But I'm not as naive as I used to be, and while I'm still a strong proponent (or exponent?) of manned spaceflight, I'm reaching an age and level of maturity where I'd like to see results. Manned spaceflight, yes. But preferably, manned spaceflight for a reason, and not just so we can say we have some government employees floating around up there.
Let's cut the mustard (or the cheese) right up front: people in space appear to generate very little in the way of fundamental science. When you name some of the most fruitful space explorations in terms of raw scientific output, they're always unmanned: Hubble Space Telescope, Galileo, SOHO, Voyagers 1 and 2, Viking - the list is endless. What great hauls of scientific data has manned spaceflight brought back? Umm....
The point of people in space isn't to do Big Science. People actually get in the way of that. Ever wonder why there isn't a big telescope mounted on the ISS? Because the vibration of all those people moving around, and all those fans and pumps that keep the people alive, makes for truly miserable seeing through a telescope.
Well then, what's the use of sending people into space at all? If it's easier and cheaper to launch robotic probes, and if the scientific haul is better anyway, why send people up there at all? Well, basically, to study how people live in space. The goal of putting people in space should be to eventually develop the ability to send them somewhere and establish, if not an actual colony, then at least a semi-permanently manned facility. So when we send people to the ISS now, it should be with the goal of developing the capability for manned interplanetary spaceflight.
NASA seems bad at articulating this sort of strategy. They present all sorts of arguments in favor of the ISS, but never the most important one. They talk about the science, the economic benefits, the technological spin-offs, but they never seem to come out and say "We want to learn how to live and work in space so we can go to Mars." I'm not naive and I know why they don't - going to Mars sounds like science fiction, and very expensive science fiction at that, and if the average lawmaker in Washington suspected that NASA was having Martian dreams, they'd probably preemptively de-fund the whole thing. In the same way that von Braun had to build vengeance weapons for Hitler to pay for his private dreams of colonizing space, NASA has to do what Congress will allow it to do so it can have its private dreams of colonizing space too. And as Carl Sagan once said, if Teflon is your main justification for the Apollo program, wouldn't it have been cheaper to just develop Teflon in the first place and skip that whole moon business?
The point of putting people into space is to send them somewhere so they can live. Ultimately, so that if something dreadful happens (asteroid impact, nuclear war, pandemic) and civilization on Earth crumbles, there'll be other human civilizations out there that won't go down the drain with the mother planet. That is the basic reason for going - so that if the worst happens, there'll still be people out there somewhere who remember Beethoven.
But where should we go? The moon seems like an obvious candidate - we've already been there, and it's close at hand. But I think building a permanent presence on the moon would amount to a long and very costly sideshow.
Moon proponents point out that eons of exposure has filled the crust of the moon with a rare isotope of helium, helium-3, and that it might be commercially lucrative to mine the lunar regolith for helium-3 and ship it to Earth, where it could be used in fusion reactors to provide essentially free energy. And that argument might make sense if we actually had fusion reactors that could use helium-3, but we don't, and probably won't for another hundred years pending some exotic breakthrough in magnetohydrodynamics.
I think Mars is by far the most logical candidate for future human colonization, much more so than the moon or the asteroids.
Mars has water. Lots of water. And water is practically the sine qua non of a space colony. And Martian water is probably going to be a lot easier to get at than whatever scant amounts the moon can offer.
Mars has an atmosphere, which means you can do all sorts of things with heat shields and parachutes to lose velocity that you can't do on the moon. Aerobraking and parachute-retarded entry have engineering challenges of their own, but as recent Mars probes have shown, once you figure out how to do it, you can use the atmosphere as a powerful brake and save enormous quantities of rocket fuel.
Mars has free carbon dioxide in its atmosphere, free for the taking. Carbon dioxide isn't too useful to humans in its native state, but it can be used as feedstock for chemical reactions that produce things that are useful to humans.
The Martian atmosphere provides pretty good protection from meteoroids, so you can think about building large inflatable structures without having to worry too much about them being deflating by any passing grain of dust. Large impacts can still deflate your domed city, but the Martian atmosphere essentially removes small objects as potential threats.
The Martian atmosphere provides at least some radiation shielding. Mars has no ozone layer, so the surface is exposed to full-bore ultraviolet radiation. And Mars has no magnetic field, so the solar wind isn't deflected as it is around Earth. But random collisions with the Martian atmosphere would attenuate at least some of the radiation threats. You'd probably still need to bunker in and sleep underground to protect yourself from the solar wind, but you'd have to do that on the moon anyway.
The Martian atmosphere offers advantages in cooling. On the moon, the only means of cooling anything is radiation. But on Mars, heat exchangers or radiators become possibilities, so the power density of your power generation systems can presumably be increased because of the more competent cooling schemes available. There wouldn't be a lot of cooling by convection or direct transmission, but some is a lot better than none.
The Martian day is pretty close to an Earth day, which would seem to have advantages in terms of adaptation. A lunar "day" is about two weeks long, which would take some getting used to, but a Martian day is about twenty-four-and-a-half hours.
The Martian atmosphere moderates temperatures. On the moon, temperatures vary wildly as objects pass through shadow and sunlight. Temperature swings of hundreds of degrees exist, and engineering things so that they aren't damaged, overwhelmed or even prematurely fatigued by wild temperature excursions is tricky. But on Mars, it's mostly just cold. There are temperature extremes, and it still gets plenty cold, but the atmosphere limits the scale of the swings so your engineering challenge is somewhat less daunting than it would be on the moon.
Mars isn't perfect. The atmosphere is extremely thin and some sort of pressure suit would still be required. It isn't a vacuum and it wouldn't kill you as quickly as a vacuum, but it would still kill you, and in a matter of minutes rather than hours. The topsoil on Mars isn't very hospitable either. The incessant bombardment by ultraviolet radiation (which is bad in and of itself) creates weird peroxides and superoxides in the Martian soil, and it isn't entirely clear to me if they would present a health risk if you tracked in a bunch of that junk on your boots. And since Mars has no magnetic field, you can't rely on compasses to tell you which way to go. But these caveats are all true of the moon as well, and the moon doesn't appear to offer any compensating advantages.
The moon has, as near as I can figure, only two real advantages. The first is that it has a low escape velocity and no atmosphere at all, so it isn't entirely unrealistic to imagine that one could launch cargoes from the moon using some kind of mass driver or rail setup. The other is that the far side of the moon is the only spot in the solar system that is permanently shielded from Earth's endless electromagnetic radiation, and it would be a good spot to build big radio telescopes.
But past that? I'd rather be a Martian than a Lunatic.
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