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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.
Liberal (adj.): Free from bigotry; open to progress; tolerant of others.
let's look at the facts: Big government bureaucracy. Foul smelling, funny looking employees. Interplanetary highway construction. It's all there in black and white.
NASA is run by the Vorgons.
There are some people that if they don't know, you can't tell 'em.
According to MOND there is no dark matter. So you wouldn't have to worry about its gravitational effect. You also wouldn't have to worry about bumping into it.
The Moore-Murphy Law: The number of things that will go wrong will double every 2 years.
As much as I love to hear theorys like this out of NASA, and as much as I love NASA, I think they have a few other bugs to iron out first.
While this is a great idea.. and something that has been proposed since the earliest days of Sci-Fi, (using heavy masses as centerpoints for gravitational slingshots, among other things), we
need to get a lot of other things settled first.
People back on the moon looking for raw materials, some actual exploration of Mars, the ISS up and running properly and actually doing something that John Q Public cares about, would be a good start.
This is really coool, and Hubble will probably help a lot, as well as that Muckin Huge Telescope they are building, and SETI may even factor in, as it picks up signals from objects that we cant see, but we can hear.
Its good to see that even in times of "national trouble" NASA is forging ahead and is out on the edge with theorys and predictions, but unfortunately, thats all they are, or are likey to be, unless the Gubmint gets serious about funding space travel. Or NASA becomes self sufficient.. which they could be, if only they collected royalties on the mundane uses of some of the hundreds of things that have been invented/developed by them for the space program.
*sigh*
in a perfect world...
Maeryk
Feminine Protection? What is that? A chartreuse flame thrower?
The research is about finding low-cost paths through the solar system, not interstellar space. The dynamics of the solar system are very well understood, and all of the important gravitating bodies are known (there isn't any significant dark matter inside the solar system, by the way). You just have to do some heavy-duty computations to take advantage of all that.
You're right in that we (so far) cannot solve (in the sense of a mathematical proof) a 3 body problem using nice neat equations like we can for 2 body problems. However it is possible to calculate a trajectory and has been for some time. Takes a reasonably large amount of computing horsepower and a good idea of the initial conditions but a useful approximation can be calculated. Not an elegant or exact method but does work.
i am sure this can be empirically figured out. send hundreds of thousands of little probes all over the solar system and track their movement. each probe only need to be a beacon w/ a solar panel so they should be make very, very light. (prefabbly something degradable so no more space trash! -- or crash all of them into jupiter later, so something).
this way you can figure out to a good degree what the gravimetric forces are within a good error margin.
p.s. there is no accepted theory on what, or where dark matters exist. frankly so far their interactions we can see is on a galaxy-level. hence their existance, or effect within something as small (ha!) as the solar system is not well understood; and since we pretty much sent all the other probes etc (say, voyager) on their routes fairly predictably, i would say contemplating about dark matter interactions within the solar system is unnecessary.
but, if you really wanted to, you could ;-)
My life in the land of the rising sun.
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.
Note to M1-ers: a curt but otherwise insightful message is not "Flamebait" or "Troll".
any "effect" where you use grvity to move with zero fuel is called falling.
no need to give it fancy names.
Which makes sense for interstellar travel.
in interplanetary travel, these areas are probably constantly shifting, and so I wonder if the speed of shift is faster or slower than current space craft.
- Each planet and moon has five locations in space called Lagrange points, where one body's gravity balances another's. Spacecraft can orbit there while burning very little fuel. To find the Interplanetary Superhighway, Lo mapped all the possible flight paths among the Lagrange points, varying the distance the spacecraft would go and how fast or slow it would travel. Like threads twisted together to form a rope, the possible flight paths formed tubes in space. Lo plans to map out these tubes for the whole solar system.
They apparently delivered the software tool to NASA back in 2000."It is a greater offense to steal men's labor, than their clothes"
A similar idea was proposed many years ago (and used for one of the satellites studying the moon). Do a google search for "Earth-Moon fuzzy boundary" for references to that particular application.
The idea is that you can more or less coast through regions where the competing gravitational effects of many bodies cancel out, making part of your path from point a to point b less expensive than the standard transfer orbit.
The article describes an extension of this idea.
There's an alternate theorey that seems to be gaining presidence in the scientific community that modifies Newton's Second Law (F=ma) on a galactic scale. The modification of the Second Law eliminates the need for "dark matter." Interesting stuff. An article on the theory is in this month's Scientific American.
Go to the website here:
http://www.genesismission.org/
includes pictures, decent diagrams, etc.
