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Caliche? On Mars? Are you serious? I have heard nothing about that.
Caliche is a dirty, low-grade limestone from sea-bottom sediments. It's usually a white rock without much structural integrity, and it's usually fractured. It is very hard to dig holes in. Ground finely, that's road base "lime". Calcium carbonate limestone with a lot of other crap polluting it.
If there's really limestones on Mars, then some version of cement is possible. The process here is to grind it up, then heat it. It is energy-intensive to do both jobs.
GW
Hmmm. Too bad nitrogen is in short supply on Mars. Apparently. (There's a bunch on Titan, with a weak gravity well on that moon, although Saturn's gravity well is pretty strong.)
Because, nitric acid and NTO are both decent, easily-storable liquid oxidizers. Liquid methanol is an easily-storable liquid fuel. I'd hazard an educated guess that nitric acid and methanol are hypergolic. Run it fuel-rich, to reduce flame temperatures, at the expense of an increase in the smaller component, and I'd bet you can build piston, turbine, or external-combustion engines of several kinds. There's your rover propulsion.
So, where do we get nitrogen on Mars? Anyone?
GW
Why not start with something do-able, that doesn't depend upon already-solid relations between Russia and the US/Canada. There was a proposal a few years ago to bridge the Bering Straits with a combined rail and pipeline link. So, do it. Include a highway link as well. Bridge, tunnel, makes no difference. Pick one.
Working together on real commerce between them and us is how things might actually get better on the geopolitical front. Already seen it happen with the EU. Consider where Germany, France, Britain and the rest were, between 1900 and 1945. Look at them now. Different!
GW
Awww, I was trying to be nice and let Atlas-5, Delta-4, and Falcon-9 do the job. So, use 2 or 3 Falcon-Heavies (which will fly very soon), or even 1 SLS (if it ever does fly). Probably around 10 ton per module, I'd hazard a guess.
I think you'll really spend more on the modules than on the launchers. And I was trying to upper-bound things, like I said in the post. (Only NASA would actually let it be that expensive.)
GW
For buried foundations, there is "icecrete". It stays cold down there, and the overburden prevents ice sublimation.
All you need is a sieve-bottomed bucket on your front end loader to extract the right gravel from the regolith (you'll need two sieve inserts for lower and upper limits on gravel size). Then a spinning barrel tumbler to round the sharp edges off the gravel. You'll need the rock dust equivalent of sand (two more sieve inserts for your front end loader bucket). And you'll need water. Your spinning barrel tumbler can double as the mixer.
Build closed (self-pressurizing) forms that can hold 5-10 mbar pressure (water vapor atmosphere over the unfrozen icecrete as you pour it, and over the fresh-poured icecrete as it freezes). Then bury the foundation before it sublimates. You're pouring the same kind of "mud" into the same kind of hole there, as we do here when we pour concrete here.
So, what do we use for concrete out on the surface and in the sun? In a non-oxidizing atmosphere without any nitrogen, whose pressure is a first cousin to hard vacuum?
GW
True, true! Well-said, Quaoar! Spacecraft designer's NB: never ever, ever obstruct access to your pressure shell. You must be able to reach and fix leaks in seconds!
GW
Myself, I think it'll be centuries yet before the major nations might begin to unify this world. Culturally, even the most advanced of us are still quite primitive. We all still have the same stone age brains we had 2 M years ago, with all the distorted-perceptions-and-emotional baggage that entails.
That being said, alliances are a thing we can do. Some of us have done it fairly well for a few centuries now. There is something to be said for a North American alliance, and certainly some sort of European alliance formed out of EU and NATO. It would help if we did this without driving Russia and China together. I have no clue what to do with the Third World belt. Most of those nations, if you want to call them nations, are really just warring tribal factions. They're about 3 to 6 centuries behind us.
Inspiration might offer an alternative to naked force at inducing the cultural change in the backward places (where the wars are mostly coming from recently). I saw hints of that with the Apollo landings on the moon. But those advantages were quickly frittered away, gaining humanity nothing at the time. There is an opportunity to try that again with Mars and some other places out there, not so much the moon (false "we've been there" attitude), and maybe the asteroid defense thing.
It's just my opinion, but if we don't start to unify, we will eventually destroy ourselves in one of these idiotic wars. That's the trouble with modern weapons in hands controlled by stone age brains. Fundamentally, that's really why you want a manned space program.
