Gravitational Currents Could Slash Fuel Needed For Space Flight 177
Hugh Pickens writes "BBC reports that scientists are mapping the gravitational corridors created from the complex interplay of attractive forces between planets and moons that can be used to cut the cost of journeys in space. 'Basically the idea is there are low energy pathways winding between planets and moons that would slash the amount of fuel needed to explore the solar system,' says Professor Shane Ross from Virginia Tech. 'These are free-fall pathways in space around and between gravitational bodies. Instead of falling down, like you do on Earth, you fall along these tubes.' The pathways connect Lagrange points where gravitational forces balance out. Depicted by computer graphics, the pathways look like strands of spaghetti that wrap around planetary bodies and snake between them. 'If you're in a parking orbit round the Earth, and one of them intersects your trajectory, you just need enough fuel to change your velocity and now you're on a new trajectory that is free,' says Ross. 'You could travel between the moons of Jupiter essentially for free. All you need is a little bit of fuel to do course corrections.' The Genesis spacecraft used gravitational pathways that allowed the amount of fuel carried by the probe to be cut 10-fold, but the trade off is time. While it would take a few months to get around the Jovian moon system using gravitational currents (PDF), attempting to get a free ride from Earth to Mars on the currents might take thousands of years."
So... (Score:5, Funny)
Space Travel is just like the internet. All you need to do is navigate a bunch of tubes.
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Space Travel is just like the internet. All you need to do is navigate a bunch of tubes.
Get your facts strait man!
Its like a series of tubes, if you bunch them up, its just like bending a garden-hose.
The pressure from all the bits that cant get through might spring a leak!
Then you would have bits of bits all over the place.
Re:So... (Score:5, Insightful)
Space Travel is just like the internet. All you need to do is navigate a bunch of tubes.
Yeah, and you can get it for free as long as you're okay with it being slow.
Now we just need to find the Space Travel equivalent of your neighbor's unsecured wireless router, and we can even solve that problem!
Re:So... (Score:5, Funny)
I believe that would be an unsecured cargo bay.
Hello DentArthurDent (Score:5, Funny)
Re:Hello DentArthurDent (Score:4, Funny)
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I can tell you this, space travel is not a dump truck!
We're Swimming in a Sea of Energy Right Now (Score:3, Funny)
Like fish in the water, we are swimming in an immense sea of energetic particles but we can't see it. An analysis of the causality of motion leads to the inevitable conclusion that we are moving in an immense sea of energetic particles. Soon we will understand how to tap into the sea for energy production and extremely fast transportation. It will be an age where vehicles have no need of wheels, move silently at enormous speeds with no visible means of propulsion and negotiate right-angle turns without slow
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Cool! Once we do, I'll be able to power up my phlogiston generator so I can use the caloric to power my N-ray emitters!
Colonic (Score:2)
Actually, that was a typo in the manual of the sales demo. If you read the errata on the product you bought, you'll see that the word is "colonic".
Re:So... (Score:5, Funny)
The pathways connect Lagrange points where gravitational forces balance out. Depicted by computer graphics, the pathways look like strands of spaghetti that wrap around planetary bodies
I knew it! My belief in the one true faith is justified!
-- Strict Constructionist Pastafarian (Bolognaise)
old idea (Score:5, Informative)
Re:old idea (Score:4, Funny)
There's also Dupe Currents, and if one knows how to correctly navigate them, they can avoid dupes.
But I think it's okay if Slashdot posts the same concept every 5 years or so. There is turnover in users. Woodstock is not a dupe if you missed the first one. (Then again, most Woodstock attendies were probably too strung out to remember the first one anyhow.)
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As others have said, not news. In my deskPix directory, from which I randomly pick a background each login, I have "Interplanetary_Superhighway.jpg" dated Sept 8, 2005 which is as far as I can tell, exactly the same picture used in the article. Doesn't beat the 2003 Slashdot date, but the illustration matches.
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It's a neat picture, but I'm disappointed with it. The planets are in motion, so the corridors are changing shape. I want to see an animation of how these corridors move over time. Anything else is a simplification, surely.
