tag:blogger.com,1999:blog-28823501.post1056657070965092766..comments2023-06-19T23:26:32.126+10:00Comments on QuantumG's Blog: Choosing A New Home For HumanityQuantumGhttp://www.blogger.com/profile/17336493213317053535noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-28823501.post-16193311400211004012011-01-07T07:00:39.279+10:002011-01-07T07:00:39.279+10:00Rotating habitat structures (like the looping trai...Rotating habitat structures (like the looping train) are approximately as reasonable on bodies like the Moon and Mars as in asteroids. You just give them a slight slant to add the native gravity to the artificial.<br /><br />It's maybe a toss-up as to which is easier to construct; mining inside a loose-aggregate asteroid might be easy, or it might be impossible (the whole body could just fall apart for all we know). We have plenty of experience with terrestrial mining, which will help in a Lunar or Martian context; the material on a planetary surface will vary, but may not be quite so friendly to tunneling as some asteroids.<br /><br />However, I'd say the presence of lots of nice round holes on the surface of Luna or Mars could be plenty helpful: build a track around the crater walls (possibly in a cutting) and cover it in stone, regolith concrete, or loose regolith over an imported framework structure.Cameronhttps://www.blogger.com/profile/13602720143375847324noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-91436624834738285442010-06-30T16:09:23.039+10:002010-06-30T16:09:23.039+10:00Nathan, the absence of evidence of the reproductiv...Nathan, the absence of evidence of the reproductive success of mammals in non-standard gravity means we have to assume there will be problems.. not the other way around. More simply, until we know it is safe to have kids on other planets we can't make serious choices about where to build our space colony.<br /><br />In regards to radiation, it clearly is a concern as it kills people when they get excessive amounts of it, and slowly kills them even when they get a little of it. Remember, we're not talking about brave astronauts here, we're talking about our children. Mars and the Moon do indeed have plenty of dirt that you could live under, and so do asteroids, and that's why I gave them a score of 1. Earth and Venus, on the other hand, both have *natural* radiation protection and that's why they got a score of 2.<br /><br />Both radiation and gravity on Mars, the Moon and asteroids are "a problem". That you think you've got solutions to those problems does not at all change the fact that they are problems.<br /><br />I believe the net present value could best be accounted for in the metric I called "accessibility". With that included, you could call it "strategic value". The "resources" metric is really a measurement of the potential for growth and self sufficiency.<br /><br />Thanks for the comments.QuantumGhttps://www.blogger.com/profile/17336493213317053535noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-45881136380737820062010-06-30T14:45:50.655+10:002010-06-30T14:45:50.655+10:00Both low-gravity and radiation strike me as somewh...Both low-gravity and radiation strike me as somewhat poor / inconsistant metrics to evaluate entire worlds on.<br /><br />For one thing, it's fallacious to say that humans need full G to stay healthy. We have essentially no data at all on how human physiology performs in low gravity -- our only two data points are full G and microgravity. We know that microgravity has many negative effects, from calcium loss to suppression of the immune system, but it is erroneous to assume that you can simply make a straight-line interpolation from full G to zero G and extrapolate the results from there. Biological systems don't behave that way. Many of the ill effects of microgravity come from fluids not being able to orient themselves, and it is thought that even a small amount of gravity may be enough to counteract this. So you can't simply say that lunar 1/6th G, for example, will be 1/6th better than zero G. It may be, or it may be 95% better -- we just don't know. But it's a very good bet that the health effects of low gravity will be highly non-linear.<br /><br />In the case of radiation, while it's true that most of the surface of Mars and the Moon are bathed in it, it's also true that there are large volcanic caverns on both bodies which form almost perfect pre-made radiation shelters - providing radiation protection on par with Earth's atmosphere - and are likely to be the first colonization sites on both bodies. It's unlikely that asteroids come with such features, so radiation is a more legitimate concern there.<br /><br />So, to sum up: radiation should not be considered a problem on the Moon and Mars, and gravity is unlikely to be a problem there either. Radiation probably <i>is</i> a problem on Asteroids, but artificial gravity should take care of any gravity concerns.<br /><br />As for resources: those should be measured not in terms of their presence but in terms of their Net Present Value, which would account for both the cost of extraction and the value of time while returning them to earth. Deep gravity wells and long distances both count against NPV... but that's a subject for another rant.Nathan Korenhttps://www.blogger.com/profile/16860581086371951026noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-82153112722345854132010-06-30T09:00:14.525+10:002010-06-30T09:00:14.525+10:00I've also reevaluated Venus with some actual d...I've also reevaluated Venus with some actual data and linked to a study. It's now on-par with Earth.QuantumGhttps://www.blogger.com/profile/17336493213317053535noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-17559041216521957082010-06-30T08:07:32.967+10:002010-06-30T08:07:32.967+10:00Clark, done.Clark, done.QuantumGhttps://www.blogger.com/profile/17336493213317053535noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-45346794994075598362010-06-30T07:40:37.141+10:002010-06-30T07:40:37.141+10:00> The question of how much gravity humans need ...> The question of how much gravity humans need to<br />> produce healthy offspring must be answered <br />> before we can seriously discuss the <br />> colonization of the solar system.<br /><br />Really the answer is you need full G to stay healthy. Space advocate folks don't like it, but folks on the ground don't like needing exercise. Given we can pretty well duplicate zero G bio med effects with bed rest. Its the tidal effect on cardio vascular system acting as exercise. Even doing a couple hours of cardio a day in orbit, is less excessive then spending the day siting up watching TV.Kelly Starkshttps://www.blogger.com/profile/07859020384869273575noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-3412658453074574372010-06-29T23:20:22.353+10:002010-06-29T23:20:22.353+10:00You should include large in-space habitats as anot...You should include large in-space habitats as another option. There will be a continuum between non-rotating stations and gigantic rotating O'Neill type of artificial worlds. It's quite possible to consider a sizable but fairly near-term habitat that uses a tether and counter-mass to provide significant spin-gravity if not 1 g.<br /><br />WRT rad protection, I agree that on the near term, simply piling up bulk mass will suffice for surface habitats. Perhaps there will be caves available as well. (In-space habitats can also build up mass over time. Each vehicle that comes to the habitat will leave behind additional material. Waste materials should be used for rad protection rather than returned to earth.)<br /><br />On the longer term, though, there could be more imaginative approaches. <br /><br />For example, water is an excellent rad protection material. (As is any hydrogen rich material. Much better than metals, which produce nasty secondaries.) It also has the nice feature of being transparent. Since water needs to be stored in large tanks anyway, they could be used as walls for habitats. Add windows on the sides and you have sunlight streaming into your living area.Clark Lindseyhttp://www.spacetransportnews.comnoreply@blogger.comtag:blogger.com,1999:blog-28823501.post-42593621493828307482010-06-29T21:20:09.057+10:002010-06-29T21:20:09.057+10:00Hello Trent,
Could be interesting to expand candi...Hello Trent,<br /><br />Could be interesting to expand candidates to far bodies (Titan, Europa...).Gabrielnoreply@blogger.com