You are not logged in.
Those are all good ideas.
Actually, doffing and donning a compression glove in a multipiece MCP rig is not all that hard. It's like donning thin tight rubber gloves, then pulling a zipper up the back of your glove to increase the compression.
For most purposes, there would be little need to doff the compression gloves. These are about as supple as wearing thin tight rubber gloves down here. But, if I was trying to install a bunch of tiny machine screws with a dinky little screwdriver, or tap a drilled hole down in the 1/16 inch range or smaller, I might have to doff the gloves, given safe handling temperatures.
GW
For nuclear engines, I have often said in other threads that the best place to test such things is on the very near-by moon. Testing any kind of rockets requires a stable thrust stand where you wring it out before you ever consider flying.
Solar PV power is possible in large sizes. The shuttle bay was 65 feet long (about 20 m). The insides of those doors were a solar array, rated at a max of 25 KW. That's now an older design, but it still gives you a notion of the size of the thing vs its power. (The second layer of door panels was the waste heat radiator.)
I quite agree that the politicians are completely perfidious and behave nonsensically with respect to space, to nuclear, or to any other science or technology issues one cares to name. They won't change until we hold them responsible for what they have done, and have not done.
GW
For a rocket-burn landing, that's what we did on the airless moon. It's exactly the same as a gravity-turn ascent, just done in reverse.
Now, on Mars, there's enough atmosphere to be a heating problem, both ways. What speed you will be going when you hit atmosphere depends mostly on the altitude of your parking orbit. So, park fairly high to reduce speed at entry.
Hit the sensible atmosphere well into your gravity-turn-in-reverse trajectory, at speeds well below the orbit speed. You'll do canted burn with assistance from heat shield aero drag, then canted burn with assistance from a parachute (or series of chutes) once you're below about M2.5-ish. Then canted burn to touchdown. I think that's what they're really going to do with one-way Spacex Dragons on Mars.
The point is to use aero drag to reduce the thrust required during what is otherwise a continuous-burn descent. Reducing thrust reduces propellant demand. It's not a huge effect, but every bit helps. There's no such help during ascent, but there is also no need to cant the engines. Even during descent, once the hypersonics are over, there is no need to cant the engines. Straight-axis thrust eliminates the cosine loss.
Now, the instability of straight-axis thrust with the jet straight into the oncoming hypersonic stream is a real problem. Whether computer-controlled attitude thrusters can cope with it, well, some experiments need to be done. My intuition suggests it is possible, but your attitude thruster system needs some real force to it. If it could be done, the need for canted propulsion engines during descent disappears.
For the delta-vees needed to do this job on Mars, either as a one-way descent vehicle, or as a two-way lander, "reasonable" mass ratios and the rocket equation generally seem to rule out chemical Isp's, except as staged vehicles. What is "reasonable" for mass ratio? Well, that depends on whether the vehicle is to be used once, or many times.
What we are used to building is one-shot throwaway rocket stages, for which inert fractions in the 8-10% range seem feasible at this time. Maybe a tad higher for those with heat shields and landing legs, say 10-15%.
A reusable vehicle, on the other hand, needs to be tougher than an old boot in order to take the abuse of repeated spaceflight entry conditions (and they are very abusive, even on Mars). I would point to airplanes, which are very reusable flight vehicles. Transports and bombers for decades have been in the range of 40-50% inerts. So was the X-15 rocket plane (40% inert).
The lander we are discussing in this thread is not an airplane, and likely has no wings at all. It's a different structure. But I would hazard a guess that a reusable "landing boat" vehicle would have an inert fraction closer to the 20-25% range than anything we've seen in prior rocket vehicle designs. It's simply not strong if the material isn't there. And that material has a weight to it.
So, that's what brought me to the nuclear rocket technology for a single-stage two-way Mars landing boat: about 20% inerts puts you into a simple tradeoff of payload fraction vs propellant fraction. At Isp 400-class, I couldn't solve the problem single stage. At Isp 1000-class, I could, and with an out-of-plane capability to boot. That's solid-core nuke, something we know we could build, because we did it before.
