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Road Trip On The Interplanetary Superhighway
eegad writes: "CNN has an article about a new idea from NASA springing from chaos theory called the interplanetary superhighway. It will purportedly allow easier space travel by steering through regions where the net gravitational force exerted by nearby bodies is smallest. The actual NASA news release is here. Sounds like an interesting concept but it is unclear how the scientists will account for every source of gravity, including the elusive dark matter."
Dark Matter?! Absolutely negligible on interplanetary scales.
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The Mongrel Dogs Who Teach
Uh, just back up a minute there. Chaos theory also punches a massive hole in the idea which none of the articles seem to address. To be able to utilise this idea, you need to know in advance exactly where the planets will move to. Chaos theory states that this isn't possible, since you would need a tremendous amount of precision (down to inches) to be able to predict how and when all of these planets will be just right such that you are in a zero-gravity path. If you're wrong, you have to burn fuel to get onto the path, assuming you aren't too far off in the first place. After all, predicting where planets move requires a "complex iterative model", and if your starting data is even slightly out, then it will drift far away from the correct answer over time.
Each planet and moon has five locations in space called Lagrange points, where one body's gravity balances another's.
Right. So what you're saying is if I have the Earth and the Moon, there will be five points where the gravitational forces from the both of them cancel out. Uh, wouldn't there be *TWO* such points? Think about it.
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any "effect" where you use grvity to move with zero fuel is called falling.
no need to give it fancy names.
I'd just like to point out that you can't send degradable stuff into space since there's nothing to degrade it, and even if you did degrade it, the matter would still be floating in space in a different form.
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Nowhere did Mr. Lo describe in his paper that the gravity cancels out on these paths (only that they were minimum energy and connected the Lagrange points).
;^)
The whole idea of a minimum energy paths through the solar system is that it's a dynamical systems of greater than 2 dimensions. The weird thing about dynamical systems of 3 dimensions is that trajectories in some of these systems exhibit a type of predictability called a "strange" attractor.
Strange attractors for trajectories are different than the attractors you normally see in 2 dimensions (like local minima or orbits that retrace themselves) in that small pertubations can cause greatly divergent behavior. Even though the behavior appears chaotic, in some systems, the behavior can still be described as nearby a "strange" attractor. This is effect is often called chaos, and the study of strange attractors is called chaos theory.
Apparently Mr. Lo has worked out a theory where the minimum energy trajectories under this complicated dynamical system (planetary gravitational attraction) exhibits attractors that looks like "tubes" that exhibit the chaos-like behavior of strange attractors.
At first glance, these tubes appear to have the dynamical structure similar to n-body orbits (this factoid about orbits was first discovered by Michel Henon in the 60's). "orbits" in n-body systems don't actually retrace themselves, but sort of looks like a coiled up extension cord. The envelope or attractor of the orbits look sort of like a mis-shaped torus (squished donut), where the orbits can pretty much be anywhere on the surface of the donut (the attractor), but the path it takes is somewhat unpredictable (chaos) and highly dependent on initial conditions. There are more complicated attractors (some involving little islands of stability inside the donut) depending on the energy level, but this is the basic idea. This discovery seems to extend this known factoid about orbits to the structure of minimum energy trajectories in n-body gravitational fields.
All this will be moot, however, when in the 2004 election, Al Gore wins the presidency by taking credit for inventing the Interplanetary Super-Highway while giving a campaign speech for an increased budget for Nasa leading all the l337 geek-crackers to rig the newly approved, non-tamperproof election computers... I boldly predict this will be henceforth called the "butterfly-ballot" effect... But I digress...