Which planet in this solar system would be most appropriate to terraform?

[siiix]

I'm not sure where you got the 160 mile disk number, apparently you and Ryan are speed reading. The original poster said 100 kilotonnes, but I understand where you are coming from. Obviously if u wanted to completely shade the entire planet at once (to drop the temperature quickly) the object would have to have a greater diameter then the planet itself. It of course doesn't need to be that big if we are a little more patient. Unfortunetly the post was a little light on most details so it is hard to refute.

i don't think it has to be as big as the planet as the sun is far away, you just have to position the disk at an optimal distance between the sun and the planet AND move the disk so the sade of the disk is constantly covering the planet < and that's the hardest part

 

[JonDE]

Just to keep this going, if colonizing Venus was the objective, is there any way we could speed up its rotational? From sunrise to sunrise its 116 days. If somehow we actually managed to make the atmosphere earth-like this could pose problems with heat transfer from the day side to the night side. Most likely very strong winds from day to night side, while still having a large variance in the temperature.

 

[JonDE]

i don't think it has to be as big as the planet as the sun is far away, you just have to position the disk at an optimal distance between the sun and the planet AND move the disk so the sade of the disk is constantly covering the planet < and that's the hardest part

It does have to be bigger if you are going to block the entire planet all at once. Think of a solar eclipse, the entire planet is not in the Umbra, let alone the Penumbra.
Obviously this isn't to scla ebut I hope you get the picture.
http://en.wikipedia.org/wiki/File:Geometry_of_a_Total_Solar_Eclipse.svg

 

[siiix]

It does have to be bigger if you are going to block the entire planet all at once. Think of a solar eclipse, the entire planet is not in the Umbra, let alone the Penumbra.
Obviously this isn't to scla ebut I hope you get the picture.
http://en.wikipedia.org/wiki/File:Geometry_of_a_Total_Solar_Eclipse.svg

but that's exactly my point , if you look at that picture if you move the moon father away from the planet the shadow would be bigger, obviously its impossible to make that huge of a disk , so its easier to just keep the disk at a bigger distance

cant be to far either , it has to be the OPTIMAL distance to get the maximal possible effect

 

[JonDE]

but that's exactly my point , if you look at that picture if you move the moon father away from the planet the shadow would be bigger, obviously its impossible to make that huge of a disk , so its easier to just keep the disk at a bigger distance

cant be to far either , it has to be the OPTIMAL distance to get the maximal possible effect

The further away you move it the less of the effect of the shadow. Think of the relation between Venus and the moon. When venus is in between the Earth and the sun, it casts a shadow across the entire earth, yet you can't really tell, as far as temperature is concerned, I'll bet the effect is negligible.

Edit: I see where you are going after re-reading. You are arguing about getting the entire planet in the penumbra, while I was arguing about getting the entire planet into the Umbra.

 

[siiix]

The further away you move it the less of the effect of the shadow. Think of the relation between Venus and the moon. When venus is in between the Earth and the sun, it casts a shadow across the entire earth, yet you can't really tell, as far as temperature is concerned, I'll bet the effect is negligible.

Edit: I see where you are going after re-reading. You are arguing about getting the entire planet in the penumbra, while I was arguing about getting the entire planet into the Umbra.

again i know , but that's TO far, it has to be the optional distance where the shadown is still effective , but big enough

 

[vemvare]

Wouldn't it be kind of difficult to keep a large object stationary relative to a planet if it isn't located in one of the Sun-Planet lagrange points?