Now, in my design study, I did not cant the engines, I only had one. But I could have used 3 or 4 small ones instead. Those could be canted slightly on descent at a cosine loss, and gimballed straight on ascent. I'd fire through the heat shield from near center. It simply lays out better as a big conical vehicle that way, with a cockpit near the tip of the cone, away from the radioactive stuff.
Anyhow, that's my two cent's worth.
GW
I think I'd take the bikes and a big rover with a drill rig on it, pressurized or not. But I'd go with MCP suits, either way.
I'd completely divorce the vacuum protection from all the thermal and mechanical protection. The MCP rig is just vacuum-protective underwear plus a gas breather helmet. You wear then ordinary coveralls, ordinary hiking boots, ordinary leather work gloves, an ordinary wide-brimmed hat (on top of the helmet), or whatever is required. Doff what you don't need, whenever circumstances warrant.
With an MCP suit made of separate pieces (one-piece union suits make little sense to me since they hold no gas pressure), if dirt temperatures are between around -10C to 45 C, you can doff the work gloves, and the compression gloves, and thus handle dirt and rocks absolutely bare-handed on Mars (or in deep space) for up to about 10+ minutes at a time. That limit requires you re-don the compression gloves before swelling (tissue edema) sets in. The old experiments seemed to show significant pain and swelling in hands, starting around 20 minutes of exposure to vacuum.
Can you imagine being able to do fine electrical, plumbing, or mechanical assembly work in LEO with a suit like that? All you need is an unpressurized bay inside a an enclosure, with enough lighting power to bring the workpieces up to a range where you can touch them barehanded without frostbite or burns (-10 to 45 C).
Wow!
GW
Oops, sorry if I insulted somebody. Didn't mean to.
I'm already very sure the crudely-45 degree canted Super Dracos will work during entry anywehere, because the thrusters on all the capsules and shuttles we ever flew worked. Effectively, they're canted thrusters, too, just different angles. It's only right into the airstream that's unstable.
Somebody asked why you couldn't reduce velocity before entry. You can, it just costs a lot of propellants. With chemical rockets, the Isp and practical mass ratios limit you to using as much aero deceleration as you can get. With solid core nuclear, you just begin to get into the regime of Isp at which you can reduce velocity before entry, and still maintain a decent mass ratio.
Advanced gas core nuclear concepts do even better, but we never built any of those, just solid core. And we quit even that in 1973, right before we were to fly them. The guys who did it are mostly dead now. But I met 3 survivors last August. They're in their 80's now. The "engineering art" dies with them.
Solid core nuclear is enough to rocket-burn to landing from low Mars orbit, and still rocket-burn back to orbit, in a single stage vehicle of "reasonable" mass ratio. In other words, we could build a single-stage, re-usable "landing boat" out of that technology!
Send one lander and a lot of propellant for it, and make many landings with it, refueling in orbit after every trip. I was looking at 10% payload, 20% inert structure and equipment, and 70% propellant (liquid hydrogen), for the round trip, at 30-degrees out-of-plane maneuver both ways! 60 ton lander, 6 ton payload. Wow!
Do you like that prospect? I sure do.
GW
RobS:
Sure, the canted thrusters will work. That idea worked very long ago for the tractor rockets of the escape towers on Mercury and Apollo, and also for parachute delivery of very heavy items like tanks, with last-second rocket braking. It was the Soviets who actually fielded this parachute/rocket braking.
If one is using a descent trajectory that involves at least some rocket braking (so you can steer arbitrarily) during the hypersonics, then precision landings become possible, regardless of the atmospherics. The missing piece is a radar transponder to home-in on. Once a first landing at any given site has been made, that is how one precisely guides subsequent properly-equipped vehicles down to exactly the same site.
GW
I am guessing that, in part, that is why the Super Draco thrusters on Dragon are canted roughly 45 degrees off axis. You "heat shield it" partway through re-entry, then burn to make sure you're down to around Mach 2 (that's a ribbon chute limit, it's actually closer to Mach 2.5), deploy a chute, then chute plus thrusters to land. Or just thrusters to land.
