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Yes well I think we shouldn't do them anyway until first we investigate the - perhaps remote chance - that there is life already in the clouds. Because if there is life in the Venusian clouds already - then it must be biologically unique.
It's hardly likely that present day Venus could be seeded by meteorites from Earth - anything on them would soon be destroyed on the surface, and meteorites small enough to disintegrate in the upper atmosphere would not be big enough to shelter microbes from solar radiation except in very fast transits from Earth. At least can't say for sure but I'd think a bit unlikely it has a more recent common ancestor than at least a few billion years - and might be the only remnant of an early Venusian ecosphere actually independently origins.
So, I think we need to study the atmosphere first remotely - and if there is any risk of Earth life spreading to the clouds - treat it as a Category III location so sterilize the balloons etc as for Viking on Mars - at least until we have a much better understanding of the upper atmosphere of Venus, it's habitability for Earth life, possibilities of impact of Earth life on it, and whether there is any Venusian life or not.
But - certainly can send balloons to the Venus atmosphere as that's already been done, so can do more of that, longer lived balloons. That's not such a vastly expensive mission and can do more ambitious things also at not too much expense as launch costs come down.
It might well turn out to have no life there.
Article suggesting possibility of life in the cloud tops
http://www.newscientist.com/article/dn2 … sjTz9JdXh4
Detailed model that found the observed levels of OCS without life
http://www.issibern.ch/teams/venusso2/m … sky_12.pdf
Discussion here about planetary protection issues for the Venus cloud tops - back in 2006 the study group decided is no chance of Earth microbes contaminating the Venus atmosphere or any Venus microbes if they exist contaminating Earth.
http://www.space.com/2065-planetary-pro … venus.html
But was one dissenting astrobiologist not part of the group who was not so sure of their conclusions. I wonder if a present day re-examination would come to the same conclusion - as ideas do develop and we discover microbes on Earth with increasingly surprising extremophile capabilities.
For cloud cities and terraforming of anywhere I think surely you are talking about at least a few decades into the future and I think that is how it should be as we simply don't know enough to make such irreversible decisions about any location in the solar system right now, and why hurry to start a process that will take centuries to complete?
But, keeping an open mind, once we know enough about Venus - and meanwhile can be a fine basis for sci fii. stories, films, and scientific studies. These are long term projects anyway if feasible, only our descendants a few centuries from now will really get the fruit of them, if they work, and I think myself that's one of the great things about them, chance for more long range thinking than the short term decade or even few years approach to much of space policy. Whether we eventually do them or not.
A few links that might be of interest:
Venus society, at Linkedn discusses issues of terraforming Venus
http://www.linkedin.com/groups/Venus-Society-4897138
Many posts on Venus ideas by Jon Goff at Selenium Boondocks blog
http://selenianboondocks.com/category/venus/
I've got a section on Venus cloud colonies in my article "Trouble with Terraforming Mars".
http://www.science20.com/robert_invento … ars-126407
First suggested by the Russians in the 1970s, and more recently by Geoffrey Landis, the idea that just ordinary Earth atmosphere is a lifting gas in CO2 and if you work it out then apparently a normal Earth habitat with Earth normal atmosphere would be bouyant enough to float naturally at the right level in Venus to be at the cloud tops, and would be internally and externally in equilibrium at about Earth normal atmospheric pressure and protected from cosmic and solar radiation by the upper atmosphere and also coincidentally at just the right level for tolerable temperatures or humans too in range 0C upwards. Plus most of the resources humans need can be extracted from the atmosphere. In many ways is actually more habitable than just about anywhere in the solar system apart from Earth if you can figure out how to deal with the acid droplets and how to travel there and back. For getting back it might help that rocket stages also would float in the Venus atmosphere if you left a bit of fuel inside to use as lifting gas to keep them floating in the Venus atmosphere.
One idea there is the idea to use rail guns to fire the atmosphere of Venus as dry ice to Mars and terraform both planets in one go - that is assuming we try to terraform Mars also.
If you just blow the atmosphere of Venus into space in same orbit as Venus, there is so much of it that it just gathers it back up again over geological time.
