Planet Four Talk

Just a Spider Theory

  • PaulMetcalfe by PaulMetcalfe

    BELOW is just my initial layout of thoughts for formation of spider features and they can and most probably will change. Consider it to be a generic format that could vary according to many variables such as location. I do thank anyone for comments as they can make me re-examine what I think I see in some pictures but I do not necessarily discard my interpretation.

    There are hundreds of variables (known or surmised) that need to be taken into account and I am not the person to do that in any scientific manner. One example is – I am basing this on a venting gas but could a venting liquid or thermal stream be substituted for it. I am rather keen on a thermal stream but I will stick to gas for this.

    IT IS JUST AN IDEA BASED ON WHAT I BELIEVE I SEE IN THE PICTURES AND ARTICLES I HAVE VIEWED.

    Stage 1 – Before the Spider

    This could be at a fan location or to best suite my idea at a vent-hole in the surface where a gas issues at high pressure. This could be continuous eventually subdued by ice or only at certain climatic conditions (say when a thick ice sheet already covers it.) At this stage, there are no spider legs.
    Possibilities I am considering for a gas vent are:-

    1/ A continuous high pressure vent.

    2/ A low pressure vent that intermittently becomes a high pressure vent.

    3/ Related to 2 above a vent that acts like a high pressure vent due to conditions such as thick ice on surface.

    4/ Related to all above – Could a large gas, liquid or thermal ‘reservoir’ exist below the ground in spider territory. Could a thick ice sheet under certain conditions warm the surface beneath the ice. (This is an off-shoot thought at the moment)

    One thing I would like to know – Are there any available low-resolution maps of the whole of mars that depict (not in detail) the features (as seen on Zooniverse) at different time intervals (say annually) as they could help here.

    Stage 2 – Initial Spider leg formation

    As conditions get colder the surface starts to ice over. Some gas still finds its way straight up but some is forced between the surface and the ice sheet where it too begins to freeze but is pushed along by the pressure from the vent gouging out the surface where it is weakest (also dependent on type of surface). A hard rock and you may not get the gouging.
    I postulate that the spider leg formation would result because as a channel is being gouged, it will exert pressure all along its path into the surface. Another channel might only be successfully gouged if it routes out at an angle from its neighbour avoiding that pressure, thus they would grow out like spokes on a wheel.

    Stage 3 – The Ice Spider

    As more ice lays on the surface, the venting mechanism above continues and the ‘ ice legs’ above the gouged channels grow in thickness. The highest pressure is still at the vent so the ice surface will theoretically bulge higher at that point and lessen towards the leg ends. The central ice pack may also start to sink into the vent, as it gets heavier and block any further flow to the legs. In addition, the gas may be more likely to freeze near the vent at this stage.

    Stage 4 – Pressure release

    Extreme stresses may radiate along the legs now causing cracks that produce minor plumes. The main pressure is still on the central core above the vent that like a volcano may eventually erupt, probably throwing an ice plug into the air plus ejecta. It is possible for it to form plumes as it exits, but it may also be too bulky and of large texture that it just falls in a pile over the ice spider. While it is still cold and with the pressure released, the central core can once again start icing up to maybe form another plug. I also consider that if enough fan venting takes place along the legs or weakest points, then there may not be a plug eruption. I am also considering a vortex under the very top ice (from the confinement, flow and pressure) that may rotate the growing inner part of the plug into an ice ball.

    Stage 5 – The spider has legs

    When all the ice has gone or at least diminished the vent will now have the spider legs on the surface gouged out by gas and ice.

    With each occurrence of the above, the same channels will be used and possibly enlarged together with new channels being gouged out.

    Some of the questions I still ask myself about this.

    1/ Why would there be a high pressure vent? (Most important question)

    2/ Is that vent continuously active or just intermittent?

    3/ Is there a warming agent below the surface?

    4/ Is the central core ice plug or part of it being rounded into a ball by small amounts of gas escaping that way (rotating effect in the gas stream).

    5/ Is the plug just shattered by pressure and not ejected.

    I do hope there may be some interest in this. Initially, I am interested in comments etc. on the Stage 1 part above. At this stage, plain English please. The scientific jargon etc. can be introduced later if the above idea has any serious possibility of being considered by the scientific fraternity. That is a long way off.

