Mars Settlement precursor thread

[arobie]

JonClarke,<br /><br />Then with that definition of preliminary expeditions, I think our current and future landers, rovers, and orbiters could be them. They explore different area's of Mars' surface, study it in detail (even more so with the upcoming rovers), can determine whether it's possible to grow food, can study the atmosphere and ground for resources, and are mapping and studying Mars as a whole to give us better insight to find suitable settling (sp) spots. <br /><br />The only things they can't do is gain experience in Martian operations, the human factors of such, or prove it possible to live and work on the planet for years. Although for the latter, they can point strongly one way or the other by determining resources (mainly water) and factors that would either make it more or less difficult to live on Mars.

 

[SpaceKiwi]

""Going there may be an end in itself for some, but not for most. There has to be a rational justification and purpose. "Manifest destiny" just won't wash.""<br /><br /><br /><br />Jon,<br /><br />I agree with you, and disagree with you also! (don't like to commit myself one way or the other, you know!) While I believe and agree that Science is a very admirable justification for going to Mars, I also believe you make Science the cornerstone of your rationale for going at your peril.<br /><br />Undoubtedly good science will flow from a long-term presence on Mars as sure as night follows day, and it might keep the bean counters happy to have such a black/white justification for such a mission. But I also think you DO have to have a more philanthropic or holistic view as your initial mission focus. It has to be simply about 'because it's there', as anything else is putting the cart before the horse as it were.<br /><br />The Antarctic model has its merits, but perhaps the ISS model would be even more appropriate to a Mars mission? While 'science' might be going on at the ISS, and it makes for good copy in the media and with the political masters, the current problems highlight the danger of placing too much emphasis on it. There is obvious disappointment at the 'science' output of ISS thus far, and concern for the anticipated 'science' output of the facility moving forward if the facility can not be fully crewed.<br /><br />I would contend that ISS has been sold to the general populace on false assumptions, leading to understandable disappointment that the scientific benefit has not been as expected, and may never be in actuality. Further, I personally view the ISS as more correctly being in a construction phase, and continuing to be in this mode until approx 2010. For me, at least, the ISS mission is about learning how to build and maintain a base in such an extreme environment.<br /> <br />Any 'science' gleaned as a result of this building activity should be the only scient <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[JonClarke]

Arobie<br /><br />There is no comparsion betwen what a human precursor mission could achieve and even the best robots. On average the MER rovers achieved in a year what a human astronaut could do on foot in a single day. When you actually compare what a well equipped human mission will do, then it will achieve several thousands of times what a robotic mission can. And that is simply with respect to field studies. I cannot envisage any realistic robots determinging how best to grow food, find and extract resources, or any one of a hundred things that will be needed to determine whether settlement is feasible. Robots are good at simple, repetitive, predetermined tasks. They are very bad at tasks requiring flexibility, adapatability, evolving goals, high levels of dexterity, judgement, and instantaneous decision making under such conditions. Robots are good scouts, good monitors, but inefficient explorers. Robot missions are precursors to human missions, but not human settlement. <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Hi S_K<br /><br />I agree and disagree, like you. Realistically there will be a cluster of reasons - as there is historically in Antarctica. So science, economics, and feel good human endevour are not mutually exclusive. But equally, realistically science will be the up front rational for Mars, since economics and strategic neccessity won't be.<br /><br />The ISS is good alternative model example to Antarctica. and I would argue that it has achieved all that it can be expected to have achieved to date, scientifically and technologically. It has been enormously valuable, and its value will increase as it expands. Whether or not the public understands it is irrelevant, the policy makers understand it and fund it at a level the public will accept. the same is true of most science. The public generally does not understanding the ocean drilling program or Anatarctic research either, let alone fundamental physics.<br /><br />Science and innovation allows policy makers to point to concrete results - publications, innovations, increasing skills as tangible rewards for investment. Expanding human presence off planet, a second home for humanity, the new frontier will not, in itself, pay the bills,long term, even if they are valid reasons (and I happen to think they are). <br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[spacester]