"It is a greater offense to steal men's labor, than their clothes"
Scientist1: Well, it appears that there's some parts of space where there's no gravitational pull. So, if we chuck the craft along one of these paths, it will umm...
Scientist2: It will probably need less energy.
Scientist1: Right. Since it doesn't have to do any work counteracting any gravity.
Reporter: Makes sense fellas. Now, you called a press conference. What's that all about?
Scientist1: Well, that was it.
Reporter: (short pause) I see. (another longer pause - an uncomfortable silence, actually) Now, seeing as you just worked this out, how did you fly craft before then?
Scientist2: Well, gas was so cheap and all...
(Scientist2 slaps Scientist1 and NASA lose what funding they have left)
IN RELATED NEWS: Liberal Arts graduate? Want to work for the JPL? We're hiring! Call NOW!
Blearf. Blearf, I say.
The reference to "dark matter" makes no sence to anybody ever studied general relativity. External gravitational field doesn't vary significantly in the Solar system, therefore it's irrelevant. Even if we all accelerate in the gravitational field of some dark matter, we do it uniformly.
I'd hate to take the written exams to pilot one my own space wagon, though.
You are at an intersection of 17 interstellar space lanes. You will now listen to the astrogation control channel for 30 seconds. Choose an entry vector to the roundabout, calculate a trajectory towards the Hyades Cluster, and engage warp drive. Remember to follow the astrogation control channel protocol. Refer to the attached astrogation table for nearby mass concentrations. You have two minutes to complete the procedure.
The driving test should be much better: you just grab the joystick, stamp on the warp pedal, and hope for the best.
"I have opinions of my own, strong opinions, but I don't always agree with them." -- George H. W. Bush
It is essentially the slingshot effect taken to extremes: calculate all possible "slingshot" effects and all their interactions and plot a trajectory that takes optimum advantage of all of them (that is not literally how it is done, of course).
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
With the slingshoting spacecraft around planets, the goal and effect is to increase the speed of a spacecraft by passing it by a planet in a special trajectory so that the spacecraft takes some of the planet's momentum. There is an upper limit to how fast a craft can get, because the higher the difference in velocity between the planet and the craft, the closer the craft must come to the planet's centre of gravity. If you're too fast, a collision would occur.
This method of space travel is quite different, much lower speeds are involved, and the trade off is that one can travel the 'space lanes' indefinately, and the craft is essentially coasting anywhere it wants to go. The only fuel needed would be for minor corrections, and to actually get on/off the lane at the beginning and end of the trip.
Put in short, the slingshot effect is at much higher speeds, and is limeted in use, while this method using lagrange points is slower, more reliable, and can be used indefinately.
Bork!
CHAOS THEORY...
It does apply to everything, but the little bit that is applies to really big things like planets and their effect on a space craft is negligile.
SLING SHOT...
A lot of people are talking about using gravity to propel a space craft, but don't seem to understand exactly how it works. When a space craft sling shots around a planet, what happens is this. The SC is captured by the gravity of the planet. The SC begins to fall towards the planet. However, it is falling at such an angle that it will never hit the planet or a significant portion of its atmosphere and is therefore release back into space. Now, conservation of energy applies and says that the kenetic energy gained by falling towards the planet is lost when it escapes on the other side. BUT (this is the heart of how the sling shot works) the planet is orbiting the sun. When the SC begins falling towards the planet, it also gains some of the energy from the planet itself. The SC picks up a significant portion of the velocity of the planet in it's orbit around the sun. When you apply the law of gravity for 2 bodies, you will figure out that the planet actually slows down because some of its energy is given to the SC. The end result is a SC that is going much faster and it didn't have to burn any fuel.
SPACE CRAFT'S FUEL...
several people are saying that the SC doesn't need to use fuel. If we could calculate exactly where everything is in the universe, then we could do it with almost no fuel. But we can't. Also, as all the calculations are only a pretty good estimate, the SC carries enough fuel to make in flight corrections.
LAGRANGE POINTS...
There are 5 points where gravity cancels exactly.
1. directly between the earth and the moon.
2. leading both the earth and the moon. It is in orbit around both the earth and moon, but does not move realtive to them because it can't fall around both.
3. same as 2, but trailing instead of leading
4. on the opposite side of the earth from the moon
5. on the opposite of the moon from the earth.
HOWEVER, only 2 points are STABLE. Points 1,4 and 5 are unstable, points 2 and 3 are stable. If you solve the problem, you realize that points 1,4, and 5 are sources and points 2 and 3 are sinks.
Now to qualify myself. I've only had 2 astro engineering courses (taken for fun) a few years ago back in college, so if i've made any mistakes, please forgive me and correct me.
If I drive fast enough at the red light, it'll appear green.