Dragon is a one-way vehicle to Mars's surface like that, so we're likely talking unmanned probe or cargo carrier. The canted thruster plumes avoid most of the hypersonic instabilities you spoke of.
The other reason they are canted is for launch escape service on the manned version of Dragon. Match made in heaven. I like well thought-out systems.
GW
Louis:
I sort of disagree about the living space requirement. Bigger really is better, ask any prisoner who ever served time in solitary. But, inflatables really make the best sense, provided access to the pressure shell is unimpeded by the equipment inside. You have to be able to patch leaks very quickly. There have been some hints about cramped living from the old Salyuts, Mir, and even the ISS. But not from Skylab. Too little space we already know is very bad from Gemini 7: 2 weeks of a 3 week plan nearly cracked that crew up (I know that was really, really, really cramped, though).
I agree with using a modular transit vehicle. I had slightly-modified Dragons as crew return vehicles in the mission design in my paper last August, at the Mars Society convention in Dallas. My transit vehicle was a stack of propellant modules, a nuke propulsion module, a 3-part habitat module, and two crew return Dragons, for a crew of 6. It was a long stack, so you could spin it end-over-end rather slowly for artificial gravity. (The landers went to Mars with all the landing propellant as separate vehicles. They were single-stage, reusable nuclear.)
GW
Josh:
The MIT design is being forced to achieve a design target of 1/3 atm compression. They cannot meet that goal yet.
But they could easily meet Paul Webb's 190 mm Hg level.
The 1/3 atm goal (about 253 mm) is unrealistic given the materials we have, and further, it is unnecessary, given what is actually needed for life support (actually a bit less even than Webb's 190 mm, you only really need somewhere between 152-190 mm.)
GW
Practicality of a supple MCP suit? Yep. We already know it works.
Look at the 1969-vintage video of Paul Webb's elastic spacesuit tests way back then. The test subject was riding a bicycle ergonometer (at high effort level) for an extended period of time in an MCP rig, in a vacuum tank, at a simulated 87,000 feet (way above the "vacuum death point" for an unprotected human). He was sweating right through the MCP garment into vacuum, so he needed no cooling system other than his own biological one.
Webb did that with a breathing helmet and tidal volume bag, a bag restraint jacket, pure O2 at 190 mm Hg total (absolute) pressure, and a garment made of 6 layers of the then-new pantyhose material. The whole rig, including a liquid O2 supply, weighted 85 pounds total. Most of that was the helmet and O2 backpack.
Yeah, we can do this. We could have done it years ago. We could have done it decades ago.
GW
Falcon-heavy will launch 50-53 ton payloads to LEO from Canaveral. We built the ISS with 15-25 ton payloads in the Shuttle. Assembly is not a problem. Cost will be, once the payload size threshold for practical assembly (25 ton) is crossed. Falcon-heavy is projected at $800-1000/pound of delivered payload.
Do you really think a government heavy-lifter will ever be that cheap? (I don't.)
If so, please tell me why, when shuttle was $1.5 billion for 25 tons. And Delta-4 is way above the competition curve between Atlas-5 and the Falcon family. Falcon is the better choice, by the way. I posted that data on "exrocketman" a little while back. It's a strong function of payload size, but flattens some as you get into the 20 ton + range.
If not, then why do we need an expensive 100-ton lifter when 2 cheap 50-ton lifters will do the same job?
GW
The reason I asked the questions I did is the history of government behavior re: space since the space race ended with Apollo 11. You don't get to do what's smart because no one wants to spend the money. You actually get to do very little in the way of missions.
Private corporations are largely even worse: they invest in nothing that's not near-term profitable. Musk's Spacex launcher business is exactly that. His Mars dreams are the exception to the rule. I cannot name one other.
I rather suspect the US government (probably partnered with the others) will support 1, or maybe 2, trips to Mars with men, and that will be it. No more. Period. All else is fantasy.
The prospecting and resource development you spoke of, and the real exploration that makes it possible (that I keep yammering about), will have to get done in those 2 missions, or else no one will ever have the necessary info to successfully locate a survivable settlement! You can't turn over rocks peering down from an orbiting robot, that's just not good enough.
