Slashdot Mirror
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."
The key scientists behind this project are Dr. Bartholemew J. Simpson and Dr. Dennis "The Menace" Mitchell.
Mike
It's already been proven that any cable of that length made using any currently-known material would snap under the tension of whirling an object of even the mass of a tennis ball. They're probably talking about meters and not miles.
Dennis the Mennis apparently grew up and got a job at NASA!
Swoop down and clobber spacecraft in lower orbits, smashing them into tiny pieces that could go one to clobber other spacecraft. Or perhaps larger pieces that re enter in fiery displays of wasted millions.
Or it might work. That'd be something.
I once used sling shot power to hurl little rocks at my neighbor's cat. Used the middle finger from a rubber kitchen glove, a cut-apart 2-liter soda bottle, and a pipe clamp.
If they built one of those in space, they'd be able to scare the shit out of my neighbor's cat.
- A.P.
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
FOOD FIGHT...
(forget missiles)
- The Fountains of Paradise by Atrhur C. Clarke
- Mars Trilogy by Kim Stanley Robinson
I'm sure there are more.In SOVIET RUSSIA, the slingshots fire you.
Look Ma, no hands !!
I'm glad to see NASA looking at alternatives to rockets. This project, as well as the Space elevator are good ideas that if implemented could revolutionize space travel.
It seems that the greatest two motivators of technology are SciFi authors, and sales people.
This approach was used by Robert Heinlein in several books; it is a pleasure to see his vision honored.
As for sales people, I can't count the number of times that I have had to create what they have sold.
Alien species put up huge fences to keep us outside of their garden, and now we're going to be shooting stuff at them...
[Dennis the Menace]
Hey Mr. Freeeblgwaaxx!1
[/Dennis]
Black and grey are both shades of white.
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.
I'm too busy to RTFA...
I'm picturing this working in a similar fashion to the way the 'squids' in Matrix:Reloaded would throw the bombs. Cool.
"the ultimate dos-Ã-dos swing machine."
I know the caption says it uses old technology- but I'm not trusting my space flight to something that runs on DOS.
It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
"It's sort-of like a one-hundred kilometer long fish-net stocking in space, only it's incredibly strong, and it can withstand many years of bombardment by orbital debris," Hoyt said
Say, if they make these smaller, maybe I won't have to keep buying pantyhose for my girlfriend!
This is the real signature
(Beats those shadows on the cave wall, don't it?)
Would this not knock your socks off, literally? or would it simply travel at the same speed (or close to) as the shuttle? 'splain it to me pls k thx
Seems that the Chinese would have started a sort of the space race when the annnounced to go to the Moon.
Instead, we're looking into slingshots.
I want a moonbase as fast, or faster than China can get one up.
I don't think I would enjoy getting smacked upside the spacecraft by a cable going 25,000 MPH faster than me.
Can anyone say whiplash?
Sucks on us if they caught the moon and give it a fling
hey we could fling all our refuse and waste into the sun!
course if we miss it'll come back and endanger the planet a thousand years from now...
(c'mon who knows where that's from)
A huge slingshot for space shuttles called a MiXER, this can not be a real story. In other news space.com has began hiring former reporters from the the NY Times.
When probes from outer space attack the earth, we can use the slingshot to go back in time to retrieve the exact species of whale they're trying to contact!
Slingshots never worked out very well for the Coyote. Doesn't anyone pay attention to the great value of cartoons? Sheesh... how many boulders must fall on the heads of coyotes before someone gets it?
On the other hand, rockets never worked for the Coyote either... maybe NASA is on to something! Is it possible... could cartoons be... unrealistic? Noooooo!
A sling shot is not the same as a sling.
A sling shot uses a rubber band to propel its payload.
A sling uses the sudden stop of centripedal force.
Sling shot = Dennis the Menace.
Sling = David killing Goliath
Slings are good for hunting small animals, apparently.
