[meteorite-list] Martian Cave Entrance Detail
Hello all, Regards the images and test on this page relating to new HiRise image from Mars. http://www.planetary.org/blog/article/0984/ I reckon it's strange so many took someones word that there is NO detail in the BLACK part of the image without attempting to process the image themselves. Why there is a NASA statement that says NO detail visible in the black, when there clearly IS detail after processing is beyond me. This was done in a 2 step forward 1 step back process. All I manipulated were brightness, contrast, density. Here are the final two processed images. This data is from the full resolution 440 mb JP2 download. It appears that the camera scan lines are now visible as dark diagonal lines, there is a little more there as well, noise, dark image, Something anyway, not nothing. http://www.mediamax.com/vk3ukf/Hosted/KsBlackHole001.JPG and, http://www.mediamax.com/vk3ukf/Hosted/KsBlackHole002.JPG Regards Kevin. _ Advertisement: 1000s of Sexy Singles online now at Lavalife http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Flavalife9%2Eninemsn%2Ecom%2Eau%2Fclickthru%2Fclickthru%2Eact%3Fid%3Dninemsn%26context%3Dan99%26locale%3Den%5FAU%26a%3D29219&_t=762256209&_r=june07_endtext_search&_m=EXT __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Martian Cave Entrance Detail
On Thu, 14 Jun 2007 12:39:20 +1000, you wrote: > >It appears that the camera scan lines are now visible as dark diagonal >lines, there is a little more there as well, noise, dark image, > >http://www.mediamax.com/vk3ukf/Hosted/KsBlackHole002.JPG > Hm. Looks like the collapse has revealed part of an underground railroad, similar to the one dug beneath the US south by Harriet Beecher Stowe (author of Uncle Remus) during the revolutionary war. Might be a sign of past Martian slave trade... __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Martian Cave Entrance Detail
Hi, Kevin, List When I looked at your processed image and mentally subtracted the stitchlines and the periodic noise, what I saw was vague dark arcs nested inside each other toward a darker center. So I took your image and fiddled with it in the manner you described (luminance, contrast). Your processed image definely has a darker center. As you stretch the contrast, the center darkens more than the rest and so on, for a bigger and bigger dark center. Now, if this was a vast cavern under the surface and the hole was a "skylight" break-through, even if the "floor" was thousands of feet down, the center under the skylight would be faintly brigher than the edges, brightest at the center, the opposite of this. IF (that was a big "if") the center is darkest and the circle near the center is next darkest and so on, it can only be interpreted as our looking down a very deep, relatively straight tunnel or pipe. Why would Mars have a vertical tunnel miles deep? A.) This feature is located on the slopes of a big volcano. Volcanoes frequently have side vents, vent pipes, lava tubes, a variety of geological "plumbing" extending from them that release volcanic gasses. B.) Please note that in the unprocessed photo of the "hole," there is clearly a whitish "stain" or discoloration of the terrain that is plume-shaped and that extends away from the "hole." Hot CO2 or H2O vapors might have produced the plume, but I think a sulfurous gas more likely (as frequently seen in Earthly volcanoes). Is there infrared spectroscopy available on this small scale? It would be worthwhile to identify the substance because we could then estimate long it would persist on the surface and correspondingly get an idea how recent the activity that deposited it was. Sterling K. Webb -- - Original Message - From: "Kevin Forbes" <[EMAIL PROTECTED]> To: Sent: Wednesday, June 13, 2007 9:39 PM Subject: [meteorite-list] Martian Cave Entrance Detail Hello all, Regards the images and test on this page relating to new HiRise image from Mars. http://www.planetary.org/blog/article/0984/ I reckon it's strange so many took someones word that there is NO detail in the BLACK part of the image without attempting to process the image themselves. Why there is a NASA statement that says NO detail visible in the black, when there clearly IS detail after processing is beyond me. This was done in a 2 step forward 1 step back process. All I manipulated were brightness, contrast, density. Here are the final two processed images. This data is from the full resolution 440 mb JP2 download. It appears that the camera scan lines are now visible as dark diagonal lines, there is a little more there as well, noise, dark image, Something anyway, not nothing. http://www.mediamax.com/vk3ukf/Hosted/KsBlackHole001.JPG and, http://www.mediamax.com/vk3ukf/Hosted/KsBlackHole002.JPG Regards Kevin. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Martian Cave Entrance Detail