    Posted

  • wassock by wassock moderator

    Paul, for this to fly you need to propose a source for what is venting, can you explain what you mean by "thermal stream"?

    Do you have any images we can look at which support the ejected central plug part?

    As far as other maps of mars go, theres a handy android app called mars map, and theres also google mars, which is like googleearth

    Posted

  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    Paul, could you provide some image ref. numbers to enable us to visualise your thoughts. I'd like one showing 'ice plugs' if possible. ~Pete

    Posted

  • PaulMetcalfe by PaulMetcalfe

    There is one other possibility for ‘Stage 1’ that I meant to include. However, I can see no positive evidence for it yet. It is quite simply that all the spider channels originate deep under the surface from the possible sources I have already mentioned in tunnel form. At the weakest points and/or points near the surface they crack and issue fans. As the surface erodes away by wind, ice or other means some of the tunnel system is exposed, eroded and left as a spider feature after which my ‘Stage 3’ onwards could still apply. I would even suggest that the pictures posted in 'Muck about with this one then' may point towards this being plausible.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to p.titchin's comment.

    I really want to start at 'Stage 1' where the only pictures I have seen are the surface spiders. I will put together a few reference pictures of 'What I think' are possible supporters of Stages 3 & 4 but I want to analyse 'Stage 1' first. An ice plug as a separate entity does not exist, it is my term for the central ice blockage that MAY be ejected under pressure.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to wassock's comment.

    I cannot explain a 'Thermal Stream' at the moment as I am concentrating on gas stream first, which of course could be warmish.

    Thanks for the google mars info.

    Posted

  • wassock by wassock moderator

    Paul, as in the other thread, the main problem with the idea of a central plug being blown out at the start of an eruption is that there are not all that many spiders with a nice fan coming out of the middle - do you have any examples?

    NB "Warmish" is a relative term mostly it's pretty cold out there

    Posted

  • Kitharode by Kitharode moderator in response to PaulMetcalfe's comment.

    Good write-up Paul. Some of your ideas are clearer now. I have to agree with the others and suggest that examples, images, quotes from articles and such like, which support and illustrate your ideas, would be really helpful. 😃

    There are many different types of spidering and some of them are more easily explained by freeze/thaw cycles, or 'polygonal shrinkage' effects, without any need of vents and such like. 'Lace Terrain' would be a good example: http://planetfour.org/subjects/standard/50e741055e2ed2124000308b.jpg which leads me to suggest that perhaps you should find, and focus on, those types of spiders that might fit your theory. This is only because I'm not comfortable with the idea of 'one size fits all' when we talk about spider formation. I might well be wrong. 😉

    Stage 1 - Before the Spider: Continuous high pressure vents might produce a continuous 'thermal plume'. If so, might they be seen by the thermal imaging instruments around Mars. ( http://themis.asu.edu/about )

    Variable pressure vents. Diurnal variation springs to mind. Days are short and solar radiation is weakest when the fans begin fanning. Days get longer and sunlight stronger as Spring progresses.

    Heating of the surface under the ice is part of the standard theory. It's known as the 'solid-state greenhouse effect'. It says that some wavelengths of light penetrate the translucent icelayer and warm the surface beneath. This warmth allows the ice to sublime at the bottom of the layer and pressure begins to build. Any dust that was trapped in the ice now becomes free to settle on the surface.

    You might have noticed my interest in the South Polar Layered Deposits (SPLD's) and the possibility that they play a significant role in what types of spider will form, or not. Your "vents in the surface" as a starting point idea does not sound good to me, if you have them on the SPLD's. However, vents in the surface of Mars away from the SPLD's might well be worth consideration. If you don't already have it, this is a really useful chart for the SPLD's: http://www.nasa.gov/images/content/171411main_pia09224-thick-annot-516.jpg

    Posted

  • Kitharode by Kitharode moderator

    PS: Your 'exposed tunnels' idea is very novel; I personally don't go with it, but it's very inventive. 😉

    These data maps might be of interest: http://global-data.mars.asu.edu/bin/hirise.pl

    Posted

  • mschwamb by mschwamb scientist, translator in response to PaulMetcalfe's comment.

    Hiya,

    There are also clearly fans where there are no spiders, so i think your theory needs to explain that if you want to offer an alternative to what has been proposed for the origin of these dark fans and blotches . We also know there is a carbon dioxide ice sheet on top of the spider features (and over all regions we see fans/blotches) and that the fans are on the top of the ice especially in the spring and early summer, so I think there is evidence to suggest that there this is surface, ice sheet, solar insolation driven features.

