New Mars Forums

Very nice picture - so sharp!   :up:

    There was something about the scene which looked vaguely familiar but I couldn't quite place it. Then I remembered.
    It looks a little like the debris field of the Titanic on the floor of the Atlantic Ocean! The search camera cruised across a level plain of rippled mud that looked very much like this, before pieces of debris from the ill-fated vessel slowly came into view.

    I can easily imagine Meridiani under several metres of sea-water, the sun filtering through the water and shimmering on the sandy bottom. I wonder if it was ever like that?
                                               ???   

Many Happy Returns, Chat!!     :band:

    44 is an auspicious number and you should have a good year.   

This is a wonderful site!!
    I think it's great to have so many talented and well-informed people from all over the world engaged in intelligent discussions like this one.
    It's a privilege to be able to be a small part of it and I just thought I'd thank you all and wish you a fabulous Festive Season!
                                                 

    [Hi Rex!  Interesting comments from you, as always. My thoughts on the lighting in the photos are similar to your own, I think, though your explanations are more detailed and therefore better than mine. It's always gratifying to think one isn't entirely alone in one's opinion about something, too. So thank you for that!
                                                       :up:  ]

Yes indeed, Doug.
    A very Happy Birthday to you.   

    Well, now I've not only got Doug, NASA, and Atomoid telling me Spirit's obviously dustier than Opportunity, but Graeme's joined the fray as well!!
    I'm starting to feel inadequate here!   :laugh:

    I still can't convince myself that the difference in appearance isn't largely to do with different lighting or filters or some other treatment of the images. I'm just looking for evidence of physical obscuration of detail by a layer of dust - and I'm not finding much consistent visual evidence for that.

    But I have to face reality here and admit I'm up against a few factors which weigh against my position on this:-
1) Spirit's power is down compared to Opportunity's.
2) Spirit is travelling in dustier surrounds than Oppy's sandier
    environment, so you might expect more dust.
3) It's certainly possible to interpret the pictures Doug has
    presented as showing more dust on Spirit's panels (though
    I personally find the evidence inconsistent).
4) NASA and a majority of people engaged in this debate are
    convinced dust is the explanation.
5) I have no plausible alternative explanation.

    Another thing is that I don't know how much dust I'm looking for. The amount of dust required to reduce Spirit's power output by so many hundred units is not clear to me - maybe I'm looking for more dust than is necessary to cause the reduction. I don't know.

    Since I'm unable to come up with anything useful to add in my own defence, and faced with overwhelming odds, I'll have to withdraw from the debate - still unable to explain the situation satisfactorily in my own mind. But I do appreciate all the feedback I've had, especially from Doug who's gone to a lot of trouble to elucidate the discussion. (Thanks again, Doug.)

    In any case, this all started with me suggesting dust may not be such a major problem for future Mars expeditions, after all. That was the main point I was trying to make in my post.
    The fact that it's even possible for someone awkward, like myself (! ), to argue they can't see a great deal of evidence of dust on solar panels exposed for nearly a terrestrial year to martian conditions, is enough to bolster that suggestion in my view.
    Dust or no dust, my bag is packed and I'm ready for NASA's phone call!      

We all share the crushing disappointment Dr. Bell exudes from every pore of his skin and a great deal of discussion at New Mars has dealt, and still deals, with the problem of cheaper access to LEO. Cheap access to LEO is what it all comes down to in the end and everyone at New Mars knows it.
    The trouble with Bell is that he thinks he's one of only a select  and exclusive group of academically superior individuals who've spotted this fact. In addition, he sees the very real stumbling blocks to human space exploration much more clearly than he sees the potential for overcoming them. In other words, he's thrown in the towel and now stands jeering from the sidelines at the rest of us who still have hope.

    That's O.K. He's entitled to his opinion and I'm sure all of us here support his right to speak his mind. But just because he's earned himself a Ph.D in astrophysics (something he seems to think makes him very special indeed), doesn't necessarily make his opinions any more valid than those of the rest of us. Admittedly, he must be better informed on technical issues than the great majority of space advocates, including me, but he is no more highly qualified than Dr. Zubrin, whom he denigrates roundly at every opportunity, or Dr. Chris McKay of NASA Ames.

