New Mars Forums

Thanks, Daniel!
    That fits in with the information I found while writing my post-before-last. I wasn't sure that the Sasol complex in South Africa was still producing petroleum from coal, now that the trade barriers against Apartheid have been dropped.
    It's interesting to see that the process is ongoing because that means it must be reasonably cost-effective once you have the infrastructure in place.

    In the absence of a viable alternative to oil over the next decade or two, I feel sure coal will once more become our chief energy source.
    Perhaps the 20th century will one day be seen as 'The Oil Interval', in the centuries-long 'Age of Coal', which started in the early 19th century and may extend some centuries into the future.

    So, looking at the big picture, I don't think there's any danger of a worldwide power shortage over at least the next century or two. And, with the recently renewed interest in cold fusion (apparently many scientists are now coming around to the idea that there's definitely something anomalous involved which needs more investigation), plus the tentative search for ways to tap into the theoretically huge energy in the quantum vacuum, I think new technology will provide new alternatives long before the fossil-fuels are gone.
    Our problems may seem great but I believe human ingenuity is boundless when we're pushed to perform!
                                                 

Thanks, Atomoid. Interesting idea, this 'slab pull' thing - I don't think I've ever heard the term before. It certainly sounds feasible and I think your comment that tectonic activity and volcanism (sorry, I believe I misspelled it above) are mutually conducive is probably a fair evaluation of the situation.
    As for water in the subducting crust lubricating the plates, I believe this is a widely accepted theory. Without the water, friction would bring most of the sliding plates to a halt until the pressures became titanic. As I mentioned, Venus doesn't have enough water for this and its hypothesised periodic episodes of catastrophic volcanism have been attributed to just such long-term pressures causing unimaginable volcanic eruptions - perhaps in a 700 million year cycle.

    I have a book called "The History of Earth", by William K. Hartmann and Ron Miller. If you find it in your local library, it's worth spending a few minutes thumbing through it.
    It suggests that calculating backwards, using the Moon's known rate of recession from Earth, it's possible to determine with some degree of accuracy how fast Earth must have been rotating just after the Moon-forming collision occurred about 4.5 billion years ago. Apparently, a day was only about 5 hours long - 2.5 hours of daylight followed by 2.5 hours of darkness!
    This situation didn't last long, of course, because the Moon was so close that it raised simply enormous tides, probably of magma at first and later of water, which swept around the planet at proportionately high speeds. The major frictional drag involved caused a rapid transfer of angular momentum from Earth to the Moon, which consequently moved quickly away from Earth. In other words, the days lengthened much more quickly at the beginning than they're doing now - it hasn't been a linear process.

    With Mars, it's not currently possible to know how its rate of rotation may have varied in the past. There's no high-mass moon receding steadily from the planet to use as a gauge. And, if Phobos and Deimos are the only moons Mars ever had, they would have had a negligible effect on Mars' rotation rate over the eons.
    I sometimes look at vast impact basins like Argyre and Hellas, though, and speculate as to how the events which caused them could have altered the length of a martian day. To me, the fact that Earth and Mars have nearly the same day-length, is as astonishing as our Moon and the Sun being exactly the same apparent size as seen from Earth at this particular moment in time - a time when an intelligent species happens to have arisen here with the awareness and the technology to appreciate the cosmic coincidence!
                                                 

Thank you, Cindy, for explaining so eloquently what I was trying to put across. I couldn't have done it better myself!
    The 'trickle-down effect' is as good a way of describing it as any, and forms part of the logic which seeks to point out that economics don't have to be a zero-sum game.

    And yes, Smurf975, the rich will indeed get richer. As Cindy describes so well, even the poorest American can now eat ice cream, a treat once reserved for royalty. In the past, I've cited the fact that poor Mexicans can be seen driving 25-year-old Cadillacs in places like Tijuana. This represents a standard of transport totally unavailable even to the wealthiest American of, say, 1904.
    Obviously, it would be nice if every Mexican (or American, for that matter! ) could afford a brand new Cadillac. But in the present-day absence of such a pipe-dream, can we not take comfort in the fact that, as the wealthy get wealthier, so do the poor? You can eat your heart out with envy and righteous outrage and decry the rich for having more than you have but, in absolute terms, everybody is becoming materially better off and there's no denying it.

    You can look at the wealth that exists now and fret and fume about how to part the rich from their money so that you can have it - Oops! Sorry .. I meant so that 'the poor' can have it! Or you can open your eyes and see that the standard of living of the wealthy people of today will be a pretty mean thing compared to the average standard of living of a space-faring civilisation of tomorrow.
    The politics of envy spring from an inability to see the big picture. Let's not fight over who has the biggest slice of our one and only apple pie; let's bake more pies!