    Cheers,

    ~Meg

    Posted

  • mschwamb by mschwamb scientist, translator

    Also we know from year to year there is not a large change in the surface so that spider formation is very very slow. I think Anya estimated hundreds of years.

    Cheers,

    ~Meg

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to wassock's comment.

    I do not believe I have suggested that fans come from the top of Spiders (although they could - maybe). I have suggested that under intense pressure the central core of the spider erupts throwing out heavy material that does not blow with the wind.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to wassock's comment.

    Nearly Forgot. I believe Mars is very cold and I used the term warmish (maybe flippantly) in that context meaning 'less cold'.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to Kitharode's comment.

    Thanks for a good input with plenty for me to chew on. I agree about the continuous stream being a poor candidate as I too would have expected evidence of this by now (but I think it was worth chucking in with the list of 'possibles' just so I can discard it.) I will certainly look at the links.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to Kitharode's comment.

    Yes, this was an initial serious thought but not one that I would consider following from the information I have seen.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to mschwamb's comment.

    This was a re-posting of this idea onto this board, so I may have confused the issue by not including posts previous to this. I am not trying to replace accepted fan/blotch theory in any way. In my own non-scientific way I was saying that these phenomena away from Spiders and on Spider legs were a more gentle eruption of gas/ejecta that could blow with the wind. I am suggesting that the centre of Spiders may be ejected under pressure throwing up heavy material that falls over the Spider in a big heap. The Spider formation and ice covering would be an essential part of this theory of mine for it to have any chance of erupting, (Stages 2 onwards of my idea.) But it does ONLY apply (in my idea) to Spiders that have a large pressure build up in what I will call its central core.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to mschwamb's comment.

    I agree that Spider formation may be very slow, but the bigger they get the bigger and heavier the ice becomes covering the central point. My idea is basically an alternative/additional exploration of why these spiders start and grow. I have never suggested that these grow over-night. I think I would tend to agree with Anya's estimation. Also if a Spider in my idea erupted to release pressure, it may be a very long time before it erupts again.

    Posted

  • mschwamb by mschwamb scientist, translator in response to PaulMetcalfe's comment.

    I think you would need to find images where you see a ring of debris around a spider for what you're proposing. I don't believe we've seen that in HiRISE data. Have you seen that?

    Cheers,

    ~Meg

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to mschwamb's comment.

    I agree that one would expect to see a ring of debris (especially when defrosted) and that has perplexed me and I have been looking. The only possibility I can think of (not a good one though) is that large chunks of 'dirty ice' shatter into smaller chunks that disperse by defrosting and wind.

    I know, I don't like it either.

    However, a high pressure eruption could throw some debris a great distance as boulders etc. I will continue looking.

    I also think that 'young spiders' will behave differently to older spiders. There are pictures APF00010ev and APF00010t2 that appear to me as young spiders with ice balls or indents (not sure which) on top of them. Another picture AFP000035e intrigues me. To me this appears to be a row of spider tops covered with dark material (possibly from eruptions) that is sat on top of, or changing to a lighter blue/green material (I understand this may be frost). To the right are what appear to be balls and/or indents. I believe the general consensus is that they are boulders and I can go with that. The question I would ask, is could they have been ejected from the spiders.

    Paul

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to PaulMetcalfe's comment.

    Sorry, the 3rd picture should be APF000035e

    Posted

  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    Hi Paul, the third image is interesting, It shows the type of ' boulder' groups often associated with the ridges in Inca City, and although spiders sometimes occur close by, I don't think I've seen any associated with the ridge boulders. If you have any, I would be grateful if you could post them to further my exploration of 'boulders' ~Pete.

    Posted

  • Kitharode by Kitharode moderator in response to p.titchin's comment.

    Pete: Have you looked at my Inca City dropbox? Lots of images there. If you haven't, see first post here: http://talk.planetfour.org/#/boards/BPF0000008/discussions/DPF0000fj8 Do you want boulder images on here, or somewhere else? Cheers.

    Paul: I saw your recent comment on an image about spiders 'going down', rather than up. All spiders go 'down' because they are channels carved into the surface. They are not 'ridge-like' objects on/at the surface. Or have I misunderstood your comment? 😃

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to p.titchin's comment.