    It's the easiest thing in the world, when the going gets tough, to retire from the struggle and belittle those who choose to carry on. That's Bell's position.
    Maybe he's right that our cause is a forlorn one. Maybe the petty politicians and nay-sayers and Luddites, with their heads stuck in the sand, will ultimately hold sway. But I don't happen to think so.
    I think people like Bell will one day be sidelined, permanently, and that humanity will expand into the Solar System. I'm happy to play whatever small part I can in that hopeful future and will continue to do so.
                                                   

John:-

    Me too!

    A blind visionary!   :laugh:

    Sorry, John. It just struck me as funny, that's all. 

    I don't know that Zubrin wants to cancel everything except the Mars thing. Back in the sixties, NASA managed all sorts of space research while methodically progressing through 'Mercury', 'Gemini', and 'Apollo' to get men to the Moon.
    We could have Mars Direct up and running for about $4 billion a year over 10 or 12 years, so I'm told. There's still plenty of cash left over for the unmanned stuff, isn't there?
    I suppose it all depends again on whether we're connecting two posts economically or just selling rope.
                                          ???

Interesting. Thanks, Doug.
    These are much better pictures than I've been looking at and the detail is far clearer in colour. Nevertheless, while the actual solar panel segments on Spirit appear paler than those on Opportunity, so does everything else - even though the detail on Spirit is just as vivid, perhaps even more vivid.
    I still don't see convincing evidence that Spirit is carrying significantly more dust than Opportunity.

    Could the Spirit pictures be more exposed than those of Opportunity? Or could the Opportunity pictures have been taken through a filter?

    I'm not going out of my way to be a pain-in-the-posterior here. I'm genuinely trying to see more dust on Spirit than Opportunity but the clarity of the detail on Spirit honestly leads me to think otherwise. Even the (upside-down) printed part number, 10207341-1, is at least as readable on Spirit as it is on Opportunity - if not more so.

    As for the dust-devil idea, I remain totally unconvinced by it. At one stage, NASA was claiming that dust-devils must have blown straight over Opportunity on three separate occasions to explain the surges in electrical power in recent months. Yet, no evidence of dust-devils has been apparent in the hundreds of photos taken by either MER. And who's to say a dust-devil wouldn't deposit more dust on a MER's solar panels than it removes anyway?
    I've lived in a desert climate long enough to know that, when I wash my car in that kind of environment, a strong 'willy-willy' (Australian for dust-devil) means I'm going to have to wash the car again! And I've never ever seen a willy-willy clean the dust OFF anybody's car!!

    But then, you and NASA are probably perfectly correct. God knows, you've got more brain power on your side than I have on mine! 
    But I still haven't seen enough evidence from your side to convince me.
                                                     

Hi Doug.
    I understand that the electrical power rating of Spirit is about 400-odd Whrs/Sol and Opportunity's is about 900.
    It is assumed that dust is responsible for Spirit's low electrical production but I have no way of knowing for sure, and neither does NASA, it seems.

    All I have done is look at the evidence available to me, the pictures from Mars, and check for dust. Maybe it's the resolution of the pictures, I don't know, but I don't seem to be seeing a great deal of the dust purported to be responsible for the problem.

    NASA is so at a loss to explain the extraordinary power production of Opportunity that they've even invoked dust-devils as a possible agent to clean the solar panels!
    Their next best guess is that water condensation on the panels is causing beading of the dust and freeing up more surface area for insolation.
    The fact is, nobody really knows.

    I don't like accepting everything at face value just because a NASA scientist tells me so. We're not entirely stupid. We don't need a Doctorate in astrophysics to look at a photograph and decide whether a solar panel is choked with dust or not.
    We've been told dust is the explanation for Spirit's poor electrical production but NASA doesn't have an adequate explanation for Opportunity's unexpectedly good electrical production. So why believe the Spirit story unreservedly, when the people telling that story seem unable to account for the condition of their other Rover?
    This problem is currently open to consideration and we should consider it .. carefully.

    At present, the dust story is inconsistent.
    Question it!
    That's how discoveries are made.   

I'm beginning to think that dust on Mars may not be such a major problem after all. Although we've been expecting the MER's electrical power to gradually die from dust accumulation on their solar panels, very little of such an effect has been encountered.