I noticed on one of the diagrams that the orbit of the slingshot itself degrades after each launch pick-up. Maybe the decrease in orbit isn't very significant, but would this system require self-adjustment? How would the system stay in service over the long term?
True believers seek redemption from the sin of death.
Is this something that can be done with conventional materials, or is this another carbon nanotube based idea that might never come to pass?
"you've got your ass in a sling now!"
brain getting ready to explode...
New type of weapon to fire at our enemies?? :)
Steve Job's shat in his pants when he saw this at a NASA preview...
If brevity is the soul of wit, then how does one explain Twitter?
By Gregory Benford. In either "Great Sky River" or "Tides of Light" Benford (physicist and astronomer at UC, Irvine), can't recall which, there is an organism that does this...only its ends actually come much farther down into the atmosphere than NASA's proposal. This organism was even used by the main character in the story to hitch a ride into space.
In Bushworld, they struggle to keep church and state separate in Iraq as they increasingly merge the two in America.
IIRC, a similar-sounding device (known as the Pinwheel) appeared in "Beyond the Fall of Night", by Gregory Benford. This book was a sequel to the Arthur C. Clarke short story "Against the Fall of Night", which Clarke later re-wrote as the full-blown novel "The City and the Stars". All three tales are well worth a read!
Tubal-Cain smokes the white owl.
In some ways the neatest thing about it is that it does away with the need for reaction mass, which is is nothing else an environmental improvement.
Lacking <sarcasm> tags,
Won't using the earth's rotational momentum like that take energy from the earth to give to the spaceship? Hell, after a couple hundred thousand launches our days might be an hour longer. THIS IS PREPOSTEROUS!
Isn't this how Commander John Crichton got sucked into that wormhole? He didn't use cables, but he did use the earth's gravitational field to slingshot him through space.
Karma: Chevy Kavalierma.
i think i saw this on jackass... but in the end i don't think they even got over the ramp into the lake.
MARIJUANA, SHROOMS, X: ONLINE?! - E
This thing is going to transfer momentum to the space craft it is boosting, right? Where is it getting it from? Something has to get that cable spinning, and I don't see how to get the tether started/respun after it has be put in orbit/used to boost without using just as much energy as you have saved by using it.
I am sure I am missing something, but I don't know what, could someone fill me in?
P.S. I did RTFA, doesn't explain it...
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
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.
Next thing you know, Doctor Tsukumo will sue for patent infringement.
(Idly curious whether or not anyone at all will get the reference...)
Gives new meaning to "Projectile Vomiting".
Heh. Alright, I'll go away now.
My experiments in ground-based hurling involved the horrible Yukon Jack liquor as a liquid oxidizer and resulted in a Nasal launch that slingshotted an entire package of pre-digested ramen, nearly parking it in one of the LaGrange points.
I'm sorry, you must be confused. King George II lived in Germany and died on 25 Oct 1760 from a burst blood vessel. You should get current...I can understand being a few days behind the times, but 243 years?
--Jubedgy
Si hoc legere scis nimium eruditionis hebes
  ÂNot to pick nits, but shouldn't this be called MEER?
This is a special excite
This
hilarious!
redundant? WHAT IN BLOODY HELL!? I had the FP, nothing I say is redundant!!!
In the works you site they build an elevator all the way from surface to space; in other words it is extremely long.
In this case, the craft is much shorter and already in space. Rather than lifting something all the way along a cable, you accelerate it by swinging a shorter cable and throw it off.
From an energy perspective, you exchange rockets working inefficiently for a short time for solar-powered engines working efficiently but slowly for a long time. In the space elevators you mention, you rather use more conventional engines like in an electric train.
Tor
Comment removed based on user account deletion
... "sling" != "slingshot". They're two completely different things. Conflating the two is kind of like calling a canvas-sided trailer with some rusty tanks and piping a "weapon of mass destruction."
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
IAALS.
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. :^)
Slashdot's first reaction to VMware
if I'm not too much mistaken they did something like that in the Bubblegum Crisis: Tokyo 2040 series.
