I think the point they're trying to make is that people are able to live on the amount of water in the Sahara, so lunar colonisation is therefore feasible from the water front.
It's a bad analogy twice over. There's huge amounts of aquifer water under the it, just not much on the surface. If your removed surface bodies of water from Earth and needed to place an outpost somewhere where you could still get water, you could do a lot worse than the Sahara.
I wonder what it would take for some nation or über-nation to set the goal to terraform Mars. That would be a goal worthy of mankind in the 21st century.
Mars has a lot less sun and atmosphere then the Earth, so terraforming it would involve a large investment in greenhouses and nuclear energy.
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.
If you want to populate somewhere, how about Canada and the unpopulated, beautiful plains out there to the north. It is already colonized but has virtually zero population density. The fact is people don't live there for socioeconomic, environmental, and political reasons. I don't think populating Antarctica and Siberia holds much value except as an experiment. There are plenty of places for people to live in.
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.
The main value of going to the Moon and Mars is shallower gravity wells. The Earth is the largest terrestrial body in the Solar System - the most expensive place to live in terms of getting somewhere else, except for the gas giants where we can't live anyway.
Of course, in terms of life support it's by far the cheapest place around.
You are laboring under the notion that people want to travel to and live on other planets because there is not enough habitable land on Earth.
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.
This is kind of "putting all your eggs in one basket", though. If we're going to be terraforming and altering global or continental environs, we might as well do so on the Moon or Mars so that we have some insurance in case of nuclear war/meteor/other apocalyptic death scenarios.
If you go through all the trouble to adapt to living in space for travel between the planets, why bother landing? Colonize the asteroids and short period comets, which are full of resources and much easier to access. No landing vehicles and ascent rockets are required. The gravity is so low that a spacecraft optimized for interplanetary travel can dock with them, or loiter nearby and transfer people & goods with space tugs.
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.
1) It's much cheaper protect yourself from nuclear war and meteors while staying on the Earth (e.g. digging down) than move to the Moon.
Moving to Mars/Venus is even worse than Moon.
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.
On Venus? Still won't get you close to habitability. I'm not sure how long it'd take it to radiate its excess heat away, but it'd be a long time. And then you've still got an atmosphere which is horrendously poisonous and corrosive.
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?
Venus is 0.722 AU from the sun so it revives about twice the energy per m^2 than the earth does. Even if you where to remove the greenhouse gas problem it would be nowhere close to habitable.
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.
Even if you where to remove the greenhouse gas problem it would be nowhere close to habitable.
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.
The summer temperature at earth's north pole is for June, July and August is 0°C or 273K. Assuming pure radiative cooling, twice the incoming sunlight (2 * 273K^4)^1/4 = 50.85 degrees Celsius or 123.53 degrees Fahrenheit for three months at a time. Which is at the outer edge of habitable.
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.
Why you need to build planet-sized shield? Why not pollute top layers of atmosphere with something bright? SO2 will be good choice. One satellite with few tons of SO2 can pollute Venus atmosphere in few weeks, and it will stay polluted for thousands of years.
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%.
Maybe some of the ecological aspects, but changing the atmosphere and climate sounds like a risky affair. I'm pretty sure if we were able to do some heavy handed climate modification, we would want to do it somewhere else, not in a fragile environment like Earth where extinction or at least long-term catastrophe of many ecosystems is on the table.
Not the whole of Australia; NSW is fine, it's Queensland that needs to be made more habitable. Start by removing the Maroons; some toxic rocks found there.
There is the idea that if they were able to effectively catch the summer wet season in the north they could reclaim it from desert and turn it into a food bowl.
Asteroid mining and electricity generation have the near-term potential to turn space into a lucrative economic endeavor, instead of an exotic money pit. They are the only two things I know of that could profoundly change the World's exploration of space.
Low earth orbit satellite constellations, especially using cheap picosats, also have a good chance of being lucrative. To date, they've been fiascoes (iridium, globalstar), but given a cheap RAMAC launcher to put $250k delivered cost satellites up, it should be feasible to do something like global EDGE coverage. The biggest issue is RF engineering (to get small antennas and tx power on both sides, maximum frequency reuse) and political (getting spectrum; steal it back from the 2.3ghz "we're a satellite network but operating entirely terrestrially" network).
Earth's crust already has a helluva lot in the way of most metals. Until I can dig it out of an asteroid more cheaply than I can dig it out of a hole in the ground, it's not going to help to kickstart the space industry.
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.
Iridium, if nothing else. We've mined all the terrestrial iridium we can reach (there's all that magma, but it's going to be a helluva lot easier to get an asteroid than to get to the magma).
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.)
This bit is interesting: "In the 2,900 cubic kms of Eros, there is more aluminium, gold, silver, zinc and other base and precious metals than have ever been excavated in history or indeed, could ever be excavated from the upper layers of the Earth's crust.
That is just in one asteroid and not a very large one at that. There are thousands of asteroids out there."
As soon as you've got millions of years worth of metals, you saturate supply, the price falls and you're back to a mission that isn't economically viable.
I think the global diamond market serves as a counterexample to your scenario. The producers would simply limit the supply to whatever level is sustainable. If multiple competitors increased supply or decreased prices too quickly, there may be a temporary freeze on production, but once the supply dwindles production will resume.
Yeah, you aren't going to be selling asteroid mined metals to Earth any time in the foreseeable future, the math just doesn't add up. However, selling metals and other materials to other off-Earth colonies might be economically viable. But that just raises another question.
At a minimum it would take practical fusion power. To terraform mars you would need to add a lot of air and water, which would have to come from somewhere.
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.
>He and his colleagues estimate that 5.6% of the total mass of the targeted lunar crater's soil consists of water ice. In other words, 2,200 pounds of moon dirt would yield a dozen gallons of water.
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).
No it's not. 2200 pounds on earth is 363 pounds on the moon (moon's gravity is 0.165 that of earth'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)
Heat it to room temperature, squeeze it to a pressure of 1 atmosphere, and the ice should just melt and run out the bottom.
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".
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.
"Lots of it" seems like a bit of an exaggeration. This particular site, a large crater close to the South Pole which manages to avoid direct sunlight, has 5.6% water by mass, but what does that come down to in Earth terms? A small lake? I suppose it depends how deep the water goes.
* 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.
Are we really discussing science from the WSJ? Any science reporting in the WSJ is meant for the sole purpose of bolstering the non-political credentials of what is becoming an ever more right-leaning publication, thereby allowing its readers to participate in their own radicalization by pointing to articles like this as evidence that their source is "fair and balanced". Politics or pure Wall Street grist from WSJ, sure. Science?! We have plenty of better resources for it.
Ok, surely there has to be something better to compare this to than one of the largest deserts in the world.