    A time is coming, and maybe quite soon, when the average human will have routine access to almost everything s/he currently desires and a lot of things s/he can't even imagine today. It will seem incomprehensible that there was a time when people fought over food and material goods and had to toil at tedious unstimulating work.
    I believe that becoming a space-faring civilisation is central to this vision of a better future for everyone. To remain in our planetary cradle, bickering as we've done for millenia over our limited resources and how to allocate them, would be the ultimate betrayal of our potential as a species.
    I believe we're better than that.
                                                   

Don't get me started on "the common person", Josh!
    When I think of all the people (real life flat-landers! ) I've met, who can't see more than 10 km above their empty heads, THEN I get depressed about our future!
    If we become a truly space-faring civilisation - and we're right on the threshold of doing that - the wealth we can create will be staggering. America has been the engine room of unprecedented world economic growth for many years but it took clear vision and great effort on the part of Europe, spending money they  no doubt could have spent at home on other things, to kick-start that 'New World'.

    There'll always be a gap between rich and poor. There'll always be economic injustice. But turning your back on the future because you feel disgruntled about it, dismissing the chance to vastly multiply the wealth and technology of the human species because you're worried someone else might benefit more from it than you will, is short-sightedness and pettiness of the worst kind.
    Let's create the new wealth first. We can always fight over who gets what afterwards! And there'll be so much more to go around - wealth we can hardly imagine today.
                                         

Yes, Lunarmark. It would certainly be fascinating to investigate the surface of Venus for longer than a matter of minutes.
    In theory, it's possible to refrigerate a probe on the Venusian surface for as long as you like - provided you have the machinery to create a sufficiently large temperature gradient between the inside and the outside, and the power supply to run the machine.
    I suppose, if you had a powerful nuclear reactor and a refrigeration arrangement efficient enough to pump heat from the probe, and excess heat from the reactor, out into the Venusian environment, you could cruise around on Venus for months.

    I guess the main problems are launch weight and, therefore, money. And what if all you found was hot basalt?!!
                                                            ???

I agree.
    Almost all the trouble is politics or money or bad management. If you really think about it, most of us could probably grow vegetables and raise chickens in our backyards if we had to. (We had a chicken run in our yard when I was a kid.) And fruit trees aren't so hard to grow either.
    The above may seem like puerile suggestions in the face of world poverty and starvation but, if each one of us really thought seriously about food production and what we could do to become as self-sufficient as possible, like the old days, the industrialised world would have a much bigger surplus.
    And if agricultural subsidies were eliminated, as they have been in Australia (well, nearly, we're down to only 4%, while New Zealand provides only 1% support to its farmers), farmers would be forced to grow what is actually needed.

    The world has plenty of food for everyone, Cindy, or at least there's no good reason why it shouldn't have. The famines in the world are all due to money, politics, and other bulls***!!
                                               

Quote from Dicktice:-

    Ha-ha!!  :laugh:   What a comical scene that brings to mind.

    But I wasn't just kidding around. I was sure I could remember reading about Nazi gasoline supplies coming from coal during the war, so I looked it up. It's actually quite interesting.

    The most informative site was http://chemed.chem.purdue.edu/genchem/t … .html]THIS ONE.
    For those of you with better things to do with your time than wade through the history of fuel synthesis (! ), some of the most relevant stuff is as follows:-
    To cut a longish story short, you first produce something called 'synthesis gas' (CO + H2) from coal. (This requires energy to achieve and is one of the reasons crude oil has taken precedence.) Now, on with the story:-

    As an alternative to this, you can also use synthesis gas directly to produce methanol:-
    CO + 2H2 ---> CH3OH
    Methanol can be used directly as a fuel or, using catalysts, be converted into gasoline.

    But on with the story again:-

    This is the bit which underlines what I was trying to say:-

    Getting all this into some kind of perspective, I found interesting facts and figures http://chemed.chem.purdue.edu/genchem/t … .html]HERE.:-

    From this last statistic, I deduce that if the U.S. had to produce all its energy from its own coal, it could go on doing so at 1990 consumption rates for about another 500 years, assuming no other sources of coal were discovered in the meantime.

    Ignoring CO2 emissions as a potential ongoing problem, perhaps this is one of the reasons the western world isn't panicking as much as one might expect at the prospect of declining oil supplies.
    If things like solar-power, wind-power, wave-power, geothermal, cold fusion, controlled hot fusion, or exotic alternatives like the fabled zero-point energy, all come to nought in the short-to-medium term, the industrial world can fall back on hundreds of years of coal-based energy.