Even if it never pans out, it's nice to see them trying to make fiction into fact...if only in well grounded theories
-- Wiccan Army, 13th Airborne Division "We will not fly silently into the night"
This thing doesn't happen to say 'ACME' on the side, does it?
Maybe they can rig one big enough to throw out the International Space Station.
--"The perfect example of the man of action is the suicide." - William Carlos Williams
Aldrin has been talking about this for years for a Mars transit system.
No mention of him at all?
This really just seems to add another layer to already complex and dangerouse rocketry. Think about it first you have to get the thing in orbit. then it has to catch the ship/satalight/explorer then afterwards it looses its higher orbit and then must be refueled, presumbly by another spaceship so it can reach the higher orbit to do it again. How would this be cheaper then the old way. God this just seems stupid. I mean you have to use multiple launches to the the work of what normaly is one launch.
hook
Wandaba Style!
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?
Heat things with a giant magnifying lens until the object smokes or pops. Nope
Shoot bb guns at stop signs (not lights). Nope
Slingshots...that's taken.
Blow darts with straws and paper...hmmm, yes, giant air pressure pipe to launch space capsules into orbit.
Anyone know a good modernized implementation of pouring salt on snails?
If you're trying to use a tether system to transfer from a low orbit to a high orbit, a tether will only get you halfway there. The transfer from a low orbit to high involves one thrust event to change your orbit from circular to elliptical, with the perigee (closest point) staying the same, but the apogee (farthest point) higher up. The second thrust event happens when the satellite hits apogee, accelerating it so that the orbit becomes circular again.
You can hurl rocks up high all you want, but you'll need another force to make sure they stay there.
Note that this doesn't apply to the moon shots or interplanetary boosts. I'm only talking about parabolic and circular orbits, not hyperbolic or complex orbits. I'm sure this would be cool for those cases.
Kevin Fox
Something like this would certainly solve the speed vs. weight problem faced by the current set up. The only problem I could see is space. Unless you have a hell of a lot of space, or some super powerful mechisms for building such a thing, it could be impractical.
This signature has Super Cow Powers
Don't these guys know anything about thermodynamics?!
By launching a ship in this fashion, they will be STEALING momentum from the earth's rotation, degrading the planet's equilibrium and ultimately destroying the orbit and sending us to a firey death in the sun!
This is obviously a "plan B" coming from those same wackos who want to send the moon crashing into earth by harnessing the energy in the tides.
like the Horny French Skunk?
Ooo... bahby... I like your stripes!
I'd give a link to the correct Dilbert strip, but don't have time to find it before I go to work.
Experts have been talking about the space elevator for a few years. Someone at NASA comes up with the ! brilliant idea "what if we make it shorter to save money?" This is a Rube Goldberg solution to a problem that demands greater simplicity.
A space elevator can (theoretically) last a relatively long time with with little maintenance, and is fairly easy to keep operational once we get it constructed. It experiences atmospheric drag, but not at supersonic speeds, and an aborted launch most likely means a stuck elevator car. The elevator can be easily copied simply by weaving new cables along side it. After we make the first one, constructing duplicate systems becomes easier, and requires MUCH less energy, allowing for new elevators to be quickly created for other terrestrial, lunar, and even Martian sites.
I suspect Nasa's idea of a short spinning tether is another boondoggle. It will constantly need to be boosted to a higher orbit (boosted by what system?). It will suffer from material degradation due to heating during the scooping maneuver. It must be manufactured entirely on the ground and must be lofted into orbit. It can only be replaced by launching an entirely new one. It still relies on rockets to get the payload to scooping altitude. In short, it's an energy hog that never gets any easier to maintain.
Safety is not a concern -- regarding catastrophic failures, this is not much of an issue for either system. Both systems can be designed to fragment safely into smaller segments that do little harm on reentry.