Great posts. <br /><br />Going thru to find any problems . . . ah . . .<br /><br /><font color="yellow">I cannot envisage any realistic robots determining how best to grow food, find and extract resources, or any one of a hundred things that will be needed to determine whether settlement is feasible.</font><br /><br />OK Jon, this is the crux of what I see as the inevitable conflict between Scientists and my plan. You make a true statement, but I need to re-set the context. We are not going to determine whether settlement is feasible, we are going to settle and thereby find out if settlers can settle. The plan is under-ambitious as far as creating a colony in one fell swoop, but quite ambitious in the initial level of settlement. Secure the settlement, that’s job #1 before anyone goes out tromping around with a geologist’s hammer. Sorry about that, be patient.<br /><br />Those guys tromping around on your early missions are wasting their energy. They should be back at the habitat with the rest of the settlement crew, working on ISRU and actual food production and all the other things needed before we can say we have our encampment secure. We have sufficiently characterized the environment to build the habitats, we have built them, landed them, supplied them, tested them, time to move in. (Food production is assumed to be nil for the first hitch – there will be a surplus of food on location before anyone shows up)<br /><br />I’m a bit more in kiwi’s camp than Jon’s, those are good solid thoughts on the motivation.<br /><br />Just because IMO settlement is self-justifying doesn’t mean I’m going to try to sell it on that basis alone to the public. But it’s a pretty good argument for the majority of non-space geek people; so, it’s the first argument. It’s definitely not the last argument. In fact, I hope we have as many arguments (plus one) as we have objections. <img src="/images/icons/laugh.gif" /> Inclusiveness is good.<br /><br />A cluster of reasons, yeah, that’s on tra <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

Spacester?<br /><br />Do you conceive, like Arobie, having a settlement without preliminary missions? That is a very high risk approach. I can't imagine any settlement until we know that people can live and work on Mars for the duration of at least one mission cycle, and more likely two. Otherwise we would be like people in 1960 planning on people living for a year in orbit before anyone has even been in space. Especially as the scale of operations needed for a mars settlement will be up to an order of magnitude larger than a precimilanary mission. Now we can still plan, but we must assume a certain level of experience has happened.<br /><br /><br />In this I am assuming rational decision making and normal circumstances. Do we want to broaden our assumption to include irrational decisions or abnormal situations?<br /><br />Best<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[spacester]

Well, let's look at whether we're dealing with an irrational decision by me or simply a pre-conceived notion by you. This is what this precursor thread is all about.<br /><br />Certainly every plan I've seen has a minimal initial crew, the pathfinders, the trailblazers. I'm depending on you to hear me out and not use those previous conclusions as your guide to rational thinking. Let's go to first principles, not argument by authority. Normal circumstances are that we'll not be going to Mars for another 60 years and that's not acceptable. So please consider my abnormal approach.<br /><br />Your analogy of planning one year missions in 1960 is completely invalid. We have all the freedom in the world to put people into LEO for any length of time we want and bring them back any time we want. This does not apply to Mars. It's 2-1/2 years, baby, once you go, you're committed. And we know a heck of a lot more about what we're doing than in 1960.<br /><br />If you're not prepared to keep 24 people alive, why should I think you're prepared to keep 4 people alive? The only difference is that of scale. And it is fairly well accepted that the larger the group, the larger the capability to get things done.<br /><br />At some point in time we will be sending humans to Mars. The first people are not any more or any less precious than the later people. We're not going to send anybody until we are confident they will survive the first hitch.<br /><br />The only real logic I see to sending smaller initial crews is that if you kill them all, you kill fewer people. That and of course total cost, but we're going to develop a plan with the best chance of success and then go get the money. We're not gonna take a given amount of money and figure out the safest way to send the fewest people.<br /><br />Yes, we must assume a certain level of experience has happened before people show up. But this experience will be remote monitoring. Once we have the ISRU running well enough and the habitats provisioned <div class="Discussion_UserSignature"> </div>

 

[arobie]