    Pete, you will need to make your mind up about APF00001cw at Inca City. It appears to have boulders and what may be Spiders.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to Kitharode's comment.

    I think it was just a misunderstanding. I know that on the surface they are carved channels (I think I made that clear in my Stage 1 paragraph). By 'up' I was referring to the ice build up above the channels when covered by ice. In my theory, anyway (Stage 3).

    Posted

  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    Yes Paul, that image has a nice boulder in a spider leg. What I tried to say was that the boulders on ridges are often in groups, but not with spiders, the spiders are off the ridges, and may or may not be associated with boulders, which if present, are not in groups.~Pete

    Posted

  • p.titchin by p.titchin in response to Kitharode's comment.

    Thanks Kith, anywhere is fine, but as I suspect this thread will get very long, perhaps citizen science-objects would be OK.~Pete

    Posted

  • PaulMetcalfe by PaulMetcalfe

    The following may already and probably has been considered by others out there, so I apologise if it has, as I have not read all threads etc.

    I was looking for phenomena on Earth that may offer an explanation to Spider formation and growth. I found an article where ice riggers sailing on iced over lakes hit flat but weak parts of the ice. Anyway, Methane gas bubbles leaking from ‘Gas holes’ on the lakebed percolate through the water and cause the thin ice above the hole. Apparently, it is a gentle release of gas.

    My thought now include (right or wrong) that if you have a slow release of gas from a ‘Gas hole’ on Mars when defrosted, it may be slow enough not to show up as a jet of gas (On Earth it shows up as gentle localised bubbles in the water when not iced over). Then the ice comes and blocks the stream where stage 2 of my proposal starts.

    I have also noticed that some of what I call ‘young or small spiders’ appear to have balls on top and ask myself could this be a ballooning effect on the ice directly above the ‘Gas hole’ that may go ‘POP’ or just defrost. In larger or older Spiders, could this ballooning effect occur hidden in the ice core and eventually erupt as more gas can accumulate beneath it due to the size of the channels.

    Okay you can stop laughing now but it would be interesting to hear what someone knowledgeable on the dynamics of gas trapped by ice has to say.

    Posted

  • wassock by wassock moderator

    Paul, you need to propose where the gas is coming from. At the moment we are working with the theory that the gas which is vented comes from the sublimation of the underside of the ice layer which gets warmer than the layer itself due to solar radiation and a 'greenhouse' effect caused by the transparent ice.

    There is ice in the ground and the presence of the polygonal cracking could be explained by a freeze/thaw, expansion/contraction system which would mean that gas is coming out of the ground at some stage. Some of the features on the surface (can't place the ref for this) are explained by "shrinkage" which I take to mean that the ice which was there has departed (into gas). BUT none of this has so far been cited as a factor in either the formation of the spiders or the fans (far as I know leastways) - may be it should, leastways so far as the lace spiders is concerned (Kith?).

    My view of how this works is that there's a thaw in the summer (after the ice layer is gone) and some of the ground ice turns to gas and escapes then the while lot freezes again come winter time just slightly smaller as some of the ice is not there anymore. I have seen somewhere (Anya?) an estimation of how long it would take to loose a an amount of 'ground' by this process.

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to wassock's comment.

    I appreciate what you are asking and I think that the course you and the others are pursuing is probably the best and most scientific until you all prove or disprove it.

    I can give what I consider could be sources and you may already have thought of them and dismissed them for valid reasons.

    The problem is that I am suggesting that the gas vents from under the surface (not for fans and other sightings) and to my knowledge (correct me if I am wrong) no one has delved deep under the surface of Mars and that will make any suggestion of mine 'to be based on imagination and not evidence' unless we can backward engineer a vent to the source.

    I am going to jump in here without a parachute and say is there any possibility of 'natural fracking' where gas is released from rocks or some natural reservoir by tectonic or thermal activity deep down. It may find a fissure to escape through and keep open or take the hard route and seep to the surface, if that is possible.

    I think I have just landed with a thud but it is just a withheld idea with no evidence whatsoever. However, it is not Earth, so perhaps something along the lines of 'natural fracking' can occur.

    Posted

  • mschwamb by mschwamb scientist, translator in response to PaulMetcalfe's comment.

