Even if we manage to prove a planet is within all the planetary habitability conditions that might support lives, it will be too far of a distance that we hardly can put it in real useful investment for any human being to travel to such planet like a gamble of his future, unless we have major breakthrough in interstellar journey, which makes such journey so short as intercontinental travel on Earth today's.
Put our search back to Solar system, our choice seems to be Mars, the red planet in our star system. Though Mars is a small planet that following conditions rule out Mars being a suitable planet for human next mass habitat of colonies.
1. Atmosphere being too thin to protect colonies from direct impact of mini asteroid, which would otherwise burn out in Earth environment.
2. Mars is too far from the Sun, which means the solar energy is too weak to support planetary scale of warming. Though engineering solution can create heat shelter to insulate colonies from heat lost.
3. Gravity of Mars is only 38% of Earth, it has long term damage to human's body if residents live too long on it without artificial gravity compensation. Any potential lives grown in such gravity environment will be a different specie from planet Earth.
How about Venus. It has very hot atmosphere, which is impossible to be transformed into habitable planet by today's technology. But in my opinion, if we cast our human history of a million years of natural evolution, we have to say thank you to the tribe that took their migration out of African jungle. Our ancestors did what the choice that matters to future generations of civilization. In real term, our modern civilization started 250 years ago when engines were developed.
Geo-engineering of environment so far is quite limited by human society but it is nonetheless happening, especially in the view of long-term impact by what we have been doing. Planet Venus could be a potential of second home to humanity if we plan for a time frame of 10,000 years, which is only a blink of eyes for our universe.
Can we cool down Venus atmosphere with outer space light weight shelter fully or partially surrounding the planet? There have been some speculative publication on such potential. On the Venus atmosphere, about 50 km of altitude, the temperature and pressure is just like planet Earth at sea level, which makes it the perfect environment for buoyancy floating colonies, which can be used as factories of photosynthesis, or hotels for space tourists. In the floating cities, we can create factory which use algae in special built photosynthesis tanks to absorb CO2. Algae can produce oxygen that can be used by human beings living in the floating colonies. We can then fabricate carbon fiber net using dry algae material to make light weight solar shelter material. It would take time to cover Venus outer space with such net to block Solar light, which will cool down Venus eventually.
Other solutions is to place such shield in Lagrangian point L1. This would require much larger area to achieve the same result when shield is on the Venus atmosphere. But the solar blockage will be long term and pemenant.
With buoyancy engine, geostationary colonies above Venus atmosphere don't have to be on Lagrangian point. It can be anywhere above any star or planet. Our second paper will discuss how powerful buoyancy engine is in terraforming of a potential earth like planet.
In order to have continuously algae based photosynthesis process on the upper Venus atmosphere, water is essential to support its operation. Water can be found through comets by towing these comets from asteroid bell. So the algae photosynthesis in upper Venus will create carbon fiber net for shelter while O2 will be stored until Venus air temperature drop. In order to fast track the cooling, we can also consider removing gas from Venus into space using solar energy. Due to this is simple gravitational process, we can expect energy neutral. Gas, mainly CO2, can be contained by large pressurized cargo spaceship and accelerated to escaping velocity into vacuum space.
Our next blog will concentrate on the effect of buoyancy engine on Venus terraforming.
(To be continue)
* Fogg, Martin J. , Terraforming: Engineering Planetary Environments, SAE Press, 1995. ISBN 1560916095, ISBN 978-1560916093
* Jump up ^ Landis, Geoffrey A., "Terraforming Venus: A Challenging Project for Future Colonization," paper AIAA-2011-7215, AIAA Space 2011 Conference & Exposition, Long Beach CA, Sept. 26-29, 2011.
^Wikipedia: Discoveries of extrasolar planets