We do not have the resources or the opportunities to go there and do these things in too-small a way on each mission, because there won't be enough missions to get it all done that way. It's going to have to be just about all-or-nothing, on each mission.
A smart plan responding to a financial squeeze like that would be a multi-landing exploration on the first mission, based from orbit. The more sites (identified from all these probes) the better, and concept prototypes for ISRU also get tried out as experiments. That was the gist of my paper at the Mars Society convention in Dallas last August.
The second mission visits the best one (or at most 2) sites, as verified from the first mission, but is based on the surface, located at that one site or two. That mission does the heavy-duty prospecting and tries out engineering-prototype ISRU equipment identified as promising from the first mission.
Then, later, if "somebody" decides to fund a permanent base or settlement of some sort, it'll be the best one of those sites verified by the second mission. That's about where Musk might jump in, in the lead role. And if he is successful, others might follow. But the governments will not. They never have. Never will.
"Cassandra has spoken" (and her news is never good)
GW
Rails, like any beam gravity-loaded on top, typically resist the worst heavy bending loads between the crossties, and the worst shear as low-to-moderate shear forces at the ties. The support case is continuous span across many ties, not the "simply-supported beam" case.
Bending is tension in the "fibers" away from the loaded side (on the bottom), and compression in the "fibers" close to the load (on the top). Up to the elastic limit, the stress distribution is linear between the tension and compression extrema, and zero at the "neutral axis" somewhere in between. Once you exceed the elastic limit, another more complicated model applies, plus you permanently bend the beam.
You're going to need a shape that takes advantage of tension resistance (the bottom flange) and a stable compressive column (another flange in most I beams, the rail cap in RR rail), and a thin web continuously-connecting them that resists the shear. Rails are just modified I-beam shapes, configured to match up with flanged tapered wheels.
For use this way, the material requires considerable tensile strength. That's why we like hardened alloy steel for RR rails (nope, it's not just plain carbon steel, it's extremely tough to withstand the heavy pounding and the wear). In metals, shear strength is usually around 60+% of tensile test strength. In other materials like rock fiber and crystals, nope. The compressive strength comes from the stable column geometry, not the true material compressive strength.
Concrete (and similar) materials are strong in material compression strength, and have some strength in shear, but are very weak in tension. That's why we add reinforcement of good tensile strength, and high stiffness (!!!), to make concretes that can take some bending. These reinforced concrete materials get used mainly in compression columns and foundations with compressive loads, and maybe a little bending and shear, but only if reinforced for it, like erectable wall panels. The extreme case is the pre-stressed concrete bridge beam. Very complicated reinforcement.
In a composite like a reinforced concrete, you have to pay very careful attention to how much of each material is present, and how stiff each material is (Young's modulus and some geometry). The stiffer one wants to pick up more than its share of load first, and may fail before the other component can even load up. The details of actually doing that kind of design analysis are neither simple nor easy.
With metals like steel and aluminum, you also have to consider how many times the structure gets loaded ("fatigue"). On a log-log plot, the load level vs cycles-to-failure is a descending linear line, down to a fatigue limit stress, where the line is horizontal, no matter how many cycles. That fatigue limit stress is way below the tensile yield stress, and way-to-hell-and-gone far below the ultimate tensile stress for the material.
The fatigue limit for steel is typically a bit higher relative to its yield than with aluminum. That's why we build things that don't have to fly out of steel way more often than we do with aluminum. Things that fly, the higher strength/weight of aluminum is better, unless it gets too hot.
Concrete and organic composites (and wood) are quite different from the metals. Concrete life is limited by weathering of the surface and corrosion of the internal steel reinforcement. Shrinkage and weathering cracks are inevitable; that's how water gets in to do its evil corrosion work. Organic composite life is limited mainly by UV damage or simple impact damage. Wood life is limited by wet or dry rot.
All suffer nuclear radiation damage, but it really does take quite a lot.