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They do what they can with a 2D projection of a 3D+time situation. But even at that it's an overly simplistic picture, with "a highway" zipping a loop through the planets, and the planets aren't even in any sort of solar-centric positions, even if they did choose to exaggerate sizes for the case of illustration. For that matter, it would be fascinating to get a better idea of the shape of these corridors. Are they simple spokes, radial from the Sun through each planet? Do they have a curve? Why? etc, e
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That would be great. I would love to do something like this, and I could probably manage the graphics side of things, but the mathematics is currently beyond me. I would need to do quite a bit of studying before I understood what I was supposed to be generating pictures of.
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Not only that, but Asimov wrote about this in 1952 [wikipedia.org]!
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Not only that, but Asimov wrote about this in 1952!
Damn! 1952!
He must have a two digit uid at most!
Re:old idea (Score:5, Informative)
Or if you'd RTFA you'd see the part where they talk about the Apollo missions and how it is not the same concept.
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In my day... (Score:5, Funny)
In my day we went to Mars uphill both ways unlike you kids who coast the whole way - and we LIKED IT!!!
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"Damned space liberals, always looking for a free ride, sucking gravity right from the pockets of tax-paying Jupiter and the moon."
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At least you got there quickly, instead of having to wait 1000 years.
Next: $150 trip to Mars (Score:3, Funny)
Next:$150 trip to Mars
Come on MIT boys, pump up that balloon and add another handwarmer.
Re:Next: $150 trip to Mars (Score:4, Funny)
Pffft, Russians do it for $40, and survive more.
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Pffft, Russians do it for $40, and survive more.
Well, $40, yeah, but 'survive more', not so sure. Plus if you DO fail, or your political clout goes south, you could be erased from history. Not worth it to save $110, especially for current values of US $110.
fracking lawyers theyre everywhere (Score:3, Interesting)
... Jovian moon system suing gravitational currents ...
Lawyers... IN SPACE!!! (Score:5, Funny)
While it would take a few months to get round the Jovian moon system suing gravitational currents (PDF)...
I had never before considered using the power of lawsuits to drive an inter-planetary vehicle, very interesting. But is it feasible? What's the TPL (thrust per lawsuit) against a given gravitational current and how many lawsuits can a lawyer put out during the life of a mission? Does the size of the gravitational current matter? I imagine so since they said the system is much faster suing Jupiter's gravitational currents than Earth's and Mars' currents.
I haven't seen any solid details on this yet, I think this whole plan is still a ways off yet.
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What's the TPL (thrust per lawsuit) against a given gravitational current
DPL (Disgust Per Lawsuit) is even more powerful!
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Given how many lawyers later become politicians, and how many sex scandals politicians seem to become embroiled in, I also wonder about the TPL (thrust per lawsuit).
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I propose a theory wherein the postulated dark matter is actually the bullshit that is a natural byproduct of lawyering. Dark energy is their concentrated greed. The historically unprecedented litigious nature of our society is responsible for the accelerating growth of the universe. Newton's perception of the "fixed heavenly bodies" was not an error on his part--they were truly stationary since the universe had not yet accumulated enough legal excrement to cause the stars to move.
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Q: What do you call a thousand lawyers launched into space?
A: a good start!
suing the currents (Score:5, Funny)
Apparently the Rocket Industry Association of America found out that people were planning to travel for free by stealing gravity from nearby planets. They also discovered that gravitational currents are aiding and abetting these crimes by making it easy to find and use the gravity. These pirates think they can escape prosecution by relocating to the Jovian moon system, but the RIAA lawyers were able to track them down and sue them within a few months.
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Getting out of Orbit (Score:5, Informative)
The vast majority of fuel usage is simply getting out of orbit. I imagine this would be musch more useful for vehicles that are simply motoring around the solar system, but not dropping to the planet, or even going into LEO.
Re:Getting out of Orbit (Score:5, Interesting)
Which is why we need one of these: http://en.wikipedia.org/wiki/Launch_loop [wikipedia.org]
Have a look at the economics:
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I can't look at the economics - because there aren't any economics to looks at, only theories based on some questionable assumptions.