 

[siiix]

Wouldn't it be kind of difficult to keep a large object stationary relative to a planet if it isn't located in one of the Sun-Planet lagrange points?

its would be insanely difficult, far more difficult then building it (and that not easy either)

its not really stationery, it has to constantly move as both planet and the sun are moving, and it can't be in orbit as then it would need to be to big to be possible (about planet size)

maybe it would be easier to create millions of orbiting satellites with huge mirrors+solarpanels, powered my solar energy and all networked so they won't collide

but i don't know about this plan, because the ground pressure is still 95 x higher then earth, even if the temperature drops, to much "air" makes also takeoff and landing more difficult

and converting all that CO2 into O would take how knows how many 100's or 1000's of years, also can't really convert it all there is just to much of it, let's say we do 50% oxygen 50% CO2 that would make the planet very flammable, and pressure would be still to high (estimating 60-70x earth), as there is no hydrogen O would not turn into water, at least not much of it

 

[Janus]

but that's exactly my point , if you look at that picture if you move the moon father away from the planet the shadow would be bigger, obviously its impossible to make that huge of a disk , so its easier to just keep the disk at a bigger distance

cant be to far either , it has to be the OPTIMAL distance to get the maximal possible effect

Yes, the further the Moon, the larger the penumbra, however, this also decreases the "deepness" of the shadow. The amount of light striking each square meter would go up. This increase of Light level in the penumbra increases faster than the surface area tha the penumbra covers does. Moving the moon further away can only increase the total sunlight striking the Earth.

 

[mofobro]

Terraforming is of course extremely speculative. A "terraforming future" isn't a future with a couple of thousand NASA/ISA scientist-astronauts flying around the solar system, it is a future where millions of people live their lives in massive space stations, where thousands of people leave and return to Earth each day, and where asteroids are moved around, smashed to pieces and mined! As such, it is likely to be distant future, which of course means that huge advances will be made in science, so much of what we're speculating about here will be laughably wrong if read by the generation that actually start the terraforming process.

I agree, the timescales here are not centuries, but millenia. That's why we have to start the process soon, so that capacity keeps up with the projected growth of our civilization.

Because of this, I believe that Venus is a poor candidate for terraforming, as it will eventually be subject to the increasing luminosity of the sun as it finishes the main sequence. Earth, too, will be in danger, so it would be wise to select a planet that has a good chance of escaping the red giant phase if we really do intend to survive and prosper indefinitely.

Mars is quite appropriate for several reasons.

1) Reasonably similar gravity to Earth's (0.376g)
2) Conveniently reduced escape velocity for transfer of materials to and from orbit
3) High oxygen content (in iron oxide)
4) Bearable temperature & pressure ranges
5) Proximity (~7 minute delay in communications, regular resupply from Earth feasible)
6) Familiarity - we've already started exploring it and have the technology today for landing.

The easiest way to go about the terraformation would be to send over a probe full of our favorite lichen, moss, and (genetically modified?) microbes that would start clambering over the surface, devouring iron oxide and releasing heat & H20.

Perhaps we can one day slingshot magnetic materials around it at ridiculous speeds to jump-start the core and provide a magnetosphere to boot... if not, we'll find a way to generate the shielding we need.

Eachus said some very interesting things about starting in Martian valleys. I think that process could start within a year if we applied ourselves. Mars One estimates the cost of sending 4 crewmembers to Mars permanently to be $6 billion, about as much as the U.S. spends on defense every 2-3 days in 2012 money - so the resources are there if we can find common ground for cooperation.

Don't forget, the asteroid belt is right next door to Mars. Once we get a foothold on and around the red planet, it will be that much easier to access those resources and relieve scarcity even back home.

The moons of the gas giants will be great resources for a network of space stations throughout the solar system, but terraformation will be much less feasible owing to the gravitational stripping of their atmospheres caused by the planets they orbit.

With the limitations we experience here, I can't help looking past Earth and imagining an interstellar future for humankind. Our homeworld will always be sacred, but future lies among the stars.

 

[Ryan_m_b]

I agree, the timescales here are not centuries, but millenia. That's why we have to start the process soon, so that capacity keeps up with the projected growth of our civilization.