GW
There's little benefit to gravity when you're asleep, or bed rest studies would be no surrogate for microgravity at all. That means you should be experiencing close to 1 gee during daily work and exercise. Less is tolerable for other activities, less yet for sleep. Even zero gee would likely be OK for sleep.
In a design with different decks at different gee levels, I'd put the work stations and gym stuff on the deck with the highest gee, and the supply storage at the least gee, with the sleeping quarters up there near (or at) lowest gee. How much you get depends upon the nature of your design. But go for 1 gee on that lowest deck.
As long as most of the daily work and exercise takes place between 0.8 and 1 gee, I'd bet it's pretty effective. You'll only get zero gee at the center of rotation itself. Even a little bit of gee makes free-surface water possible: that makes conventional cooking and conventional water/wastewater handling feasible (including real toilets and real showers and baths).
Sure would be interesting to dock together a string of modules, maybe Bigelow inflatables, and spin it alongside the ISS as a free-flying "centrifuge annex". Sort of a habitat prototype for a Mars or asteroid ship. We could rather quickly establish answers to (1) how much gee is enough? and (2) how fast is too fast to spin? In a year or so.
Brute force / hard way / worst case cost: maybe 10 to 15 modules 10 m long, for a 100 to 150 m long baton, at longest. At one per launcher, and $80M per launch, that's 0.8B to $1.2B to launch them. If that's 20% of your program cost (rule-of-thumb), your program falls in the $4B to $6B range. That might be "cheap" at twice the price!
We do seem to have strayed far from rover propulsion. But it sure has been interesting!
GW
I second the motion, Josh! Well said.
GW
You could use bottled compressed gas storage on the rover without swapping out welding gas bottles. Just build the gas tanks into the rover, and fill them at your gas plant when you drop by to fill up. That reduces manual labor in a spacesuit, at the expense of higher pressures and storage volume required of your stationary gas plant. This is true for both plain compressed gases, and for pressurized liquids like propane. Just different storage pressures.
GW
Myself, I'd bring examples of all my ISRU gear, and try it out at all sites visited. Chances are, there will be one site where it actually worked the best. That's the one to select as a base, and leave the equipment there, and operating robotically. My concept takes enough stuff to do the basic mission, even if every piece of ISRU fails. That way, ISRU-produced supplies and propellants are a bonus that "fuels" even more explorations beyond the baseline design. That's "win-win with no lose".
That's also why I broke my visit into two phases. The first visits multiple sites, based from orbit, to find that best one. The second phase lands everyone and everything there to establish that base and try it out. Something like 6 months in each phase. I was envisioning a base on Mars, but if Phobos is better for making oxygen, propellants, and water, then that's where the base should be.
I did use something closer to 60 cu.m than 90 cu.m per person sizing out my landers. There's something like 200 cu.m for a lander crew of 3 available as two pressurized decks. The abort capsule looks an awful lot like a manned dragon, with less heat shield but a set of legs. It'll get them down alive, where another lander can go to pick them up. I used shell panels on the lander that fold out to become load/unload ramps. There's a lot of space around the engine compartment on that lowest deck to hold massive amounts of bulky gear and equipment. Load/unload is a serious logistical issue for people in spacesuits.
3 landers on the surface with 200 cu.m each, with the whole crew of 6, pretty well meets the 90 cu.m per person living space criteria for a long (6-month) stay on the surface at the selected base. The double habitat module of the orbit transfer vehicle also pretty well meets the same criterion for the 7-8 month transfers to and from Mars. I had in mind two great big Bigelow inflatables, just with different cores that fold out inside when deployed.
The real trick is not mounting stuff on your pressure shell wall, whether you are inflatable or not. Leave the gear in a fold-out core. That way you can find and seal punctures quickly, before the module can depressurize. That's one of the lessons from Mir, by the way. They could never find the leak, too much crap in the way. So they lost the module. They're lucky they didn't lose a crewman.
GW
Hi Quaoar:
Glad you liked my "landing boat" design. I didn't look at the benefits of mining water on Phobos (or Deimos), but you are correct. Anything not in a gravity well is easier to do. If you have the right equipment with you.
I know there is evidence to support the existence of water at several locations on Mars, and in a lot of small bodies like the Martian moons. The only problem is, you cannot count on it being true, until you've been there and found out for sure. That's "ground truth".
