Here's a little something learned about thermal conduction and of radiant barriers, with a lunar as well as Venus application in mind.
This is where having even reasonably good meteorite proof structures becomes rather meaningless dribble if their thermal mode of conduction is intolerable, as in DNA too hot and nasty or too cold and nasty of little value should radiant issues not be sufficiently blocked and/or well managed. Lo and behold, there's good old basalt composites and a few tonnes of JB WELD expoxy coming to the rescue.
The structural value of solid aluminum, say 100 mm worth, may offer a worthwhile barrier to those impacting dust bunnies and micro-meteorites, although per opposing any decent ccm worth of density is where aluminum is not very thermally insulative nor even all that great up against being entirely penetrated, especially if whatever's arriving is making sufficient speed. Plus for aluminum there's the initial task of getting it to the moon in the first place. And, just like in the real world of armor piercing bullets, it's the smaller package that's often better off at getting through, although if that aspect of getting through is only of the initial shell or hull breach, of whatever's left over as fragments upon entering the interior is going to create a bloody turkey-shoot, thus decompression need not be a concern if all onboard are thoroughly pulverised from all the shards of the remaining projectiles and those shards of the shattered composite hull having been relieved of whatever secondary energy. Thus an even smaller micro-meteorite of perhaps 1 mm3 that's arriving at perhaps 1763 km/s is going to be most survivable if it's partially deflected or sufficiently absorbed into the primary composite shell upon initial impact, or otherwise accomplishes a clean through-shot, as opposed to the remaining shards being splayed all over and throughout the occupied bus interior.
Incorporating a secondary interior fragment absorbson barrier of UHMW or of some other self-healing substance could become the final saving grace, though best if there's never a full otter hull breach to start off with, that plus whatever shell deflection and/or the entire bus being shifted off it's track-drives could be adequate as to sustain the occasional 2 kg worth of meteorite which hasn't been slowing down for much of anything other.
Of course, if there's in fact a somewhat more substantial amount of lunar atmosphere to behold, then there's going to be some velocity degrade, and that's certainly a good thing as opposed to the observations and imaging obtained upon those dreadful nights following the Leonid meteor shower of November 1998, whereas the aftermath devastation trail of supposedly mostly sodium atoms (a few tonnes worth of vaporised moon surface debris) that were blasted into space as the relatively tiny meteorites struck the lunar soil clearly emphasizes upon the not such good outcome, especially if your sorry moonsuit butt were situated almost anywhere on the moon. Just imagine if any of those were of 2 kg sized bits of something similar or better than iron (7.8 g/cm3) density, then as for adding in the lunar/Earth 30+km/s with the Leonid Velocity of 70+km/s and you've got a rather nasty head-on potential of exceeding 100 km/s without ever taking gravity into account. Actually that gravity has but a mere 17.38 seconds from the 1738 km altitude which isn't going to relate to making the situation much worse off by way of adding another 18 m/s.
For argument sake, lets just say if we were not having to deal with any renewable/solar radiated heat source (such as being the case for lunar periods of night and/or of earthshine, as well as for the Venus season of nighttime), the conduction mode R factor of a perfect vacuum by itself can obviously be in excess of 256 if not as great as 512 per inch by way of introducing those thin layers of IR blocking molybdenum and titanium nitrides. Though a barrier of basalt/glass or ceramic like spheres most certainly also makes for a fairly efficient radiant as well as a terrific conduction barrier, especially if there's hundreds or perhaps thousands of those little suckers aligned between whatever is too hot/cold and yourself.Aerogels use this low density technique for obtaining an R-50 per inch or R-1968/m, although aerogels are not of great thermal range, but otherwise quite spendy and hardly the least bit structural, much less of representing any radiant barrier whatsoever, thereby aerogels will not impede much of anything unless it's of merely vibrating/spinning atoms of thermal conduction, or of other relatively low density physical fluff instead of the usual item being a particle or shard of basalt, iron or speck of somewhat greater than silver density that's arriving at 30+km/s.
A perfectly valid reason why radiant barriers must be included, and as for their being so effective in a vacuum such as outer space, is that vacuum or of whatever outer space in of itself only prevents the conduction transfer of heat in any way other than radiation mode. This is often where there's been some confusion about atoms of fewer electrons and protons that are supposedly not considered nearly as good of insulators as those of xenon or even CO2. However, if we give those few H2 atoms contained within their individual abode that's in the form of a microsphere (each microsphere shell acting much like an extremely heavy sort of element atom), then to utilize many such microspheres as for creating a barrier opposing thermal conduction as well as radiance is ideal, and especially if that's still somewhat structural. Lo and behold, without having to import hardly anything from Earth we've got ourselves that internally structured sort of physical barrier that's now capable of achieving great resistance to thermal transfers while not adding all that much density unless we desire it, yet a basalt composite retains a great deal of resilient and/or physical energy absorbson capability due to the structured cellular and fiber composite aspects of what the LM-1 bus hull can easily deliver.