    Phew! Looks like we can breathe a sigh of relief as, once again, we realise the sky isn't really falling at all.
                                               

Here in sunny Australia, I'm paying about $A4.00 per Imperial gallon (A90c per litre), which is quite steep by recent standards.

    I seem to remember Nazi Germany producing gasoline from coal in WWII. Obviously, pumping it out of the ground is cheaper but at what price for crude oil does it become economic to make gasoline out of coal?
    Australia has enough brown coal to keep us in energy for over three hundred years. Dirty stuff, I know, but if needs must ... !
    There has to be a certain point at which artificially producing gasoline from coal becomes worth doing. Then, when the process is widespread and efficient, gasoline will become price-stable and may even become cheap again. And with the world's vast coal reserves, we may be able to go on running V8 SUVs for centuries to come!

    Or am I dreaming?   

I think we're going to have trouble persuading the Moon to hang onto an atmosphere for as long as we'd like it to.
    I read somewhere of estimates of 3000 years for an atmosphere to leak away from the Moon, and some people here have read figures of 100,000 years.
    I have a feeling even the 3000 year figure is optimistic.

    Here at 'Terraformation', over in the 'Water not CO2' thread, I've been discussing leakage of helium, and by extension hydrogen, from Earth's gravitational field. In the process, I've had to look into various facts and figures and use them in a few calculations.
    It occurred to me to examine the situation of atmospheric loss from Luna, using the same kinds of figures. But this time, I've looked at the rate of loss of a mix of gases such as we have on Earth - i.e. 78.08% N2, 20.95% O2, and 0.93% Ar - with an average molecular weight of 28.94. This assumes we would be able to somehow import such an atmosphere in the first place (the O2 might be present in the regolith but I don't know about the nitrogen.)

    I have made some rough assumptions, which may be vulnerable to attack by those among us with better knowledge and data (I'll risk it! ). Firstly, I've assumed the exosphere of any new lunar atmosphere will be at a similar altitude above the lunar surface as Earth's is above terrestrial sea-level - about 800km. Secondly, since the Moon receives much the same insolation as Earth, I've assumed the kinetic temperature of gases at that altitude will be much the same as gases in Earth's exosphere - about 2000K.
    Using the formula for escape velocity:-
  V.esc = Sq. Rt. of (2GM/R)
            Where G is the Gravitational Constant
                      M is the mass of the Moon (kg)
                      R is the dist. from Luna's centre to 800km (m)
    And the formula for particle velocity in a gas:-
  V = Sq. Rt of (2kT/M)
            Where k is Boltzmann's Constant, 1.38066*10^-23
                     T is temperature (K)
                     M is the mass of a particle
    I have inserted the figures into the equations and the escape velocity 800km above the Moon is 2147m/s, while the average velocity of an air molecule at that altitude (i.e. at 2000K) is 1073m/s.

    These figures make it look as though the Moon will retain air molecules indefinitely but Maxwell and Boltzmann discovered that, in any gas of a given temperature, while the majority of particles (molecules, atoms etc.) move at speeds commensurate with the average temperature of the gas, a significant number of particles at any given moment will be moving much faster. (See the Maxwell-Boltzmann Distribution curve)
    From this, a scale has been developed based on the ratio of the escape velocity of a body, V.esc, to the average particle velocity of a gas, V.av, to give an estimate of how long the gas in question can be retained by that body (planet, moon).

    In the case of Luna, according to my figures above, the V.esc/V.av ratio is 2147/1073 = 2
    According to the scale of ratios (see the other thread at 'Water not CO2'), this means the Moon would lose an N2/O2 atmosphere in much less than 3000 years - perhaps not much more than 300 years!
                                               

    I admit some of my parameters are only assumptions and perhaps nobody really knows how gases would behave in an artificially constructed lunar atmosphere, but I think most of the figures I've seen for the Moon are looking way too optimistic.
                                                   ???

Oceans of water at 4700 deg.C ?!!!
Only 3% methane?

    Ooops! I think some of those surprises Sagan and Clarke promised me have hit home already!!
    I really need to brush up on my general knowledge of the outer planets.
                                            :laugh:

Sorry to butt in. Is it just me who can't access the posts at 'Simple Mars Vehicle' here in Planetary Transportation?
    Even Cindy's trick of pressing the Add Reply button doesn't seem to produce the goods.
                                               

A very sensible and intelligent post, Karov. It's impossible to disagree with such logic.