Suppose we are able to make Mars a slightly smaller version of the Earth. We have an ocean on Mars, we’v planted forests, anfd the atmosperic pressure is similar to that of La Paz, Bolivia. What next? How long will it take to transport 1 million earger colonists from Earth? How much energy? Suppose we find that Mars has a nasty side-ancient bacteria seep up into the ocean, and attack the fish we’ve stocked the Martian Seas with-we will be stuck with an expensive version of the Salton Sea? Anyway, after a few generations, will humans living on Mars be unable to live on earth (gravity too strong?) 
Not as long as you think. If each woman has an average of (say) 5.3 children that is replacement plus 3 more, we can reach a million in fairly short order. Add to that the fairly modest in-migration of say 500 more couples per year.
People breed like rabbits.
By the time we’re technologically able to terraform an entire planet, our space travel technology will be so vastly advanced that it’s impossible to say. If we have that kind of ability, there’s no reason we couldn’t transport a million people inside a few months or even weeks.
There’s no possible GQ answer. You’re talking magic technology since nothing today could possibly get a million people to Mars or support a colony of a million people. It’s all hand-waving and blue-sky speculation.
Oy. We have yet to get one person to Mars, not to speak of millions.
Also, while it’s not impossible, it’s highly unlikely that any truely alien “bacteria” could feed on terrestrial life, or vice versa.
I’ll leave the manifest difficulties in terriforming to another thread, merely noting that the amount of solar radiation you’ll receive on Mars will be about 40% of that on Earth. It’s not clear that you’d be able to maintain the thermal throughput to keep Mars warm enough to be habitable and allow enough sunlight to grow plants.
Stranger
This one really calls for speculation, rather than being an answerable question.
Let’s try IMHO.
samclem
Beanstalk here, beanstalk there. People take the elevator up from Earth, light-sail or ion-drive from here to there, then down to Mars. No problem.
Or we could do it with flying monkeys. They’re very fast. :rolleyes:
Stranger
Oh, come on now. Nobody here is under the illusion that any of this is possible with modern technology. But to suggest that it will never be possible is, to put it kindly, unimaginative. For instance, if there’s not enough solar energy to keep the planet warm enough, then we can put ginormous Mylar mirrors in orbit to capture additional sunlight and reflect it to the planet. No, of course we can’t do that now–or likely even 50 years from now, but if we’re around long enough as a species we’ll be able to eventually. There aren’t any laws of physics being broken here, there are just problems of practicality and economics to be solved. I think it’s fun to speculate about future tech; I think all of us here understand that it is just speculation.
Sure, but what bugs me is the last statement: “No problem.” Even positing a hypothetical inexpensive ground-to-orbit system only solves part of the problem. You have to provide for protection of passengers across interplanetary space; you have to have some kind of propulsion system capable of making that journey ([thread=324185]solar sails[/thread] will probably be inadequte for the mass and duration of this transit), and so forth. These are significant issues. Granted, by the time that you can terraform Mars (if ever) such problems will already have been solved (they’d almost certainly have to), but at this point how they will be solved is speculative at best; dismissing these issues as “no problem” isn’t really credibly speculating, it’s just errant hand-waving.
Stranger
Once it’s all done, there’s no magnetic field to stop the solar wind from blowing the Martian atmosphere away.
Well, I don’t think he meant it as a literal “no problem”. More as an offhand throwaway statement; at least I choose to take it as such. There comes a point where it is pointlessly counterproductive to take things too literally.
That would likely take at least a few hundred thousand years. Besides by the time we’re capable of even as basic a terraforming feat as making an atmosphere, we will probably be able to provide our own magnetic field for the planet. If not then, then by the time atmospheric thinning becomes an issue, we ought to have developed the capability. We’re talking thousands, if not tens of thousands of years from now.
Of course, we could also be extinct by then. One can never tell.
The most efficient way to get a million people to Mars is to send most of them as fertilized ova. I just pity the adults accompanying them, when they “hatch.”
I’d expect that you’d have a pretty sizable human population on the planet from the beginning, to actually carry out the terraforming. We’re talking about an engineering feat surpassing anything (maybe everything) we’ve done on Earth up to the current day. The labor force for the project would probably be close to a million people. Maybe more. Maybe several million.
