New Mars Forums

Don't be fooled by the term 'snow' in relation to the highly reflective highlands on Venus, Cindy.
    Although the condensation of these metal compounds at altitude is technically similar to the condensation and freezing of water here on Earth, the temperature at which the venusian 'snow' forms is radically different.
    Even though the 'cold' highlands on Venus may be up to 80 deg.C cooler than the hot lowlands, they're still approaching 400 deg.C !!
    The 'snow' we're talking about here is nothing like terrestrial snow.
                                             

Maybe they don't mean using nuclear propulsion to get to the Moon but nuclear power to provide electricity for a lunar base(?).
    I wonder whether people really appreciate how difficult living on the Moon will be during the long periods of cold and darkness. With temperatures dropping to -180 deg.C and no sunshine for 340 hours at a time, a nuclear reactor would be a good thing to have handy!

[P.S. I know there'll be ethereal Earthlight to provide at least some relief but there's still that searing cold to contend with.]

Yes indeed, Dickbill. Just because this little crater doesn't have sandstone outcrops, or even carbonate outcrops, doesn't mean there aren't any in Meridiani.
    It's quite probable that there has been no significant body of water in the Meridiani region for at least a billion years. Since then, no doubt, there have been various events which have left their mark in the area including impacts, distant volcanic eruptions, deposition of dust, and wind based erosion.
    As you suggest, the outcrop under examination right now is almost certainly a relatively recent feature. The crater in question is only about two metres deep at present and may never have been much deeper than four or five metres deep when formed(?), having probably half-filled with wind blown debris since. The 'bedrock' revealed by the impact, and currently under investigation, may have formed in just the past few million years - a blink of the eye in geological terms.
    Any evidence of large long-standing bodies of water would more likely be found deeper in the ground; perhaps several metres or even tens of metres deeper.
    It's times like these we need a human being on the spot with digging and drilling equipment!

    Spirit may be in a better position to discover sandstone or carbonate strata in the bigger crater it will soon be visiting. If the impact which caused that crater has excavated the ground to a depth of ten or twenty metres, our chances of finding older bedrock are of course much better.
    I tend to think the stuff Opportunity's looking at is just superficial weathering products.
                                                ???

    Any thoughts?

Sorry, I wasn't thinking of something as complex as a self-sustaining biosphere. And I certainly haven't the expertise to make any sensible comments about the evolution of such an atmosphere over time.
    All I was doing was pointing out that, at least temporarily, and with constant 'external' adjustments to maintain it, the kind of atmosphere I mentioned should be acceptable to dome-dwellers on Mars.
    I'm sure you are right that a self-sustaining atmosphere is an entirely different proposition.
                                               

Thanks, Cindy and Robert! (Both mines of fascinating information in their own inimitable ways.    )

    It sounds like we'll need specially prepared rubber or we'll have to stick with some other solution, like metal tracks or mesh.
    If we can't rely on rubber to help mop up the bumps, I suppose we'll have to rely more on the suspension. It just occurred to me that perhaps even steel springs might be more prone to breakage if expected to compress and decompress while very cold ( .. say, -80 deg.C or colder).
    Perhaps even gas-filled shock absorbers and other mechanisms with critical seals might seize up and fail in some of the coldest regions of Mars.
    Has there been a lot of research into this sort of thing in places like Siberia, Alaska, and northern Canada?
                                                ???

In response to Dickbill's comment about a perceived lack of agreement on the pressure and composition of artificial atmospheres in space, I was getting the impression that a practical consensus was emerging.
    An atmosphere of 350 millibars (~5 lbs/sq. in.), with 210 millibars of O2 (~3 lbs/sq. in.) and 140 millibars of N2 (~2 lbs/sq.in.) seemed to be popular.
    If I remember correctly, someone said this was the atmosphere used aboard Skylab and it worked well enough.
    Evidently, at that sort of pressure, with that concentration of inert nitrogen, spontaneous fires aren't a problem and it obviously satisfies human physiological requirements. Such a low pressure makes engineering a little easier too.
    I suspect this kind of air will become the standard on Mars; both inside habs and domes to begin with and, hopefully, on a planetary scale in the long run.
                                               

I think I read somewhere that people are trying to clean up places like Everest, where years of expeditions have left tonnes of garbage lying around(?).
    In addition, of course, many of the indigenous people in neighbouring regions regard Everest as a sacred place, or even a divine being.