    I think the hypothesis that the blotches are formed when the wind is not blowing and the fans are produced when the wind is blowing when the geyser ejects material is still more consistent with the observations. There are blotches where there are not spiders, so i don't think you can explain both blotches with spiders and without in the same way with your theory.

    Have you read some of the science papers on what has been proposed for these features. I think you would find them interesting to read and may help clarify and form some of your ideas.? Some of the papers I can send or other Planet Four volunteers on here are also reading and I'm sure happy to share.

    Cheers,

    ~Meg

    Posted

  • Kitharode by Kitharode moderator in response to PaulMetcalfe's comment.

    Paul: Although delving deep into the martian surface is an ongoing operation, there is actually quite a lot of information available that would be relevant to your ideas. Michaelaye has just posted a great geology link with some great maps and images: http://sp.sepmonline.org/content/sepsp102/1.toc and you might also find the MOLA stuff useful: http://mola.gsfc.nasa.gov/structure.html

    My understanding of tectonic movement on Mars is that it ceased a long time ago, so personally I wouldn't make use of it for present day studies. Thermal stuff underground seems to be popular with a lot of scientists (as well as us lot) so probably important, but I think more at the surface, or just below the surface, rather than 'deep down'. I might be wrong with that, but as far as planets go Mars is pretty dead so I'm not in favour of 'deep heat'.

    The question of where gas comes from is, I think, well explained by the standard theory as described by wassock above. Whether this gas vents and makes spiders or not, whether the gas comes fast or slow, doesn't really matter. If you need gas the standard model provides it, so I'm still unsure why you're proposing 'undergound gas and surface vents' (?)

    Wassock: We probably have seen articles about shrinkage/lace spiders, etc, and I'll try to find one. I've a feeling you're right that they don't cite shrinkage as forming fans/spiders, they just explain polygonal processes in ice/rock.

    Posted

  • Kitharode by Kitharode moderator

    Meg: If you're saying that it's ok to share the science papers we have, then we surely will. We wouldn't want to break any copyright protocols and such though. Many of them can be found (eventually) on't th'internet, but not all of them. What say you? 😉

    Posted

  • Kitharode by Kitharode moderator

    Pete: Zoom in on dark 'cliff' across centre of image. I see boulders being formed, breaking away onto the slope, settling at the bottom over time. Light comes from the top(ish) and I'd suggest that some of the 'boulders' just below the cliff edge are actually pits (?!) Comparison of images over time would be interesting. http://viewer.mars.asu.edu/planetview/inst/hirise/ESP_013707_1035_RED#start

    Posted

  • PaulMetcalfe by PaulMetcalfe

    Thanks everyone for the interest but I would prefer not to receive any science papers as I cannot devote a lot of time to this fascinating exploration of Mars. I did not want my idea to be so distracting, but to be just an idea that may have slotted in to a current avenue of research. I will follow developments as and when I can plus view any papers released to public view with interest but I think this thread should now cease for the benefit of focused scientific research.

    I will still mark fans etc. when I can but serious research I unfortunately cannot fit into my schedule. Let us face it, if I had the answers, I would probably be helping plan future Mars missions. Perhaps some or all of you are doing that. I just hope you land a probe near where it can examine spiders (might be a bit dodgy).

    Best of luck and let us hope you solve the mysteries of Mars. I still think Spiders are snowball machines.

    All the Best Paul

    Posted

  • p.titchin by p.titchin in response to Kitharode's comment.

    Great image Kith, At first look, these boulders have a n obvious development, time sequence would be good. Doesnt help my boulders on the plains though!! ~Pete

    Posted

  • Kitharode by Kitharode moderator

    Pete: No it don't help there I agree, but a possible solution for some boulders we see in the images we mark. It kinda emphasises the usefullness of the HiRise link I think, because we might see boulders from a cliff with the cliff being out of image (if that makes sense)!

    Should I take it that 'boulders on plains' are your main interest/focus, rather than 'ridge boulders' and such?

    Paul: Speaking for myself, I don't find your ideas at all distracting. You've sparked some good discussion, as well as reminding me of a couple of things I need to find out. You should bear in mind that outside of the science team there may be some of us that know (think we know) some science, but Mars is such a weird place we're all kind of at the same level here - level one, groping in the dark, bringing up wild ideas. 😃 Like I said, I'm speaking for myself there.

