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Using Sling Shot Power to Hurl Into Orbit
the_2nd_coming writes "space.com has an article
about a new application of a very old technology.
NASA is putting money into Momentum-eXchange/Electrodynamic Reboost tether technology -- MXER for short -- an innovative concept that if implemented would station miles and miles of cart-wheeling cable in orbit around the Earth. Then, rotating like a giant sling, the cable would swoop down and pick up spacecraft in low orbits, then hurl them to higher orbits or even lob them onward to other planets."
A bunch of whirling cables in space? I wonder how many satellites will happen to stray close enough to those cables to get the crap beat out of them.
The Japanese have failed recently with using the slingshot for space purposes, although in a different application. They tried to use the Earth's gravity to slingshot a probe to Mars but screwed it up the first time causing a 5 year delay. It's coming around for it's last try now, but it's damaged and not very maneuverable and will likely wind up being a total loss.
I'm trying to picture these windmill like cables floating around in orbit and all I get is an image of something from a Bug's Bunny cartoon.
If they do go for it, I hope they put alot of research into making sure it works and isn't prone to failure and unexpected consequences.
Is this something that can be done with conventional materials, or is this another carbon nanotube based idea that might never come to pass?
The elevators AND this "slingshot" have the same problem. Tension ripping the cable. This has the added fun of the acceleration mashing you into the rear wall...i hope they don't sling the craft TOO hard!
From an earlier experiment it is clear that there are forces that will wreak havoc on most equipment. Travelling that fast through even the thinnest atmosphere or magnetic field will do some serious stress on things.
The tether system (more at www.tethers.com) decreases its potential energy after propelling the payload. Which is why they suggest a mix of tether technologies, one for the payload transport, and another electro-dyanamic propulsion. Brin wrote a story about the latter.
What is kind of sad is that Dr. Robert Forward was one of the originators of the technology but he never got to see his work in space.
Again, tethers.com explains it all much better than I can.
--foolish
Rockets would also work, but would be much more wasteful. Solar sails might work too, but I suspect you'd need some honkers to get adequate results.
Lacking <sarcasm> tags,
unlike on earth, there is no atmosphere in space. Once you give something a little momentum, it keeps spinning until a counter force. Now all you need is very short/small burst of power to get it started. And using the centrifugal force, the outside spins faster than the center.
_______________________________
"I'm not Conceited...I'm just a realist..."
One similar device is the Jules Verne Gun -- essentially it is a huge cannon that fires things into space, at about 1000 g's. The idea originated from Jules Verne's book From The Earth To The Moon. Popular Mechanics had a write-up about it a few years back (check out the pictures on page 2!) -- apparently some guy at Lawrence Livermore National Labs is trying to build one that actually works. :^)
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it is about the amount of power needed not he amount of energy needed.
power is damn expensive, so the less power you need to get that smae work done the cheaper it will be...to maintain the orbit of this thing and keep it spining will cost a hell of a lot less than it would be to keep launching chemical rockets which get the same work done but in a shorter time/distance. plus you have to carry all the energy with you withthe rocket but with a spining sling you have all that energy saved in the sling so you need less energy with you in order to rondevue with the sling.
I am the Alpha and the Omega-3
A sling that "falls" each time you use it is kinda wacky to me. Why not just build gigantic railgun instead and magnetically accellerate the spaceship (once in low orbit) instead?
Yep, another poster already pushed the title but I believe it was a mono-molecular carbon fiber cable that they finally developed to support a "space elevator" application. Someday maybe :)
errr....umm...*whooosh* *whoosh* Is this thing on ?
Charles Sheffield's Web Between the Worlds deals with not only Elevators, but Slings as well.
A retractable lanyard might work, just hook the sling thing onto the lanyard type device which would reel out quickly at first and then slowly apply braking to the reel to accelerate the spacecraft. Then when you are ready to slingshot out, cut the lanyard.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
Ahh, but the question is, are they stealing momentum from the earth as it orbits the sun, or from the earth's rotation? One would spiral us into the sun. The other would lock one face of the earth towards the sun. (Wasn't there a SciFi novel with that theme? The beings lived in the twilight ring between the scorching desert hemisphere and the frozen dark hemisphere). Not sure either is a good deal. /frank
And the worms ate into his brain.
Actually, I made and learned to use one for Eagle Scouts (a lot) of years ago. They're not too hard to learn - it's just a matter of timing. Took me maybe 3-4 hours to be able to put a marble into a target about 100 ft away, a few more hours to do so consistently.
:-) Ooops. It didn't penetrate the vinyl interior but left a nice hole in the door metal, and we had to take the truck door apart to get the rock out. My friends' folks were understandably pissed.
They can be devastatingly powerful. I put a small round stone about the size of a marble thru a pickup truck door once
What works best for cord is something non-stretchable - makes you aim better - and small diameter, to cut air resistance. As I remember I used carpenters string (used for leveling, strong stuff) and a plastic shot pocket from a wristrocket.
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
Given that one of Heinlein's books is titled "The Man Who Sold the Moon," i think he saw both sides of the issue. However i'm not sure if sales people as motivators of technology was more of a "vision," or just a concession to reality.
This Space Intentionally Left Blank
He has lots of other cool ideas, such as using magnetic propulsion to levitate satelites by having them capture slugs fired from the ground, reverse their course, and fire them downwards again (== upwards momentum on both halves of the equation). I'd draw ascii-art, but your loving slashdot team have deemed that "lame" so you get none.
Satelites that levitate above the poles by tacking with solar sails against gravity (higher the "orbit", smaller the sail needed).
His book "indistinguishable from magic" is basically the worlds best anti-patent protection. more power (postumously) to him.