B.) Please note that in the unprocessed photo of the "hole," there is clearly a whitish "stain" or discoloration of the terrain that is plume-shaped and that extends away from the "hole." Hot CO2 or H2O vapors might have produced the plume, but I think a sulfurous gas more likely (as frequently seen in Earthly volcanoes). I'm not at all certain that's the case. Certainly, if you look at a lower resolution image that's the impression. Look closely, however, and you'll see that the area above the hole is actually a different texture- apparently sand dunes on a ~10m scale, quite different from the surrounding area. My guess is that these are the product of a complex wind flow around the hole. I don't see anything to suggest that a plume from the hole is responsible (and it seems likely that the ever shifting sands would have long ago covered up a true material plume, since it's presumed that Mars has been volcanically inactive for a very long time). I have my doubts that the processed image is showing anything other than noise. The HiRISE team, working with ~14-bit data, couldn't stretch it enough to pull out anything above the noise floor (a parameter I'm sure they are familiar with). I certainly wouldn't expect that real details would be present in the much lower dynamic range JPEG2000 image. But even if there is some faint detail, there would be nothing surprising about it. The hole is probably an opening onto a lava tube, so it's likely the floor is not more than a few hundred meters down. Even at the low (38°) Sun angle, it's possible that enough light is making it down to allow for a tiny signal to be recorded. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: "Sterling K. Webb" <[EMAIL PROTECTED]> To: "Kevin Forbes" <[EMAIL PROTECTED]>; Sent: Wednesday, June 13, 2007 10:02 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail Hi, Kevin, List When I looked at your processed image and mentally subtracted the stitchlines and the periodic noise, what I saw was vague dark arcs nested inside each other toward a darker center. So I took your image and fiddled with it in the manner you described (luminance, contrast). Your processed image definely has a darker center. As you stretch the contrast, the center darkens more than the rest and so on, for a bigger and bigger dark center. Now, if this was a vast cavern under the surface and the hole was a "skylight" break-through, even if the "floor" was thousands of feet down, the center under the skylight would be faintly brigher than the edges, brightest at the center, the opposite of this. IF (that was a big "if") the center is darkest and the circle near the center is next darkest and so on, it can only be interpreted as our looking down a very deep, relatively straight tunnel or pipe. Why would Mars have a vertical tunnel miles deep? A.) This feature is located on the slopes of a big volcano. Volcanoes frequently have side vents, vent pipes, lava tubes, a variety of geological "plumbing" extending from them that release volcanic gasses. B.) Please note that in the unprocessed photo of the "hole," there is clearly a whitish "stain" or discoloration of the terrain that is plume-shaped and that extends away from the "hole." Hot CO2 or H2O vapors might have produced the plume, but I think a sulfurous gas more likely (as frequently seen in Earthly volcanoes). Is there infrared spectroscopy available on this small scale? It would be worthwhile to identify the substance because we could then estimate long it would persist on the surface and correspondingly get an idea how recent the activity that deposited it was. Sterling K. Webb __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Martian Cave Entrance Detail
Darren, Are you really that history challenged? The underground railroad was not underground. Stowe wrote "Uncle Tom's Cabin" and it was the Civil War not the Revolutionary War. Dan - Original Message - From: "Darren Garrison" <[EMAIL PROTECTED]> To: Sent: Wednesday, June 13, 2007 8:52 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail On Thu, 14 Jun 2007 12:39:20 +1000, you wrote: It appears that the camera scan lines are now visible as dark diagonal lines, there is a little more there as well, noise, dark image, http://www.mediamax.com/vk3ukf/Hosted/KsBlackHole002.JPG Hm. Looks like the collapse has revealed part of an underground railroad, similar to the one dug beneath the US south by Harriet Beecher Stowe (author of Uncle Remus) during the revolutionary war. Might be a sign of past Martian slave trade... __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Martian Cave Entrance Detail