Welcome to the forums, what projections are these? Considering the demographic transition of the developed world and the increasing development of everywhere else I can't see population growth being a global problem (and increasingly becomming less of a local problem). This is all mainly thanks to modern medicine ensuring children reach adulthood, contraceptives ensuring pregnancy is optional, female education and emancipation freeing women from being babymakers and childcarers and the labour requirements of post-industrial economies that reduce the need for mass unskilled labour in favour of skilled (read: expensive to train) labour.

Because of this, I believe that Venus is a poor candidate for terraforming, as it will eventually be subject to the increasing luminosity of the sun as it finishes the main sequence. Earth, too, will be in danger, so it would be wise to select a planet that has a good chance of escaping the red giant phase if we really do intend to survive and prosper indefinitely.

The increasing luminosity of the sun is a problem so far in the future that it dwarfs the age of our species by several orders of magnitude. I highly doubt homo sapiens will be extant when this is a problem.

Mars is quite appropriate for several reasons.

1) Reasonably similar gravity to Earth's (0.376g)

How is 37% reasonably similar? Indeed without further research into the effects of low-gravity on embryology, development and general health of all necessary species within a human supporting ecology how can we even begin to claim what is reasonable?

4) Bearable temperature & pressure ranges

The average temperature on Mars is -50C and the pressure 5-10millibars that really doesn't seem bearable to anything but extremophiles. Sure there may be areas where the temperature peaks to above zero but that does not a healthy environment make.

The easiest way to go about the terraformation would be to send over a probe full of our favorite lichen, moss, and (genetically modified?) microbes that would start clambering over the surface, devouring iron oxide and releasing heat & H20

Unless you want any chance of a biome within several hundred million years or more you're going to have to do more than dropping extremophiles onto the planet and waiting for it to change. It took billions of years for enough free oxygen to be liberated on Earth for larger organims to exist.

That's not to mention the hellishly complex task of constructing an ecosystem from scratch on a world with different characteristics. Ecosystems are not modular systems you can just build up species by species, they are (at minimum) complex, dynamic trophic webs that rely on the interaction of thousands of species to remain somewhat sustainable.

Perhaps we can one day slingshot magnetic materials around it at ridiculous speeds to jump-start the core and provide a magnetosphere to boot... if not, we'll find a way to generate the shielding we need.

Off the top of my head that's going to require some serious amounts of energy i.e. significant fractions of the solar output for a significant amount of time. I'd be interested to see some math on that.

Eachus said some very interesting things about starting in Martian valleys. I think that process could start within a year if we applied ourselves. Mars One estimates the cost of sending 4 crewmembers to Mars permanently to be $6 billion, about as much as the U.S. spends on defense every 2-3 days in 2012 money - so the resources are there if we can find common ground for cooperation.

I'd take Mars One's estimate with a massive pinch of salt. Bear in mind that we're only at the stage where after years of work by tens of thousands of experts can land a <1 tonne probe some of the time. And what we're talking about is the mass development of multiple academic fields with an increase in industrial capability that greatly dwarfs what we have today (the social effects of which would be very interesting). There's so many critical paths of R&D involved that even allowing for as much funding as humanly possible the task is by no means guarenteed to be attempted well for a long time.

Don't forget, the asteroid belt is right next door to Mars. Once we get a foothold on and around the red planet, it will be that much easier to access those resources and relieve scarcity even back home.

IIRC from LEO there is little difference between going to Mars and going to the belt. We don't need Mars to mine asteroids. Also for space mining to be profitable there would need to be huge advances in automation and in situ resource allocation, so much so that I highly doubt we'll need humans for anything more than troubleshooting from afar.

With the limitations we experience here, I can't help looking past Earth and imagining an interstellar future for humankind. Our homeworld will always be sacred, but future lies among the stars.

I can't see what we could get from living off the Earth than we could get from Earth given the resources and technology needed to achieve the former. I'm not opposed to the aesthetic value but I've never seen a reasonable argument that we need to.

 

[mofobro]

Now that's a prime example of "chickity-check yourself before you wrickity-wreck yourself." Thanks for the warm welcome, I look forward to improving my phys-fu.