    In either case, or both cases, wouldn't it be difficult to get permission to set up a sizeable pressurised 'base' at the summit, requiring strong foundations buried in the rock to stabilise it against the fierce winds, a base constantly visited and observed by teams of scientists coming and going?
    There's also the problem of how to get building materials, crew and visiting observers to the peak. Ordinary heavy-lift helicopters don't fly to altitudes of 8.8 km.
    But, having said that, I do acknowledge that the problems associated with building a Moon-base make a base on Everest relatively straightforward!
                                             

[P.S. Just to clarify my position again, I don't see the Moon as a sensible testing ground for human Mars missions because the conditions are quite different there. And the idea of launching a Mars mission from Luna just doesn't make sense in terms of delta-v. I'm informed by those much wiser than I that there are other places we could launch from (in space) which are much more economical in terms of rocket fuel.
        The existence of water ice in shadowed polar craters on the Moon is yet to be demonstrated beyond doubt. Even if it's there, how much mining infrastructure would have to be sent to the Moon's south pole before we could access it? How long would it take to build up the infrastructure? Etc. etc. etc.
         By all means have your outpost on the Moon, but don't make crewed missions to Mars conditional upon it! ]

Hi Dicktice!
    I think you might possibly be underestimating the task your maglev rail launcher faces in trying to replace the first stage of the Saturn V.
    At burn-out, the Saturn V's first stage had lifted the rest of the rocket to an altitude of 200,000 feet (38 miles) and given it a velocity of 6000 mph (roughly 8 times the speed of sound at sea-level).
    Kilimanjaro is 'only' 19,330 ft high, or less than 10% of the altitude to which a Saturn V first stage propels itself and its cargo.

    I'm not saying your idea isn't a good one, I just think in this case you may be a little over-enthusiastic in your comparisons!
                                             

A noble cause.     

Thanks everyone for keeping us all up to date. It's great news about Spirit!
    I can hardly wait to see what comes to light when we get those little beauties rolling!
                                             

Tsk tsk !  Women!!
                                    ???

In response to Remcook's point about the lack of haematite where the airbags have bounced, I'm prepared to throw in an explanation.
    I mentioned previously that the regions of the regolith affected by the impact of airbags seemed slightly raised, at least to me (maybe I'm wrong, I'm not sure). An explanation occurred to me, which I put forward at the time, based on the notion that the regolith has briny water mixed in with it, quite close to the surface.
    I continued by comparing the pressure of the impact of an airbag with the effect of a human foot on wet beach sand at the edge of the sea. Initially, the pressure of a foot causes a 'dry' area around it and then water wells up from below when the pressure is removed.
    Imagine a similar effect on Mars. The sub-surface brine, in the process of welling up after the airbag has moved on, might create a muddy briny slurry, which soon freeze dries in the thin cold martian air. This would explain the 'magic carpet', which surprised NASA, and might help with the haematite question too.
    I'm assuming the haematite granules are denser than the other material in the regolith. So, when the surface is temporarily converted into a briny slurry, the heavier haematite granules sink while lighter material floats to the surface, thus obscuring the haematite.

    This is just a hypothesis I've been chewing over and there are doubtless many reasons why it would be shot down in flames by Steve Squyres if he got to hear of it!   

    Nevertheless, the question was raised and I thought I'd throw my 2 cents worth in.
    Any arguments for or against? Or is it really too speculative and unlikely even to warrant consideration?
                                         ???