GW
Given a supple MCP suit, I don't see why not. Just use fat balloon tires that are very tough to resist sharp rock puncture. Pressure can be quite low, just 3-6 times local atmospheric. Won't be easy riding in rocky dirt, but the fat tires make it a lot better. The fatter the better.
If they go with the gas balloon suits, no way. Need at least a tricycle, but a quadricycle is more stable. Trouble is, the more wheels, the more drag in dirt (it's also plowing forces, not just rolling friction). Puts you into needing a powered vehicle very quickly. But if you fall over, it's likely you will puncture the suit.
Suit puncture or tear is not much of a problem with MCP, especially if you have a vacuum-rated duct tape.
GW
Elysium 0 lat 155-160 long sounds like a pretty good site for the first manned exploration trip. Need a geologist-type to go prospecting for the ice, the lava rocks, the iron ores, etc. He'll need a real drill rig, too.
I'd bet you've got a least a dozen similar such sites you could make very good arguments for. Maybe a lot more than that.
A smart first manned mission would visit all of them, and leave transponders. It's a lot of trouble to send men that far. Why just make one landing?
GW
I think you have to consider what you can actually accomplish with 1-3 astronauts landed (hopefully not a one-way suicide mission) at one single site on Mars, and maybe just barely enough gear to go home. This matters little whether the return gear is prepositioned, locally produced, or carried with them.
Your not going to accomplish very much beyond flag-and-footprints and a couple of tow sacks of surface rocks. Even if you have a rover, the surface sampling will only be a few dozens of km apart. That's basically the same model as we used with Apollo going to the moon, and, in hindsight, that never really "explored" the moon.
It's been the probes since Apollo that did what "real exploration" we actually have accomplished (on the moon and on Mars). Exploration fundamentally answers two deceptively-simple but difficult questions: "what all is there?" and "where exactly is it?". A lot of the stuff we'd like to find is buried deep, sometimes very deep. And it is never, ever uniformly distributed.
I haven't seen in any of the Mars mission proposals, even Zubrin's, anything that addresses doing real exploration. Not in all these years since the "battlestar galactica" concepts first dreamed up in the 1950's.
But "real exploration" is exactly the prerequisite for siting bases, prospecting, and eventually establishing permanent settlements. You cannot utilize local resources effectively until you answer those two questions. And it is not easy to answer them. Some can be done by robots, some of it must be done with men. That's just life.
Mars is a lot farther away than the moon. For a robot, that's no problem, for humans it is. I have not seen since Skylab in the 70's a habitat spacious enough to support a mentally-healthy crew for the 2+ year round trip to Mars, with the kind of rockets we have.
And nobody seems to want to face up to the need for artificial gravity, either. The only spinning designs have been "battelstar galactica" concepts from NASA mostly, or else complicated nonrigid cable things that cannot be course corrected without disassembling everything.
It doesn't need to be that way. But, you have to give up the Apollo flag-and-footprints model, and you have to face up to the question of safely sending healthy people all that way, and getting them back alive. That is not done with a minimalist approach. It is constraint driven.
Those constraints are a time limit of 1 year to endure zero gee, cosmic radiation near the tolerable limit but that we can't shield and that will be a career limit in one round trip, solar flare dangers than can be shielded, and the need for a Skylab volume for 3 (to no more than 6) men that is not jammed full of stuff either.
Back to "real exploration": it's a very long trip to Mars. If we're going to all the trouble of sending men there, then why not plan on more than one landing? Really do a proper sampling all around the planet. That's not a minimalist design, but it need not be "battlestar galactica" either.
And once you're past the 25 ton shuttle payload, anything you send can be assembled in LEO from docked payloads. It's the lowest cost per payload mass that counts. Falcon heavy is 53 tons at $800-1000 per pound. So who needs a gigantic launch rocket?
Just some things to think about.
GW
Man, I dunno about all the thermonuclear fusion reaction stuff. I'm a aero/mechanical engineer, not nuclear.
But, I do recall from reading the old writings of the Los Alamos team that setting off atmospheric fusion was initially of concern for the Trinity test in New Mexico 1945. They figured out it was of no risk (with dissenters), so they went ahead with the test, and the attacks on Japan.
