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Japanese Begin Working On Space Elevator
thebryce writes "From cyborg housemaids and waterpowered cars to dog translators and rocket boots, Japanese boffins have racked up plenty of near-misses in the quest to turn science fiction into reality. Now the finest scientific minds of Japan are devoting themselves to cracking the greatest sci-fi vision of all: the space elevator. Man has so far conquered space by painfully and inefficiently blasting himself out of the atmosphere but the 21st century should bring a more leisurely ride to the final frontier. Japan is increasingly confident that its sprawling academic and industrial base can solve those issues, and has even put the astonishingly low price tag of a trillion yen (£5 billion) on building the elevator. Japan is renowned as a global leader in the precision engineering and high-quality material production without which the idea could never be possible."
maintaining geosynchronous orbit while tethered to the ground is not a good idea. there are so many factors that could turn a space elevator into a complete disaster. a cat-4 or 5 hurricane could potentially put so much drag onto the cable that the whole thing tumbles to earth. an earthquake could yank it out of orbit. tidal pulls from the moon could rip it from the ground. lightning damage. i'd love to see this become a reality, but i just dont think that will happen.
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A practical space elevator could use vehicles powered by electric motors, which would get about 70-80% efficiency. On the way down, the motors could be used as generators, getting back probably around 30-50% of the original energy supplied. The total energy consumption might only be a percent or so of that needed for a rocket. The design of the cable with electrical conductors on either side reaching all the way up to geostationary orbit is, of course, left as an exercise to the reader.
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Technically, a weight in geosynchronous orbit would remain at the same altitude indefinitely with no other forces in effect. A space elevator will require a weight placed in an orbit which will supply tension â" otherwise it'd be pulled out of orbit. It would probably be close to geosynchronous, but not quite.
Couldn' this be achieved by moving a counter-weight downwards from space while the elevator moves up?
The total force on the weight in orbit would remain constant wouldn't it?
I thought a millionfold increase in length was also required?
Does not matter how strong they are if you cannot make them long enough.
A space elevator essentially just needs certain advances in materials science. It's a big engineering project, but nothing more than that.
AI, on the other hand, is something that nobody in the world has any clue how to achieve. They're simply not comparable. We may very well see AI before a space elevator, but it will be because computer technology advances vastly more quickly than space technology.
And just for the record, I did not claim that FTL is impossible, merely that it's impossible according to accepted physical theory. And that statement is absolutely true.
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The cross-Britain maglev (16 billion pounds, http://en.wikipedia.org/wiki/Transport_in_Glasgow#Future_Plans) is estimated at approximately twice the price of mankind's rope into space.
So for the price of what Wall street caused US government to pay, you could get a space elevator for each country in the world (almost - the smallest ones will have to share ofcourse)
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If you bring net mass down from orbit, you can actually make an energy profit (just on the elevator, I'm not saying that it would offset the costs of hauling propellant, etc, for asteroid miners and such).
Yeah of course you can't win overall, but nevertheless wouldn't it be totally awesome to bring back a load of minerals from an asteroid and get a "free" lift of your next load of fuel and supplies?
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It's not clear that the costs will be greatly reduced. There simply isn't that much demand (or foreseeable need for) "sending small unmanned craft to do [unspecified] things". Even with tourism (the likely largest market in the near term), you'll have a hard time charging enough to recoup your costs as well as operating expenses.
Not to mention that cost specified is almost certainly laughably low.
He left out the base assumption there, that everyone leaves out.
Once you pay for the space elevator, the incremental cost for sending a KG of cargo into space is cheap.
This is the same statement, less clearly made, as the comment somewhere above here that talks about costs of a space shuttle flight. It says, looking at total program costs, the space shuttle costs $1.3 billion per flight as of 2006, but looking at incremental costs, it is only $60 million per flight.
The unobtanium is, of course, part of the initial cost, and which most people on here seem to think is underestimated in the Japanese announcement.
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it would take a guy in the spacecraft a minimum of 4.3 years to arrive at Alpha Centauri
The ggp's point is that it would not. If you accelerated quickly enough, time would contract enough so that, in the spaceship's reference frame, the trip would take well under 4.3 light years. In fact, it could take an hour ( if the acceleration didn't kill you ).
What you mean is that, in Earth's reference frame, the trip would have to take at least 4.3 years.