br />I hear this is on the flanks of Arisa Mons. Anyone know if the hole at an angle or is the ground here fairly flat? <br />It looks flat to me. Wish there was a virtual flyby of these caves to watch.

 

[fear]

Does any one know how big across the hole is? <div class="Discussion_UserSignature"> </div>