I do believe the benefits of maintaining most any good zone of structural cellular vacuum can and should be effectively introduced as just such an artificial in-between zone comprised of micro-balloons or microspheres containing as little H2 or of whatever gas as possible, thus the conduction mode is essentially broken much like the aerogel, with the least possible mass except for those conductive atoms of each basalt microsphere shell, of which there should be at least 100 such spheres per 25 mm, each contacting one another by as little as 1% without any binder, and perhaps 10% with a thin binder. Though even a 100% JB WELD like epoxy surround isn't going to eliminate the bulk of thermal resistance, though it's sure as hell going to make whatever damn rough.
Using as an example; 100 spheres interfacing at 1% contact each is hardly going to offer all that much thermal conduction, as even if those 1% physical contacts from sphere to sphere were individually to somehow wildly conduct by as much as 50% (R-2), whereas the end result becomes a rather pathetic amount of conduction, or lack thereof, as well as hardly any residual radiant mode to speak of. Utilizing natural processed basalt as to accommodate this feat is certainly a thermally stable alternative to just about any composite structural and insulating alternative one can think of, and that's certainly another fact that's not even rocket science.
Obviously the lunar environment seems to more than fulfill the nearly absolute vacuum criteria, whereas on Venus that similar affect of achieving good vacuum would have to be artificially created, as well as such buoyant substances structurally contained, less it'll quickly float away due to the rather horrific buoyancy created by even a partial vacuum of 0.1 bar. What ever you do, don't even get me started on Venus atmospheric buoyancy, as that's been yet another can do consideration upon facilitating those nifty rigid airships cruising nicely through their crystal clear surrounding ocean of mostly CO2, even as per obtaining altitude above those relatively cool nighttime clouds is another fact that's not rocket science, more like airship physics duh-101.
As for one alternative method of creating and sustaining an artificial vacuum for a toasty Venus environment, this is accomplished by having a suitable zone (structured void) filled with said microspheres, each of those spheres filled with perhaps as much as 0.1 bar worth of H2 instead of the 75 bar worth of mostly CO2 that's existing at the elevation of 5 km, though a 0.001 bar containment of H2 seems certainly doable, thereby the number of thermal conduction atoms per sphere interior are reasonably low, perhaps not 1/1000th that of the surrounding atmosphere. Each presumably basalt sphere representing by far whatever remainder of thermal conductivity, though if these spheres are numerous as well as surrounded by absolutely bone dry N2, and their physical contact between adjoining spheres is representing less than 1%, the thermal conduction mode has certainly become minimal.
BTW; even the component of CO2 that's CO, as a remainder that's extracted once the CO2-->CO/O2 process is accomplished, as the pure CO element is another perfectly good candidate for being within those spheres as not. This composite would obviously work quite nicely for all those TBI to death Mars missions that Dr. Zubrin thinks are of the morally right sort of thing to be investing hundreds of billions if not trillions upon doing. That way when they're all failing by way of receiving too much EVA radiation as well as for their dosage of just getting to Mars in the first place, at least they'll remain warm and cozy up until the very end.
Radiant barrier wise, the relatively low emissivity of basalt spheres of 250 nm or less diameter should each react as an effective micro unit of thermally reflective barrier, whereas a whole, every 10 mm worth of spheres might offer as much as R-32 if those spheres were surrounded by N2, and perhaps better than R-64 if surrounded by near vacuum, such as per what's supposedly existing on the moon. Thereby the amount of layer depth of said microspheres need not be all that great, leaving the remainder as a rather high density composite of basalt fibers and JB WELD epoxy.
If need be, basalt microspheres of a maximum of 250 nm diameter could even include an element or coating of or internal and/or external deposit of titanium nitrides, further reducing their emittance factor, thus sustaining their structural worth without diminishing their radiant barrier potential.
