New Mars Forums

Thanks Cindy for the run-down on hemachromatosis (Call me a relic, call me what you will. Say I'm old-fashioned, say I'm over the hill. Today's spelling ain't got the same pizazz, I like ye olde worlde spelling jazz!!)
   So I guess if we don't want a nasty case of hAemachromatosis, we'll just have to go with that filthy perfluorocarbon stuff .... yechhh!! Unless we can come up with some kind of inertial propulsion system, which UFO buffs claim is what stops aliens getting spread all over the walls of their flying saucers when they do 90 degree turns at several thousand kilometres per hour!
   Wouldn't it be nice to catch a glimpse of future propulsion technology in a crystal ball or something?!
                                         

Aetius, it appears to me you're way ahead of most of us mere Martians!   
   Your enthusiasm for O' Neill settlements way out among the gas giants is highly infectious, though!!
   One of the questions that springs to mind, at least for me, involves those hybrid fission/fusion reactors. Even if you can import material from the icy moons out there, how much of it needs to be fissile material?
   My basic problem is that I don't know much about fission/fusion reactors! But I'm under the impression that there's probably not much in the way of elements with high atomic mass in the outer suburbs of solaria! What little there may be, is probably concentrated in the rocky cores of the ice moons under many kilometres of steel-hard ice. If your reactors need recharging with, say, uranium every few years, would you need to import it from Mars or even Earth? Would that be much of a problem? Is the asteroid belt likely to have heavy elements suitable for the purpose?
   There's no heavy irony here (groan! ... sorry!! ). I'm genuinely curious, not having given much thought to this region of the solar system and how best to utilise it.
                                     

You have to take into consideration the low gravity on these outer solar system moons.
   Although Ganymede seems relatively large, it is a low density world and therefore its mass is small .... it would take 40 Ganymedes to equal Earth's mass.
   As a result, its surface gravity is only 1/7 of Earth's
   This means that any problems we may have envisaged for settling Mars, in terms of gravity, are at least twice as bad on Ganymede. And solar cells will likely be borderline technology due to the low insolation so far from the sun. Nuclear power is probably the only way to keep warm on Ganymede, and we don't know where you'd get new fuel rods (except from Earth) when the old ones become exhausted.
   With our present level of technological development, exploration of Ganymede is just about feasible, but I think settlement is a whole different question (IMHO).
                                       

Nice post, Bill!
   I draw great comfort from realising that the essence of Hamilton's words forms part of my world view of human relationships. Why comfort? Because Hamilton's eloquence  very obviously reveals an eminently insightful human being. So, if I share his views, I MUST be on the right track!
   Though I could never hope to express it as simply and beautifully as he did.      Great stuff!
   Thanks again, Bill!
                                         
                                           

PS. Just thought I'd thank Adrian again for his fair and even-
     handed running of this site.   

Auqakah, you write well and I love your thought-provoking analogies. I've always thought analogies are a very entertaining and evocative way of making a point. Your analogies serve you well because the reader gets a good feel for your mindset on a particular problem ... in this case terraforming.
   The pillars of your attitude appear to be caution and circumspection, sensible ways to approach most problems, to be sure. However, humanity is a young species. We're full of energy and curiosity ... maybe more than any other species this universe has yet seen. Who knows. While there is always a danger of us making mistakes, that danger will always be there no matter how mature a species we become. There are always more ways to mess things up than to get them right!
   But will our restless need to explore always be there? Will our technology keep improving or will a new dark-age set us back a thousand years? We live in a risky cosmos in which mindless forces of unimaginable destructive power could wipe us out tomorrow ... and our whole existence would go unrecorded and unlamented ... forever.
   Nobody can see the future. What we do to Mars may be the biggest mistake we ever make .... or easily the smartest thing we could ever do. Centuries of careful deliberation and soul-searching won't tell us which. We have to do it!! Seize the day! (There may not be a tomorrow.)
   We're an impetuous species. Maybe some all-powerful God arranged our existence for just this sort of thing .... to amuse Him with our audacity!!
   Let's not disappoint Him!
                                           