    Posted

  • p.titchin by p.titchin in response to Kitharode's comment.

    Hi Kith, I'm sure that our term 'boulders covers many different features, probably very different in composition, permanence/transience, mode of formation, and of course, age. I am trying to find a rationale to categorise what we see, so at present I am just collecting and observing where the boulders occur, so all 'boulders are of interest. The ridge boulders seem strange, as I would expect to see boulders down-slope from the crest (as in your cliff image) but not as we often see them-- perched on the crests. Different again, there are boulders that cluster like 'henges' on hill tops. I suspect the answers will continue to elude me but I'm enjoying the hunt! 😃 ~pete

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  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    Hi Paul, I'm with Kith- your ideas stimulate , and you don't need to spend lots of time. I have often only a few minutes a day, but there is always something to get the old grey cells firing, though in my case, the thoughts may prove wrong. With Mars, part of the fun is that no one knows the answers, so we can all 'fly our kites', and there are few areas where one can sit at home and have access to such amazing scientific tools. Stay on board for the trip of a lifetime! ~Pete

    Posted

  • mschwamb by mschwamb scientist, translator in response to Kitharode's comment.

    They can't be posted online if they're still on a firewall, but if there's a paper someone wants they should ask me or someone else on the science team and we'll see what we can do.
    Cheers,
    ~Meg

    Posted

  • Kitharode by Kitharode moderator in response to p.titchin's comment.

    Thanks Meg. Understood. We'll keep an eye open for specific requests and if we can't help out from our 'libraries' we'll pass the enquiry over to yourselves. Cheers.

    Pete: I like your approach and I really like your categories. I'm a big fan of 'collect, categorise, inspect, conclude' because it's amazing how often something comes to light when you do this. OK, maybe not major discoveries or items of great importance, but interesting and often useful nonetheless. I'd still like to see a new Boulders discussion though, so I can follow your quest and maybe even join in.

    "Boulders. The final frontier? These are the adventures of P4 Pete. To seek out new boulders. To boulder-ly go where no-one has gone before." ** 😛 **

    Posted

  • PaulMetcalfe by PaulMetcalfe in response to p.titchin's comment.

    I am not abandoning the site as it is a good way of keeping my 'old grey cells on the ball' but occasionally I will be away from the computer or making full use of it on other commitments for many weeks. I would hate to start an in-depth discussion and then find I cannot respond. Hence I do not want to get too deeply involved in the real serious stuff. Let me just fly this little private motto your way (It was a motto of me and my friends years ago) and I think it applies to Mars exploration -

    'Not everything can be found, but everything can be lost for the sake of not finding.'

    I still stand by that today.

    Back in a few days

    Posted

  • PaulMetcalfe by PaulMetcalfe

    Posted here so as not to clog up Pete’s thread if anyone thinks I am not being strictly ‘boulder’ here.

    Pete, I very much like your current boulder theories and wondered if you could point me to links to show each of your ‘type classifications’. Although I still believe surface vents and/or gas seepage from below the surface MAY be involved in Spiders and some boulders I also accept (quite strongly) that it may be a surface phenomena such as warming of the lower layers of ice. I am not trying to refute any other boulder or Spider theories, just fishing for ‘out-of-the-box’ info.

    As you know I believe some (mainly spherical) boulders MAY originate as ice plugs and/or balloons (explained previously). Therefore, TO ME a boulder could still be forming or been ejected in the images we see.

    1/ Is there any information as to the furthest distance (in the regions we are looking at) that spherical boulders have been seen from Spiders, fans or blotches?

    2/ Are there any time-separated images that show a boulder and then a fan, blotch or darkened spider top (or vice versa) at the same location?

    3/ Are there any images that show signs of a boulder rolling? Actually, I think this was answered in your thread as a YES.

    It may well be that questions 1 and 2 cannot be answered but it could be of immense value if they could.

    I noted that the question was posed as to why boulders on the Moon appear bright. Just a couple of off the cuff ideas here but the astronauts/Moon-scientists should know.

    1/ They are illuminated by strong reflected light from the surface as well as from above (not my favourite idea).

    2/ If they have rolled they may retain a coating of surface dust (no wind to remove it) and thus have the same reflectivity or better than the surface.

