> Humans are part of a universe where time is measured in billions of years and economics is largely irrelevant.
Only if you have a narrow understanding of "economics".
Economics is the study of scarcity and how to deal with it. For example, arguing that energy is less scarce on Mercury than Mars is making an economic argument about which is a more desirable place to be. Given the myriad constraints on a colony, the only way to make an apples-to-apples comparison between two possible colonies is to invoke economic concepts.
The survival of the species very much depends on economics. We're in a race between the capabilities of our growing capital and the risks that could destroy us.
Much of what we do and have today would seem totally impractical to people from poorer eras. Likewise, solutions to problems that seem impractical to us (like geoengineering and space colonies) can become very practical given enough economic growth.
It's physicists bias. Economics doesn't make very accurate or precise predictions. I mean, economic systems are complicated, it's not really possible to foresee all of the influences on a system. It's not an attack on economists, it's just how it is.
Physicists, however, expect 5 digits of precision.
Depends on your definition of economic success. If you define it as the ability to distribute resources necessary for survival, and extend that to the species, then interplanetary travel is the only eventuality that makes economic sense.
5 digits accuracy ... that's essentially being entirely wrong :).
(and for various new physics theories I'd argue that 5 digits accuracy is not actually there, and there's the matter of the holes in the theories, like gravity)
Agreed. Space travel may be more interesting to read about, but, frankly, economics is more consequential. Before you can do anything, you have to think about what it will cost, and who will pay for it. Just ask NASA.
I need to.find.the article.proposing Venus colonization,.but.in short: Venus has very dense atmosphere, it.was figured out that a balloon filled with Earth air at 1 ATM will float high enough in Venus to have a reasonable temperature, and can.be driven as needed to follow sun and shade as required. The only problem with that setup.is that mining would.require some tether technology we don't have, but that Venus idea is still.better than mars, because it is cheaper to do, have more energy available, and the expected conditions of the balloon is closer to here than anything we can figure on mars
Isn't Venus described as a "living Hell" ? With very high temperatures, high speed winds, toxic atmosphere and so on? If Mars is deemed inhospitable, it's nothing next to Venus.
IIRC Venus doesn't have active plate tectonics, but does have a molten core. Meaning every so often it undergoes a massive global resurfacing event. Several things support the theory, and we can't date when or how often it happens, just a while longer than we've been actively watching it and the next one is due: well we don't know yet, so whenever. Not to mention the crushing pressures and temperatures hot enough to have molten lead on the surface.
Floating cities are really the only way to do it on Venus.
I'm hoping it's a clever code that when broken leads to a cool Easter egg he plants just to see who cracks it.
But vgrepping his comment history, I'm guessing he used his phone which inserts a period when he double taps space. Doesn't explain where the. Missing. Space. And. Capitalization is, though (assuming the auto-complete behavior is consistent across platforms). So I've still got hope for the first.
Kim Stanley Robinson's recent ‘2312’ has an interesting colony on Mercury. Tracks are built encircling the entire planet along a line of latitude, a huge city—‘Terminator’—rides on these rails like a train. It's pushed along by thermal expansion of the tracks at dawn, the city slides perpetually ahead of sunrise. Interesting stuff!
2312 is loosely a sequel to his Red/Blue/Green Mars series; Mercury was colonized, and Terminator built during that era. It's been a while since I've read the series, so I don't remember if there was any significant discussion of other kinds of potential settlements on the planet.
Deep underwater colonisation hasn't been properly tried yet and we are thinking of Mercury and Mars. Sounds a bit unreasonable when the best we've tried is this http://en.wikipedia.org/wiki/Biosphere_2
Wouldn't a self sustaining underwater colony protect us from all but the worst asteroid impacts? If you go even 100m down surely you would be protected from pretty much everything but the earthquakes?
Depends on the size and location of the event just like land. Being underwater didn't protect the water based dinosaurs from the impact that ended the dinosaur's reign over the earth.
It would have been the biosphere collapsing, that killed off the water based dinosaurs. But if our hypothetical colony was self sustaining (perhaps as some sort of precursor to space colonies) it should be ok.
Well, you could use geothermal energy or make use of the temperature gradient between the top of the ocean and the 100m down.