However one issue with this is the global resurfacing of Venus every few hundred million years (instead of steady continental drift). Perhaps you would do better to leave a fair bit of the atmosphere there which would also help to insulate your colonies from present day eruptions also as Venus is probably geologically active.
Paper on the global resurfacing
http://onlinelibrary.wiley.com/doi/10.1 … 8/abstract
For the oceans idea why not live under the ice? The ice would insulate and also warm up somewhat by the solid state greenhouse effect. Is amazingly insulating I remember figures for Mars someone calculated that after a major impact on the polar regions you'd get melted subsurface lakes that last for millennia before they freeze through completely again.
I think that long term it is likely to make more sense to use the material from Ceres to construct free-floating habitats. That's because there is enough material in Ceres to create material for several hundred times the surface area of Earth by way of adequate cosmic radiation shielding in Stanford Torus type habitats - a calculation from the 1970s.
See my article here: http://www.science20.com/robert_invento … ths-116541
Hi I'm the author of this post at Science20.com
Trouble with Terraforming Mars
It goes into various things that could go wrong when terraforming Mars. The main message for discussion is that Mars is quite a bit different from Earth, as many posts here address, and we are nowhere near the level of knowledge we need to predict what will happen.
So, we need to learn a whole lot more before we make any decisions about whether or not to terraform Mars and how to do it. Depending on what we find out, we or our children might want to
* Leave it as it is (if ancient Mars deposits turn out to be of extraordinary interest for evolution such that we want to spend centuries studying Mars in its pristine state before we do anything)
* Paraterraform it with greenhouses but keep humans and higher organisms well away in the early stages
* Terraform using ecopoesis, and to terraforn quickly, keep aerobes and the other microbes that hitch a lift with humans and higher organisms well away in the earlier stages.
* Paraterraform or terraform with humans on the surface from the get go.
* Make it a better habitat for native life (if found) - especially if it has unique and unusual biology e.g. not based on DNA - Chris McKay's "Mars forming" (as I call it) - could give us an exoplanet with alternative life in our own solar system
* Attempt to turn back the clock to early Mars, recreate the atmosphere and early oceans - and just let it evolve - at least for long enough to get an idea of how such a planet works, what the cycles are, what primitive life forms do in practise, how evolution works at whatever stage Mars has reached and so on.
The last two options and pristine Mars are especially interesting if evolution hasn't yet reached the stage of the first cells on Mars, or if it is some kind of pre-cursor life less complicated than Earth microbes or based on different XNA.
Imagine what it will be like if we find that Mars is an exoplanet like that in our solar system - at a different stage of evolution from Earth or life with a different basis? We might learn things that would otherwise require voyages of many light years to exoplanets around other stars in our solar system to discover.
See How Valuable is Pristine Mars for Humanity - Opinion Piece?
We need to explore with an open mind and leave our options open in my view.
Meanwhile we shouldn't do anything irreversible to Mars - as with our current levels of knowledge, that could easily put it into a state that is worse for terraforming than present day Mars.
Introducing life to Mars I think is especially problematical because it is surely impossible to remove micro-organisms from Mars after they are introduced, so is an irreversible step, and could easily interfere with terraforming in many ways. And I think human colonists to the surface would bring greatly elevated risks of doing that.
Luckily
1. There is no hurry at all. Terraforming would probably take millennia. For the first few centuries then Earth will remain far more habitable than Mars even immediately after a giant asteroid impact.
2. Humans in orbit around Mars can explore it just as effectively, indeed more effectively than from the surface. Spacesuits are vastly overrated for a planetary surface exploration in my view with the clumsy gloves and so long to put on and off and with reusability maintenance issues, at least with present technology.
For the same cost as a surface mission you could send astronauts to orbit around Mars and replace the bulky and heavy human rated rovers on the surface with numerous smaller lighter telerobotic avatars controlled from orbit.