Over the decades, an awful lot of what we thought we knew from remote sensing actually turned out to be wrong. Prior to Mariner 4 in 1965, we thought it was pretty certain that Mars had a nitrogen atmosphere with a little CO2 as a secondary component, and a surface pressure near 85 mbar. Winged airplanes were thought to be possible on Mars. Boy, was that ever wrong!
After 1965, we pretty well believed Mars was rather airless and very much like the moon. Until, we put Mariner 9 in orbit in 1969. Boy, were we ever wrong again! And the history has been like that ever since, just not quite as extreme from one discovery to the next discovery. We're homing-in on the truth. We're not there yet.
Gross features like the weather reports I believe. Atmospheric composition, too. Maybe not so much the inferred subsurface conditions. There's ice (we've seen it), but no one yet knows how much, or how much it can be concentrated or dispersed, or admixed with "other stuff", at any given site. The history of sites here on Earth is wildly different from site to site, even in the same general type of terrain. Why would it be any different there?
And we won't know the answers to questions like that until people have actually been there for a while. Myself, I hate betting lives on answers to the unknowable. So, I tend to take everything necessary from home, until we find out "for sure" that the answer is what we thought, or something different.
That's what I call "suspenders-and-belt, and armored-codpiece" thinking. It's what you have to do to make sure that the crew comes home alive and in decent health.
GW
Mars has a neutral atmosphere, not an oxidizing atmosphere. So it's not about the fuel the way it is here, it's really about the oxidizer. That will be the biggest, heaviest thing you have to carry, by far, on Mars.
If it's oxygen, you're either looking at cryogenic LOX or bottled gas. Of the cryogenics, handling LOX isn't too bad. Breathing oxygen systems have long used a Dewar of LOX as a source. It's easier to get uncontaminated O2 that way, than it is by the O2-producing emergency solid propellants. Those often cause problems. I'm surprised they do it that way, but they do.
GW
Methanol should be relatively easy to make on Mars, if you can make methane. In fact, here, that's the cheapest way to do it: from natural gas, not destructive distillation of wood or waste. Easy to store, too.
But (there's always at least one "but", in this case two): (1) as Josh says, we have no "good" oxidizer for it, and (2) methanol is very poisonous if you get careless with it. A lethal dose can be absorbed right through the skin. It's not the most energetic of the fuels, but it is useful.
The real problem is oxidizer. If you use oxygen, it's either compressed gas or a cryogenic liquid. Not much choice there, either way it's heavy, and the amount you need is large compared to the methanol (or the methane, or the propane, etc).
Now, using it: as fuel-oxygen, or as fuel-oxygen-diluent. The difference is around 500-1000 C in terms of flame temperature, at temperatures pretty close to 2000 C if you have diluent. That's tough to design for, even here. "Air" cooling on Mars would be quite difficult, because the "air" stream has too low a density to hold any heat for you. It's directly proportional to specific heat capacity, density, velocity of flow, and temperature difference. Density is the problem, at 0.7% of what we're used to here. That applies to direct air cooling, and to the final heat rejection radiator of a liquid-cooled system. Either way, on Mars, unlike here, you'll have more heat rejection potential from thermal radiation than you will convection to the local "air".
I still think the most straightforward solution for a chemically-powered rover is something like welding gas bottles of compressed gas reactants. If you have a tank of methanol for fuel, so much the better. But your oxidizer is likely to be gobs of bottled oxygen. Just swap the bottles out each trip. Unless somebody comes up with a better oxidizer idea.
Myself, I'd go for the fuel cell electric instead of a combustion heat engine, precisely because there is one whale of a lot less waste heat to reject under conditions that unfavorable at best. But that drives you right back to LOX-LH2 or compressed gaseous H2 and O2 as the most technologically-ready fuel cell reactants.
GW
Putin's Russia has pulled a fait accompli, occupying the Crimea. They may or may not do the same in eastern Ukraine, that remains to be seen. I doubt very seriously whether Europe will do anything about any of it. That being the case, very little (if anything) the US attempts, will have any effect, either.
The real question is "what's next?" Not being stymied by the west, Putin will likely pull more such stunts, trying to rebuild the old Soviet Union. Now that he has embarked on this path, you can forget Russian help solving world violence almost anywhere. It's more important to Putin to stymie the US (and the entire west), than to actually do anything to improve the lot of Russians, or anybody else.