Its true the that pressure difference between vacuum and sea level is much greater than between sea level and deep underwater. However you have the advantage of not having to lift everything up to orbit. You you can build a really heavy steel tank using relatively 'simple' construction techniques, then just tow it out to position, before sinking it and anchoring it to the seabed.
The more I think about it, the more it sounds like like a self-sustaining undersea colony would be a affordable and useful way both ensure species Survivability and act as a prototype for a space colony.
How so ? Neither water-based, nor land-based dinosaurs are actually extinct. They've (mostly) shrunk a lot, yes, but that's about it. Location and size protected both kinds of dinosaurs, land-based or sea-based.
All birds are dinosaurs (in the same sense that humans are apes). Hell, you've probably eaten a dinosaur egg this week. And the water-based dinosaur descendants are very well known and the inspiration for how dinosaurs now look in musea, the crocodiles, when we're not actually sure whether crocs or chickens looked more like land based dinosaurs.
Large animals go extinct on a regular basis. The reason animals become big is for efficiency, and so often a prelude to extinction (of that particular branch). A rat is much more efficient (work/energy) than an insect. A cat is (a lot) more efficient than a rat or a mouse. Cows and other large mammals are unbeatable when it comes to the amount of energy a kilogram of cow tissue requires to stay alive. But there's usually a reason animals become efficient, and that reason is that their methods of gathering energy are actually becoming unusable, and so energy available to the species is lowering. So the species reduces in numbers, and the physical size of individuals grows. Increased efficiency only happens out of necessity, and if it can't turn the tide, the next step is extinction ... And yes, humans definitely count as large animals. I wonder if we're an exception.
Theoretically if said base could hover above the surface of the sea-bed during an earthquake scenario, perhaps it could resist most of the damage, provided it could remain stable.
Hmmm, perhaps if it was sort of tethered to the ocean floor using cables? Using a tethered base would also allow you to build in shallower water, as the flexibility would allow you to withstand some of the effects of a tsunami.
One of the biggest points of the article was that Mercury has abundant available energy from the sun - just stick up some solar panels, or the thermal gradients are perfect for running turbines - large enough to supply a lot of power, but not so large that engineering becomes hard. While there are some energy sources available underwater, it would seem to be much more difficult to exploit them.
or the thermal gradients are perfect for running turbines
They're completely useless, actually: they're in insulating rock with no ability to conduct away heat. As soon you try to exploit a temperature gradient, you destroy it.
If we're talking about survival of the species after an asteroid impact it seems a lot more feasible to keep a group of people alive on Earth until the surface is habitable again than to pin your hopes on a Martian colony being able to survive absent continual support from Earth.
But the goal isn't to just colonize any old planet. It's to colonize a place we can successfully terraform. Mars is the clear winner in that respect, and it's not close.
Mercury needs basically a planet's worth of water and atmosphere to be imported. Mars on the other hand could be (we hope) good to go. The only question for Mars is whether there are abundant amounts of nitrogen locked up in the soil. But even if not, the amount of stuff we'd need to import by bombarding the planet with asteroids would be orders of magnitude less than for Mercury.
I think the article makes the case that you do not need to import water, it is supposed to already be there. If you have a ready supply of hydrogen and oxygen (which indications are Mercury does) and an incredible amount of energy that can easily be converted you reduce your import burden substantially. This has always been my doubt about Mars, is the energy available that we need to get anything done over there? (I also agree that Nitrogen availability is a serious issue for any food production, regardless of the strategy, and this is likely a Mercury weak pont.)
Terraforming is not the goal, it is a means to an end of making a survivable planet that does not required resources from earth. Limiting your options to terraforming is not required and may not be desirable.
I'd say the goal is to find a survivable planet that can support billions of people. In that sense, the amount of water ice that is in a couple of permanently shadowed craters is really negligible. And on Mercury you're talking about only a narrow zone around the poles that you can support people if you excavate massive amounts of rock underground.
If you're talking about the energy required on Mars to change the atmosphere on a planetary scale, is there a source that says that would be a limiting factor? None of the research on this that I've seen considers it to be an issue. Mars receives about 1/3 the incident sunlight that Earth does, measured at vacuum. But the amount of that incident sunlight that will reach the surface will be higher on Mars due to the thin atmosphere and lack of cloud cover.