On Wed, 13 Jun 2007 22:49:38 -0600, you wrote: >Darren, > >Are you really that history challenged? The underground railroad was not >underground. Yeah, right. Next you'll be telling me that there was no Negro Space Program. http://www.youtube.com/watch?v=T6xJzAYYrX8 __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Martian Cave Entrance Detail
Chris, List, > it's presumed that Mars has been volcanically > inactive for a very long time... Presumptions were Born To Be Tested. Which is not to say that you (and it) are wrong, by any means, but since we are presumably going to poking about these curious apertures (instrumentally at least), it could be done if there's a multiband instrument suitable (I don't know). As for the albedo shift, I think it's real. I'm looking at it at the scale of 25 cm per pixel. As for the dunes, I see several light dunes that run right out of the bright and continue without a break into the darker area -- where they are dark, the same dunes. They may be more eroded and rounded over so that their shadows are not as pronounced but even so the peak of the dunes in the light area are noticeably brighter than any other feature in the photo except for the illuminated rim of the "hole." It could be very light frost from water vapor coming from the hole, or a dusting of sulfur, or a chemical alteration of the soil, or ground that was trampled by the boots of a crowd of spelunking Martians... well, no, not that. The most annoying thing about Mars (going to bitch about a planet, now?) is that you see something interesting but what you don't know, can't know, really want to know, is did this happen yesterday, 10 years ago, a century, a millennium, a million years, a billion? Don't know what you meant by "a very long time," but: http://www.universetoday.com/am/publish/mars_volcanoes_active.html "The timeline proposed from studying the complex Olympus Mons caldera suggests there have been lava flows from intense volcanic activity within the past 2 million years." A puff of steam isn't that intense. Sterling K. Webb -- - Original Message - From: "Chris Peterson" <[EMAIL PROTECTED]> To: Sent: Wednesday, June 13, 2007 11:35 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail > B.) Please note that in the unprocessed photo of the > "hole," there is clearly a whitish "stain" or discoloration > of the terrain that is plume-shaped and that extends > away from the "hole." Hot CO2 or H2O vapors might > have produced the plume, but I think a sulfurous gas > more likely (as frequently seen in Earthly volcanoes). I'm not at all certain that's the case. Certainly, if you look at a lower resolution image that's the impression. Look closely, however, and you'll see that the area above the hole is actually a different texture- apparently sand dunes on a ~10m scale, quite different from the surrounding area. My guess is that these are the product of a complex wind flow around the hole. I don't see anything to suggest that a plume from the hole is responsible (and it seems likely that the ever shifting sands would have long ago covered up a true material plume, since it's presumed that Mars has been volcanically inactive for a very long time). I have my doubts that the processed image is showing anything other than noise. The HiRISE team, working with ~14-bit data, couldn't stretch it enough to pull out anything above the noise floor (a parameter I'm sure they are familiar with). I certainly wouldn't expect that real details would be present in the much lower dynamic range JPEG2000 image. But even if there is some faint detail, there would be nothing surprising about it. The hole is probably an opening onto a lava tube, so it's likely the floor is not more than a few hundred meters down. Even at the low (38°) Sun angle, it's possible that enough light is making it down to allow for a tiny signal to be recorded. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: "Sterling K. Webb" <[EMAIL PROTECTED]> To: "Kevin Forbes" <[EMAIL PROTECTED]>; Sent: Wednesday, June 13, 2007 10:02 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail > Hi, Kevin, List > >When I looked at your processed image and mentally > subtracted the stitchlines and the periodic noise, what I > saw was vague dark arcs nested inside each other toward > a darker center. So I took your image and fiddled with it > in the manner you described (luminance, contrast). Your > processed image definely has a darker center. As you stretch > the contrast, the center darkens more than the rest and so > on, for a bigger and bigger dark center. > >Now, if this was a vast cavern under the surface and the > hole was a "skylight" break-through, even if the "floor" was > thousands of feet down, the center under the skylight would > be faintly brigher than the edg