    Here is another serious but potty idea I thought about. It would be great if we could see some of these images from ground level to get a better impression of what we see. I realise that a Lander probe is probably out of the question but a good artists impression based on an image and elevation data (without artistic licence) could be as good. Any artists out there?

    One last thing as I have not found it myself. What is the measurement of the images we see? For example are they 1 square Kilometre.

    Posted

  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    hi Paul, I just got home and read your thread. So much to try to answer, and not much time tonight. As has been said on your thread before, we all start on the same level here, and apart from the 'guru gods' , we are just 'citizen scientists, who give our time to Mars and theP4 site. I will try to put my ideas to you on the questions I have done some work on, but I haven't time tonight. In the mean time you may get input from one of the others. Keep on trying out your own mental threads though, as you may then help some of our seized up ideas! Hope to get back in the next day or so ~Pete

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  • wassock by wassock moderator

    Paul from my viewpoint he answers to your questions are thus:

    1. There are boulders prettymuch everwhere and there are spiders of various geni all over the place as well, so it would be difficult to generate some sort of causal relationship methinks.

    2. There are plenty of timelapsed images which show the progression that you outline, however there are even more which show nothing and then a fan or blotch.

    3. Images which show any sort of movement of the surface, other than fans/blotches and dustdevil tracks are very rare, mostly occurring on steep inclines and involving slumping of one sort or another.

    Not found the reference to boulders being brighter on the moon but there could be any number of reasons why that might be so, not least of which being that they are taken with different cameras and that most of the images we are looking at have the sun fairly low in the sky.

    Cant do that comparison for the South pole but there are plenty of images available taken from the lander(s) and of the same area from HiRise so you could get some idea of how one compares with the other.

    the images put up for classification are of the order of a couple hundred meters(ish) if you click on the hirise image link and then look at the greyscale.jpg you will see a scale for the image top right. Best to try this with a classification image with an obvious feature that you can find on the larger image and therebye figure the scale of the small one.

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  • PaulMetcalfe by PaulMetcalfe in response to wassock's comment.

    Thanks for the information and it is quite informative to me as I am not only looking to find info to assist my crazy ideas but also to find absolute evidence to disprove them. That is just the way I investigate things.

    I agree totally with all your 3 answers.

    With regard to A1, If spherical boulders had been seen on say a flat ice terrain with no activity at say a distance of 10Km from any active area, it to my mind would add another dimension to the investigation.

    With regard to A2, this is something I would expect as I would not assume that every active spot produces or assists in boulder production.

    With regard to A3, I have not yet seen or recognised any boulder tracks. I have seen accumulations of what I think are boulders at the bottom of inclines but that I would expect. It is when I see ‘spherical’ boulders sitting on ice with no sign of rolling and just the smallest amount of dark material at the base that two thoughts come to mind.

    1/ An ice bubble is forming that is allowing small amounts of gas to escape from beneath it or

    2/ A boulder that has impacted, cracking the ice and releasing gas/material. However, I might expect to see cracking of the ice as well. Of course if the boulder is an ejected ice bubble then it could be the bubble that is leaking residual gas from its interior after impact. Mind you, the ice surface and bubble would have to be very hard not to show any other damage.

    Anyway, I think Pete’s investigations are better informed than mine on boulders etc. so I will not distract attention with too many fishing trip questions.

    The reference made to the Moon was at the bottom of page 2 on the BOULDERS thread.
    Thanks as well for the scale info.

    All the best Paul

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  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    Hi, Paul, Wassock has very concisely answered your post, so I will only add two things.

    1. When you do find repeated images of an area, you have still to be careful when comparing, as full image from which our classifying image is taken is unlikely to be centred exactly the same, and so the shot angle may well differ. Also illumination angle and intensity are likely to differ.
    2. Boulders do move without impacts etc. On terrain where polygonal plates form (high latitude patterned ground) the plate expansions and contractions with seasonal changes tend to 'sort' the boulders on the surface. Smaller boulders tend to end up in the cracks and depressions outlining the plates, whilst larger ones seem to remain, and so appear to be 'sorted' to the middle parts of the plates. The mechanisms are reasonably well understood, but too lengthy to put here.
      Hope this is of interest. ~Pete

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  • PaulMetcalfe by PaulMetcalfe in response to p.titchin's comment.

    HI,
    Thanks for the info and carry on 'Boulderly'.

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