Perhaps the eventual goal is billions of people on another planet, I think the medium term goal is just a large enough gene pool to ensure survival of the species. You do not need billions for that. The truth is that even if you want billions you do not necessarily need a whole lot of space for them, if you examine the total area of arable land on earth and how many people you can pack into a city the space requirements are not as large as one might first assume if you have climate controlled growing conditions and a 100% urban population.
I have read a lot of material about the energy required to sustain some sort of colony on Mars but I have never read anything estimating the kind of energy strategy required for terraforming or building a substantial colony. This is why I have doubts about it, I do not see it being properly considered. For example most of the terraforming schemes involve the generation of greenhouse gases, creating a more opaque atmosphere and nullifying the thin atmosphere advantage. So now you have a sun-starved version of earth without the repository of hydrocarbons to dig up and burn off that earth has. I'm no expert though, this is a fairly uneducated opinion.
"Terraforming" is just a concept. We have no idea how to do it and whether it's even possible. And even if it were, it would take hundred of years and would need constant life support from Earth for that time. Hardly a good bet either...
Mars has no magnetosphere which makes it a non-starter due to radiation unless you live underground or in heavily shielded dwellings.
If you have to do that you might as well start at either the Moon or my personal favourite Europa - a vast ocean of water kept warm by tidal forces underneath a thick protective crust of ice. Power would be a challenge, but there might be a way to harness either those tidal forces or the radiation from Jupiter.
Mars is a non-starter? I think you've received some bad information.
Average radiation on the Mars surface is 10-20 rem/year. With a thicker atmosphere it will be less. And for people spending 12-15 hours a day indoors in shielded dwellings it will be a lot less. It's not a showstopper at all.
If you want to colonize Europa, you'll have to dig a lot deeper than on Mars or the moon. Cosmic ray dosage on the lunar surface is around 30 rem/year. On Mars, it averages 50.
On Europa, it's around 500-600 rem per day. That's a fatal dose.
Asteroid impacts and stray planets colluding with earth make great movies and special effects. Yet, P(human environmental damage irreparably damaging the ecosystem) >> P(10km asteroid hitting earth)
How would you like to spend your money? Based on how often you see one in movie theaters, or based on reality?
This x 1000. Seriously, it's like that newspaper photo of the pregnant lady smoking a cigarette while the caption reads "Area woman concerned about the effect of the sound of jackhammers on her baby."
>The magnetic field of Mars is .1% of Earth, and its atmosphere density is 2% that of Earth, so protection from ionizing radiation would require underground habitation, the same as on Mercury.
Curiosity has gathered data that suggests radiation on the surface of Mars is actually tolerable to humans [1], comparable to low-earth orbit, and presumably not too difficult to deal with for long-term surface habitation. I presume this article is a few years old due to the mention of Spirit and Opportunity but not Curiosity.
Instead of thinking how to colonize other planets while we have really low tech capabilities to do that, it is probably more effective to design efficient Asteroid defense. There are several interesting ways to do that (such as having something orbiting around the Asteroid to progressively change its course).
ANd anyway I seriously doubt people living on Earth are going to be OK with their politician telling them: "Oh, there's a huge boulder coming our way, but don't worry! The Human race is safe, we have 10 guys and women living on Mercury! Aren't you glad we planned for this?".
Ten people is an outpost, not a colony, but your point that we should also be working on impactor defense is well-taken. In fact, colonies along with impactor defense is an example of the concept of "defense in depth".
Well, you know what I mean. Even if you had 1000, it would still look pretty bad for the billions of people living on Earth. And let's not talk about genetic diversity in a population of 1000, oh no, let's not talk about that.
EDIT: since you modified your post. Well, agree with you. Just like everyone here should have good offline and online backup strategies for their data.
I know this is what they are pushing to congress now, and I think it isn't a bad idea to do what we can to defend ourselves, but terraforming is where it is at. We need to be able to terraform and colonize places outside of Earth to survive long-term. Unless you start with 10 guys off-planet you'll never get to a million, or a billion, or...
Couldn't we do a practise run on earth? I'd expect an underground colony built to specs to survive indefinitely on Mars or Mercury could also do so on Earth even in the event of a large impact (assuming it isn't a direct hit on the colony itself).
Probably yes. Surviving indefinitely is not a requirement - we can always ship supplies from Earth (or Mars, or one of the ice-rich moons further out).
