Moon Not Only Has Water, but Lots of It
online.wsj.com
online.wsj.com
Ok, surely there has to be something better to compare this to than one of the largest deserts in the world.
As far as rare and valuable materials go, I'm not aware of any which are more common in asteroids than they are on Earth. Most space rocks are just the same few elements over and over again; iron, nickel, silicon, magnesium.
"The physical composition of asteroids is varied and in most cases poorly understood" - http://en.wikipedia.org/wiki/Asteroid#Composition
That is just in one asteroid and not a very large one at that. There are thousands of asteroids out there."
Oh, also: the disadvantage of mining the Earth's crust is all those people and other things living on it. The environment is not an issue with an asteroid - you'll be using up the whole thing anyway.
Longer-term, of course, you can set up a big mirror and smelt the whole asteroid in situ for much, much lower prices than a terrestrial smelting furnace - with the added advantage that you'll be able to breathe in Gary, Indiana. (If you still think getting your metal out of the crust of the planet you're living on is a good idea, I invite you to visit Gary. It's way better than it used to be, since China and Korea have volunteered to poison themselves in its place, but it's still bad enough.)
But Venus has an excess of sun and heat, and parts of its super dense atmosphere could potentially host floating algae, which absorb CO2 and rain down to the surface when they die. (Where they could burn and release all the CO2 again, but maybe a tiny bit stays out of the atmosphere.)
I guess what I'm saying is, we might be able to "seed" Venus and then sit by and watch as a carbon sink is created. And with less CO2 the atmosphere would start to cool off.
Now my very amateur understanding of Venus is that because the greenhouse effect creates super hot temperatures the magma underneath the crust of Venus does not form hot and hold spots like it does on Earth, it does not flow or erupt. There are no volcanoes, the crust is too "baked", too hard and thick.
But over long periods of time the crust still tends to break up: At a massive scale, planet wide, the whole planet surface is then covered with lava, the lava eventually cools and the cycle starts again.
This is why the surface of Venus looks suspiciously smooth except for a very few, very recent craters.
Now imagine we are able to "infect" Venus with life and it does manage to suck CO2 of the atmosphere and cool down Venus to the point where the surface of Venus can support liquid water.
It seems that could either trigger another planet wide cracking of the crust or maybe just huge volcanic eruptions. But I think once life is widely distributed even that could not expunge it. And with a much cooler atmosphere softer elements would not be baked out of the crust and the Venus crust would start to resemble Earth's crust, complete with softer and harder and lighter and heavier components and volcanoes.
And one day we could move in.
By this point it's probably easier to tow Mars to a better orbit. Or just blow Venus up and make a (partial) Dyson sphere.
1) Populate Australia and Siberia first.
2) Convert some oceans into land (or cover oceans with land).
3) Colonize Antarctica.
If you still have not enough land to play with -- consider spending money on playing with Moon, Mars, and Venus.
Of course, it's a matter of preference. Many would still prefer to live on a planet. A dispersed civilization that includes the small bodies would be even more resilient to any one collision. More eyes out among the asteroids would also increase the chances of spotting potential collisions.
2) If you want to "insure" our civilization from disappearance -- focus on developing smart machines that can travel anywhere and carry our civilization accomplishments to other places. Sending people to other planets/asteroids is extremely inefficient in comparison with other options.
If you refer to turning Siberia, Northern Canada, Antarctica into a useful piece of agricultural land, yes that theoretically has value, but I doubt is practical given the risks to our climate. Plus I hope advances in agriculture and mining will not require terraforming those regions.
I think the main value of going to the Moon, Mars, or Venus is to have people be on multiple terrestrial bodies to hedge some extinction risk, to begin some sort of space exploration infrastructure in the future, and maybe find significant economic value in mining. We need those benefits even if we haven't colonized or terraformed all of Earth.
Of course, in terms of life support it's by far the cheapest place around.
That's not the case. People want to go, that's all that matters. Eventually technologically and economically it'll be feasible for that want to be met, and it will be.
Besides, once you've got the technology and materials to build a solar shield which is an appreciable fraction of planet-sized, you might be questioning whether a planet is really the best place to live. Why not just live in your giant space stations?
If you look at the Day/Night cycle on earth 1 week without sunlight would probably drop Venus into sub zero temperatures. Depending on how much over kill you provided a few months would be plenty of time to cool down to reasonable levels.
Per unit surface area, how much less sunlight do you get at Earth's poles than at Earth's equator? That's too hard for me to figure out off the top of my head (taking the seasons into account), but I'm pretty sure it's at least a factor of two. So I think a planet with an Earthlike atmosphere in a Venusian orbit would be habitable in the polar regions.
However, the atmospheric pressure at the planet's surface is 92 times that of the Earth. So the difference in temperature in the summer is far less than the earth because a lot more energy is transferred to the poles. If you where to somehow remove that atmosphere not just change it's composition the poles may just barely become habitable.
Also wind speed is temperature dependent (Wind being a heat engine) so even with earths atmosphere a lot more energy would make it to the poles in summer.
There is already a crap-ton of SO2 in Venus's atmosphere (about 40 teratonnes, to be precise), that's where the sulfuric acid clouds come from. If we sent a supertanker full of SO2 to Venus every single day for a thousand years we wouldn't affect the amount of SO2 in the atmosphere by even 1%.
It would take immense amount of energy to move the water from other bodies.
This is a probably a 22nd century possibility, not a 21st.
http://en.wikipedia.org/wiki/Terraforming
Interesting how long the concept has been in science fiction, since at least 1942.
5.6%: impressively high, wouldn't have guessed that at all. Though it was in a crater, so could be abnormal.
2,200 pounds of moon dirt: weighed here or there? Where's metric when you need it, instead of where it's a PITA (mass instead of volume in cooking == ?!) ?
edit: that's one of the lamest animations I've seen in a while... where did they get it? Remind me to black-list the animator(s).
1000 kilograms on the moon is 1000 kilograms on earth and vice versa. Pounds is a measure of weight and not mass. Weight depends on the strength of the gravitational pull.
Also, please note that when people in Europe say they weight "75 kilograms," they're lying. What they mean is, they weight 75 kilograms-force or kilogram-pounds, which are again measures of weight and not mass. In truth, they would weight 7.65KG which equals 75KGF)
What would be the best water extraction technique?
Or just heat it until the water sublimates, then collect the vapour and cool back down to liquid/solid.
I guess it depends on your constraints vis a vis time, energy and amount of equipment you want to bring to the moon. It doesn't sound too tricky, but the main part is that you have to bring the dirt "indoors".
http://science.nasa.gov/science-news/science-at-nasa/2009/07...
Best of all, microwave extraction can be done on the spot. And it requires no excavation -- no heavy equipment for drilling into the hard-frozen lunar surface.
At least 95 percent of the water added to the simulant was extracted (vaporized out of the soil) with 2 minutes of microwaving.
* Create Oxygen and potable water for life support system, saving having to ship that from Earth.
* Build greenhouses with artificial lighting to grow in situ foods, saving having to ship that from Earth and vastly increasing the self-reliance of a Moon base.
* Create a rocket propellant factory (LH2 and LOX are a quite useful and indeed common propellant for exo-atmospheric spaceflight).
This means that after you set up the initial moon base and infrastructure later missions can skip sending as much water, Oxygen, and food. And, much more importantly, don't have to send a fully fueled return vehicle. Given the exponential nature of the rocket equation, this is huge.