JonClarke,<br /><br />We don't need to send humans to determine if it is possible to live and work on Mars. <br /><br />Let's look at it this way. What factors do we need to know to be able to conclude whether or not we could live, work, and survive on Mars? <br /><br />Firstly, we need to know and understand understand everything falling under the environment such as: temperatures, radiation levels, low gravity's effects on humans, weather (dust devils & other phenomena), and terrain. We need this information so as to be able to decide how protect ourselves and our infrastructure from it's hazards. Our landers, rovers, and orbiters can, have, and will continue to provide us with all of this information except low gravity's effects of the human body. But if we must solve this enigma before we settle on Mars, we don't need to send people to Mars to do it. If we wanted to, this can be solved in Earth orbit with a spinning ship or space station station.<br /><br />Secondly, we need to know where to find resources; where to find water, what we can pull of our the air, and what we can pull out of the soil, and where we can find what. All of this information our landers, rovers, and orbiters have, are, and will also continue to provide us.<br /><br />Thirdly, we need to be able to decide where to place the settlement. Our rovers and orbiters won't decide this for us, but they are gathering the information to help us make this decision. They are finding where there could be and is water, they are finding where interesting scientific spots are, and they are finding much more information about Mars that will be of use to us when deciding where to settle. <br /><br />You are right about human's being able to accomplish much more science and exploring than robots, but by the time we are ready to send an expedition mission to scout out, all of the scouting will have been done by our robots. We will already have all the information that we would be looking for...and we wouldn't have had

 

[alpha_taur1]

I tend to think that Phobos would be a good place to put a staging base. It has the advantage of a very low gravity, a substrate on which to place a permanent base and plenty of material for shielding purposes.<br /><br />One of the problems that MIR had and later the ISS is that of stability. A tremendous amount of effort is taken to establish a configuration that doesn't oscillate slowly causing all sorts of problems in the medium term. With a solid substrate on/in which to build, we solve many of these problems without working too hard. <br /><br />Apart from that, Phobos is an incredibly interesting place as a potential source of fuel and nutrient. It gives every indication of having the same composition as a carbonaceous chondrite or C class asteroid. With a low density, there is a good chance of volatiles such as ice, organics, including even amino acids.<br /><br />In many ways, if we could overcome the problems of working in low gravity, Phobos might even be a better candidate than Mars itself. <br /> <br />That's why I'm looking forward to the launch of the Phobos Grunt probe, which is designed to return a sample of Phobos regolith.

 

[JonClarke]

Spacester<br /><br />I expressed myself poorly, I did not intend to imply that you were irrational. I certainly have preconceived notions, having invested a vast among effort into thinking about Mars exploration and settlemt, amd read a lot of literature of the subject I am entitled to them <img src="/images/icons/smile.gif" /> . However do believe they are open to modification!<br /><br />What I am trying to say was that I believe rational settlement requires a reasonable level of understanding of what the issues are with living on Mars because we commit to settlement. We simply do not know the answer at present. I don't think people are going to commit to settling unless they know there is a good chance they will live a reasonally long and fulfilled life, and that there children and grandchildren can do the same, instead of dying from some nasty posioning by hexvalent chromium or of skeletal degeneration from the low gravity. This is rational.<br /><br />The only exceptions to this I can imagine are if settlement is being carried out on the commands of by some meglomanic, or where a rational settlement is not possible. Now both these scenarioes are good SF. but I do not think they help us, as they simply muddy the waters.<br /><br />I think my space station model is completely vald. Suggesting we settle mars using present knowledge is exactly the same as proposing in 1960, before Vostock or even in 1970 before Salyut that a space station be established at that time that had people living in space without any option of return except once a year. We did not know it was possible. We now know it is, but it has taken many years to gain the experience. Short cuts will lead to disaster.<br /><br />It is reasonable to commit to a human mission to mars based on what we know now and with a 10 year time frame (although I think this is unlikely). But not settlement.<br /><br />There is no substitue for humans on the spot to explore, develop, and carry out the neccessary research <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Aerobi<br /><br />What do we need to know? We don't know whether humans can live out a healthy and happy life exposed to traces of Martian dust and 38% G. people aren't going to risk their children and grand children until they do.<br /><br />There is a huge difference between scouting, which is all the MERs are good for, and the sort of detailed field science a human can perform, let alone what is required to establish a permanant settlement. The MERs can't even pick a rock up. An The ExoMars rover will be able drill shallow holes to perhaps a metre. To do site investigations for a settlement you will need to drill dozens of holes to 10's of metres, to develop a ground water supply you will need to drill scores of holes to 100;s of metres. It will need to carry out a lot of research on the physical, chemical and biological proerties of literally thousands of samples. For some areas there will ne a need for several Martian years, maybe even decades, of baseline environmental data. The amount of geotechical work and environmental needed to establish a settlement is high - I have been involved in establising mine sites - and not the sort of thing that is easy to roboticise or hurried. It can take a decade or more on earth where environmental properties are well understood and if the project fails people can still go on breathing. There is far less margin for error on Mars which, as our flightless friend pointed out yesterday is much more hostile than even the Antarctic.<br /><br />Best wishes<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[spacester]