Re: [meteorite-list] Martian Cave Entrance Detail
Hi, I have had a go at reprocessing the Martian cave detail, see http://www.freewebs.com/fordmeteorites/martiancaveentrance.htm There is certainly something there that is more than noise (well not normal random thermal noise anyway) Looks like a dark spot in the centre which is probably where the light fades out as it goes down futher. Wow - It's a big hole! Mark -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Sterling K. Webb Sent: 14 June 2007 07:02 To: Chris Peterson; meteorite-list@meteoritecentral.com Subject: Re: [meteorite-list] Martian Cave Entrance Detail Chris, List, > it's presumed that Mars has been volcanically > inactive for a very long time... Presumptions were Born To Be Tested. Which is not to say that you (and it) are wrong, by any means, but since we are presumably going to poking about these curious apertures (instrumentally at least), it could be done if there's a multiband instrument suitable (I don't know). As for the albedo shift, I think it's real. I'm looking at it at the scale of 25 cm per pixel. As for the dunes, I see several light dunes that run right out of the bright and continue without a break into the darker area -- where they are dark, the same dunes. They may be more eroded and rounded over so that their shadows are not as pronounced but even so the peak of the dunes in the light area are noticeably brighter than any other feature in the photo except for the illuminated rim of the "hole." It could be very light frost from water vapor coming from the hole, or a dusting of sulfur, or a chemical alteration of the soil, or ground that was trampled by the boots of a crowd of spelunking Martians... well, no, not that. The most annoying thing about Mars (going to bitch about a planet, now?) is that you see something interesting but what you don't know, can't know, really want to know, is did this happen yesterday, 10 years ago, a century, a millennium, a million years, a billion? Don't know what you meant by "a very long time," but: http://www.universetoday.com/am/publish/mars_volcanoes_active.html "The timeline proposed from studying the complex Olympus Mons caldera suggests there have been lava flows from intense volcanic activity within the past 2 million years." A puff of steam isn't that intense. Sterling K. Webb -- - Original Message - From: "Chris Peterson" <[EMAIL PROTECTED]> To: Sent: Wednesday, June 13, 2007 11:35 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail > B.) Please note that in the unprocessed photo of the > "hole," there is clearly a whitish "stain" or discoloration > of the terrain that is plume-shaped and that extends > away from the "hole." Hot CO2 or H2O vapors might > have produced the plume, but I think a sulfurous gas > more likely (as frequently seen in Earthly volcanoes). I'm not at all certain that's the case. Certainly, if you look at a lower resolution image that's the impression. Look closely, however, and you'll see that the area above the hole is actually a different texture- apparently sand dunes on a ~10m scale, quite different from the surrounding area. My guess is that these are the product of a complex wind flow around the hole. I don't see anything to suggest that a plume from the hole is responsible (and it seems likely that the ever shifting sands would have long ago covered up a true material plume, since it's presumed that Mars has been volcanically inactive for a very long time). I have my doubts that the processed image is showing anything other than noise. The HiRISE team, working with ~14-bit data, couldn't stretch it enough to pull out anything above the noise floor (a parameter I'm sure they are familiar with). I certainly wouldn't expect that real details would be present in the much lower dynamic range JPEG2000 image. But even if there is some faint detail, there would be nothing surprising about it. The hole is probably an opening onto a lava tube, so it's likely the floor is not more than a few hundred meters down. Even at the low (38°) Sun angle, it's possible that enough light is making it down to allow for a tiny signal to be recorded. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com ----- Original Message - From: "Sterling K. Webb" <[EMAIL PROTECTED]> To: "Kevin Forbes" <[EMAIL PROTECTED]>; Sent: Wednesday, June 13, 2007 10:02 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail > Hi, Kevin, List > >When I looked at your processed image and mentally > subtracted the stitchlines and the periodic noi