In the late 1960's, I remember reading published accounts from the likes of the fusion weapon physics folks, and some USAF generals, about the slim chance of an implosion wave detonation pattern setting off fusion burning in Earth's atmosphere during a WW3 extinction-event-size exchange of around 3000 warheads or so.
As I said, I dunno myself, and those fears back then don't seem to square with the reaction data I see posted above, but I do very clearly remember that those fears were very real at the time. There must have been some plausible reason for it, those were very knowledgeable folks. The specifics are very probably still classified data, perhaps rightly so.
Assuming those 60's experts weren't wrong, then it seems to me that there might be a way to do it on Venus, and "blow off" that thick blanket in one bright piece of fireworks. If so, I'd be less concerned about the fallout, since the solar wind is a far larger source of nuclear pollution than any puny fireworks we can dream up for some centuries yet. Sort of a matter of perspective, I guess.
GW
It would be difficult to generate significant horsepower with the ambient atmosphere of Mars, because it is so thin. At ordinary compression ratios (numbers under 30), you are looking at engine combustion chamber pressures of under 200 mbar (1/5 atm), compared to the 20 or 30 atm we are used to looking at. It is difficult to extract much energy from hot gas expansion at pressures that low, no matter the engine type, or that the exhaust back-pressure is next to zero.
This is why compression of the extremely-thin Martian atmosphere as a source of CO2 is such a big issue with me. It is to all engineers who actually look closely at the issue. Tenuous gases really aren't of much use, given any of the technologies that we actually have.
That is why I suggested closed-vessel evaporation of mined dry ice as a source of self-compressing CO2. The closer the fit between the dry ice chunk and the closed vessel, the less heat energy this will require to reach compressed CO2 at, say, the around-150 atm of a "typical" welding gas bottle. It's only heat, you can get it easily from concentrated solar. The only trouble with this is that dry ice is only known to exist at the poles, or maybe only the south pole, of Mars.
GW
For the Earth, I don't know if it was O-O or N-N fusion. Given enough density, all are possible. The density is created by the implosion wave. The propagation or quench depends upon the mass that you "implode".
On Venus at high density, you have the prospects of both O-O fusion and C-C fusion. None of these involve the hydrogen species we are used to thinking about. All are involved in creating the heavier elements in the cores of stars.
GW
I'm with you about multiple duty. I, too, would go with aluminum, unless we just happen to find big copper deposits. Electrified rail is something we already know works quite well here on Earth. It used to be quite common, although diesel-electric has pretty much taken over, here at home.
It's all in the prospecting, something we've not yet programmed any robots to do.
GW
You need not "melt the iron twice" if your reduction reaction produced molten pig/sponge iron instead of solid. I am not familiar with the Mond process, but the net effect should be similar to that old plant in Mexico, I suspect in solid form. Once you get this stuff, you have to convert its composition to that of steel, and that is a melt process, no way around it. That's what the electric furnace would do, at essentially local ambient conditions as a substitute for vacuum on Mars. You may need to blow or bubble oxygen through the puddle.
Once you have molten steel, you cast the ingots, but you need not let them cool all the way. Temperature distributions will be necessarily very, very nonuniform during cooling, but once solidified, you bring the ingot to a uniform forming temperature. Then you can forge, roll, and hammer to your heart's content. It is hard to describe just how useful, plate, flat, bar stock, pipe, angle, tubing, and I-beams are.
GW
Void:
I was thinking a bit smaller than you, just how to get started. At first I was skeptical, then, when the aquaculture angle occurred to me, I was won over. My background is many decades as a real, practicing engineer, but I am not a one-specialty guy (a rarity in more than a century now). Basically skeptical, I am hard to win over. And with good reason.
I was thinking about ice-covered lakes, and ran a few numbers for depth versus what I know about life support. If the pack ice plus regolith cover is about 6 meters or so, you have sufficient hydrostatic pressure on your body to safely approach the bottom of the ice pack without a pressure suit. That means pure oxygen scuba is practical and safe, to depths (on Mars at 0.38 gee) of around 18-20 meters below the 6 meter cover (the 1 atm partial pressure O2 limit). Below that, one needs diluent gases in the breathing mix.