Hi Jon<br /><br />I’ve said for years now that if we’re going to actually go to Mars instead of just talking about it, someone is going to have to out-Zubrin Zubrin. He reduced the mission mass and complexity by an order of magnitude or more. But do you see a way to reduce it that much again? So if my statement is correct, the next generation of Mars plans will need to incorporate a radical shift in thinking that will be as profound as introducing ISRU etc. was.<br /><br />Forgive my ego; I have pondered this long enough to believe I have a kernel of an idea to base a plan on that will actually happen.<br /><br />Settling Mars is a unique problem. I firmly believe that those who do not learn from history are doomed to repeat it, yet I do not believe anything mankind has done before serves as a reliable model or even a solid analogy for Mars settlement. We can learn from the past but how exactly do we apply the lessons?<br /><br /><font color="yellow"> I believe rational settlement requires a reasonable level of understanding of what the issues are with living on Mars because we commit to settlement.</font><br /><br />I agree, we need to know as much as we can. We want to have a 99% chance of success. But do we have to know <b>everything?</b> Of course not – it’s impossible – we need to prioritize what we learn before people show up and what we can learn only by actually being there.<br /><br /><font color="yellow">I don't think people are going to commit to settling unless . . . </font><br /><br />The first settlers are going to have to take risks in certain areas. We cannot eliminate some particular risks. Those risks we can identify we will do everything in our power to eliminate. Those risks we know we cannot do anything about we will accept, mitigate and go anyway, finding out as we go. A key survival strategy IMO is “safety in numbers” – if the goal is a settlement, let’s not send an expedition that fails due to lack of human resources. Let’s not let t <div class="Discussion_UserSignature"> </div>

 

[spacester]

Phobos is very interesting and I gotta believe a valuable resource for Martian settlers.<br /><br />But quite frankly I have not figured out a way to include Phobos in my plan. On this, I defer to others. For now, I am assuming that some other organization (presumably Russian) will be working on Phobos and time will show us how to utilize its resources. In the meantime, it's a distraction.<br /><br />The main problem I have with Phobos is that it is not the same thing as the Martian surface. The main advantage is that it potentially gives you access to anywhere on the Martian Surface.<br /> <div class="Discussion_UserSignature"> </div>

 

[thalion]

Ditto--Phobos should wait until there a settlement established. It seems like a waste to go all the way to Mars and not land on its surface, but that's just my two bits.

 

[grooble]

Spacester, why not plan for the settlement to take place after the NASA mission, that way it could take in all the latest human research and experience.<br /><br />It depends what your timeframe is though.

 

[spacester]

NASA? Who is this NASA you speak of?<br /><br />Oh yeah, the space agency in Houston.<br /><br />J/K . . . <br /><br />Whatever those folks can learn and are willing to share with us while we go about our business will be welcome.<br /><br />The timeframe is ASAP (P = Practical).<br /><br />Not gonna wait for NASA, not gonna wait for Congress. <br /><br />Not gonna wait for the general public to rise up and demand progress in space.<br /><br />Not gonna wait til we prove or disprove existence of life on Mars. <br /><br />Not gonna wait for a magic pill to deal with reduced gravity. <br /><br />Not gonna wait to get started. <div class="Discussion_UserSignature"> </div>

 