If those spheres were to be contained between structural panels of composite basalt, as for the lunar application of a 100 mm thermal/structural barrier comprised of a basalt composite outer and inner panels or shells, having the volume filled between with the basalt microspheres displaced with not more than 0.001 bar of internal H2, would likely exceed R-512. The hot/cold lunar environment of +250°F down to -250°F is exactly where the R-512 will come in real handy, even though the LM-1 unit could apply a conventional circulation of fluid that should help to neutralize the imbalance during typical EVAs, there's still no substitution for having as much thermal barrier potential as possible, especially since the thermal barrier can offer rather substantial structural as well as remaining entirely passive, of taking no further energy nor technology as required with fluid circulations.
Basically, we're talking about establishing a thermal barrier for minimizing conduction mode as well as a structural product that's internally blocking radiant transfers, thus effectively achieving a great deal of R-factor per volume. Obviously the thicker the basalt composite panel, filled between with spheres containing H2 is going to become structurally impressive, as well as the next best thing to using an absolute vacuum along with the sorts of radiant barriers such as the (GSC-14386) blankets proposed by NASA, as of those recently engineered by Michael K. Choi. I'd thing a GSC-14386 outer blanket could become a necessary part of this metro EVA bus, as basalt composites are generally of dark (near black) surface, thereby some genetic form of outer reflective coating and/or blanket would become a part of the package.
For one other significant worth about those basalt microspheres; External pressures exerted upon them by having their interiors at vacuum, as well as for whatever be the surrounding pressures that could be imposed upon them, is not even a factor, as the resistance to crushing and/or implosion is rather enormous, thus no practical limits exist as do with aerogels and, certainly there's little if any temperature limitations for the lunar and/or Venus applications. In addition, extremely thin chemical binders could essentially create panel solids comprised of such basalt microspheres, therefore the absolute best of both structural as well as thermal barriers is being accommodated.
Creating The Lunar Metro EVA Bus (LM-1)
Since the lunar environment is fully and continuously exposed to micro and larger meteorite impacts of 10+km/s, the survival aspect needs of a mobile lunar bus intended for extended EVAs is rather imperative that at least the outer shell become considerably impact resistant, as well as affording a suitable thermal barrier. Fortunately, basalt composites will easily accommodate if not surpass this criteria, even if that requires the outer shell portion of the LM-1 as being of at least a solid 50 mm worth of basalt composite that's making up the external structure and subsequent density of outer shell, plus another 25 mm volume of those basalt microspheres plus the interior shell of solid composite of 25 mm into representing an overall 100 mm thick structure, achieving an overall density of perhaps as little as 250 kg/m2.
Basalt Continuous Fiber Mechanical Properties
Raw Basalt fiber 2.7~2.8 g/cm3 or 2700~2800 kg/m3
Tensile strength MPa = 4840 (4.84 GPa)
Elastic modulus: GPa = 89
Elongation at break: 3.15 %
JB WELD (epoxy) Properties in lbs/psi (MPa)
Tensile Strength: 3960 (27.3 MPa)
Adhesion: 1800 (12.4 MPa)
Flex Strength 7320 (50.5 MPa)
Tensile Lap Shear 1040 (7.2 MPa)
Thermal Resistant to 500ºF / 260ºC
Density: 15.8lb/gal (1.87 gm cm3)
Basalt/JB-WELD(30%) matrix/composite = 2486 kg/m3
Basalt/JB-WELD(25%) matrix/composite = 2530 kg/m3
Basalt/JB-WELD(20%) matrix/composite = 2574 kg/m3
Basalt/JB-WELD(15%) matrix/composite = 2618 kg/m3
Basalt/JB-WELD(10%) matrix/composite = 2662 kg/m3
If we're talking about a basalt/JB-WELD(20%) matrix/composite = 2574 kg/m3, then the portions of wall or shell thickness of .5 meter is going to amount to a density/weight of 1287 kg/m2.
Somewhat dependent upon shell/hull configuration, if the largest of the LM-1 outer shell/hull dimensions were 5 x 20 meters = 250~275 m2 of composite.
Less critical portions of this LM-1 hull could be of 0.25 m thickness (such as the bottom portion) being of 644 kg/m2. However, the shell/hull and associated track drives alone could still represent 400 tonnes. Plus outfitting along with a few tonnes worth of h202/c12h26, 30+days worth of O2 for the crew, other essential provisions (beer and pizza) and crew itself might represent the overall 600 tonnes.
600 tonnes worth of any fully loaded bus may sound like a great deal but, this is only 100 tonnes as for residing on the moon.