Like this one: The launch loop will, unlike any other significant project ever, come in at or under budget and at or under schedule. Or this one: That it will generate sufficient revenue in the first year(s) of operation to pay not only operating overhead, but also interest and principal. (Highly doubtful as there isn't any backlog of pay
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Can you pay in rubles?
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People complain that the space elevator would be too dangerous, but if that wiki article is correct you'd have about 700 TRILLION KILOGRAMS of iron whizzing about at Mach 42. Rough calcs place that stored energy somewhere around 16.2 million megatons equivalent.
Yeah. No. Space elevator might be a hazard but at least it won't cut the fucking planet in half.
=Smidge=
Mission to Mars (almost) (Score:2)
I heard this suggested as an easier way to get to Mars and back: don't stop.
Rocket to Mars. Stay in high orbit. Drop some remote control vehicles to the surface. Operate them manually without the long delays that Earth-based controllers would suffer. Recapture some very small sample return vehicles from the surface. And shift back into a cheap return-to-Earth trajectory.
I think it's an awful lot of trouble just for more responsive remote controls. But it could be a big savings of fuel/mass and might be a wi
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n-body problem (Score:2, Insightful)
This is a great idea but the difficulty is in solving n-body problems incorporating all the gravitational bodies in the solar system.
Even finding the Lagrange points between the earth, sun, and moon is very difficult. Throw in all the other moons and planets and you have a even harder task on your hands.
Re:n-body problem (Score:5, Informative)
Depends on your time horizon. Millions of years, no. Human time horizons, however, we can handle.
A good, modern, numerical integrator at quadruple precision can handle the Sun, planets, and hundreds of asteroids with very small numerical errors (microns over decades). Bigger errors are introduced by observational uncertainty, primarily in the masses of the asteroids. But, even with that, errors are 100's of meters over decades.
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You can't dumb down rocket science (Score:5, Insightful)
But TFA makes it sound like you can find 'just the right spot just past the Moon' and zoooooop! Off you go the the gasoline seas of Titan.
BS.
Douglas Adams stated that "Space if really big." The image in TFA makes it looks like a skate park. Try drawing the Solar System to scale, and you begin to get the idea. A local community college has a scale MODEL. The sun is about a meter in diameter a frisbee throw away is Earth, this tiny dot with a tinier a fly's wingspan away. It took us a Saturn V to get there and 4 days. TFA wants us to think that once we get there, we can "freefall [down] pathways in space around and between gravitational bodies. Instead of falling down, like you do on Earth, you fall along these tubes." That's crap, without a metric a55load of Delta V.
'If you're in a parking orbit round the Earth, and one of them intersects your trajectory, you just need enough fuel to change your velocity and now you're on a new trajectory that is free.''
BS.
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". Try drawing the Solar System to scale,"
I did, now get the hell off my map~
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"If you use enough time (and money) a solar sail will get you there for free."
Any reasonable solar sail probably gets you there faster than the low fuel corridor anyway.
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From TFA
Wouldn't that be the opposite of what you just said?
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A few months to get around the Jovia
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The general public doesn't know how long it takes to get there. They think we can get there in a couple hours using impulse engines. We can't.
Hell, if you don't have inertial dampeners, you're not going to realistically push humans for long periods with anything more than 1G acceleration even WITH impulse engines, so it'll take you weeks to get to any other planet in the solar system. Impulse engines aren't the hard sublight technology from Star Trek as far as I can see, compared to 'inertial dampeners'.
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If I'm in orbit around the sun, stationed at an L1, 2, 3, where do I get the delta V (change in energy) from Earth's circular orbit to Jupiter? What magical force adds energy to my current trajectory?
I'm looking at a reference to "a great book written by Edward Belbruno on his design of advanced trajectories called "Weak Stability Boundary Trajectories". http://www.tobedetermined.org/2008/10/fly_me_to_the_moon.html [tobedetermined.org]. I see a trajectory which flies from Earth to lunar d
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This [caltech.edu] article provides much more detail. The "Interplanetary Transport Network" article at Wikipedia contains references and links to more, if that isn't good enough.
Summary says it all (Score:4, Insightful)
Now, I can go back to sleep
Wish I had mod points. (Score:2)
The best ideas of the 1970's ! (Score:4, Interesting)
This is not new. Almost every mission going further away than Mars or Venus uses these gravity assists, and has since Mariner 10 (1974).