We've seen this before, many times. The most notorious example is Nazi Germany. But there are many others.
He does have Europe "by the balls" with that natural gas. No surprises there.
GW
Magnesium burns in CO2, producing MgO slag (usually a liquid), and carbon black (a solid). If you run excess CO2, you can get hot gases, too, mostly just CO2, some CO. Hot gases at high pressure are what is required to do mechanical work in an engine of any kind. Solids and liquids do absolutely nothing for you.
Alone of all the old-time "ramjetters" of 1970-1990's, I used to use magnesium for a ramjet engine igniter. In operation, it looked a lot like the silane "sparklers", except the mag produces a brilliant incandescent sheet of flame, burning in air.
I did it with a solid propellant. It was about 20% AP oxidizer, 20% silicone rubber binder, and 60% fine-ground mag powder. This stuff was utterly reliable at igniting fuel-air reactions, with just about any fuel you can think of. As a solid propellant, it was pretty safe, too. We were stretching things to classify it as a Class 1.3 explosive.
I used it for two decades as tiny cartridge-loaded "motors" that screwed onto bosses on our test articles. But I also used exactly the same propellant as a solid gas generator fed ramjet missile fuel about 1976-1978. It worked just fine in both roles.
Sorry, just adding turbidity to an already murky conversation.
GW
Solar, whether thermal or PV, tends to be a "low density" and rather "slow" energy source, here on Earth. It's worse yet further out from the sun. Dunno, might be better at Mercury. 10 times higher light flux there.
What about using solar as a way to derive and store the captured energy in a different form? A form that can be used very rapidly. One example is solar electrolysis of water into LOX and LH2. Liquify them, requiring more energy yet, which in principle could also be solar-derived. Then burn those propellants "suddenly" in a rocket engine, to go where you want to go. That way your vehicle need not carry around all the gear required to make its energy source.
GW
Protesters will find something to protest, whether it is nuclear or not. Most of the time it is just bad publicity. But, it is a reminder to take a good hard look at what you are doing, to make sure that the protesters do not have a valid point. Sort of a double-edged sword, it actually does serve a purpose.
As for NASA, if nuclear materials were not a government monopoly, I'd say screw NASA, just go do it on the moon. Might still be able to do it without NASA if the DOE nuclear materials monopoly could be broken or sidestepped somehow. That will take political action in Congress, unfortunately. They're worse than NASA, by far.
Somehow, we need to develop a new government-business partnership model besides the government lab-contractor model that seems to be so exclusive these recent decades. I'm talking about a seismic shift in the way we do things.
It's been done before. Last time was around 300-400 years ago, though. But if we were to do it that way, NASA would be replaced, by something that might work better for a while. One of my life's lessons is that government bureaucracies over about 30-40 years old stultify into total inaction. There are very few exceptions to that rule of thumb.
As for testing nuclear engines flying out in space: really bad idea. The last century's experience very clearly shows that you need a stable thrust stand for your basic test work. You cannot do that flying in free fall, where every test becomes a vehicle flight test. You cannot isolate the phenomena you are trying to understand that way.
That's only done on a planetary surface somewhere, so that the thrust makes nothing move. I like the moon, because there is no air and water to pollute, no neighbors to disturb, and there are pre-existing crater walls to act as debris catchers when you screw up. And you will.
GW
Why should it cost so much to put stuff on the moon, when a Falcon-Heavy can reach the moon pretty easily, and cost under $100M every launch you purchase (and that's commercial retail!)?
Going to the moon has been billed as super expensive, when it need not be. Does require not repeating Apollo, though. This is no longer 1963.
GW
All we need to build domiciles on Mars, the moon, or the larger asteroids is a cold/vacuum substitute for concrete, and a substitute for tempered glass. That and a vacuum-operable front end loader.
The building is a core with a cap, resembling a mushroom in shape. It sits on a suitable foundation, and is ballasted above with regolith (that is also the radiation shield) to contain internal atmosphere pressures. You "hang" a transparency as a series of columns and panes, all around the perimeter of the mushroom cap. I have such a concept documented as "Aboveground Mars Houses", dated 1-26-13, and posted at http://exrocketman.blogspot.com. This is a concept whose maximum scaled size is limited by strength of materials and the square-cube law effect.