Re: [meteorite-list] Martian Cave Entrance Detail
Hi, Mark, List Well, since your processing pulled out exactly what I thought I saw, only in greater detail, I naturally think you did a great job! Seriously, there are artifacts: the two "stitch lines" show up just as they did in Kevin's processed image, and of course, contours re-enforce the suggestion of depth. Still, center-darkness is clearly THERE. Sunlight is coming from just below the left horizontal axis of the photo, yet near the illuminated (right) side of the "hole" is another very dark area which ,since it is adjacent to the illuminated rim, must be very far below it. The World Cave Database: http://www-sop.inria.fr/agos-sophia/sis/DB/world.bydepth.html says the deepest cave on Earth is over 2000 meters! Don't even ask about the longest cave on Earth, which stretches for 580 KILOMETERS under the Earth (Mammoth). Apart from the possibility of caves too deep to have an access to the surface, the chief limit on cave depth is gravity. Mars could have much deeper caves than the Earth does (it has mountains three times higher). Would you believe a five-kilometer- deep hole? There's a great future exploration! Sterling K. Webb -- - Original Message - From: "mark ford" <[EMAIL PROTECTED]> To: "Sterling K. Webb" <[EMAIL PROTECTED]>; Sent: Thursday, June 14, 2007 4:25 AM Subject: RE: [meteorite-list] Martian Cave Entrance Detail Hi, I have had a go at reprocessing the Martian cave detail, see http://www.freewebs.com/fordmeteorites/martiancaveentrance.htm There is certainly something there that is more than noise (well not normal random thermal noise anyway) Looks like a dark spot in the centre which is probably where the light fades out as it goes down futher. Wow - It's a big hole! Mark -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Sterling K. Webb Sent: 14 June 2007 07:02 To: Chris Peterson; meteorite-list@meteoritecentral.com Subject: Re: [meteorite-list] Martian Cave Entrance Detail Chris, List, > it's presumed that Mars has been volcanically > inactive for a very long time... Presumptions were Born To Be Tested. Which is not to say that you (and it) are wrong, by any means, but since we are presumably going to poking about these curious apertures (instrumentally at least), it could be done if there's a multiband instrument suitable (I don't know). As for the albedo shift, I think it's real. I'm looking at it at the scale of 25 cm per pixel. As for the dunes, I see several light dunes that run right out of the bright and continue without a break into the darker area -- where they are dark, the same dunes. They may be more eroded and rounded over so that their shadows are not as pronounced but even so the peak of the dunes in the light area are noticeably brighter than any other feature in the photo except for the illuminated rim of the "hole." It could be very light frost from water vapor coming from the hole, or a dusting of sulfur, or a chemical alteration of the soil, or ground that was trampled by the boots of a crowd of spelunking Martians... well, no, not that. The most annoying thing about Mars (going to bitch about a planet, now?) is that you see something interesting but what you don't know, can't know, really want to know, is did this happen yesterday, 10 years ago, a century, a millennium, a million years, a billion? Don't know what you meant by "a very long time," but: http://www.universetoday.com/am/publish/mars_volcanoes_active.html "The timeline proposed from studying the complex Olympus Mons caldera suggests there have been lava flows from intense volcanic activity within the past 2 million years." A puff of steam isn't that intense. Sterling K. Webb ------ ----- Original Message - From: "Chris Peterson" <[EMAIL PROTECTED]> To: Sent: Wednesday, June 13, 2007 11:35 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail > B.) Please note that in the unprocessed photo of the > "hole," there is clearly a whitish "stain" or discoloration > of the terrain that is plume-shaped and that extends > away from the "hole." Hot CO2 or H2O vapors might > have produced the plume, but I think a sulfurous gas > more likely (as frequently seen in Earthly volcanoes). I'm not at all certain that's the case. Certainly, if you look at a lower resolution image that's the impression. Look closely, however, and you'll see that the area above the hole is actually a different texture- apparently sand dunes on a ~10m scale, quite different from the surrounding area. My guess is that these are the product of a compl
