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The kinetic energy of an object is proportional to the square of its velocity, and objects arriving at the moon from Earth will be moving about 2.4 km/s. An object going this fast has a kinetic energy roughly equal to its weight in dynamite, and will release that energy instantly on contact with the ground or any stationary object.
The moment your fishhook touches the ground, it will vaporize and create a small crater. Kaboom.
Yes, you can use mass drivers in reverse. Sorry, but it's not a new idea. The big challenge is that if the incoming payload is even slightly off target, it crashes into the mass driver, turning both into a cloud of expanding vapor and a shiny new lunar crater.
You're thinking farther along in the colonization process than I am: I'm imagining the difficulty of the first steps, when megastructures like a railgun aren't available.
That said, electromagnetic launch is totally doable on Mars. Atmospheric pressure is already 300 times less than Earth's, and if that's not enough, just build your space cannon on the slopes of your favorite volcano, reducing atmospheric pressure by another factor of 10.
Can you cite a source? Not aquarium owners' street smarts, something that includes actual numbers. Gills and water are very different from lungs and air, so the important measurement is whether fish can tolerate much higher CO2 concentrations *in their blood* (corresponding to much lower blood pH) than humans.
A terraformed Mars requires something like 100x as much CO2 in the atmosphere as on Earth. Can any vertebrate survive that kind of CO2 concentration in their blood?
You can't use gravity assist at a planet to change your orbit with respect to that same planet. So for instance, the Galileo spacecraft couldn't use Jupiter to change its orbit around Jupiter, but it could (and did) use Jupiter's moons. Same for Cassini at Saturn. Sadly, neither the Moon or Mars have any useful moons. (Mars's moons are way too small.)
Also, going from a flyby trajectory into orbit around a planet requires a *lot* of orbital change in a very short amount of time, and gravity assists aren't usually strong enough. Even Galileo brought plenty of rocket fuel.
As to it taking less fuel to get to mars then the moon... How? Just explain how that is possible.
Aerobraking. The vast majority of your spacecraft's fuel and cost is spent getting out of Earth's gravity well. If you've burnt enough fuel to get into a lunar transfer orbit, it takes just a little bit more to escape Earth entirely and go to Mars. But to *land* on the Moon, you need to spend more fuel to slow down and stop on the surface. To land on Mars, you just need a heat shield, because Mars has an atmosphere you can use to slow down.
So that's reason #1 why Mars's atmosphere isn't a joke.
I'm quite certain you could "throw" things from the moon to the earth. So the return trip wouldn't even take fuel. You could literally just give it a push.
Unless you can throw things at 2.4 kilometers per second, no. The Moon's gravity is less than the Earth's, but it's still serious business. You need quite a bit of fuel to take off from the Moon. You need fuel to take off from Mars too, but Mars's atmosphere has carbon dioxide: bring a little hydrogen with you (or use the local water) and a source of energy (solar panels or a reactor) and you can synthesize methane and oxygen fuel while you're there. No need to carry fuel for the trip home!
Reason #2 why Mars's atmosphere isn't a joke.
[Mars's atmosphere] is not enough to appreciably reduce radiation to the surface.
Oh, but it is. Mars's atmosphere is thick enough to shield radiation about as well as several inches of concrete, reducing radiation exposure by a factor of 2-3. It's also further from the Sun than the Moon, which reduces solar radiation by a factor of 2. Neither of these effects are enough on their own: you're right that Mars habitats will have to be underground too. But going outside is noticeably safer.
Reason #3 why Mars's atmosphere isn't a joke.
Mars's atmosphere doesn't provide complete radiation shielding, but it does provide complete protection from meteorites up to about 1-2 meters in diameter.
Reason #4 why Mars's atmosphere isn't a joke.
And finally, the Moon has craters and lava flows and that's all. Mars has those, plus volcanoes and canyons and ice caps and wind and clouds and storms and snow and glaciers and sand dunes and landslides and groundwater and river valleys and maybe an ancient ocean and maybe, once upon a time, life. Why? Because Mars has an atmosphere.
Reason #5 -- the most important one -- why Mars's atmosphere isn't a joke.
As to why not do it on earth? That question doesn't even make sense.
It was a rhetorical point, not a serious proposal. I'm saying that if you're going to spend your whole life hiding in a sterile burrow, does it really matter that you're on another planet?
