In our on-going ambitions to colonise space — and our search for exo-planets in goldilocks zones, it is often overlooked that the most Earth-like area known to us is in our own Solar System, and very nearby — the upper reaches of the Venusian troposphere.
Whilst the surface of Venus invokes classical images of Hell — a dark sea of fire and brimstone, where temperatures raise to an incredible 450°C — hot enough to melt lead, tin and zinc, and pressurised to such an extent (92 bar) that in these conditions the atmosphere ghosts in and out of an ocean of supercritical carbon dioxide — sulphur dioxide tints the air, and sulphuric acid rains down on volcanic plains. One just needs to look to the skies…
At about 50 km to 60 km above the surface, the upper reaches of the Venusian troposphere, the environment is quite different. At these high altitudes the temperature is in our comfort zone of 0°C to 50°C, and the air pressure similar as habitable regions of Earth.
An atmosphere rich in carbon dioxide (96.5%) and abundant solar radiation, the conditions are ideal for photosynthesis. One could imagine solar energy powered crafts could easily sustain ecosystems where the ideal conditions for photosynthesis ensure an abundant source of food and oxygen for inhabitants. The solar energy here is abundant and in all directions — the high reflectivity of clouds below causes the amount of light reflected upward to be nearly the same as that coming in from above, with an upward solar intensity of 90% — so aircraft would not need to concern about electricity or energy consumption. Indeed, that energy would not even be needed to keep the craft airborne — as the oxygen store would also double up as a natural lifting agent for such aircrafts, as in the Venusian atmosphere of carbon dioxide, oxygen is a lifting gas — in the same way helium is a lifting gas on Earth. With temperature, pressure, gravity, and a constant source of food and oxygen via plant growth all accounted for, not to mention close proximity to Earth, waste & water recycling would be the main challenge for the permanence of such Venusian aircraft — where the initial establishment of a balanced ecosystem is key. The engineering challenge would be far less than that of establishing a colony or base on Mars. Just don’t look down!
Food and water supply from plant growth — check
Solar energy to run the craft — check
With the above given necessities, one has to ask the simple question — why go to the trouble of constructing floating crafts and putting them into the atmosphere of such a dangerous planet where any error or malfunction guarantees certain death?
If we have the option of building craft with onboard aggricultural facilities, artificial eco-systems, why not build them in gravity-free space within the solar system away from planets, with systems to forewarn again meteoric or comet activity to move the craft out of the way as and when necessary, where repairs and reconstruction as and when needed can be carried out with lesser risks and without disruptions?
Until we develop the capabilities to create artificial eco-systems on less volatile spheres like the moon or Mars or the technology to travel at hyperspeeds to reach similar planets as our own, artificial worlds in space would be the safer and more practical options. We’ve already developed space stations, its time to work on building up upon that experience. No, its not easy, and trillions of times easier to talk about it. However, what is most feasible ahead is the litmus question.
Creatively we tend to get stuck in the loop of engineering and inhabiting environments similar to Earth. Given that the majority of planets found so far are gaseous i think this sort of approach provides exciting and possibly more practical solutions to the colonization of the solar system and beyond.
Harish — the reason to do so would be to establish bases with the long term goal to terraform Venus (see earlier blog — the runaway greenhouse reversal — cooling Venus).
http://lifeboat.com/blog/2012/02/the-runaway-greenhouse-reversal-cooling-venus
Aircraft in the upper atmosphere of Venus is a much safer and more accessible alternative to interstellar or interplanetary craft — where your suggestion of any malfunction guaranteeing death is much more applicable — where you have to consider you have to transport your own oxygen, shield from cosmic radiation, heat the craft from near zero kelvin to our comfort zone, artificially generate gravity,.. you are dealing with a much more complex craft, in a much more dangerous environment — one air leak and you are in trouble — where repairs and reconstruction are MUCH more difficult, and much further from Earth to rescue if your ‘artificial ecosystem’ starts to fail.
On your consideration of Mars or the Moon as less volatile — consider how many seconds you would survive on Mars or the Moon — with no atmospheric pressure — if your eco-bubble ruptured. The Venus proposition by comparison is a solid one.
This method would require the acquisition of a vast amount of resources if an effective bioregenerative life support system is to be cultured. Fortunately carbon is present in abundance. However; water, nitrogen, phosphorus, potassium and other essential elements seem to be scarce, requiring unprecedented logistical support for importation.
I once did some calculations to estimate how long it would take to cool Venus’s atmosphere to the point where terraforming could be done on the surface. By blocking the sun with very light material such as that used for solar sails, it looked like about a century would do it. Not bad compared with what it would take to create an atmosphere on Mars. Where I saw some difficulty was the apparent lack of water. Still, floating craft with a little water, which could be recycled, could pump out a lot of oxygen, if done on a large scale, and the planet could eventually be made liveable.
It seems to me that floating craft on Venus, while possible, isn’t particularly useful, though Venus could serve as a great source of carbon and oxygen for space habitats in earth orbit.
The key to any large scale engineering seems to me to be to first create a self replicating self maintaining set of machines, then just feed them mass for 50 or so generations. If a doubling time of two weeks can be achieved (which seems quite possible), then in two years from building the first set of machines, everything changes.
The moon seems like a good source of mass — low gravity well, very little atmosphere.
You probably should change “Venetian” to “Venusian” in the title, since the former refers to Venice, Italy, whereas the latter refers to the planet Venus. I suppose you could build colonies in the tropopause over Venice if you wanted to, but the Venetian surface is not really a burning, hellish environment. Last time I was there, cute little gondolas were toodling around with starry-eyed tourists. The Venusian surface — i.e. the planet Venus — is another matter…
Thank you, Phil :o Yes gondolas rather than lifeboats for Venice.
To draw comparison — if one ventured 50km to 60km above Earth (yes — even Venice), we would be at the edge of the stratosphere — where temperature and air pressure would be rather too low to support life. Though the views there are of course quite spectacular -
I wonder if we would ever be able to find some kind life outside earth… if we do that we be one of the greatest discoveries of human history