I only speak in relative terms of the "reasonable" attributes of Mars. It's not like we have a hard day/night split like on the moon, and the gravity is neither crushing nor negligible.

You're absolutely correct about what you've said, though. I'll have to be better prepared next time before I go around declaring my opinions.

 

[H2Bro]

i don't think it has to be as big as the planet as the sun is far away, you just have to position the disk at an optimal distance between the sun and the planet AND move the disk so the sade of the disk is constantly covering the planet < and that's the hardest part

The optimal point was mentioned as L1, which fixes the distance and necessary size. I'd think a massive light-collecting array could produce power to maintain obliquity through thrusters and etc.

I still see Mars as an attractive option for permanent settling. It would be within the range of current technology (though perhaps not within political sentiment for funding) to construct a series of probes that attach to comets with favorable intersect orbits with mars. Boosting up to comet speed is energy intensive but small adjustments using solar powered ion thrusters or plutonium reactors over a reasonably long period of time would do the trick to have the comet captured by Mars and eventually impact.

Say, aren't the poles of Mars covered with frozen CO2 and H20? Wonder how much of an atmosphere we could get out of those with a few 1000-megaton equivalent impacts.

 

[H2Bro]

Also, a nice sobering read for the difficulties of humans "making it in space"
http://physics.ucsd.edu/do-the-math/2011/10/why-not-space/
(somewhat related to the grand vision of terraforming)

 

[Ryan_m_b]

Also, a nice sobering read for the difficulties of humans "making it in space"
http://physics.ucsd.edu/do-the-math/2011/10/why-not-space/
(somewhat related to the grand vision of terraforming)

I have a lot of respect for Tim Murphy and really enjoy reading his blog. I disagree with him on some aspects but IMO he is right on the money here. The prevailing narrative of the 1950s/60s that space is the next-big-thing has lasted long past the time where it was clear something was wrong with it.

As I said above I'm by no means opposed to the idea that people might one day live in space in significant numbers but I don't see it happening any time soon and I don't see any reason to do it other than for the panaché.

 

[Hercuflea]

It is my belief that no terraforming project will be sustainable if it is based solely in that name of "science" and done under the auspices of some tumorous government entity like NASA. There has to be some economic benefit that will attract private sector entrepreneurs into space, otherwise the project will be a huge money-pit with nothing to show except a few dirt samples. I'm not saying there are no economically attractive attributes of outer space (read Lewis' book Mining the Sky), I'm saying it's a waste to do it in the name of some government bureaucracy.

 

[Ryan_m_b]

It is my belief that no terraforming project will be sustainable if it is based solely in that name of "science" and done under the auspices of some tumorous government entity like NASA. There has to be some economic benefit that will attract private sector entrepreneurs into space, otherwise the project will be a huge money-pit with nothing to show except a few dirt samples. I'm not saying there are no economically attractive attributes of outer space (read Lewis' book Mining the Sky), I'm saying it's a waste to do it in the name of some government bureaucracy.

Terraforming would require such a radically different political, social and economic climate that speculating on whether or not private or public enterprise would do a better job is basically groundless.

 

[twofish-quant]

The prevailing narrative of the 1950s/60s that space is the next-big-thing has lasted long past the time where it was clear something was wrong with it.

The 1950's/60's narrative was more like going into space proves that we are better than the Russians. Once the US planted a flag on the moon, and the Russian economy was in no position to match that, there really wasn't any point any more.

One very interesting thing to read the *entire* "let's go to the moon" speech

http://www.jfklibrary.org/Research/Ready-Reference/JFK-Speeches/Special-Message-to-the-Congress-on-Urgent-National-Needs-May-25-1961.aspx

Space was item 9, and the famous quote "I believe that this nation..." has been taken wildly out of context. If you read the whole speech it was clearly, "I think that we should go to the moon, but we need to talk about this, and if we decide not to then let's give up right now rather than go half way."

