Interplanetary Superhighway 241
rotenberry writes "The current issue of Caltech's Engineering and Science magizine contains the article "Next Exit 0.5 Million Kilometers - A Caltech/JPL collaboration explores the 'Interplanetary Superhighway.'" which describes "...the Interplanetary Superhighway - 'a vast network of winding tunnels in space' that connects the sun, the planets, their moons, and a
host of other destinations as well. But unlike the wormholes beloved of science-fiction writers, these things are real. In fact, they are already being used." However, it takes a very long time to get there."
how this works (Score:2, Informative)
for those who didn't read the article... (Score:4, Informative)
The structures aren't fixed (Score:5, Informative)
The thing about the wormholes is, though, that they're governed by non-linear dynamics, and are therefore extremely convoluted and difficult to calculate. But that doesn't imply that they're static, just that they're usually not the shortest distance between points A and B.
Poincare Conjecture (Score:3, Informative)
The Poincare Conjecture [claymath.org]
IIRC, solving this problem should make some major advances in this 'tube-theory'. Can anyone explain how though?
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Re:yes, it takes a long time. (Score:1, Informative)
Lagrange Points (Score:3, Informative)
This technique is used to keep the SOHO [nasa.gov] sun observation satellite at Lagrangian point 1 [montana.edu] in the earth/sun system, so that it keeps a constant view of the sun.
The concept behind this is extended in this instance to reveal tunnels which offer the 'path of least resistance.'
In fact, this has been discussed [slashdot.org] on Slashdot before. Slashdot users have also discussed Lagrangian points in relations to one [slashdot.org] or both [slashdot.org] of Earth's sub-moons.
Re:huh? (Score:5, Informative)
It's not. You have to constantly calculate where the low energy paths will be and and then choose one that will take you where you want to.
When the planets move around these paths will change and to get to the same place you may have to take a different 'route' for journeys that start at different times.
Calling it a 'network of tunnels' is a poor simile, lets see if I can do any better. It's more like a set of deep valleys connected to each other over a small rise. The valleys are formed by the gravity of the planets and moons, and the layout of the valleys change as the planets move around.
To get from point A to point B, you can either use lots of energy to go in a straight line up and down the deep sides of the valley or if you follow the bottoms of the valleys and aim carefully at the connection between different valleys you can use less energy to move.
As space is frictionless, not only do you have to spend a lot of energy to get up the side of the valley (ie getting the spaceship up to speed for the journey), you also have to spend a lot of energy to stop from rolling on past where you want to go to (ie slow the spaceship down once it there). This is a problem if you want to send a probe to go and look at several planet/moons in a mission and spend a reasonable amount of time around each one. If you just accelerate/decelerate to get to and from each orbit you'll need a lot of fuel.
What's cool about this is that if you want to, you can bounce around within the valley so long as you don't roll at the low connection to another valley. This means that the spaceship/satellite could stay in one orbit around a moon for a while, and then when the time comes to move on, it can fire its rocket for a very short time just to aim at the low connection to the next valley. This will then make the ship move into orbit around the next planet/moon and it will be in a stable orbit around that until it decides to move on again.
You are so full of crap (Score:5, Informative)
They have discovered a new type of route throughout the solar system, besides the conic sections typically used today, requiring orders of magnitude less energy. They can also predict up to 100 orbits into the future, with multiple ports of call on the itinerary, which is much more sophisticated than the simple slingshot method you're alluding to.
They are using chaos theory and orbital instability to their advantage. That is something most certainly not done in traditional conic orbital maneuvers, which are of such a short duration and simple nature that chaos and instability don't enter into it.
Re:The structures aren't fixed (Score:5, Informative)
These are even often refered to as "Highways on the Sea," and calling these "Interplanetary Superhighways" is no doubt derived from this.
Of course there is no actual structure.
The only real difference is that in space the "continents" are in continuous and *rapid* movement as well, and thus the "currents" and "winds" are in a constant state of flux.
Other than *that* Mrs. Lincoln. .
KFG
Re:The structures aren't fixed (Score:5, Informative)
NASA's been taking advantage of such "gravity assist" trajectories for a while. How do you get to Jupiter? Slingshot around Venus, flyby Earth twice, then you're on your way. It seems roundabout, but sometimes, paths like that are the easiest way.