But I'd still suggest a permanent presence on the Moon before we attempt one on Mars or Mercury. When things break (and they certainly will, multiple times) we can plan a rescue mission. If we have to plan one for Mercury, the colonists will have to sit patiently and wait for rescue. On the Moon, we can also perfect remote control heavy machinery, something we just can't do anywhere else, only putting humans there when the habitat is assembled and operational.
Redundancy and continuous rescue are the way to do it.
The standard space program is to talk about it for 20 years (paying salaries all the way) to figure out the "best" way to do it, then do it, once, then fire everyone and destroy all the construction jigs, blueprints, etc.
The way to colonize is to ship them enough "stuff" to build 2 or 3 colonies per shipping season. Every time. And ship somewhat less than 100% staffing so there's plenty of spares. The only safe way to live on a space colony is truly post-scarcity by limited population.
Current aerospace standards would be 5 years in, The air cleaner fails and it'll be 20 years of R+D and one shipping season before we can send you another.
The right way to do it is 5 years in, the air cleaner fails and that's cool because there's 10 spares on site, two shipped for each year the colony has been in operation, and there are 3 backup colonies within one short walk and/or we'd just abandon the one building of this colony because we wisely don't centralize anything. And enough junk will arrive on the next transport ship to set up yet another small colony.
An extinction-level impactor on earth would opaque the skies for decades. Unless you have a power source that's going to last that long without refueling, and that's sufficient not only to supply the direct needs of the human occupants, but also their indirect needs, in the form of light for their crops, then no; probably not.
That's one of the more compelling points about Mercury, according to this argument: pretty much nowhere else in the solar system is power going to be that cheap and abundant.
On Mars you'd need a long running power source anyway, so the same one used on earth should suffice. I think a good argument could be made that Earth is better than Mars for a survivable outpost, and that Mercury has a compelling energy advantage but not much else.
Earth is better than Mars for a survivable outpost
...except that the context of the discussion is having a survivable outpost for humanity in the event that Earth was no longer habitable. TFA makes the case that, of the options we have left, Mercury may actually be among the best.
> ... in the event that Earth was no longer habitable
The most likely scenario is that regular city folk find it no longer habitable. Self contained/reliant underground outposts could still survive. An event that makes all of those outposts untenable is far less likely.
In terms of the situation on earth, you don't need a large amount of survival from an extinction level event. Even if it was a few thousand diverse people in underground nuclear powered bunkers we would eventually build back up.
If the impact is big enough, the resulting worldwide earthquake and volcanic activity would destroy the colony, surface or underground. Given underground colonies _rely_ on equipment just to stay alive, the destruction of this equipment would have greater damages than surface colonies. Then, if the main power source of an earth underground colony is solar power, then they would not end up much better than the surface one. Getting closer to earth core as seismic insulation and power source may or may not solve the 2 problems mentioned above.
"Also, concentrated uranium deposits are probably less common [on Mars] than on Earth because they depend on sedimentary and hydrothermal processes which are much more prevalent on Earth."
To me, the obvious reason to look outwards rather than inwards in the solar system is that it is easier to heat an environment that is too cold than to cool an environment that is too hot. The possibility of underground areas on Mercury being the just-right temperature is intriguing, though.
The thing is, though, to cool something in an airless environment you just put up some sunshades and suddenly everything is a ridiculous -100 C or so. No convective or conductive heat transfer to speak of, so it's entirely radiative, which means a couple layers of tinfoil reduce it to functionally zero. Assuming your tinfoil doesn't melt, of course.
Agreed. I've read a lot of SF, and whenever a Mercury colony has appeared, it's always been in the context of, "Well, now that we've figured out this colonization thing on Mars, and some of the gas giants' moons, and the asteroids, and, and, and... we'll try the hard places, like Mercury."
This article makes a powerful case for that thinking being exactly backwards.
(Well, except the asteroid part. I've thought for a very long time now that the easiest set-up for an offworld colony, in terms of overall expenditure of effort and resources, would be to tow an asteroid to a Lagrange point, hollow it out, and spin it up for centripetal "gravity".)
agreed Lagrange point asteroid is much easier than any of the other options. you don't even need a big one, you just need enough of a continuous supply of resources to build a really big space station. centripetal gravity really doesn't work for this scenario though since most practical arrangements for overcoming bone loss require ~1km radius which means carbon nanotubes.
First, we would need some time to get the experience to reach that rock.
