> 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.
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.
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
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.
"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.
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?
>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?".
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.
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.
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.
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.
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.
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, 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.
[+] [-] ef4|13 years ago|reply
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.
[+] [-] jfoutz|13 years ago|reply
Physicists, however, expect 5 digits of precision.
[+] [-] mtdewcmu|13 years ago|reply
[+] [-] speeder|13 years ago|reply
[+] [-] ricardobeat|13 years ago|reply
There is also a Wikipedia article about it: http://en.wikipedia.org/wiki/Colonization_of_Venus
[+] [-] ekianjo|13 years ago|reply
[+] [-] fusiongyro|13 years ago|reply
[+] [-] nfg|13 years ago|reply
[+] [-] rosser|13 years ago|reply
[+] [-] muyuu|13 years ago|reply
[+] [-] hfx|13 years ago|reply
> Outer space has -15 psi, extreme temperature swings, and occasional micrometeorite impacts. Five miles subsea has, let's see, 11,800 psi...
(http://www.quora.com/International-Space-Station/Given-the-a...)
[+] [-] hartror|13 years ago|reply
[+] [-] digisign|13 years ago|reply
[+] [-] Apocryphon|13 years ago|reply
[+] [-] adastra|13 years ago|reply
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.
[+] [-] JamisonM|13 years ago|reply
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.
[+] [-] ekianjo|13 years ago|reply
[+] [-] tjmc|13 years ago|reply
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.
[+] [-] duaneb|13 years ago|reply
[+] [-] utopkara|13 years ago|reply
How would you like to spend your money? Based on how often you see one in movie theaters, or based on reality?
[+] [-] aggie|13 years ago|reply
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.
[1] http://www.marssociety.org/home/press/announcements/curiosit...
[+] [-] ChuckMcM|13 years ago|reply
[+] [-] ekianjo|13 years ago|reply
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?".
[+] [-] rogerbinns|13 years ago|reply
[+] [-] rbanffy|13 years ago|reply
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.
[+] [-] rosser|13 years ago|reply
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.
[+] [-] Elv13|13 years ago|reply
[+] [-] wtracy|13 years ago|reply
There is some evidence otherwise: http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor...
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.
[+] [-] feefie|13 years ago|reply
[+] [-] cookingrobot|13 years ago|reply
[+] [-] djmdjm|13 years ago|reply
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.
[+] [-] NamTaf|13 years ago|reply
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.
[+] [-] rosser|13 years ago|reply
[+] [-] unknown|13 years ago|reply
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[+] [-] cletus|13 years ago|reply
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.
[1]: http://en.wikipedia.org/wiki/Fermi_paradox
[2]: http://en.wikipedia.org/wiki/Excession#Outside_Context_Probl...
[+] [-] Everlag|13 years ago|reply
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...
[+] [-] rosser|13 years ago|reply
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.
https://en.wikipedia.org/wiki/Gravity_tractor
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...
[+] [-] pja|13 years ago|reply
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?)
[+] [-] lightknight|13 years ago|reply
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.).
[+] [-] batgaijin|13 years ago|reply
[+] [-] danso|13 years ago|reply
[+] [-] unknown|13 years ago|reply
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[+] [-] antninja|13 years ago|reply
* 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.
[+] [-] lightknight|13 years ago|reply
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.
[+] [-] abecedarius|13 years ago|reply
[+] [-] stcredzero|13 years ago|reply
[+] [-] satori99|13 years ago|reply
I thought it was a neat idea.
[+] [-] meric|13 years ago|reply
[+] [-] bayesianhorse|13 years ago|reply
The deflection would probably need less fuel than putting a colony on mercury (or mars or the moon) that could survive independently...
[+] [-] antimagic|13 years ago|reply
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.