Just for another example that's a bit smaller (SUV like); If this entire mobile bus (LM-1) were to require 48 m2, obviously the primary composite shell would contribute 12,000 kg (12 t). Add the machinery, fuel, provisions and crew aspects (plus the all essential beer and pizza) and we're likely to be exceeding 36 tonnes, which is 6 tonnes per lunar gravity, creating roughly 2 tonnes per track drive if three are utilized. For simplifying the math; If each track were .5 m by 2 m, obviously that's representing 2 t/m2, or I believe as little as .2 kg/cm2.
Obviously a fully configured 48 tonne LM-1 bus is within the cards, as that's still only 8 tonnes worth of machinery having to be track driven about, thereby it's certainly worth considering a 96 tonne machine as a mere 16 tonnes worth on the moon that may require somewhat additional track drive area. Fortunately the basalt composites for creating this sort of lunar bus is already on location, entirely doable from the raw lunar surroundings, with the exception of chemical binders that can be robotically delivered in relatively large quantities from Earth, as otherwise the process energies do exist in sufficient amounts for converting raw basalt into the sorts of fibers as well as microspheres.
Lunar radiation barrier wise, the 25+g/cm2 worth of density offers way more than what's adequate for those TBI nasty but well illuminated earthshine outings, and still remaining sufficient for limited solar illuminated EVAs. A thicker foundation of basalt composite could surround the essential crew cab as comprised of heavier elements, if need be of incorporating uranium fibers as delivered initially from Earth could be included so as to easily exceed a density that should provide for whatever the task demands. This much added structural density is also a rather important improvement in integrity issues, highly beneficial for fending off those micro and not so micro meteorites that are bound to strike the LM-1 upon nearly very outing, if not hourly.
Even if this sounds all perfectly fine and dandy, what I'd like is some of your feedback and/or support, as I'm not funded nor as qualified as some of these words might indicate. I'm essentially connecting various dots of information, learning from others and by way of deduction, and of extrapolating upon certain applied technologies, compressing all of that data into what I believe is doable within existing technology and by way the expertise of folks such as yourself.
Another page I've recently updated that includes other matters pertaining to certain other benefits of the lunar metro bus (LM-1) is worth a glance, though I'll likely condense both of these pages into a book chapter that's hopefully better composed and offers meaningful calculations to boot.
It's probably true and thereby boring that there's never been a civilized community of folks surviving on the moon before (although as traveling within is still up for grabs), perhaps not even as panspermia microbes. Even being more so than Mars, since the galactic/cosmic irradiated surface is what the moon represents, that plus a terrific sort of meteorite morgue that's only been further solar flak bombarded ever since the beginnings of it's arrival into our solar system or frame of existence, whereas is seems rather downright odd that those Apollo astronauts were being isolated rather than receiving the necessary transplants of their own banked bone marrow, as for such if any lunar spores of truly horrifically TBI microbes should have been quite sterile to say the least.
Thus the focus of media attention (focused and being funded along by all those spendy NASA infomercials), whereas just about anything lunar or even Venus hasn't a chance in hell against the potential of uncovering the remains of past civilizations that once may have utilized Mars as their home or go-between habitat while there was a sufficient influx from Sirius, though for darn good reasons of being so easily pulverised and sub-frozen to death left that home away from home none too soon, and of those that didn't were summarily pulverised by meteorites and/or intentional WMDs in the form of meteorites, and then summarily frozen dry as well as irradiated to death long before their DNA/RNA could compose upon any workable alternative. As for going underground wasn't all that much of an option, unless a substantial geode pockets could have provided the necessary shelter and resource of energy that simply hasn't been detected anywhere near the surface.
Fortunately, for those I'd like to believe are the Cathar lizard folk of Venus, their demise isn't necessarily as over with as our esteemed wizards might like to think, as in terms of geological as well as evolutionary time was on their side, as well as having such a terrific radiation and anti-meteorite shield surround plus such an abundance of energy resources to boot is more likely than not responsible for such individuals surviving their present day greenhouse, and that's even in spite of their being situated nextdoor to the most pathetic and arrogantly populated planet of dumb and dumber folks in the entire universe, of which Earth has clearly become way more of a threat to itself than of any other planet.
Of course, all of this insight and discovery is worth a whole lot of squat, especially if there's no other qualified takers, whereas I'll eventually have to accomplish everything and as such I'll be assuming the vast majority of all the credits for doing just that. Meanwhile, the remainder of this pathetic Earth will have to contend with numerous resident warlords, as well as all the ongoing and soon to be tit for tats that'll become those future 9/11's and of far worse things to come. Just imagine what's going to transpire if our resident warlord (GW Bush) receives yet another green flag.