I suspect Nasa's going for the quick cheap fix with this one. I ask, what makes a small projectile fueled by explosives any less likely to go kaboom than a big projectile? As long as rockets are a part of the launch solution, the risks to payloads will remain high. If Nasa goes with this solution the U.S. is looking at another twenty to thirty years of being beholden to a complex, short-sighted, fiscally-wreckless, and bureaucratically-expedient non-solution.
Get off my virtual lawn, you damned virtual kids!
Do you think this could boost payloads delivered from small non-NASA suborbitals like Rutan's:
SpaceShipOne?
It would be great if you could just fly up to the edge of space, chuck your payload up, have a tether catch it and then land. Very cheap compared to rockets.
Also I wonder if the tether guys are working with: Carbon Fiber 60% stonger than steel
A giant space trebuchet.
Let the siege of Mars begin!
Relatively unknown but quite funny webcomic.
Be sure to keep going. It's got a lot more to the story than just the slingshot.
Mod me down and I will become more powerful than you can possibly imagine!
This morning I was typing in a long post on my /. journal (which I use as a blog) about the Hoytether article at space.com. It had lots of great stuff, with links to physicist and Hard Science Fiction writer Dr. Robert L. Forward (who introducted me to the tether concept) and to Tether's Unlimited (the company that Robert Hoyt and Robert Forward started to commercialize it).
/. ate it when I clicked 'Preview' and the back-button gave me an empty form. It was time to go to work so I said screw it; I can write it again when I come home. Yeah right. Like I would still want to post it after somebody else gets a dumber version on the /. front page!
Hell I even wrote about listening to Bob Forward (Dr. Forward to you, heh heh) tell me the story of how he found a kilt-making company in Scotland that still had old-fashioned weaving machines which could be modified to create the tethers. In fact I went so far as to link to a eulogy I wrote about Bob when he died. It was a great post! It had everything!
But then
It's like I was never meant to blog it...
- -
Are you an SF Fan? Are you a Tru-Fan?
What happens if something messes up and it releases
to early or late and comes back to earth? Talk
about a backfire. Or the cables break too early.
Nothing like going in the wrong direction for a
while.
perhaps, but I think the acceleration would cause a break up of the ship with all that friction in sub orbital altitudes.
a better solution would be a geosync type tether than simply wenched up a ship from sub orbit....if we can get the construction materials needed we could actualy have it at ground level.
I am the Alpha and the Omega-3
Swing low, sweet NASA slingshot,
Comin' for to launch me to Mars;
Swing low, sweet NASA slingshot,
Comin' for to launch me to Mars.
I looked over low orbit,
And WHAT did I see,
Comin' for to launch me to Mars,
A band of "Hoytether" comin' after me,
Comin' for to launch me to Mars.
Swing low, sweet NASA slingshot,
Comin' for to launch me to Mars;
Swing low, sweet NASA slingshot,
Comin' for to launch me to Mars.
If you get there before I do,
Comin' for to launch me to Mars,
Tell all my friends I'm being slung too,
Comin' for to launch me to Mars.
There's no wrong way, to eat a Rhesus...
Goliath's future relative in Houston walks outside to pick up the morning paper, and SWWWOOOOCK!!!
Table-ized A.I.
WOW!
Wasn't this theory widely in use by a certain coyote?
If memory serves (which it usually does just for someone else) he used the rubber bands first and rockets second, we seem to be at odds with the Acme Lab theories on propulsion.
Everything you need to know you learned from Looney Toons (even that crossdressing habit you try to hide)
... nice reference to the USB 1.1 2.0 crap... ha ha ha... made me laugh.
the question is still where do you get that force from. The point here is storing and transferring power in and from these 'rubber bands' to use to slingshot stuff. Fine, your answer tells me that I can get a strand moving with very little difficulty in space. This is not really true, since we are talking about centrifugal force, the force is similar to what we would have to apply at sea level. Yes it will stay longer, but you still have to apply the force.
Where does that force come from?
hmmmm?