Absolutely fascinating reading, Byron!! Those Hoover Dam statistics certainly put my dome foundations in perspective, don't they?!
   And Thankyou, Phobos, for those practical observations and interesting facts .... particularly the part about the 5000 cubic metres of concrete being poured in one day.
   My initial impression is that the Hoover Dam was probably a significantly more complex construction than my dome foundations, but then we have the added difficulty of having to work in a much more hostile environment (though I've read that 1930s America was a hostile environment in its own way! ). For a start, we don't need to build up. We're simply pouring concrete into a "hole in the ground". In addition, if our steel reinforcing is well constructed, watertight junctions between batches of concrete won't be necessary. All we're doing is creating coherent mass.
   Is there any difference between 1930s concrete and the stuff we use today? The reason I ask is that Phobos told of that 5000 cu.m of concrete in a day, but didn't mention anything about huge heat build-up during the setting process. In any event it may not matter to us because if there's one thing we've got plenty of on Mars, its refrigeration!! I'm sure we could come up with a way to utilise heat from the curing concrete to offset the extreme cold of the regolith we're pouring the stuff into. (Plumbing ideas anyone? )
   It's encouraging to read that the 2,600,000 cubic metre Hoover Dam took less than 5 years to complete. It may prove possible, in view of its lesser complexity, to complete the nearly 7 million cubic metre dome foundation in a similar time-frame. If the half-cylindrical ditch work, the plastic tube placement, and the steel reinforcing framework are largely completed first, it then becomes possible to start pouring concrete at many different points around the hexagonal perimeter. If two metre deep layers of concrete are poured and then left for a month to set, the work team can move on to another area, and then another. If many teams are carefully "choreographed" to work to a plan, good progress could be made. I realise this would require duplication of expensive equipment, but in principle it should work. If time is not the most important factor, then by all means minimise your equipment and do things at a slower pace.
   It may be advisable in the earlier years of colonisation to "cut your teeth" on smaller projects to test the principles of dome construction. I've recalculated the figures for a hexagonal "dome" only 50 metres on a side. A dome this size will only enclose an area of 6500 square metres (just over 1.5 acres) but needs only 5675 tonnes of reinforced concrete per side of the hexagon. i.e 34,050 tonnes of foundations in total. A much more manageable thing all together! But then your dome height won't be any more than 100 metres, which means not much air shielding against radiation.
   Anyway, what I've tried to show is that major concrete construction in a near-vacuum on Mars is at least feasible. Most of us seem to prefer the idea of living under a dome rather than under the ground. Bigger domes mean more air shielding which means safer "outdoor" shirt-sleeve living, which to me is the next best thing to living on a fully terraformed Mars. If some form of construction is desirable and enough people want it, I have great faith that a human engineer will find a way to provide it ... regardless of the difficulties involved!!
                                           

Auqakah makes a compelling case for a red Mars and his "We Can Never Go Back", which he puts at the end of each post, is almost mesmerising!!
   But I'm with Aetius! Bringing life to Mars is, in my opinion a noble gesture, not an offence against nature.
   And besides, even if Mars is currently sterile (which I do NOT believe myself), you can't go there to admire the sunsets without changing it in the process. A crew of 4 or 6 people, there for 2 months or 18 months, must contaminate the regolith with Earth bacteria. There can be no question of this not occurring. Every part of a human is laden with bacteria, the inside of the lander will be full of bacteria and moulds, and any drilling apparatus we drag out of the ship will innoculate the surface every time we use it!
   My belief is that impact exchanges and even some of our probes have transferred life to Mars already. It's no longer a virginal planet! Too late to put Mars into a chastity belt now.
   I see the future of Mars as infinitely enriched by a viable and varied biosphere .... new life, like a new baby, is a beautiful and hopeful thing! Maybe we're the cosmic midwife God intended for Mars. (Sorry if this sounds schmaltzy ... but Auqakah started it!! )
                                           

First woman on Mars (inspired by Cindy's comment):-

   "Hey, hey .... turn off that damned camera! I think I smudged my lipstick on the suit mike!!"