    Photos like this one, taken on Sol 329, show parts of Spirit looking essentially dust-free:-

    Perhaps, outside of a real dust storm, fines will present only minor difficulties to machinery on future expeditions(?). If the astronauts take precautions during storms, covering up anything vital, then Mars weather might be no more troublesome than desert weather on Earth - maybe less so.
                                           

    As I've mentioned before, when trips to the Moon were being planned, astronauts were going to disappear into many metres of quicksand-like Moondust, they were going to contract lunar diseases and/or bring them home, and the dust was going to choke up their machines and maybe their lungs as well.
    None of the above actually happened.

    I think the pro-robotic anti-human exploration lobby is doing a good job of scare-tactic-campaigning when it comes to Mars, too. And it's perfect fodder for the zero-sum Lefties and Luddites, who look for the worst in anything to do with new technology.
                                            ???

Cindy:-

    Fascinating stuff!
    I'd love to see the program if I ever get the chance. I've heard about the drastic effect of a methane bubble on a ship's buoyancy but the effect on altimeters and piston engines is new to me.

    Maybe it's not as exotic as still-functioning Atlantean super-weapons, intermittently sending out energy from their resting places in the mud on the ocean floor (*), but fascinating just the same!
                                                

[ (*)  I read this explanation in some hare-brained magazine many years ago.     ]

Hi again, ERRORIST.
    If you were to ascend vertically from sea-level on Earth's surface to an altitude of 13 miles, you would notice the atmospheric pressure drop from around 1013 millibars to only 35 millibars (not much more than 3% of normal). I mentioned this in my last post.
    The reduction in pressure will be essentially the same no matter where on Earth you begin your ascent, be it from one of the Poles or the from Equator. An unprotected human exposed to an ambient pressure of 35 millibars will die an unpleasant death because, as far as the human body is concerned, it's as good (bad! ) as being in outer space.

    The 15 millibar difference in atmospheric pressure between, say, the South Pole in winter (greater pressure) and the Equator (lesser pressure) is due to the extreme cold of the polar air causing it to sink because it's denser.
    This 15 millibar differential represents less than 1.5% of Earth's normal sea-level atmospheric pressure - in other words, it's not much!
    Meteorologists routinely see bigger differences from one side of the day's weather chart to the other as high and low pressure systems traverse your local area. And, to give you some idea of what Earth's atmosphere is capable of, the highest recorded atmospheric pressure was 1085.7 millibars, measured at Tonsontsengel, Mongolia, on December 19th 2001. While the lowest recorded atmospheric pressure, 869.96 millibars, occurred in the Western Pacific on October 12th 1979. (Courtesy Wikipedia.) The difference between these two figures ... a whopping 215.74 millibars!!
                                         
    Constructing a pipeline from the South Pole to the Equator in an attempt to take advantage of a transient seasonal pressure differential of only 15 millibars, in the hope of generating electrical power from turbines, is an exercise in futility I'm afraid.
    This pressure gradient, over the 10,000 km distance involved, comes down to a differential of 0.0015 millibar per kilometre of pipe. Friction between the air and the walls of the pipe itself would be enough to reduce any air movement to about zero - you'd have more chance of moving the turbine blades if you sneezed at them!
                                                Sorry. It won't work.

Cindy:-

    You bet!
    If you sit for a minute and just think about even the distance to the nearest star, I mean really think about it, the incredible void between individual stars can give you vertigo!
    Trying to imagine the size of our own galaxy is, in my opinion, simply so far beyond human experience of distance that it can't be comprehended by the human brain. Oh sure, we can write down the numbers and bandy them about in a seemingly knowledgeable fashion, but a visceral understanding of what we're talking about is out of our reach, I think.

    The same applies to the vast stretches of geological time we talk about so casually. I remember reading comments by a scientist (sorry, can't recall who it was) on this subject and he was trying to put it into perspective.
    On a gelogical time-scale, we talk about the K-T extinction event, which ended the reign of the dinosaurs, as though it happened quite recently. And it's true that, compared to Earth's total history, 65 million years isn't all that long.
    But if we go back to the earliest civilisations we know of, we're talking about roughly 6000 years ago. In itself, that's a difficult enough timespan to take in but we have to multiply that span by 10,000 before we get back to the Cretaceous period. Even if we go back to the dawn of modern man, perhaps 200,000 years ago, that's still only about 1/300th of the yawning temporal chasm that separates us from the Triceratops and the Tyrannosaur!

Cindy:-
   

    Never a truer word spoken!
    I know we can 'talk the talk' but I really don't believe we can 'think the thought' - our "primitive ape-brains" just aren't equipped for the job.