Making the tether out of a mesh is a pretty cool idea, but all you've done is extend the lifetime by some factor. What you really want to do is find a way to repair the damage relatively easily.
Picture two mesh tethers between the endpoints. Each tether is made of a series of lines. The lines come out of the tether and are _unwoven_ from the mesh weave. They are then looped back around and _reweaved_ into the tether going back in the other direction. Each line within a tether is actually participating in a complete loop, there are back again. Each line is an unbroken circle.
The tether is then _moved_ through the continuous loop, unweaving and weaving at each end. In this way the tether acts like a belt.
If a break occurs, then movement of the belt/tether will eventually bring the break to one of the terminals, where it can be repaired. The weave localizes the damage and ensures that the line will not simply fly off into space. The repaired line is then rewoven into the loop.
A belt-like tether like this can last indefinitely.
The parent is wrong!
Don't mod it up unless you understand!
Don't believe that propaganda about Wile getting beat all the time, that's just feel good stuff.
Remember... it wasn't the same Road Runner each time.
-pyrrho
I'd definitely hurl if they tried to slingshot me into orbit. :)
Okay Mr. Armstrong. nice and steady. use this ladder to climb up into the slingshot. Workteam: Push! *distinct hnnngh from the workteam*. Okay. here we go.. Workteam: Release! *desperate scream as Mr. Armstrong flies across the horizon to never be seen again*
GAAH! MY PRINTER IS ON FIRE!!! PUT IT OUT! PUT IT OUT!
if there are some coils in this huge wire then it'll be travelling around a huge magnetic field (the Earth). From physics class we all know that this creates some electricity. While the energy produced may be small, it should be able to get itself into the spinning motion and keep itself if power is an issue.
chillax137
The Japanese probe was using a "gravity assist". If you would just RTFA, you'd know that the scheme being talked about here involves an actual sling (a tension member with masses at both ends) not dissimilar from the one in the legend of David vs. Goliath. The only similarities between the two are that:
- Energy and momentum are exchanged between two masses, and
- Ignorant people see the word "sling" in popular descriptions and think they're the same.
Try to learn something before posting.Scientists restrict study to entire physical universe; creationist
...flung into space in a botched experiment designed by his newly contracted consultant/assistant, W.E. Coyote of Looney,Tuney,Roades&Runner, LLP.
On an upnote, Dr. Forward will have fulfilled a lifelong goal of visiting all 9 planets as he rockets past Pluto in October of 2013.
(hope this guy had a sense of humor =)
This is why electrodynamic propulsion is so attractive for this purpose. The same soup of ions which drags against a sail forms a current-return path for a conductor. Pump some current through your tether, and you can push against Earth's magnetic field; the lower you are the denser the ions, the stronger the field, and the better it works.
Scientists restrict study to entire physical universe; creationist
Scientists restrict study to entire physical universe; creationist
Sheesh. Add 4 bimbos and you get Wandaba Style.
(yes, it sucks - I have no life, therefore, anime)
This is great because it pits the money of the Hollywood media syndicate against the money of the Religious Right, which is big into editing 'filth' out of movies. Someone needs to eventually put this legal battle on DVD and serve me a bowl of popcorn!
...let's get that reentry thing down first, huh? Seriously, shouldn't every last brain cell that NASA has be committed to finding out why 7 of the world's finest citizens were killed? And they're playing with slingshots? GEEZUS.
NASA will study this, and probably shelve it due to its excessive simplicity.
Man when that rubberband finally snaps... that shit is gonna hurt!
This
Scratching numbers on my calculator watch, it looks like a 60-ton tether sat coming in at 9 km/sec could grab a 5-ton suborbital craft moving at 1 km/sec and be slowed to 8.38 km/sec (still above circular-orbit speed). If we assume that the tether itself is massless, the center of mass of the combined craft would be 12/13 of the way toward the counterweight. If the tether length was 100 kilometers, the angular speed would be (8km/sec/100km)=0.08/sec, and the acceleration on the smaller craft would be (omega^2*r)=0.0064*(1e5*12/13)=591m/sec^2, or about 60 G. That's too much for people, but it shouldn't be any difficulty to design unmanned spacecraft to handle it.