As I said above I'm by no means opposed to the idea that people might one day live in space in significant numbers but I don't see it happening any time soon and I don't see any reason to do it other than for the panaché.

Also it would seem to me that if the goal is to have large populations in space, that terraforming a large planet would be the worst thing that you would want to do. You just spent a huge amount of effort getting out of a gravity well. What's the point into jumping back into to one. Once you get out of the Earth's gravity well, you can go anywhere in the solar system if you willing to wait long enough.

 

[twofish-quant]

Terraforming would require such a radically different political, social and economic climate that speculating on whether or not private or public enterprise would do a better job is basically groundless.

The other big problem is that a civilization with the capacity to do planetary scale construction would also have the capacity to do planetary scale destruction. If humans had the ability to make Venus suitable for life, then we'd also have the ability to make Earth unsuitable for it.

 

[Ryan_m_b]

The 1950's/60's narrative was more like going into space proves that we are better than the Russians. Once the US planted a flag on the moon, and the Russian economy was in no position to match that, there really wasn't any point any more.

One very interesting thing to read the *entire* "let's go to the moon" speech

http://www.jfklibrary.org/Research/Ready-Reference/JFK-Speeches/Special-Message-to-the-Congress-on-Urgent-National-Needs-May-25-1961.aspx

Space was item 9, and the famous quote "I believe that this nation..." has been taken wildly out of context. If you read the whole speech it was clearly, "I think that we should go to the moon, but we need to talk about this, and if we decide not to then let's give up right now rather than go half way."

Interesting. You're right competition and national pride (along with a legitimate worry about loosing out to possible military domination in/via space) had a lot to do with it. It's interesting though how this bigger, better, faster, more idea of space as our future is pervasive in spite of evidence to the contrary.

Also it would seem to me that if the goal is to have large populations in space, that terraforming a large planet would be the worst thing that you would want to do. You just spent a huge amount of effort getting out of a gravity well. What's the point into jumping back into to one. Once you get out of the Earth's gravity well, you can go anywhere in the solar system if you willing to wait long enough.

Tbh if you have the industrial and economic capacity to terraform getting out of a gravity well is a negligable cost.

The other big problem is that a civilization with the capacity to do planetary scale construction would also have the capacity to do planetary scale destruction. If humans had the ability to make Venus suitable for life, then we'd also have the ability to make Earth unsuitable for it.

I'd say we have the capacity for destruction now. We could if we wanted to bomb most of the Earth's surface with very powerful nuclear weapons and let the destruction, fallout and ash take care of any surviving organisms.

The ability to destroy in most cases is far easier than the ability to maintain or build.

 

[onomatomanic]

Also it would seem to me that if the goal is to have large populations in space, that terraforming a large planet would be the worst thing that you would want to do.

Usually, the goal is more along the lines of simply spreading out, though, it seems to me. An extension of the drive that leads all species to try and colonize new habitats when the opportunity arises, as well as wars of conquest and the traditional capitalist "stagnation equals regression" mindset among humans. From that point of view, what matters first and foremost is carrying capacity per unit of effort that has to be extended to create habitable conditions, and planets do pretty well for themselves, in those terms.

I'd say we have the capacity for destruction now. We could if we wanted to bomb most of the Earth's surface with very powerful nuclear weapons and let the destruction, fallout and ash take care of any surviving organisms.

Human life, probably. But even to wipe out "just" all mammalian life, we'd need to devote a lot of industrial effort, for a long time, to building bombs. The impact that, per conventional wisdom, killed the dinosaurs (but, one notes, not the mammals), was the equivalent of millions of hydrogen bombs, says the 'pedia article. And to kill off things like ants and cockroaches, we'd need to try another whole lot harder than that. I wonder if there's actually enough accessible uranium on Earth to use that method...

