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NASA Unveils Centennial Challenges
wonderfesten writes "NASA has finally got its Centennial Challenges program off the ground. Like the X Prize, the Challenges award cash prizes to private inventors who come up with solutions to problems. The first challenges are to design a light-weight, ultra-strength tether and a means of transmitting power wirelessly. But with a prize of just $50,000, will anyone give it a shot?" Details also available on MSNBC and Space.com.
Tesla ruined himself trying to make it practical. htm
http://www.tfcbooks.com/articles/tws8c
How do these prices weigh against NASA research costs? I wouldn't mind knowing if these are done "to enhance space travel and encourage developement" or if they are just to save a few pennies... anyone know?
I like muppets.
OK, imagine this scenario:
;-)
A satellite (or other relatively still object) is up in space. It has a large collection grid that is basically a peltier in reverse (heat makes electricity). Fire a laser from the ground at the grid. Boom, wireless power.
Another model: A heat-pipe in reverse (a tank of water or highly boilable liquid with steam pipes turning a generator). Fire said laser at heating point. Liquid boils and turns generator. Liquid cools and returns to heating chamber. Boom, wireless power.
A third model: High-efficiency solar panels on the object? Didn't we recently see a story about a solar panel breakthrough in which the new panel captures infrared and converts that to electricity as well? I think it had a 25-30% transfer efficiency, WAY beyond current methods. Go talk to those guys. Boom, wireless power.
I mean, c'mon, there's all kinds of ways to do this with existing technology. I feel like I'm taking crazy pills!
Stiny! Get me a danish!
Someone who finds NASA a pair of balls should get $50,000.
Ok, maybe I'm being too harsh, it's 20/20 hindsight on my part to think that strapping people to big tanks of fuel and lighting it on fire is dangerous. We were only able to figure that out after they started blowing up, so I maybe they're justified in freezing like a deer in headlights in light of the shuttle tragedies.
Maybe it's to stimulate young minds? When you're a teenager yet to go to University or College, $50k is a lot of money.
The other thing is, some people will take part purely for the fun of it. If you had to spend money on hardware, $50k might help you recoup your costs, and may provide an incentive for the more economically-challegend amongst us.
Offering a cash prize, however small, gets you in the news. There's no such thing as bad publicity, as they say.
I'm "between jobs" just now, so $50k to me would be very useful, although if I had the brains, I'd probably enter just for the fun of it.
Money isn't everything, but is sure helps :-)
Stick Men
Space elevators ARE free floating constructions.
The elevator will only be attached in the most rudimentary form of the word. It will probably be clamped so we can dampen any vibrations that it develops but that would not effect it's strength. A space elevator can be perfectly functional floating 5 inches above the ground.
The rules of orbital dynamics are actually determined by gravity, velocity, angular velocity and acceleration. Centripetal force is a combination of velocity, acceleration and angular velocity.
As you can see orbital dynamics is just a specific application of centripital force using gravity as the acceleration source.
It is best to think of orbital dynamics as a spinning invisible string. In a two body system (the only trully stable orbit) both items lie somewhere in the middle of that invisible string (Not at the ends). Orbital dynamics allows you to predict what the objects will do when you tap them.
You are confusing the idea of a ribbon with a spinning string.
If you spun a string so that the center of the circle it creates is INSIDE the string you are correct in stating that the string will remain taught so long as both sides have the same inertia. If the center of rotation is outside the sting than the string will get flung out. The experiment is to take a record player (Old I know) and put your string one one side of the center. When you spin up the record the string will go flying.
For your model to maintain tension it would have to spin end to end. There are actually models like that already in existence but they are NOT space elevators as everyone knows them.
Now for the Space elevator. I would like to point out that we could put geosync space elevators on other planets....even planets like venus which has a single rotation per year. Based on your model it would be impossible to create such things as geosync because the centripital force created will be very different. PLUS assuming that earth just HAPPENED to have the correct spin to get a geosyn cable due to centripital forces caused by it's rotation (it doesn't) the cable itself will weigh gigatons under great force. You would have to somehow hold that weight down which honestly would be harder than creating the cable. In addition the tension would snap the cable because the bottom would have to support double the whole weight of the cable....the cable plus an equal amount of earths mass.
Finally, how would you build such a system? The only way would be to build the cable on the ground then attach massive rockets (with more delta-v than mankind has every used in it's existence) and drag it up.
So your concept of a cable is technically possible but absolutely impossible to build.
Now imagine mine....you put up a satellite into geosync orbit. It now starts to extrude cable down to the earth and up into space. The whole mass is STILL moving at geosync orbit...The cable that is closer to earth will now be moving too slow for it's orbit and will begin to fall to earth. The cable going into space will now be travelling too fast for it's orbit and will try to fall off into space....the net effect is the cable is held tight up and down with the maximum tension being one cables weight at geosync orbit.
Now it isn't that straight forward...the cable fed downwards will have a greater effect on the system than the cable feed upwards due to gravity stronger effect therefore if you wanted to use a simple cable for the system it will have to reach about 1/3 of the way to the moon. This is why the topside has a counter wieght....just to cut down on it's length.
Plus in a space cable system the ground side will have no tension and all the tension will be in the center of mass...therefore most space cable designs are actually much thincker in the middle. this allows it to hold a lot more weight. But it does complicate the orbit.
While a small part of the tension DOES come from the rotation of the cable it is actually contrary t
Space elevators ARE free floating constructions.
Ok your close but still not there.
Space elevators START AS free floating constructions.
The problem with your idea is if they're free floating then there not stable. You would start off with a Huge object in geosync orbit and take a tiny tether and drop it down to earth. The whole time your keeping it in a stable orbit with large rockets / ion jet's. After the tether is there you put it under a tiny amount of tension by moving the object just past the orbit where your structure would be free floating. Keeping that tension at all times you add more wires until you have a stable structure under tension. Now it's the tension that let's you climb the wire without pulling it out of orbit.
However, the basic idea of building a space elevator is sketchy unless we find something which is significantly stronger than carbon nonotubes that can be made in orbit cheaply it's probably not worth doing. Moving people into orbit with rockets at under 200k per person is possible if we start sending say 50,000+ people into orbit every year. We would need to build something that's about as maintainable as a modern 747 and designed around moving just people (no cargo) into orbit. As to moving cargo to orbit a simple rail gun mounted inside of a large lighter than air building that raised above 99% the atmosphere is doable, and not all that much more complex than a hydrogen filled dirigible. You would need a system to catch things in orbit or have your bullets act as rockets but it's still a lot easer and safer in the event of failure than a space elevator. (Think of what happens if your cable is cut at 1000 miles above the earth. The top of the segment you cut has a lot of angular momentum so it's not going to fall strait down but rather rap it's self around a large part of the earth. The rest of the system is going to fly into space. Where a building that's more or less lighter than air could be built out of segments that would reassemble in the even of a failure.)
PS: Think of what happens to a space elevator as it goes from day to night if it gets say 1/10 of 1% longer it would become unstable.