Now imagine something which could boost a 5-ton payload from suborbital-hop speed to LEO, GTO or even further out... once a week.
Scientists restrict study to entire physical universe; creationist
The Japanese probe you refer to used a slingshot technique several times, but it had absolutely nothing to do with a cable. As pointed out before, a sling is not a slingshot.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
i like my penis.
Yeah, so does this one. Ineptly done.
"You plastered your Teather System across my Space Elevator!"
"You got your Space Elevator caught in my Teather System!"
This Space Intentionally Left Blank
WOw, maybe they will build elevators to the moon next! Then perhaps escalators to each planet! Then a "Restaurant at the End of the Universe" wouldn't be completely out of the question :)
-L
Don't Panic.
What if we used this thing to fling all of our garbage towards the sun? Not the best idea, but it could be interesting. We could have a way of permanently ridding our planet of old TV-guides, chicken bones, watermelon rinds, E.T. Atari cartridges, Windows 98 CDs, rapists, spammers, and irreparably soiled panties.
It's not enough to bash in heads, you've got to bash in minds. - Captain Hammer
This is slightly off topic but Science News has an article on a significant improvement in carbon nanotube strand fabrication.
They've figured out how to make strands of nanotube fibers that are as thick as a human hair and more importantly, 120-200 meters long. The article focuses on the use of the fibers in textiles but to me, they make fabricating a space elevator cable more feasible than before. Carbon nanotube fabrication still constrain the cost issues but at least we now know how to make useable length fibers.
If we can figure out to make carbon tubes in bulk quantities it'll be time to start seriously looking at building a space elevator and we can forget about the tether altogether.
There's enough space junk out there already.
I am a rocket scientist. In fact I've worked both on space tethers and giant space guns
professionally.
Electromagnetic tethers work on the same principle as an electric motor - put a current
through a wire in a magnetic field and you get a force. In earth orbit, you can make electrical
contact with the ionosphere so that you have a
one-way current in your wire, and thus a net force. The wire will accelerate one way, and the
ionospheric plasma accelerates the other way, but there is plasma all around the earth, so you
don't run out.
The force you get is IL x B, where I is current
L is the length of the wire, and B is the magnetic field. Since the strength of the
Earth's magnetic field is a given, you can only
play with the current in the wire and the length of the wire to get more force.
The only consumable you have is a bit of gas
that is ionized and squirted out to make your electrical contact with the ionosphere. It turns out you only need about 2% as much gas as a normal rocket would use for the same push, and only 1/8 as much as an ion thruster, so it is very mass-efficient. It can be powered by solar panels.
The downside is it only works well up to about 600 miles. Above that the ionosphere gets too thin to be of much use. That's where the momentum exchange tether comes in.
Vertical cables, or tethers, can be built in a wide range of lengths and spin rates. Any long vertical object in orbit tends to want to remain vertical because the Earth's gravity changes with the inverse square of the distance from the center of the planet.
So the bottom of the object, being closer to the Earth's center is tugged by gravity more than the middle, and the top is tugged less. This is the same effect that causes tides.
Left to itself, then, a vertical cable will stay vertical. The entire thing takes the same amount of time to orbit the earth. So the bottom end, which is moving in a smaller orbit, is moving slower, and the top end is moving faster.
A free object in a lower orbit actually moves
faster, thus if you let go at the bottom of
the cable, you will find yourself at a suborbital speed and re-enter. Similarly, if you let go at the top end, you were moving faster than the local orbital speed, and are thus flung into a higher orbit.
So if you are heading to, say, the Moon, you could ride up in a suborbital rocket that gets you to a landing platform at the bottom of the tether, ride an elevator to the top, then let go and get flung outwards.