 

[Ryan_m_b]

Human life, probably. But even to wipe out "just" all mammalian life, we'd need to devote a lot of industrial effort, for a long time, to building bombs. The impact that, per conventional wisdom, killed the dinosaurs (but, one notes, not the mammals), was the equivalent of millions of hydrogen bombs, says the 'pedia article. And to kill off things like ants and cockroaches, we'd need to try another whole lot harder than that. I wonder if there's actually enough accessible uranium on Earth to use that method...

Very true, it would require a disproportionate amount of industrial output to nuclear weapons manufacture. I expect that the biggest cause of extinction would be the knock on effects of the initial blasts, fallout and nuclear winter leading to a domino effect of ecological collapse. Either way the point remains, it would take significantly less effort for us to devastate the biosphere than build one.

 

[onomatomanic]

There's no question that we could cause a mass extinction event if we set our minds to it. When it comes to completely eradicating life on Earth, though, I'm not sure if that would really be a task of smaller magnitude than terraforming another planet. Lots of things (lots in absolute terms, not relative to the status quo) could survive for a long time without much in the way of sunlight. So, even if you discount extremophiles and the like, eradicating life would IMO require permanently altering the atmosphere and poisoning the waters. Which, at least naively, makes it comparable to making a planet which has some sort of atmosphere and water in some form marginally suitable for life, no?

I'm not altogether convinced that this is a pertinent analogy, but while we are obviously more than capable of eradicating species accidentally, we seem to have a surprisingly hard time whenever we try to do it deliberately. It wouldn't surprise me if we manage to resurrect the first extinct species before we ever manage to kill off or even properly control the first unwanted invasive species. Mammoths versus Australian rabbits, say.

In short, life per se appears to be just as resilient as complex ecosystems are fragile, paradoxical as that may sound.

 

[Ryan_m_b]

There's no question that we could cause a mass extinction event if we set our minds to it. When it comes to completely eradicating life on Earth, though, I'm not sure if that would really be a task of smaller magnitude than terraforming another planet. Lots of things (lots in absolute terms, not relative to the status quo) could survive for a long time without much in the way of sunlight. So, even if you discount extremophiles and the like, eradicating life would IMO require permanently altering the atmosphere and poisoning the waters. Which, at least naively, makes it comparable to making a planet which has some sort of atmosphere and water in some form marginally suitable for life, no?

I agree that totally eradicating life is probably not possible, that's why I said devestate rather than eradicate. I still disagree though that destruction is comparable to creation. It's easy and quick to burn a forest down but difficult and slow to reconstruct, especially to the same biodiversity as before.

I'm not altogether convinced that this is a pertinent analogy, but while we are obviously more than capable of eradicating species accidentally, we seem to have a surprisingly hard time whenever we try to do it deliberately. It wouldn't surprise me if we manage to resurrect the first extinct species before we ever manage to kill off or even properly control the first unwanted invasive species. Mammoths versus Australian rabbits, say.

I'm skeptical of extinct animal resurrection for now despite the hype but regardless I make little distinction between accidentally and on purpose. In fact it shouldn't be surprising that when we deliberately try it's harder in the same way that removing a tumour in a limb with a scaple is harder than cutting off the arm with a saw.

In short, life per se appears to be just as resilient as complex ecosystems are fragile, paradoxical as that may sound.

Indeed. This is why It's best not to talk in terms of "life" because it tends to be useless wrt to the conversation. We wouldn't benefit from life on Mars, we would possibly benefit from a stable biosphere formed from ecosystems capable of sustaining a healthy human population.

 

[mfb]

To destroy all life on the surface, I would try to use the solar system:

Build a very good telescope in space to find many kilometer-sized objects in the Kuiper belt.
Build a supercomputer to find a solution for the following scenario: Deflect a small object (probably ~1km diameter) to get a close flyby at a larger object, in such a way that this object performs a close flyby at an even bigger object, and so on. Find some way to add small corrections as the maneuver will not be perfect. Use this chain to kick some ~100km-object out of its orbit, use a flyby at one of the outer planets and let it crash into earth.