Telerobotics is a rapidly evolving and mature technology already used for surgery (including landmark case of a surgeon in the US who operated on a patient in France using telerobotics), exploration of ocean depths, and in many situations. Already just with current technology space hardened, we could certainly do much useful science from orbit in this way, handle samples with humanoid hands, with haptic feedback so you can feel what you are doing, do experiments, drive the telerobots rapidly around on the surface, and in many ways as good as being there, and fueled just in the same way you would fuel a human mission but with no need to move humans or their life support systems around on the surface.
Later you can also use techniques developed for computer games such as lightweight portable ommidirectional platforms that let you run and walk and your avatar does exactly the same in a computer game - this could be a basis for controlling humanoid (and other) telerobotic avatars in real time in the near future, walking over surface of mars in real time like walking in a computer virtual world, could be at the forefront of developing improved ways of doing this.
It is safer for your astronauts, not going to die from a spacesuit tear or serious fall - and more interesting too, far more interesting to explore using avatars that can fly etc than to use clumsy spacesuits. The whole mission costs far less, has less by way of unproven new technologies, and you get to explore Mars more thoroughly also.
You can supply materials and habitats from Earth to Mars orbit much more easily than to the surface. Easiest is the Molniya orbit suggested for the HERRO mission - elongated orbit near sun synchronous and close to Mars capture in Delta V, as easy to get to in Delta V as lunar surface - and approaches sunny side of Mars twice every day so you can control telerobots on surface with minimal latency on both hemispheres every day.
You can use materials from the Martian moons for resource utilization, especially radiation shielding which is the main bulk of a habitat by weight whether on the surface or in orbit.
It is a win win situation, seems to me.
Anyway as I'm posting in the terraforming section - particularly want to know what you all think about what I say there about terraforming and the need for caution and to avoid doing anything irreversible in the near term.
Longer term I don't know whether Mars can be terraformed. I'm sure it could be paraterraformed if that is desirable. It could be safely paraterraformed right away actually so long as you sterilize the seeds and use the microbe free versions of hydroponics or aeroponics so that you don't introduce any microbes to the surface - and control the whole process from orbit using telerobots on the surface.
I don't think it is needed long term for colonization, because as you'll see in another of my articles, this is a calculation that O'Niel did in the 1970s, there are enough materials in the asteroid belt for trillions of colonists, enough for the land area of a thousand Earths. That's why they were so into Stanford toruses, space colonies etc.
Asteroid resources could create space habs for trillions, with land area of a thousand Earths
So, I think we can easily afford to be relaxed about colonizing Mars, take out time, and if it turns out that it is better not to colonize or terraform Mars, or not to do it for the next century or so, it is not a big deal or a major blow for space colonization. Instead that would mean that Mars is a fascinating place that we can learn much from, and a motivation for building space colonies in orbit around Mars, and to explore it using avatars instead. And space colonies may be made using the asteroids, and in future centuries use of planetary surfaces for colonization may seem an archaic early space age vision.
It would breach the Antarctica Treaty to paraterraform Antarctica. You aren't allowed to introduce new lifeforms to Antarctica because of the scientific value of it as it is. Tourists even have to be careful about what they carry onto the land in the mud on their shoes.
Same for Mars - paraterraforming would breach the Outer Space Treaty especially the COSPAR guidelines. Also not likely to be changed in the near future as we know so little about Mars. Haven't even studied it on a microscopic level, just hand lens, and not dug deep below the surface where unchanged organic deposits probably exist unchanged for billions of years.
Landing humans on Mars at all right now indeed breaches the treaties. There is no way to sterilize a human occupied ship to COSPAR guidelines as it would kill the humans, also a hard landing would irreversibly contaminate Mars straight away.
I've got a blog post about it all here, where I argue that orbital missions to explore Mars by telepresence make much more sense than surface missions right now, cost less, more scientific return, and don't contaminate the surface. Yet you will be able to walk, run and drive quickly over the surface just as you do on Earth with modern telepresence rigs and omnidirectional treadmills. Even export materials from Mars eventually, all operated by telepresence.
http://robert-inventor.tumblr.com/post/ … a-terrible
Long term them paraterraforming might well make sense, but I'd argue that you might have to choose between paraterraforming and terraforming because terraforming might be a slower more careful process which you can't do if you introduce the wrong life forms too soon.