For the record, none of these ideas are my own. I'm quoting chapter and verse from "The Case for Mars" by Robert Zubrin. Zubrin's got his problems -- he's a little too casual about the radiation dangers, for instance -- but IMO it's a good starting point for any serious discussion of colonizing the solar system.
Looks like you stopped reading Kim Stanley Robinson and started up on Paolo Bacigalupi. I'm willing to bet our actual future lies somewhere in between.
The moon is a trap. There's nothing good there to mine or explore; it takes less rocket fuel to land on Mars than the Moon; and the moon's surface is a horrible horrible place. You propose to solve that problem by living hundreds of feet underground, but if you're going to live that way, why not do it beneath the Earth instead?
One more for the list: 4) Carbon dioxide doesn't work like that.
Robinson's Mars books cheated on their terraforming. Terraforming Mars is a catch-22. To make it warm enough for humans to survive you need to add a lot of CO2, but adding all that CO2 makes the atmosphere toxic to humans. When I first read the Mars books I was looking forward to see how Robinson dealt with that paradox: I was disappointed to see that he didn't. He just let the plants suck up most of the CO2 to make oxygen while ignoring the cooling that would result, and then, realizing that getting rid of *all* the CO2 would be a problem, he waved a magic wand and genetically engineered all the humans to be CO2-tolerant. "Genetic engineering!" and "Nanobots!" are the science fiction equivalents of "Abracadabra!"
Anyway, CO2-tolerance would be such a massive evolutionary advantage to both predators and prey on Earth, if it were that easy to engineer, don't you think life would have figured out a way to do it by now?
There are ways to terraform Mars for realsies -- very large solar mirrors, or synthetic super-greenhouse gases like CFS -- but those have their own problems, and Robinson wanted to have his cake and eat it too.
I reject the submission's premise: neither the submission, nor any of the articles it links to, actually demonstrates that science is getting things "increasingly" wrong. No comparison of values over time, no controlled experiments
So why is scientific error in the news so often? The submission skimmed right past it: public relations sabotage by political and commercial interests who stand to gain by casting doubt on science. Global warming deniers, anti-vaccine nuts, anti-evolution zealots, nontraditional medicine snake-oil salesmen
And no, I don't have any rigorous data to support my claim. But according to the submission, I should treat all data as baloney and make my arguments based on truthiness alone.
The problem is that a business's profits aren't in proportion to the amount of public property (in this case radio spectrum) they use, so a tax on profits isn't an effective way to allocate that property.
Also, your "set barrier to entry, allow monopoly, tax on profits" model is really easy to abuse. Just look at cable/phone utilities as an example.
Everyone who uses that spectrum has to pay the tax since the company who bought the spectrum has to make back the $2 billion somehow. Plus interest. Plus a profit.
Exactly: the people who use the resource have to pay everyone else for it. What's the problem?
I suppose there's a problem if you believe that money paid to the government goes into a black hole, but I don't. Government spending isn't a perfectly fair way to distribute profits to the people, but neither is "give it all to Elon Musk".
Derailing my own post to throw in a quote by a guy who really understood what intangible public assets are worth: "I’ve got this thing and it’s f***ing golden, and
Of course, Rod Blagojevich wasn't selling radio spectrum, he was selling a US Senate seat, and he went to prison for it. But still.
Sorry, SpaceX, you know I love you but you're trying to cook the rules to get yourself a sweetheart deal. There's a big difference between speculating on radio spectrum and speculating on, say, silver: if you buy some silver and don't use it, a few years later you've still got some silver. If you buy spectrum and don't use it, a few years later the FCC takes it back and you've got nothing. Spectrum is a perishable resource, so nobody's going to bid on spectrum unless they really are going to make a communications network, or they plan to "flip" it and resell it to a viable user like SpaceX.
And short-term speculative bidding is *good* for the American public. Remember, this radio spectrum is our public property, and it's worth serious money. If SpaceX convinces the FCC not to allow "paper satellites", and demonstrates that it's the only bidder that's for real, then it can bid $0.01, win the auction, deploy its constellation, and keep all the profit. Allowing speculative competitive bids forces SpaceX to raise its bid, meaning the FCC, and thus the American public, gets to take a share of SpaceX's profits.
Analogy: Suppose your town decides to auction off some public park land to local developers. The biggest developer says, "only developers that can actually build a condo at least 20 stories tall should be allowed to bid." They are the only such developer, they bid $0.01, build a gigantic condo, make a fortune, and you and your town is left with no cash and no park.