John Mc Caffery asked:
Terraforming we always talk about Mars. This would entail enormous inputs of time, money and resources. But why not Venus, with its gravity the same as ours and plenty of Co2 for oxygen and water formation? The 450deg Centigrade and 90 times pressure would, of course, be a negative. But if our geologists are to be believed, this was similar to Earths atmosphere...?
Kat put this question to Stuart Higgins...
Stuart - Itís a really interesting question. Maybe I should set out to start off with that terraforming is this hypothetical idea that we could go to another planet and somehow do a very large scale engineering project that would change the environment into a living habitable environment a bit like the Earth. So people often think of going to Mars and trying to give it an atmosphere and this is a good question, why not Venus? Itís a planet that is a very similar size to Earth, it has 90% of the gravity so it would be similar in that respect. But actually itís almost highlighted in the question, itís a real problem in terms of the energy required. Venus is a very chaotic environment itís got an atmosphere made of 95% carbon dioxide, itís incredibly high density so on the surface of Venus the pressure of the atmosphere pulling down on you is 92 times the pressure on Earth.
Chris - Thatís just because thereís so much gas in the atmosphere weighing down on you on the surface is it?
Stuart - There is thereís just so much carbon dioxide in the atmosphere and as a comparison thatís like standing 900 metres under the surface of the sea so thereís huge pressure youíd get crushed.
Kat - Youíd get squished basically.
Stuart - Also the temperature on the surface, itís about 450 degrees celsius. Itís hotter than your oven on the surface.
Kat - So youíre effectively a pancake?
Stuart - Yeah, youíre a pancake on the surface there.
Chris - How did all that gas get in the atmosphere in the first place? Whyís the Earth not like that?
Stuart - Thatís a really interesting question. So there are arguments around whether different planets, say Mars or Venus, were more like the earth in times gone by. One of the issues actually, or one of the big difference between Venus, Mars and the Earth is that the Earth has a magnetic field. And thatís because we have convection currents of materials in the earthís core that create this magnetic field and that protects us from something called the solar wind and the solar wind is basically a lot of highly energised particles flying off the sun and striking the atmosphere of the Earth and the magnetic field in our case protects us from that. In the cases of Venus and Mars thatís not there to protect it so, even when you do get things such as oxygen forming those molecules can be bashed into by the solar winds and taken off into space so they wouldnít even collect them to start off with.
By my calculations, if we dump 10 kg of photosynthetic micro-organisms (from Earth) into the upper atmosphere of Venus, there will be 10 kg of dead photosynthetic micro-organisms within 20 minutes.