Then, considering the effort spent acquiring experience, it would be better to focus on a large asteroid.
In fact, it would be even better if we could find a way to spare some of the effort to put it on a stable earth orbit.
Wait then, couldn't we put this big rock already in stable earth orbit called "the moon" to some good use?? It's not like we've never been there tens of years ago!!
EDIT: gravity and chemical composition are valid reasons to mine an asteroid, you are totally right. Yet if we wanted not to mine but to have a colony to edge our bets for a meteor strike, IMHO the moon seems to be a better choice. However, I should have been clearer with my thoughts, I stand corrected :-)
The biggest strike against the Moon is gravity - its gravity well is deep enough to make rocketry expensive, even if nowhere near as expensive as on Earth. Even very large asteroids are mostly much less massive than the Moon.
For the same reason (mass), asteroid mining is probably more lucrative than Lunar mining (barring materials similar to Helium-3). The Moon seems to have a less diverse composition, with some useful minerals (which are mostly more massive) buried beyond easy reach.
The truth is that the Moon is more like a planet than like an asteroid. It is easier to reach.
I also question whether the structural integrity of these things is enough for them to withstand centripetal gravity without ripping themselves apart. We haven't even really confirmed that the large asteroids are really even one solid piece of rock as apposed to being a bunch of debris chunks stuck together.
Then rip them apart by design. There's an artist fixation on making one big non-redundant volume, but other than some surface area to volume vs mass issues there's no reason not to make something that looks more like a sea urchin than a baseball. Once you get over 100 or so little modules chained together you get some interesting dynamic stability problems but it gives the computers something to think about.
Worst design I can imagine is one single huge volume like the classic artists interpretation of an oneil cylinder. One hole and they all die and/or the thing rips itself to shreds.
"large asteroids are really even one solid piece of rock"
You'd be surprised what can be figured out from albedo and rotation measurements. The other thing is the line between asteroid and planet is purely arbitrary, but hovers around the self circularizing point where gravity is intense enough that it has to be more or less spherical. So the biggest asteroids are gravitationally guaranteed to be rounder and smoother, almost like a planet, at least compared to a smaller asteroid. And we've got direct imaging on small asteroids WRT scaling.
The reason there are no planets the size of the earth that are cigar shaped or whatever is gravitational. A giant asteroid would be a bit "bumpier" relatively than a small planetary moon, but its not gravitationally possible to be a cigar or a swiss cheese.
A substantial problem with a Mercury colony is that the planet is much deeper into the Sun's gravity well than earth - about a factor of 2.
IANARS, but I think the rocket equation is exponential for the gravitation that needs to be overcome. So sending anything back from Mercury would require at least 4x the propellant.
Assuming you don't need whatever you're sending back up the slope of the gravity well to arrive all that quickly, a solar sail would probably work quite well. When launched that close to the sun, it would maintain all the momentum imparted from the additional early boost as it traveled further out.
I decided to do a bunch of numbers about getting off each respective rock:
Using a = G * M/r^2, we get the following:
For Mercury:
AMercury = G * 3.29e23/2.44e6 = 3.68 m/s^2
ASun@Merc = G * 1.99e30/5.79e10 = 0.039 m/s^2
Atotal (if you launch off the dark side) = 3.68 + 0.0039 = 3.719 m/s^2
For Earth:
AEarth = G * 5.97e24/6.37e6 = 9.81 m/s^2 (duhh)
ASun@Earth = G * 1.99e30/1.49e11 = 0.0059 m/s^2
ATotal (off the dark side) = 9.81 + 0.0059 = 9.816 m/s^2
So even if you launch the 'hard way' from both planets (shooting away from the Sun), the gravity well you're in to get off Mercury is less (37%) than that of Earth, thanks to Mercury's far smaller mass. This isn't surprising, given that the local body completely dwarfs the influence of the Sun in both cases.
I don't have my lecture notes at work so I can't do it fully, but off the top of my head this is a rough first pass at the relative difficulty of transfers between each planet:
Earth orbital velocity: 29.78 km/s
Mars orbital velocity: 24.08 km/s
Mercury orbital velocity: 47.87 km/s
Venus orbital velocity: 35.02 km/s
d(Earth-Mars) = 5.70 km/s
d(Earth-Venus) = 5.24 km/s
d(Earth-Mercury) = 18.09 km/s
So in short, you need to change your velocity by 3x - 3.5x as much to get between Earth-Mercury, as you would between Earth-Mars or Earth-Venus (which are quite similar). Given that kinetic energy = 0.5mv^2, that's a 9x - 12.25x factor of energy to get to Mercury vs. the other two.
