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Conversely, Mars prepares us for Luna (a more hostile environmnt than Mars) and teh rest of teh universe.
Secondly, I specifically spoke of biomass to be sued in greenhouses, NOT on the surface of the planet. The latter cant sensibly happen until we're into the realms of terraforming, which I don't think would be within a century at least. And I answerd you objection on mass already. You start small, and work your way up. Heck, you start with hydroponics first if need be and work up to compost in time.
Im still puzzled by your argument on radiation,though, Clark; yes what you've just said is true, but it's still the case that the problem is worse on Luna, so how does that make Luna a better choice? It doesn't!
With regard to the use of artificail lighting or not for crop growing, on Luna crop-growing will most certainly always require artificial lighting. On mars it MAY do so, short-term. ISTR reading something on the subject saying that light levels at Mars orbit should be adequate to support photosynthesis, but unfortunately I cant recall where. However, given teh amount of insolation at Mars is about 50% of Earths, and given the range of changes in insolation due to location and weather on the Earth being considerably greater than that, I don't see that as a problem. Give the plants nutrients, sunlight, and protect them from radiation and they will grow.
Who said anything about new experience of sending folk beyond LEO? My point was that we have better technology now than at the time of Apollo. We could do the same thing but better. We may even be able to do better things - thats al I was implying. But I the went on to say that we could and should test the systems by sending a prototype MD vehicle into circumlunar orbit.
Where did I say we should go NOW? I didn't. These things take time to prepare. Prototypes have to be made and tested. Come now, you're making a silly argument, Clark, which taken to its logical conclusion would stop us ever doing anything. Personally, I think there are excellent reasons for starting on teh Mars Direct project now - so that we can start designing and building and testing prototypes. Only after we've done that can we be sure of the feasibility or otherwise- of teh project - exactly as with Apollo.
As for NASA - it isnt the only organisation on this planet interested in space. Commercial companies are starting to sit up and take notice of the possibilities for making profit by going into space. Other companies are trying to see to it that they can make profit by helping the other companies get out there. Even if governments gave up on space tommorrow, then so long as launches into space weren't banned worldwide, it's a fairly safe bet that eventually commercial enterprises will exploit space eventually. And the US isnt the only government with space know-how and launch capability. Talking only of NASA is IMO being a bit blinkered.
As for your closing comment - LOL! I might well say the same to you, m'dear. My primary interest in space, astrophysics, etc, lies in the human colonisation of the Solar System and nearby star systems, eventually. Yes, I truly do believe that one day we will get to the stars - but the Solar System comes first. Why go to teh utter desert next door (Luna) when we could go to the (relative) oasis a bit further down the road (Mars), and give ourselves an easier job to do in creating our first permanent off-Earth settlement?
Methinsk we all wnt the same thing - we just have differeing ideas as to hwo to achieve it - and in some cases, as to teh timescale, too. Im at the more cautious end of supporting Mars Direct. But I do think its superior to sticking us with trying to struggle on Luna. Once Mars is self-supporting,supplies can be more easily sent from tehre to support Luna than from Earth, too..
Esme
OK Clark - so how are Lunar colonists supposed to be any better off being that much nearer the Sun and with NO atmosphere togive ANY shielding at all? Im afraid your argument regarding radiation simply doesnt make sense to me.
As for the Antarctica analogy - America looked a pretty poor prospect to start with too - long and dangerous journey, potntially hostile inhabitants and dangerous flora and fauna - who in their right mind would have wanted to go there?! Ditto Australia - which is why the UK used it as a dumping ground for criminals. With better technology,mankind can expand into harsher environments. Much of human society already lives in artificial environments, and so do you, unless you happen to live in a cave without fire, much less a PC.
Mars is terraformable. Whether or not we SHOULD do that is another matter, but we COULD start the process going. That aside, consider why Antarctica isnt more densely settled - because theres so much more hospitable real estate nearby. Once self-sustaining settlements have been established on Mars, and there are those who want to work to make that happen, then there's no reason why it shouldnt grow into a vibrant part of human civilisation - no more attractive real estate nearby, and the prospect of eventually having an outdoors environment at least not requiring a spacesuit. Sure, we might have O'Neill colonies out there by then - but they require a far more massive engineering project to get started. We should, IMO do both - but Mars is easier for now.