The other is the aquaculture pond habitat, which is an ice-covered pond, in turn buried under regolith to prevent ice sublimation. The overburden weight pressing on the water provides water pressures such that a pressure suit is not required to swim around, only thermal insulation (wet suit or dry suit). You put light and heat under the water to do photosynthetic aquaculture. This concept is not limited by strength-of-materials / square-cube law effects. How many square miles do you want? I documented this concept in "Aquaculture Habitat Lake for Mars", dated 3-18-12, same "exrocketman" site.
Both concepts offer about the same technical difficulty as burying habitation structures, or finding and adapting caves. Both concepts offer far more flexibility as to base location. I kind of doubt the aquaculture lake could be made to work very well in really low-gravity environments. I ran the numbers for Mars, but not the moon. Might work on the moon, probably not on a really low-gravity place like Vesta.
GW
If you can make a fuel such as LH2 or LCH4 on Mars, you can also make LOX. You MUST have water to do that. All you need is a suitable diluent gas to make your engine design practical. There's plenty of CO2 in Mars's "air", all it needs is compression and storage. LCO2 is done fairly readily here.
We've talked about compressing Martian CO2 elsewhere. The first stage needs to be some sort of confined phase-change operation, to get the pressure nearer 1 atm. Once there, conventional compression is quite as easy as it is here. That first compression stage will have huge mass and volume, for a low throughput. That's inherent when your source is first cousin to the vacuum of space (which applies to making LCH4 out of the local "air" whether or not you bring your own hydrogen).
That means this is going to be a batch process, not a continuous-flow thing. You'll not build a silane-CO2 gas turbine feeding directly off of Mars's atmosphere, or any other kind of engine, even if the slag problem has a real solution. You'll instead accumulate fuel, oxidizer, and diluent materials slowly, load them up, and consume them much faster while driving. Turbine, piston, external-combustion, doesn't matter. Just realize that the volume and mass of of the oxidizer and diluent will far exceed that of the fuel. Not any different than here.
That last isn't a real problem. We don't drive around here in cars that carry their own oil refineries, either. But it does impact your planning, and it puts very real constraints on realistic rover ranges. The stationary consumables plant is producing another load, while you are out driving around. But, you must return to refuel. Nothing really hard about it.
GW
So why not test nuclear engines on the moon? Might well be cheaper than doing all the necessary restrictions to do it down here.
GW
The tale about the Canadian RadarSat I find "typical" of big-bureaucracy behavior. It's not just American bureaucracies, and it's not just government organizations. As a rule of thumb, all giant organizations are afflicted to one extent or another. The main symptom to recognize is a level of technical arrogance that is entirely unjustified by the demonstrated level of technical competence.
As for silane turbines: it's reasonably easy to design-out external threats like debris and gunfire. The problem with silane is that the silica slag is generated entirely within the combustor immediately ahead of the sensitive turbine that the combustion gas has to pass through. I'm not saying it's impossible, because you might just do a cyclone separator ahead of the turbine. But it surely won't be easy.
Some other external combustion engine might be done with silane exactly the same way: separate-out the solid slag before the stream reaches the working bits. With piston, it might be easier to handle separations in hot gases a little easier than in turbine. Maybe.
GW
Nice data, RobS. Thanks.
GW
Depending upon where folks came from, there is, or is not, a cultural history of political and personal liberties. Folks from the US and Canada, western Europe, Scandinavia, and to a lesser extent Mexico, have long cultural histories with these liberties at one level or another. Folks from places like Russia and China, very little history of any liberties.
To one extent or another, it is this history plus a desire to be part of something powerful rather than weak, that induces folks like the ethnic Russians in Crimea to want to be part of Putin's empire. Folks in Russia today, and even under the Soviets, had some personal liberties, just no political liberty. But they know nothing better, so for those in Crimea and eastern Ukraine, being part of something strong takes over the choice.
As for Texas, well, the original revolution was conducted by a mixed society of Anglos and Mexicans back about 1835-1836. These people got on very well with each other. There are as many Hispanic surnames as Anglo among the original list of revolutionary heroes.
There was a huge wave of Anglo immigration between 1836 and the US-Mexican War ending 1848. Those newcomers thought of Mexicans as second-class citizens at best, and we have been dealing with the political, social, and cultural fallout from this ever since, sad to say.
But, Texas joined the Union in 1845 primarily to get out of debt, and to be part of something stronger. That's why Texas maps from about 1836 or 1837 look so different from post-1845. We paid off the US with about 1/3 of our territory.
GW