There is life deep in the crust, living from radioactive decays (see http://discovermagazine.com/2012/jul-aug/06-tullis-onstott-2-miles-down-microbes-live-radiation for example) - I think you cannot kill this without melting (or removing) the whole crust of earth.

 

[onomatomanic]

I still disagree though that destruction is comparable to creation.

This is obviously true for an individual organism, and obviously true for an ecosystem, if "destruction" means devastation.

However, due to one of life's defining characteristics - its ability to procreate (and procreate at exponential rates at that, under the right conditions) - neither of those obvious truths entails that it is comparatively easy to destroy an ecosystem beyond hope of (some form of) recovery. It's not hard to get rid of most of the weeds in your garden, especially if you don't care what you do to the rest of the plants. But if you then go away and come back after a year or ten... there's going to be weeds there.

Maybe we need a sort of anti-Drake equation parameterizing the likelihood of extinguishing life once life has developed, so we can more soundly compare the two processes?

It's easy and quick to burn a forest down but difficult and slow to reconstruct, especially to the same biodiversity as before.

Ah, I think I see why we disagree. I'd have said that it's even easier to reconstruct a forest than to burn it down: For the latter, you have to start a fire; for the former, you don't have to do anything except wait - life will eventually reconstruct itself.

In fact it shouldn't be surprising that when we deliberately try it's harder in the same way that removing a tumour in a limb with a scaple is harder than cutting off the arm with a saw.

Touche.

 

[Ryan_m_b]

This is obviously true for an individual organism, and obviously true for an ecosystem, if "destruction" means devastation.

However, due to one of life's defining characteristics - its ability to procreate (and procreate at exponential rates at that, under the right conditions) - neither of those obvious truths entails that it is comparatively easy to destroy an ecosystem beyond hope of (some form of) recovery. It's not hard to get rid of most of the weeds in your garden, especially if you don't care what you do to the rest of the plants. But if you then go away and come back after a year or ten... there's going to be weeds there.

Maybe we need a sort of anti-Drake equation parameterizing the likelihood of extinguishing life once life has developed, so we can more soundly compare the two processes?

Ah, I think I see why we disagree. I'd have said that it's even easier to reconstruct a forest than to burn it down: For the latter, you have to start a fire; for the former, you don't have to do anything except wait - life will eventually reconstruct itself.



Touche.

I think we're thinking slightly differently. We agree that even after mass devastation (or even local devastation) biodiversity and biomass will increase as organisms creep back in but what we get back will not be the same as what was destroyed. In fact the greater the devastation the less likely that the re-colonisation of the area will resemble what it previously did.

For a real life example take North Sea cod. Overfishing has devastated cod populations but even if we stopped completely now fishing cod they still may not recover as opportunistic invasive species (jelly fish in this case) have moved in and began to inhabit the former's habitats.

 

[onomatomanic]

I think we're thinking slightly differently.

Right. I actually meant to go back and replace "disagree" with a milder, more appropriate way of putting it in my previous post, but forgot in the end. Anyway, I think we've exhausted this branch of the discussion. :)

 

[twofish-quant]

Interesting. You're right competition and national pride (along with a legitimate worry about loosing out to possible military domination in/via space) had a lot to do with it.

The other interesting thing were some public opinion polls that I've seen that showed that space exploration even in the 1960's was never particularly popular.

It's interesting though how this bigger, better, faster, more idea of space as our future is pervasive in spite of evidence to the contrary.

Blame Gene Roddenberry, George Lucas, and the writers of Doctor Who. Then there are the directors of Avatar, Aliens, and about a dozen other science fiction movies.

 

[twofish-quant]

There's no question that we could cause a mass extinction event if we set our minds to it.

It's been argued that we are causing a mass extinction event without even trying that hard.

http://en.wikipedia.org/wiki/Holocene_extinction

One reason that I don't think that it may be such a good idea to even try to make another planet suitable for human life is that we will be lucky if we just don't totally mess up this one.