These things will be too well-covered to absorb significant solar energy, even at Earthly fluxes. But artificial sunlight will be required to run photosynthesis, and its waste heat can help keep the lake unfrozen. I'm thinking a simple, transplanted, Earthly aquaculture in the lake (too bad we haven't yet developed one).
This lake idea may be the most practical way to bring pressure and oxygen to large areas on Mars to support farming. Sure beats trying to come up with gigantic transparent pressure domes. I like it.
Anyhow, I wrote it up and added a concept sketch, and posted the lot over at http://exrocketman.blogspot.com, with due credit to correspondents like yourself. It's the article posted 3-18-12, titled "Aquaculture Habitat Lake for Mars". Should be near the top as most recent.
GW
Venus is a tough nut to crack, for sure. If we learn something from terraforming places like Mars and some outer moons, it would certainly apply, after the thick atmosphere has been thinned.
By the time we can go way out there "in force", we will be wielding a lot more power than we do now. That power will provide some way to reduce the CO2 blanket about Venus. Have faith.
I just suggested the fusion blast as a way to do it "right now" with the power we currently wield. We just don't really have a compelling reason to do that "right now", but if we did, that'd be the way.
Fusion ignition of atmospheric gases is accomplished by hemispheric-inward shock compression of a significant mass of atmosphere against the solid surface at a single point. It takes a really big wave, created by the properly-sequenced detonation of an awfully lot of really big bombs. But it is possible.
You have to compress a big enough mass to self-sustain a spreading fusion wave outward without quenching. That's easier on Venus because of the higher density, but it was possible here. That's what had some folks scared about a major nuclear exchange at the height of the cold war. Not enough, but some.
Of course, if you do it (thin Venus's atmosphere) that way (with a fusion wave), most of the mass of the atmosphere is lost to space. Destructive, but effective. And quick.
GW
I, too, am pretty sure it will start with the equivalent of truck rigs on graded roads. The problem is one of energy: each rig must be self-contained. I suspect they will carry liquid or liquified chemical fuels and oxidizers. A lot of effort and energy will go into this, even if the truck rigs are robotic.
Once steel is available, you can transport at a lot less effort and energy with an electric railroad powered by a centralized power station. The only problem is i^2R losses in the steel rails. You're going to need electric cables as part of the track, feeding power to the steel rails at intervals.
That means, in addition to an iron/steel industry, you're going to need either an aluminum or a copper industry, as well. Or both. Plus some way to make insulation sheathing or stand-off insulators for the cables. The plastic we use here will not be suitable in the harsh UV and radiation environment there.
I would suggest glass for the standoff insulators. That requires a source of silica.
My how required infrastructure multiplies! Multiplies? Exponentiates.
GW
It is certainly possible to live under an ice-covered artificial lake on Mars. That requires building the lake (earthmoving, and ice-mining activities, plus energy to liquify the ice). Then you live inside the equivalent of a submarine hull, able to venture outside with a wetsuit and scuba gear. But, you are restricted to the lake, unless you dress for what amounts to vacuum as far as the body is concerned.
Why not just build the equivalent of the submarine hull on the dry surface and bury it with dirt for insulation and radiation shielding? It's less total construction activity, and less earthmoving in particular. To go outside, dressing for vacuum does not necessarily require a gas-balloon-type suit. Mechanical counterpressure garments with a gas breathing helmet rig have existed since the late 1960's.
These do not need to be one piece garments. You could doff the compression gloves for up to about 10 minutes at a time, if barehanded work could be done without mechanical or thermal injury risks. Depends on how sharp and how cold the dirt and rocks are.
Although, for recreational and agricultural purposes, being able to go outside down in a lake would be very nice. And, would that be a good environment in which to grow food? That's the easiest way I can imagine to pressurize and wet-down very large areas: under an ice-covered lake. It takes large areas to grow food for people.
Hmmmm. Intriguing idea.
GW