In summary, to get off Mercury is easy compared to Earth (duhh) and the Sun doesn't make any difference there. To get between the planets however is a huge difference and will be the limiting factor on regular Earth-Mercury transfers of matter.
Regardless of which way you go (towards or away from the Sun), you need to either shed or add the respective velocities to change from a circular orbit at Earth's orbit to a circular orbit at the other bodies' orbits.
Most of the "velocity change" in your math is done by the Sun as heliocentric potential energy converts to kinetic energy or vice versa. The minimum energy trajectory from Earth to Mercury is about the same delta V as Earth to Mars.
The problem with Mercury is you can't aerobrake, so add either a Venus slingshot or significantly increased delta V requirements to decelerate and land.
Sure, but you still have to shed that kinetic energy, which is what I was getting at the end. It's no use gaining a huge amount of kinetic energy if it just means you're on hyperbolic trajectory past the body. You need to still shed all of that energy with (traditionally) rocket thrust or equivalent which is completely equivalent to accelerating by that amount.
I was also basing it off a standard Hohmann transfer because sling-shotting and all of that jazz was out of my reach without my notes :) I am sure you can get a lower delta-v transfer from more exotic paths than just a Hohmann transfer but it's been a few years since I've crunched those numbers!
Nevertheless, aerobraking is one option of shedding energy when approaching smaller-orbit bodies but I neglected it when doing this first-pass analysis. However I agree with you that approaching smaller orbits gives you benefits that approaching larger orbits does not, by way of using the Sun's gravitational well.
My point is simply that you can't subtract the velocities of the two planets and call that your delta V. Delta V is the amount of actual powered acceleration your rocket does, which is only very indirectly related to the differences in velocities between the origin and destination planets.
For example, to get from an Earth-like solar orbit to an asteroid orbiting the sun very far away, at nearly 0 velocity, you'd need nearly solar escape velocity at 1 AU, or about 42 km/sec, minus the Earth's 30 km/sec. Even without taking advantage of gravitational slingshots or the Oberth effect, the delta V requirement is 12 km/sec, not 30 km/sec. So subtracting velocities has nothing to do with delta V.
I, like many others, find this whole area deeply fascinating. I'm particularly perturbed by the Fermi Paradox [1]. On that note, another commenter mentions a KSR book that has a city moving around a latitude to keep a certain place relative to the Sun. Alastair Reynolds certainly had that earlier (in Absolution Gap).
I'm also reminded of Iain M. Banks' Outside Context Problem [2] in a number of different ways.
The first is that space seems, from the human perspective, to be impossible big with even the nearest things being almost impossibly distant. The optimists argue that technology will solve that problem (probably whilst imagining a Star Trek like future) but the laws of physics paint a far bleaker picture if you look at just the energy cost to get to our nearest neighbour even assuming you solve the reaction mass problem and have perfect mass to energy conversion, the problem that even the smallest piece of matter (and eventually even hydrogen atoms) become deadly obstacles at even a modest %c and so on.
The second is that given the abundance of planetary systems we've already detected, the size of the galaxy (and its age) and the very real possibility of constructing self-replicating machines with something not that much beyond our tech, it seems strange that we haven't seen evidence of this.
Anyway, back to interplanetary colonization... given the relative distance to Mercury (6-7 years at current tech for an orbital intercept) such a colony would of course be essentially cut off from the Earth so would need to be self-sufficient (saying nothing of the problem of building a colony ship that could even get people there and keep them alive for such a long period).
I think about it this way: what is the "footprint" of a single person in the developed world? By this I mean we all need food, power, material things and the like. For each of those things, add in all the people required to produce, deliver and service those and keep adding those people until you have a group that is independent and self-sustaining.
Primitive people have a relatively small footprint, requiring a relatively small group but a large amount of area per person.
In the developed world, to maintain anything like our current existence seemingly requires a good portion of the planet. That's a problem for any kind of colonization effort.