[grooble]

Groovy, i'll pay for the coffee <img src="/images/icons/wink.gif" />

 

[JonClarke]

Spacester<br /><br />Pity you do not like my space station metaphor, I think it is valid, within the limits of metaphor, however that is your affair.<br /><br />The fact remains that no responsible person will risk their children unless there is a high chance of success. If they are not responsible people, who wants them on Mars anyway?<br /><br />Your approach might work if there are no insurmountable problems. But what if they are? What if it is not possible for them to return? Do you leave your settlers to die? This is not the 17th century when that was acceptable. Even ignoring the morality of it all, it is not sound financial management. The stake holders in the project will want the maximum likelihood of success.<br /><br />All I am saying is that we assume that these issues have been dealt with before we start settling. We don't even have discuss them, just flag that they have and move on. It is even a way of building up some infrastructure capital on the surface before you commit to settlement.<br /><br />Best<br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[spacester]

Jon, I’m grateful for your interest, please understand that I am not attacking you personally, just trying to state my case. Not that I think you think that is the case, I just need to crank up the language a bit.<br /><br />In this context, I just don’t like metaphors period. When it comes to this particular design problem, I see no historical parallel. Analogies and similes are always constructed to serve the purpose of the argument at hand. No quite as bad as statistics, but in the same arena. <img src="/images/icons/laugh.gif" /><br /><br />Whose children are at risk?<br /><br />Of course we want responsible people. How do you define that characteristic? Surely not in terms of adherence to pre-conceived notions that do not stand up to scrutiny.<br /><br />Ah yes, if there are no insurmountable problems, it would work. I am encouraged by your stipulation of that condition. But let’s look at the nature of such problems.<br /><br />There are three kinds of problems: those we anticipate and eliminate, those we anticipate and fail to eliminate and those we never thought about until they come up. Which of these three types of problems does a smaller initial crew better address? I can’t think of any.<br /><br />If it is not possible to return, something really weird has happened. Did the propellant that was in place on Mars before crews departed Earth somehow vanish? Did rocket engines stop working? All of them? Did we somehow fail to eliminate the problems? We sure as heck identified the capability to return to Earth as of prime importance, so we designed in multiple redundant paths to success, extra propellant, redundant access to Martial orbital re-fueling, hundreds of days to get the return craft provisioned. The most important task of all, and we didn’t get it done! Very weird.<br /><br />Would it be more likely to not be able to come home if you had a crew of 24 than a crew of 4? I don’t think so, I think a larger contingent gets a lot more done and has a better chance of accomp <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

Any mission to Mars will inevitably encounter the same fundamental 'problem' that explorers since Day Dot have experienced - the unknown. And, with that lack of knowledge or certainty as it were, comes risk.<br /><br />This mission will require a certain type of person, no question. The type of person, as spacester has highlighted, that believes the most effective way to determine the long term effects of reduced gravity is on site for example. It's little different than those historical mariners who took to the oceans when the conventional 'wisdom' was that the world was flat. The mariners had belief in what they had learned to the contrary up to that point, and in their abilities and skills to adapt to what they discovered.<br /><br />Of course, forewarned is forearmed and undoubtedly the initial settlers will want to be as informed as is possible about potential risks and solutions to those. But, make no mistake, settlement of Mars will require a group of very hardy and resourceful people if this is to work. People that won't go into seizure because they left their 3/16" drill-bit back on Earth. Unfortunately, in many cases, there will be no substitute for experience.<br /><br />I think potential major problems such as radiation exposure or low grav will dictate that children are not an option for settlers until they have been adequately mitigated. Again, I think Science Supports Settlement in this regard. These are the kinds of science-solvable issues which should occupy the minds of the initial settlers. Essentially making the settlement long-term-human-habitable. <br /><br />Only once you have that framework solidly established and tested can you then move forward with confidence, safe in the knowledge that in a worst-case scenario your presence on Mars is fundamentally assured. <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[dan_casale]

JonClarke:<br />Lets look at what we do know. <br />1) In freefall, Humans have survived for more than 1 year, and have sucessfully returned to a productive life on Earth.<br />2) Exercise reduces the effects of Freefall.<br />3) it is possible to rotate a ship and simulate gravity. All ships going to Mars should simulate Earth normal, so the people arriving on Mars will have Maximum strength. People returning from Mars should slowly be spun up to Earth normal.<br /><br />I would think that the only thing threated would be their ability to return to Earth.