I find it considerably more likely that by the time we’d have anything like the capability of terraforming a planet we’d be buiding orbital habitats in various parts of the Solar System instead. Dreams of terraforming are fine for science fiction, but once we have the capability of creating strong magnetic fields, zipping between planets like we fly from Cincinnati to Kalamazoo, and otherwise taking the whole modifying things on a planetary scale thing for granted, we’re more likely to be largely eschewing planetary bodies for manufactured habitats which can be readily moved, designed around specific needs, and don’t suffer from being in the bottom of a gravity well. This, too, is well and beyond any current technology, but it seems more plausible than spending massive amounts of time and energy trying to modify the surface of a world that is likely barely capable of supported a friendly environment even if you were able to create one.
In tens of thousands of years, I’d like to think that the human race, or more likely its artificial proxy/hybrid progeny will be venturing (slowly, barring any science-fictiony “warp” drives or somesuch) to nearby systems. Predicting what our successors of that era will be capable of is beyond rational extrapolation.
Stranger
If Q.E.D. is correct then a fully functioning biosphere should replenish the atmosphere quicker than the solar winds can blow it away.
Just by going about our normal daily business humans have affected earth’s atmosphere. It should be fairly easy to adjust Mars’ atmosphere on purpose over a scale of hundreds or thousands of years.
As far as transporting a million people there it should be relatively simply by then, shouldn’t it?
The world’s first airline was inaugurated in 1916 I believe. But it wasn’t until around the early 30’s regular airline passenger travel started to pick up. So, in 70-80 years we’ve gone from airline travel being little more than a dream for most people to a point where airlines currently ferry just about 1 billion passengers per year.
Of course, travel to Mars would probably be more like cruise ship travel than airline travel. Currently around 11 million people/year travel on cruise ships. Many ships can carry upwards of 3000 people.
I could envision a time when you buy a ticket to Mars, board a space plane which takes you to a large orbiting space port where you then embark on a 1000-passenger cruise ship equipped with plenty of supplies for a one-month journey.
Between earth and Mars, there are large, rotating space colony “ports” you stop at along the way to refuel, relax, spend some time under normal gravity, get a medical check-up and psych eval to see how you’re doing, recycle all the water & waste from the cruise ship and then continue on with your journey.
Or, the large space colonies themselves are the cruise ship with a permanent resident population which continually travels to and from Mars with a regular transient population of several thousand passengers.
It really shouldn’t take long to move 1 million people there.
If I could hijack the thread a bit, I’ve wondered on and off for years if terraforming Venus would be easier (please note the comaprative ending) than terraforming Mars. From what I recall, Venus is more like Earth than Mars is, only incredibly hot.
Venus is superficially the twin of Earth, with gravity and size being within 10% of that of the Earth. However, there’s a pretty major stumbling block: Venus’ rotation is about 243 Earth days, which is actually longer than its year. This might have some serious climate impacts, and would make any point on the surface essentially uninhabitable (or at least, incapable of supporting any agriculture) for half of a Venusian “day”. (The axial tilt–less than 3 degrees–means except for in close proximity the “poles” you won’t get significantly more daylight.) Also, Venus is believed to have significant volcanic activity which would have to be dealt with.
So even if you manage to sequester the bulk of CO[sub]2[/sub] that makes up the atmosphere and condense all the sulphur and other hazardous contaminants, it still wouldn’t be especially ideal. Nivenphiles could no doubt come up with some scheme to spin the world up to a more agreeable rotation rate, but why bother; if you have the capability to do that, you might as well build artificial suns and settle Titan or one of the Jovian moons and enjoy the view.
Stranger
While I seriously doubt that there’s any kind of life on Mars, I wouldn’t put much faith in alien bacteria not being able to find humans lousy hosts.
Remember, until Ballard found the Titanic, everyone thought that the wreck would be in almost pristine condition, instead, we found the wreck being consumed by a host of microorganisms.
If the Martian meteorites do contain fossils of ancient Martian life, then it appears to have been remarkably similar to Earthly microorganisms. So, it could be that life on Earth was seeded from things on Mars (or the reverse, but this is pretty unlikely) or both planets were seeded with organic molecules from a common source. It’s also possible that life can only take certain forms (i.e. only the compounds which compose Earthly DNA will work for creating life, so even though life on a planet zillions of lightyears from Earth may look nothing like what we have here, the building blocks are the same), so we may be “edible” to aliens.
Do the people have to be alive when they get there? 