I've been thinking again lately about the problems of building domes on Mars. More specifically, I've been chewing over the problem of pouring concrete and getting it to set properly under Martian conditions.
   In this forum and in "We need a brainstorming session ... !", we discussed using pressurised tents in which we could do concreting. But how to anchor such a tent and move it along as the building took shape was causing us problems.
   I've come to the conclusion that the only shape of tent that won't require anchoring (except against the wind), is a cylindrical tent. And I propose laying the dome foundations inside a kevlar reinforced transparent plastic cylinder which can be increased in length section by section, by the simple expedient of laser 'welding' a fresh length of cylinder onto the end of the last one.
   Let's imagine that we've reached the stage of wanting to build a large dome and that the infrastructure to do this has been developed. I suggest we build a "dome" with a base in the shape of a regular hexagon, 500 metres on a side. The curve of the transparent dome material can be decided separately, but the higher the centre of the dome, the more air-shielding we get against radiation.
   Let's assume I'm correct in my earlier premise that the upward pressure on the dome is determined by the air pressure and the ground area enclosed, and only these parameters. And let's assume we want an atmosphere of 500 millibars. Now we can do a little arithmetic.
   Without boring you with too much detail, I've calculated the ground area of our hexagon will be 650,000 square metres. 500 millibars of air pressure translates to 5.17 tonnes of upward pressure per square metre of ground enclosed. We therefore have to counteract a total "lift" of 3,360,500 tonnes!
   Assuming we want an entirely uncluttered airspace inside the dome, all of this upward force must be opposed by the perimeter foundations alone. The perimeter is 3000 metres long, which means each metre of it has to weigh 1120 tonnes. This is a lot but it's not a fundamental impediment to the plan.
   On Earth, we can rely on the average concrete mix to weigh 2.242 tonnes per cubic metre, more of course if it has steel reinforcing in it. I'm going to assume we can get Martian steel-reinforced concrete to weigh 1 tonne per cubic metre, which means that for every metre of perimeter, we'll need at least 1120 cubic metres of concrete (regocrete if you prefer, since we'll be making it out of Martian regolith! ).
   Here's where the tranparent cylinders come in! First we dig a half-cylindrical trench with a diameter of 54 metres and a length (arbitrarily) 100 metres long. Next we place our 54- metre-diameter-100-metre-long transparent kevlar-reinforced plastic cylinder with large airlock at each end, into the trench. Inflate the cylinder with standard Martian air (30% oxygen, 70% nitrogen) at 500 millibars, or whatever is most practical. The lower half of the cylinder should be a neat fit in the trench, touching the ground in most places, while the upper half of the cylinder protrudes above ground level. The air in the cylinder will be warmed by the sun during the day but may need artificial heating at night.
   Colonists can then assemble a reinforcing framework of steel bars in the lower half of the cylinder, with a continuous rail-like portion of the steel protruding above ground level. Next, the colonists, working in shirtsleeves inside the tube, can mix and pour concrete to gradually fill the lower half of the cylinder until only the steel "rail" remains visible. You now have a half-cylinder of reinforced concrete a hundred metres long, 54 metres across, flush with the ground, and with a steel rail along the centre-line of the cylinder, protruding out of the concrete. A simple calculation reveals that this construction, by serendipitous good fortune, happens to weigh 1145 tonnes for every metre of its length! (I cheated ... I did the sums first!! )
   The next stage involves extending the trench and 'welding' another 100 metre tube of plastic onto the end of the first one, with a large airlock at its free end. This tube is then inflated and the airlock between it and the first tube can be cut away from inside. We now have a 200 metre long pressurised environment in which to continue the reinforced concrete foundations.
   Eventually, you will have a hexagonal foundation 3000 metres long, weighing 3,435,000 tonnes, flush with the ground, and with a convenient steel rail running along the middle of it, to which the transparent dome can be firmly attached. Once you are satisfied that the concrete is truly set, the half of the transparent cylinder protruding above ground can be sheared off at ground level.
   This method of foundation construction allows for a worker-friendly environment and an environment in which concrete can be poured and set with relative ease. In addition, the dome itself will go almost all the way down to ground level, giving the inhabitants that all-important feeling that they are living "out in the open" on the surface of the planet. Most of the posts I've read on this subject seem to agree that psychologically this is extremely important.
   People have suggested driving piles into the ground to help secure the foundations. But this assumes the ground will retain its structural cohesion. With terraforming bringing about warming of the regolith, the piles may become less reliable as the permafrost softens. Using massive foundations, as in my plan, relies solely on weight and is therefore not susceptible to changes in the consistency of the ground.
   I have assumed we can produce steel out in the open on Mars since the vapour-pressure of molten steel is extremely low. I have also assumed we can manufacture plastics and kevlar by some form of extrusion process without too much trouble. If we can't, we might as well forget the whole thing and stay home!!
    Any thoughts?
                                           

Hope S/He knows what S/He's doing with that spatula .... does the phrase "out of the frying pan into the fire" mean anything to you ... ?!!
                                       

Hi John!
   I agree in principle with much of what you propose ... it sounds like a grand scheme.
   But lay off those "tuna cans", will ya!!!
   I and a lot of other people happen to be very fond of the idea of "simply plopping" them down on Mars! .... and the sooner the better.
                                           

PS. I wish it were as 'simple' as you make it sound.

Clark is most likely correct in his estimate of a thousand years before a human gazes across the Martian landscape with the naked eye.
   Even if we assume that terraforming is begun soon and liberates 500 millibars of CO2 from the caps and regolith quite "quickly" ... in say, 100 years, there will still be a problem with using the naked eye.
   Most of the artists' impressions of colonists working outside in shirtsleeves and using only simple "breathers", show the masks covering their noses and mouths but not their eyes. This wouldn't work! Not many people realise that the so-called clear window of the eye, the cornea, has no blood circulation except at its extreme periphery. It relies heavily on atmospheric oxygen diffusing into it from the air. Without that O2, the cells on the cornea's surface become hypoxic and begin to close down physiologically. This results in the swelling and opacification (clouding) of the cornea and the individual so affected becomes, at least temporarily, visually impaired.
   So we will need "full-face breathers" until we fully terraform Mars and bring about an Earth-like N2/O2 atmosphere. When this is likely to happen (or if) is anybody's guess, but Clark's thousand years might be pretty close to the truth.