While you were riding up the elevator, the rest of the tether is moving down due to Newton's law. Thus the electrodynamic motor, which is typically 10 km long and attached to the much longer momentum tether, is used to make up the altitude lost.
If the momentum exchange tether is short, i.e.
hundreds of km long, the difference in gravity
between the top and bottom isn't too great and
you can build it out of ordinary strong materials. When it gets sizeable in relation
to the Earth's radius, then you need materials
somewhat stronger than what we have available
in quantity.
Because the Earth's orbit has both natural and
manmade objects flying around, you need to be
able to tolerate damage to the tether. At a
minimum you need something like 6 cables, spaced
far enough apart that no single object can
take out more than 2 at a time (you can always
get 2 if you are aimed just right), and you need a way to replace damaged sections and transfer the tension around the damaged area in the mean time. The Tethers Unlimited design uses a fine mesh of many strands.
In the limit of a very long tether, you can get the bottom end to be stationary relative to the ground, and you get the space elevator. But it turns out that one that large, even using insanely strong nanotubes, weighs so much it would never make sense economically. A practical one would be in the 100s to a few 1000 km long.
Daniel
I believe this is the same thing that Wyle E Coyote tried to catch the roadrunner. Hopefully NASA will get better contractors than ACME
That's the sound of the B2 Stealth Joke Plane flying miles overhead, safely out of range.
- q.x.
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
Nasa is back to working on space stuff? I thought they gave it up to focus their energy on mattresses?
Has Ron Toms at Trebuchet.com been awarded a NASA contract?
I would slingshot a groundhog with monkey pox into outerspace to be an ambassador for all mankind.
I would call the groundhog V-GER and if you waited for hundreds of years I bet earth would be attacked by a giant three-toed space-sloth with an even worse type of pox, like ELEPHANT POX!
Don't worry, because Leonard Nimoy's great great grandson would team up with Will Weaton's cryogenically frozen head and save the day.
If airlines increased the fees for their Sky-Phones and used that money wisely, it could fund this NASA initiative.
I don't want to be here.
The image this story creates is amusing, to say the least. I find myself wanting to get about a gross of Superballs caught in this contraption, and see where they all end up...
Bruce Lane, KC7GR,
Blue Feather Technologies
You have been seeing Arte !
lol
we're getting closer and closer to a Farscape project
I said no text!
More than a few people have problems hurling into a toilet, which is generally just about right in front of them.
beauty is only a light switch away
A very large charge built up rather more quickly than the experiment designers had imagined and the wire melted and broke.
Anybody remember this?
-FL
Am I the only one to think "Frat Boy Drinking Game!"?
668: Neighbour of the Beast
At least the wreckage will fall where it won't do much damage.
This is an old application. Bing and Bong of Tiny Planets are already using this technology to travel to other planets on their couch.
Given the few but monumental failures in the software that has controlled various space missions in recent years, I sure hope this thing's perfect. I could just see the thing getting confused and launching something straight down. "Oops..."
I'm sure Pinky and the Brain are behind this!
My website
Check out this link, from the same guys: High-Voltage Orbiting Long Tether (HiVOLT): A System for Remediation of the Van Allen Radiation Belts
This sounds like an interesting idea, but what other concequences would there be to getting rid of the Van Allen Belts? There plans involve just remediating (dispersing particles from) the inner belt, but still... Since most of the particles in the van allen belts are created primarily by interactions in the upper atmosphere, would dispersing the particles in the belt closest to the atmosphere also mean that particles in the outer belts would not be replenished?
I don't know what the effects would be becasue IANAP, and there is no info on their site about it. Would anyone out there more informed about this subject than me care to share their thoughts?
Was anybody else reminded of the black wire from Larry Niven's Ringworld. . The wire that holds the shadow squares together, that is. The application, especially the one at tethers.com about satellites in tight formation is very similar to this, right?
http://www.islandone.org/LEOBiblio/SPBI116.HTMt tp://www.launchloop.com
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