I recently read and interesting article in SCIAM proposing an alternative to the mysterious dark mater. He calls his theory MOND (Modification of Newtonian Dynamics) where he states that for extremely weak gravitational fields (a < 10E-5 m/s^2), F approaches ma^2. Apparently, his equation is able to explain the stability of may galaxies well without having to use dark matter. It remains to be seen whether his theroy will hold up to serious scrutiny but already, astronomers are using it to model galaxies (using it as a calculation technique instead of an actual law of nature). He has yet to incorporate it in relativity.
More information is available at http://www.astro.umd.edu/~ssm/mond/litsub.html
Lord, bless my users that they may stop being such fucking idiots!!
No, no. You've missed it a little. Gravity is very nonlinear. It really is a chaotic system, particularly with a space vehicle, bouncing around between say the earth and the moon. With this technique they can search for and find a trajectory around bodies, and because the vehicle has small thrusters and the solar system is very predictable, they can make sure they stick to the chosen trajectory, and they end up using miniscule amounts of fuel.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"In my day, we didn't have no inter-planetary sup-er high-way. We got to Triton O-45 the old fashioned way, and it was up a gravity well both ways!
Some scientists theorize that a killer asteroid traveled along the highway when it smacked into Earth and wiped out the dinosaurs 65 million years ago.
Oh my gosh! Interplanetary superhighways facilitate terrorism! Tear it down! Think of the children!
Contrary to what you say, the position of the planets is known to astonishing accuracy- it's only over millions of years that they move significantly chaotically, over a few months their position is entirely known.
A small body bouncing around between them is rather different however- that can be very chaotic.
Plotting a course through the solar system is quite routinely achieved. Remember Voyager?
Uh, wouldn't there be *TWO* such points? Think about it.
Do a web search on Lagrange points, you'll find it. There's 5. One between the earth and moon, one the other side of the moon, one opposite from the moon, one 60 degrees ahead of the moon and one 60 degrees behind.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Being that humans tend to overdue things, I imagine that eventually we will start stealing momentum from some of the planets to such a degree that their orbits will be noticably different, possibly throwing off orbit frequency balances [1] that have been acheived over billions of years, and asteriods in otherwise stable circular orbits will start to go wacko.
I am sure they laughed at the idea that cars and factories could ruin (alter) the Earth's atmosphere. But, we did it. Maybe it will take longer to bust Jupiter, but I woudn't put it past us. If we can harness the energy of the sun from places beyond earth, then we have the potential for *huge* population growth. The energy falling on Earth is a speck compared to all the energy potentially capturable via solar panels made from asteroid materials, etc. The raw materials are all out there and so is the energy. It is only a matter of time until we learn to combine the two.
[1] I forgot what they call that. Synchronicity? Orbit Ratio patterns? Orbital Vibration? stumpage.
Table-ized A.I.
(* what Benjamin Franklin did with studying the Gulf Stream and other oceanic currents? *)
Interesting analogy. They could have called the article "Cosmic Gulfstreams" or "Gravity Gulfstreams".
(* Maybe it is more like get launched, then just coast and steer. I kinda don't see why this is such a big deal... Wouldn't some kind of gravitational radiation antenna be able to just figure out where the gravitation is lowest? *)
More likely, I think that one's position would be often checked by trangulation of appearent planet positions, etc. (or dopler radio) and if it is deviating from the modeled path, then correct the course. IOW, your ship's position is the "gravity antenna".
The idea of "lowest gravity" is probably a misnomer. As the ol' fuzz-head discovered, it is all relative.
Table-ized A.I.
Of course, this was what I had heard over 10 years ago. Maybe things have changed since then.
File under 'M' for 'Manic ranting'
While the CNN article is truely hyped and mostly fluff there is an informative paper here.
In summary: If you find yourself in orbit around a Lagrange point you only need to change your velocity a little to change your orbit radically (thats the chaos part). The orbits you can enter in the Sun-Earth system is forming two horseshoes with the Earth placed in the gap (or perhaps more precisely: Like the figure 8 with the smallest of the loops folded within the larger one and the Earth placed in the cross between the loops). One of the orbits lies within earths orbit. The other lies outside of Earths orbit.
What makes this particular interesting is that the horseshoes of the Sun-Earth system overlaps the horseshoes of the Earth-Moon system. So, if you're travelling along one of the horseshoes in the Sun-Earth system, you can pull the trick again when you cross the horseshoe of the Earth-Moon system and enter an orbit around earth with virtually no fuel consumption. It works the other way around too: If you place a spaceship in one of the Lagrange points of the Earth-Moon system you can reach far into the solar system for almost free by entering the horseshoe of the Sun-Earth system at the right time. The only catch is that you're travelling pretty slow.