I find Clarks attitude peculiar,to say the least. Why go into space at all, for that matter? Science, to escape, romaticism, prestige, curiosity - all human montivations. All apply to any kind of exploration anywhere, whether it be remote parts of Earth or places within the Solar System and beyond.
Regarding the radiation at Mars, the output from the sun in terms of what it is omposed of (as against how it gets created, another matter), so far as I'm aware, fairly well known, and it doesnt take a genius at maths to apply basic laws of physics to extrapolate from the radiation received at the Earths orbit to that received at Mars orbit to give a worst case scnario, ie: assuming no shielding effect whatsoever from Martian atmosphere or magnetosphere etc.
In short, to calculate how much radiation would be recieved if Mars were like the Moon only further out. This is off the top of my head (only just discovered this site and forum, havent had chance to go check figures) but IIRC Mars is about 40% further out thanwe are, and so will receive about half the radiation that Earth - and Luna receive. Unless cascade effects from high-energy cosmic radiation striking the Martian atmosphere more than compensate for the 50% lower soalr radiation (which I have no idea about, but think unlikely), then Mars colonies require less radiation shielding.
I've lent my copy of "The Case for Mars" to a friend, but it was my impression that Zubrin was envisaging a build-up to sending humans to Mars,including suitable study of the long-term effects of low gravity on humans. after all, there wouldnt be any point in sending a team to Mars if once there they found themselves incapable of doing their jobs.
However, some of the long-endurance missions in LEO have surely given certain amount of data on the subject, and I can think of a perfect way of testing the viability of a trip to Mars with a safety net no worse than that of manned missions to Luna - send a prototype crewed Mars vehicle into either circumlunar orbit or a figure of 8 orbit around both Earth and Luna. Average radiation hazard would be worse than for the trip to Mars, and the effects of zero gravity or if spin is used to simulate gravitational forces, then its efficacy can be found out on such a mission. The safety of such a mission would be noworse, and doubtless, due to technological advancement since - somewhat better than that of Apollo 13.
If the mission was in circumlunar orbit, it could do useful scientific work on Lunar survey and using telescopes (carried instead of equipmen which would b used solely for Mars exploration) for astronomical purposes, possibly acting as part of a VLB interferometer in conjuction with Earth-baed or other satellite telescopes.
Now, if a mission or missions like that failed - THEN there might be a case for going to Luna and establishing a base there first. If it were only partially successful, there might still be a case for Luna. Otherwise, in order to achieve a self-sustaining colony, Mars is far superior. If we have the ability to mine water from comets for bases on Luna, then we're easily able to get out to Mars and the asteroid belt, anyway - and have solved the problems of long-endurance manned missions in low gravity in the meantime, too.
As for the soil on Mars and plant life - the soil on Earth wasn't exactly full of biomass prior to the rise of life here,was it?:-)
What is to stop some of the unmanned Mars Direct landers from carrying "seed" quantities of biomass - compost - along with either hibernating useful insects or their eggs?
Sure, gradually adding a little material from Mars to it, and human wastes, will take a long while to produce huge amounts of extra biomass, but life is pretty good at extending its reach. And if I understand corectly, the chemical engineering to extract at least some of the things vital to plant growth from the soil and atmosphere of Mas isnt that big a deal.Even if an initial greenhouse failed, there'd be biomass created by it for follow-on attempts to start over with - even if they had to start with lichen and work their way up to grasses and beyond, rather than starting with more immediately useful (to humans) plants. Heck, create a pond in the greenhouse and get algae growing.... skim off a certain amount of algae every few days, and add it to the mix for new soil/biomass to support more crop plants.
(Shrugs...) Yes, we need to ensure that we dont launch into a full-scale Mars Direct scheme without first ensuring that it wont be suicidal for crew members, otherwise Mars Direct becomes pointless. But testing that point can be done as easily as sending astronauts into Lunar orbit. And if it proves to be viable, a Mars colony becomes self-sustaining far morerpidly than a Lunar one ever could.
Esme
Esme
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