But at the same time that interdependence reduces (IMHO) conflict. Imagine a world where 100,000 people could be self-sufficient and effectively cut themselves off from the rest of the world? It seems like a recipe for disaster. It seems like a recipe for creating a technocratic elite and the kind of social divergence that would ultimately create a new species (at first culturally).
So for a Mercury colonization effort you'd need to take enough to establish heavy industry in a hostile environment (assuming you'd mine what you need rather than carry it there), build habitats, food production and so on. It quickly spirals into an impossibly large effort.
Colonization in human history to date has happened at far lower technological levels where transportation and communication were (compared to space travel) ridiculously cheap.
What we probably need is automated, self-replicating heavy industry. This way we send an initial package of robots to Mercury. They build energy sources, habitats, mines, etc without the huge cost of keeping humans alive. Need more robots? They build those too.
Sound familiar? You're only one step away from the self-replicating robots that can (and apparently haven't) colonized the galaxy.
So yes investing in impact defense seems prudent. I don't know what we could really do against something that's 20km across though. That's an awful lot of mass to move out of our way.
What we really need is something that is a large part of artificial intelligence and self-replicating machines to do our work for us. This seems to me like the key to our long term survival and something we'll need to spend significant effort into developing.
As an aside, I tend to agree that the desire to colonize Mars is somewhat misguided but, mistakenly or not, Mars shares a lot more in common with us than Mercury does. It has an atmosphere (although not a terribly useful one). The cold is something that we, as humans, can and do deal with. It's also closer to Earth (~8 months at the right time).
I personally find the rover effort to be useful as the basis for building machiens that can survive in hostile environments for long periods of time, if nothing else.
What you describe sounds a lot like Stross's Accelerando with the development of ai melded with fabrication as a method of creating a sustainable environment for later space travel.
A good idea but a very long term one in a world very focused on the short term. The initial cost stops anyone but supreme businesses or massive government alliances but would grant them utter supremacy with the eventual influx of resources it would cause. Need to transport goods? Just fling them at Earth and enough of them should hit to recoup your costs within a year of the first shipment. Need to establish a colony where you can do whatever you want? Congrats on your brand new kingdom. If you want to do anything you essentially can with what is basically a new civilization.
We also have not created sentient lobsters... someone needs to get on that. We need those to man the factories...
I don't know what we could really do against something that's 20km across though.
Tow it out of the way.
If you see its approach early enough, which should be appreciably easier with a rock that size, it doesn't take much of a nudge for it to miss us — on the current pass, at least — and you don't even need to make contact with it.
If, OTOH, we don't have sufficient time to tractor it out of the way, let's hope we've established an offworld colony, 'cos we're probably gonna need it with a rock that size...
On that note, another commenter mentions a KSR book that has a city moving around a latitude to keep a certain place relative to the Sun.
Also seen in cstross' "Saturn's Children" (possibly a direct nod to KSR in his case, since that entire novel was a deliberate pastiche from start to finish?)
Hmm. The problem is that self-replicating machinery, like all robots, would get a little squirrely when exposed to that much ionizing radiation. You'd basically need several humans, hiding out in a radiation-hardened shelter, to run out every 15 minutes, to reflash the machine's OS, because the radiation is going to start randomly flipping bits, and soon, the robots that were supposed to build a reactor will start building a sand castle instead. Only there's no sand.
Look how much trouble we've had with the Mars rovers: we can't even get the instructions right half the time. And it takes several hours to see if we can recover from some really stupid mistakes. And the funny part is this: I'm saying this, and I wouldn't want to be caught dead outside during a ionizing radiation spike; you'd think I'd be all for the robots handling it all.
So I think that's the first problem we need to address: we need much better radiation shielding, and faster engines (either that or status chambers, immortality, etc.).
If an extinction level event is the justification for colonizing another planet, I wonder if the scenario we should prepare for should be nuclear annihilation, and not an asteroid event? Seems like nuclear war would be much more likely. The relevance to the discussion is that unless the nuclear annihilation is complete, then the colony only has to survive for 200 years on its own (or however long it takes for Earth's survivors to rebuild civilization) rather than forever.
I like to daydream about space colonization too. Each world has its own challenges:
* Mercury
Advantages: There's rocks we can mine and water, no need for a heating system in the underground cities, strong-enough gravity and magnetic field.
Inconvenients: Spending over 6 years in a small spaceship is quite insane, the water may be irradiated, underground cities are extremely expensive to build compared with surface cities, there's only room for two megacities at the poles unless we do a Death Star kind of urbanization (then there may not be enough water).