Now the CNN article talks a lot about interplanetian travel, but the reality is that the mechanics have only been worked out for the earth-moon-sun system and the Jovian system. Interplanetarian travel requires heavy computatios and is still in the works.
And to dispell some of the confusion in this thread about the nature of the Langrange points this page gives a good explanation.
The Slingshot effect (i.e. the Gravity-Assist) is for trajectories at much higher energies. The Interplanetary Superhighway method is useful at lower energies.
What will be cool is when we can tie the two methods together and use gravity-assists to get someplace quickly and then use lagrange points to move around after we get there... say to design a mission to orbit each of jupiter's moons one by one.
There are 10 types of people in this world, those who can count in binary and those who can't.
And the "chaos theory" probably means that they just considered the stability of their trajectories. This is hardly very exciting. The problems of unstable trajectories should be known to any maths undergrad.
Yeah, but they found a way to make unstable trajectories go exactly where they want them to without using hardly any fuel. Before we just avoided unstable areas because we thought that being unstable was bad, now we can use instability to our advantage. That's the breakthrough.
It's kinda like figuring out how to get from LA to New York without using any gas by planning one big chain reaction car wreck.
There are 10 types of people in this world, those who can count in binary and those who can't.
CHAOS THEORY... It does apply to everything, but the little bit that is applies to really big things like planets and their effect on a space craft is negligile.
There are places where the gravity from the Earth and the Sun pull on your spacecraft at almost the same amount (near Lagrange points) in these places small maneuvers can put you on vastly different trajectories... small actions have big effects... and this is where you can use chaos theory for trajectory design.
There are 10 types of people in this world, those who can count in binary and those who can't.
I never much liked the theory of dark matter. "Our calculations indicate a bunch of stuff we don't observe...must be invisible stuff." Uh, yeah. It's the ether, guys, and planets spontaneously generate from it.
Seriously, though, when a calculation doesn't match up with oberservable fact, you're supposed to adjust the calculations (chaos theory, heisenberg, quantum mechanics), not invent something. And there's a theory right now, explained in the latest scientific american (you ARE a subscriber, right? If not, drop the $35 per year, it makes you a better person), that does just that -- adjusts gravitational constants unchanged since Newton's days when matter moves very quickly. I kind of like it...it makes more sense to me than this "hey, 95% of the galaxy is invisible and undetectable and that's why things spin in wierd directions!" crap.
Dark Matter. Feh. In another 70 years it'll rank with phrenology, dowsing and psychoanalysis.
Hey freaks: now you're ju
And no, this isn't off-topic. I'm commenting on the post I'm replying to.
(still laughing from post)...
Donate background CPU time to fight cancer.
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...
Basically what happens is that there are certain points near to the earth and every other body in the solar system called the Lagrange points. The researchers have worked out a way of calculating a route that passes through the regions around the Lagrange points to jump from planet to planet with almost no expenditure of fuel.
The only downside to this is that the route is probably going to be slow; several years to go from place to place. Still, the implications of being able to move cargo/fuel to say, Mars ahead of human habitation cannot be overestimated. The other downside is you have to be fairly high above the earth initially to be able to reach the 'superhighways', so don't expect the program to give directions from route 66 ;-)
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Oh yeah, one other thing...
This is an interesting discovery since it's not obvious that the minimum energy trajectories between lagrange points follows a strange attractor (and aren't simply random or divergent). This means that if the trajectories are truly chaotic (i.e., follow tube-like strange attractors), once you get near the attractors (matching position/velocity vectors), maybe you can't predict exactly how you are going to get there, but you can be pretty sure that you will stay near the attractor so you needn't waste all your manuvering fuel trying to make minor course adjustments to try and stay on a specific trajectory. If it all pans out, this would probably turn out to be a pretty important discovery for inter-planetary minimum energy trajectories...
Absolutely fascinating work by Martin Lo. If highway coordinates are publicized this might be the best place for spaceguard and amateur asteroid searchers to look. Currently amateurs are discovering asteroids very frequently.
I also wonder if this implies a similar superhighway among the stars which could determine where a stream of matter might be coming over the millenia from outside the solar system. (i.e. where are the off-ramps to our solar system?)
The interview with Lo is much more interesting; he believes we are on a cusp of where advanced theoretical mathematics is going to inform a new generation of engineering.
I would like to understand the math better, specifically to see if it might have applications to software. I'd also like to plot the superhighway, or understand how they are doing it. But only have a year of college math. Where is a good and free place to learn about it online? Been to Mathematica.