 

[dragon04]

Grooble - "But it's better to teach engineers how to wear a space suit than to teach a geologist how to build structures on mars. <br /><br />Scientists are ok, but there should be many normal folks. Someone has to fix the plumbing."<br /><br />I don't believe an expedition of moderate to small size has the luxury of division of labor.<br /><br />And remember. While science is ostensibly the reason to settle Mars, the act of settling Mars itself falls ahead of doing experiments.<br /><br />Cross discipline training would be important, and all involved will have to help build and maintain the initial habitat.<br /><br />Jacks of all trades and Masters of Some would be my philosophy going in.<br /><br />And it's far easier to teach a geologist how to use a wrench than teaching a plumber Geology.<br /><br />The routine tasks post construction will need to be shared by all involved, I would think. And practicality dictates that the fewer people you have will force them to be proficient in more skills as well as scientific disciplines.<br /><br />It would be very risky business to have people only versed in their particular scientific fields.<br /><br />If your doctor dies, then what? If your electrical/electronic tech dies, who keeps the lights on?<br /><br />Remember. This first intrepid group are pioneers. And must be sufficient amongst themselves to not only do the good science, but also be capable of sustaining the biosphere in which they live.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[JonClarke]

Spacester<br /><br />Whose children are at risk? The settlers. I assume they are going to have children, that is part of the goal of settling Mars after all/ The alternative is that you either rotate people through the settlement, which you have already rejecteded, or send a succession of people who will live and perhaps die there.<br /><br />This is where the issue of risk becomes important. With small numbers of explorers on preliminary missions, and to a somewhat lesser extent with a base with rotating crew you can accept a relatively high level of assumed risk. the people concerned know there are risks, are prepared to take them, and are exposed for only a short part of their lives. It is a difference between test flying and commerical flying.<br /><br />If people are going to live out their span on Mars the exposure factor becomes much higher. Instead of a few years it will be many decades. Risks which are low or manageable over a few years become unacceptable of that length of time. For example, radiation exposure for a 2.5 year mission is inside the occupational limits for astronauts. However a lifetime on the surface Mars would take the astronaut well outside the limits. How this is to managed must be developed.<br /><br />Dusts are a particular health issue, a single exposure to some forms of asbestos can cause lung cancers 40 years later. We know that Martian dust is quite nasty. It is corrosive, acidic, extremely respirable, and contains a cocktail of superoxides. It may contain high levels of unpleasant things like hexavalent chromium. The risks must be quantitatively assessed.<br /><br />This brings us to the issue of low gravity. I agree that people will probably be able adjust to this in the short term (a few years) but we don't know the results of exposure over decades. There may be adaption to a base level, there may be continuous decline. We don't know. The same applies to whether or not people can readjust to earth gravity, should they need <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Hi Dan<br /><br />Responding to your numerical points:<br /><br />1) This illustrates my point. We know people can live more than a year in space, but it took decades of research. In fact it went (from memory) 90 minutes, 1, 3 6, 114, 21, 27, 56, 84, 96 days, 5, 6, 7, 9, 11, 12, 14 months. Long term living on mars sill show analogous stepwise learning.<br /><br />2) Agreed<br /><br />3) Agreed - although there are probably easier approaches<br /><br />last point - agreed. This will not be an issue when people know they can live long and useful lives on mars. But until they do I am sure they will want to be able to come back if neccessary.<br /><br />Best.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[chris_in_space]

<font color="yellow"> 3) Agreed - although there are probably easier approaches </font><br /><br />What could be the easier approaches? Making a ship rotate seems quit easy for me, isn't it?<br /> <br />But also I noticed that simulating gravity by spinning the ship appears very rarely in NASA projects, whereas it is very commun in all sorts of SF books. So does anyone know why not? Why do NASA engineers not like this option?