* Venus
Advantages: less than a year of travel away, good gravity and a big atmosphere that compensates the lack of magnetic field, rocks we can mine, the high pressure and heat are manageable with our technology (the Russian probes had insufficient protections against heat), no need for underground cities.
Inconvenients: No water (there's H and O in the sulfuric acid but the collect and transform process may be expensive), there may be no nitrogen sources to cheaply make our air, the cooling system is a critical infrastructure.
* The deep sea of Earth
Advantages: only a few hours of travel away, warm (5 to 0°C), cheap geothermic energy, extremely resilient to asteroid impacts, more than abundant water and rocks we can mine, no need to build underground cities.
Inconvenients: much worse pressure than on Venus, total darkness and the layer of sand/dust make it hard to find potential mines.
* Moon
Advantages: only a few days of travel away, rocks we can mine, gravity may be sufficient.
Inconvenients: water is expensive to extract from the dust layer, requires underground cities (or does the Earth act as a shield?), there may be no nitrogen sources to cheaply make our air.
* Mars
Advantages: less than a year of travel away, water and rocks we can mine, no extreme temperatures thanks to the atmosphere.
Inconvenients: sand tempests, no magnetic field so underground cities may be necessary, the heating system is a critical infrastructure as with all worlds beyond the Earth (but we know how to heat stuff), there may be no nitrogen sources to cheaply make our air.
* Callisto
Advantages: the only Jovian moon we can colonize (it's away from the radiations of Jupiter), water and rocks we can mine, would enable the robotic mining of all Jovian moons.
Inconvenients: several years of travel away (5?), requires underground cities, extremely cold.
* Titan
Advantages: abundant water, nitrogen and hydrocarbons, a thick atmosphere, no need for underground cities, may host life.
Inconvenients: at least 7 years of travel away, there may not be rocks we can mine on its surface (which would make it impossible to build cities), extremely cold.
Those are the low-hanging fruits of our solar system, and they're all hanging higher than we would have liked.
So...launch some floating cities, send them to Venus, send the astronauts later on. There's more than enough energy in the atmosphere to run machinery, and unless there are some truly violent lightning storms, the cities should stay afloat. As tech advances, a cable can be dropped to the surface (or several of them), and colonization take place.
Pity the atmosphere is so inhospitable, the surface so bland, and the utter lack of lifeforms. But a little work, and it will probably resemble Earth.
As for Mars, Mercury, and the Moon...Mercury is a surprising read. Mars would need nuclear reactors, I agree, or some other process for creating energy (anything in the soil that could react chemically with something else?). And the Moon...hmm. There's just a lack of data here, for all of them.
A recent novel by Kim Stanley Robinson, 2132, featured an equatorial on city on Mercury, built on rails that circle the entire planet. The thermal expansion of the tracks on the day side propel the city permanently into the night side.
Food for thought: Rather to colonize another planet, wouldn't it be easier to build the telescopes to spot a 5-20km sized asteroid and then deflect it?
The deflection would probably need less fuel than putting a colony on mercury (or mars or the moon) that could survive independently...
Well, the deflection system would still be a single point of failure for the human species. Colonising another planet of the solar system would reduce SPOFs to events affecting the entire solar system - the sun becoming a red giant, a neighbouring sun going supernova, a pulsar setting up shop too close.
Settling on another planet removes species-ending events such as asteroid strikes, global nuclear war, a really bad virus getting out, nanotech grey goo getting loose. The deflection system would only remove one of these.
I'm curious what the affects of the Sun's radiation would have with people on Mercury. It might not be conducive to vegetation or habitation even if it is underground.
Only if you have a narrow understanding of "economics".
Economics is the study of scarcity and how to deal with it. For example, arguing that energy is less scarce on Mercury than Mars is making an economic argument about which is a more desirable place to be. Given the myriad constraints on a colony, the only way to make an apples-to-apples comparison between two possible colonies is to invoke economic concepts.
The survival of the species very much depends on economics. We're in a race between the capabilities of our growing capital and the risks that could destroy us.
Much of what we do and have today would seem totally impractical to people from poorer eras. Likewise, solutions to problems that seem impractical to us (like geoengineering and space colonies) can become very practical given enough economic growth.