Re: [meteorite-list] Martian Cave Entrance Detail ADDITIONAL
Hi, All, Since it would seem likely to be a lava tube rather than a Earth-conventional cavern, the comparison should be to lava tubes on Earth. The largest (longest) is Kazumura Cave in Hawai'i: http://www.caverbob.com/lava.htm It's 65.5 kilometers long (40.70 miles) at a depth of 1101.5 meters (3614 feet). The next three longest lava tubes on Earth are also on Hawai'i; there are nine known to a length of more than 10 kilometers. The world's deepest vertical pit is at Vrtoglavica, Slovenia and is 603 meters (1816 feet) straight down. That could be a mile deep in Mars' gravity. The largest single chamber in a cave on Earth is 162,700 m2 (600 x 415 x 100 meters). Also would be bigger on Mars. There are lots of lava channels on the surface of Mars. Channels are lava tubes that have collapsed. Flowing lava always cools on top, forming a solid "roof" over the molten stream which drains and leaves the tube behind. Here are Surveyor images: http://www.highmars.org/niac/motubes.html Martian lava tubes on the surface are even bigger than the scaling of the gravity would suggest: http://www.astrobio.net/news/article1304.html "...on Mars they're hundreds of kilometers long. And the diameters are equally great. On the average they're 3 to 10 times the size of the average diameter on Earth. They are truly enormous." (The gravity ratio squared is about 6.9.) Using such caves on Mars as protective habitats for human explorers is an old idea: http://www.marssociety.org/portal/TMS_Library/Clifford_1997/view It was also proposed for the Moon, back when we thought the Moon had volcanoes. Sterling K. Webb -- -- Original Message - From: "Sterling K. Webb" <[EMAIL PROTECTED]> To: Cc: "Kevin Forbes" <[EMAIL PROTECTED]>; "mark ford" <[EMAIL PROTECTED]> Sent: Thursday, June 14, 2007 1:59 PM Subject: Re: [meteorite-list] Martian Cave Entrance Detail Hi, Mark, List Well, since your processing pulled out exactly what I thought I saw, only in greater detail, I naturally think you did a great job! Seriously, there are artifacts: the two "stitch lines" show up just as they did in Kevin's processed image, and of course, contours re-enforce the suggestion of depth. Still, center-darkness is clearly THERE. Sunlight is coming from just below the left horizontal axis of the photo, yet near the illuminated (right) side of the "hole" is another very dark area which ,since it is adjacent to the illuminated rim, must be very far below it. The World Cave Database: http://www-sop.inria.fr/agos-sophia/sis/DB/world.bydepth.html says the deepest cave on Earth is over 2000 meters! Don't even ask about the longest cave on Earth, which stretches for 580 KILOMETERS under the Earth (Mammoth). Apart from the possibility of caves too deep to have an access to the surface, the chief limit on cave depth is gravity. Mars could have much deeper caves than the Earth does (it has mountains three times higher). Would you believe a five-kilometer- deep hole? There's a great future exploration! Sterling K. Webb -- - Original Message - From: "mark ford" <[EMAIL PROTECTED]> To: "Sterling K. Webb" <[EMAIL PROTECTED]>; Sent: Thursday, June 14, 2007 4:25 AM Subject: RE: [meteorite-list] Martian Cave Entrance Detail Hi, I have had a go at reprocessing the Martian cave detail, see http://www.freewebs.com/fordmeteorites/martiancaveentrance.htm There is certainly something there that is more than noise (well not normal random thermal noise anyway) Looks like a dark spot in the centre which is probably where the light fades out as it goes down futher. Wow - It's a big hole! Mark -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Sterling K. Webb Sent: 14 June 2007 07:02 To: Chris Peterson; meteorite-list@meteoritecentral.com Subject: Re: [meteorite-list] Martian Cave Entrance Detail Chris, List, > it's presumed that Mars has been volcanically > inactive for a very long time... Presumptions were Born To Be Tested. Which is not to say that you (and it) are wrong, by any means, but since we are presumably going to poking about these curious apertures (instrumentally at least), it could be done if there's a multiband instrument suitable (I don't know). As for the albedo shift, I think it's real. I'm looking at it at the scale of 25 cm per pixel. As for the dunes, I see several light dunes that run right out of the bright and continue without a break into the darker area -- where they are dark, the same dunes. They may be more eroded and rounded over so that their shadows are not as pronounced but even so the peak of the dune