Duplicate article from July 20, 2002 (Score:5, Informative)
Re:Poincare Conjecture (Score:3, Informative)
The article has nothing to do with this. The article is simply discussing searching for trajectories whihc minimize the energy to get from A to B. The tube/wormhole terminology seems awful, if not incorrect (wormholes are very different beasts).
Re:Lagrange Points (Score:4, Informative)
Evidently the research is more immediately useful for the techniques learned in complex multi-body interacting systems problems, which fluid dynamics guys are also fascinated in.
Re:Seven Rules For Spotting Bogus Science (Score:5, Informative)
Ehh... you're 3/4 right. Centripetal force is real and coreolis force is "imaginary". Centripital force is force towards the center of rotation, keeping you from traveling in a streight line. Centripital force doesn't make it hard to walk on the merry-go-round; centripital force allows you to stay on the merry-go-round. You're thinking of the "imaginary" centrifugal force that appears to counter-act the centripital force you are applying with your feet.
Centrifugal force and Coreolis force are both imaginary forces used as short hand for taking second time derrivatives (calclating accelerations) in rotating reference frames using polar coordinates . If you're spinning at a constant speed about the merry-go-round, you keep the same polar cooarinates when in fact, a lot of corce is acting on your body to keep it constantly changing direction at a fairly high rate. In the reference frame you ae always at rest, so you don't say that momentum change is balancing out the force you are using to keep yourself "still" in the rotating reference frame, you say that this imaginary "centrifugal" force is acting on you. The two statements are equivalent, but one is a technical gloss.
Now suppose you try moving in relation to the rotating reference frame. You want to travel in a streight line in the polar coordinates. Well, since the frame of reference is rotating, a streight path in non-rotating space is a curved line in the rotating reference frame, and the amount of aparent curvature is dependent on speed of travel relative to the rotating reference frame. So when you try and walk in a streight line on the merry-go-round with out correcting for rotation, you more or less walk in a streight line in the non-rotating reference frame. In the rotating reference frame, your path is curved. The easiest way to do calculations is to make up frorces that would havepushed your path into that curved shape. It's all just short hand so that everything doesn't need to be translated to and from the stationary reference frame.
Even at the equator, you experience the coreolis effect, it's just that your axis of rotation is parallel to the ground. At the equtor, running East appears to make you lighter, running West appears to make you heavier, jumping up appears to push you West, and dropping off a ledge appears to push you East. One explination of why thy always launch spacecraft in an eastwardly-traveling orbit is that that way the coreolis force helps, rather than hinders the spaceflight. In a non-rotating reference frame this is equivalent to saying that it already has a lot of speed in an easterly direction, so blasting off to the west actually means sloing down a lot rather than using the speed it already has due to traveling at the same speed as the ground.
It's all equivalent, sometimes it's jsut easier to do the math one way. If nobody has done the math to figure out how the imaginary forces get added in in your situation, then you need to translate everything into a non-rotaing, non-accelerating frame of reference and do the calculatins and translate them back into your rotating frame of reference.
It's kinda like special relativity. If you forget the formulas, you can re-derrive them by looking at everyhting in a stationary reference frame and looking at a photon clock and a photon yardstick and figuring out what apears to happen to one secodn and what appearsto happen to one meter and what appears to happen to one kg being acted upon by 1 Newton. It's just a lot easier if you remember the formulas Einstein derrived for you instead of having to transate everything to and from the stationary reference frame.
Re:The structures aren't fixed (Score:2, Informative)
Re:yes, it takes a long time. (Score:3, Informative)
Re:Seven Rules For Spotting Bogus Science (Score:3, Informative)
The myth about no centrifugal or coriolis forces exists because it's easier to say that to freshman than to try to teach them to analyze forces within a rotating frame of reference.
Re:Deflect killer astroids, gather comet dust? (Score:2, Informative)
Material typiclly doesn't come from elsewhere in the solar system and get stuck in some system's L4 points (like the Earth-Moon L4 or L5 points). The material that is there, if any, would have existed in that location since the formation of the system, i.e., anything near the Earth-Moon L4 or L5 points was there when the Moon formed [nasa.gov].
Regarding the killer asteroids, you're totally right about deflecting them with small forces. There will be a conference next year, Planetary Defense Conference: Protecting Earth from Asteroids [aero.org], where people will propose technical plans associated with defending Earth from approaching near Earth objects (comets and asteroids). The threat will be approached from three warning levels: short-term (less than ten years warning); medium-term (ten to 30 years warning); and long-term (more than 30 years warning). The more time we have to deflect it, the smaller the force needs to be.