I really dislike the term "gravitational currents." It conveys exactly the wrong impression. The effects of 3rd bodies is almost negligable except during close approaches, so "gravitational billiards" would be much more appropriate.
not gravity assist! (Score:3, Informative)
A gravity assist trajectory is using the gravitational field of a large planet to divert a spacecraft to it's final destination. Since you are falling down a gravity well with this trajectory, you generate acceleration. The reason this works is that you are essentially "stealing" some of the momentum from the planet (think billiard balls colliding and exchanging momentum, but this is just without the collision).
This technique is almost the dual of the gravity assist in that it has the spacecraft follow th
Re:not gravity assist! (Score:4, Informative)
Just thought I'd add another clarifying point.
It's often hard to visualize this, but even though a gravity current path (the minimum energy path) in a 6-d manifold (position+velocity) has time-varying velocity 3d velocitu (because the path isn't straight in 3d space it implies some acceleration from a 3d perspective), the velocity change is still essentially zero energy because sometimes the energy for the required velocity changes can come from gravity interaction itself (imagine a "valley" of some sort in a 6-d manifold), although some may require being very near the optimal path (imagine a "ridge" of some sort in a 6-d manifold) and thus require small corrections to prevent "butterfly-effects" from pushing the spacecraft further away from the optimal path (which these small course corrections are still better than fighting gravity all the way to the destination).
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Uh, the title of the actual paper is "Optimal capture trajectories using multiple gravity assists." That is exactly what Galileo Jupiter did - I worked in support of that mission way back in the early 1980's (prior to launch).
So if there was a 10-fold decrease (Score:2, Interesting)
1. Take a craft that has the fuel and thrust to go from Earth to Mars without the tubes in X days.
2. Actively navigate the tubes instead of free-falling
3. Wouldn't this make for a shorter, more efficient trip?
4. Does navigating the currents have any effect on relativity? (Could a ship travel closer to c through these tubes?)
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Nope and nope.
It's just a low energy, weird looking, series of orbits. If you want to go to Jupiter, say, there are a couple of ways to do it. You can use lots of fuel and put yourself on a highly elliptical orbit of the sun then, when you're near Jupiter, use lots more fuel to kick yourself into orbit around it.
Or you can use less fuel to slowly spiral out to higher and higher Earth orbit, then maybe you kick into your own solar orbit, then maybe you wait until Mars is in the right place to kick you over
Re:So if there was a 10-fold decrease (Score:4, Informative)
not 4-d, 6-d (Score:3, Informative)
The "tubes" are really iso-paths in 6-dimensional (3d position + 3d velocity).
The "tubes" happen to connect the LaGrange points in 4d, though.
You do NOT have to navigate spacetime in your own power if you stay in these "tubes", although since they are 6-d isopaths, their "minimum energy" aspect to the path is really at their intrinsic velocity (which is why they are slow).
Let's try to get this one right...
No. You need an analogy... (Score:2)
Here's your analogy:
Imagine a bobsled run made of ice. Ok, but the bobsled has no steering and follows the curves when the gravity balances the centripetal acceleration (oft called centrifugal force). This is not new. It's like driving on a banked, icy road.
OK, the run was designed to work because of a very specific initial speed. Anything higher, you fly o
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we've ALL driven too fast on an icy road.
Nope, sorry. I've lived my whole life in Los Angeles. The closest that I've ever come to an icy road is one time when my ice maker overflowed.
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Senator Stevens? Is that you?
Inertial Reference Frame? (Score:2)
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They probably a set of farthest (i.e., effectively immoble) stars to define the reference frame, like the Apollo missions did.
Time travel (Score:2)
Fly part way. (Score:2)
I'm sure there are good reasons, but as a lay person watching a shuttle launch it seems like a waste of energy just "brute forcing" our way off the planet.
As far as these g
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"Up" is not the problem in getting to space; it is the velocity that is the problem. A 747 can reach a top speed of 567 miles per hour, while orbital velocity is 17,500 miles per hour. So, even if you could make a 747 carry a fully-loaded shuttle (it can't), you'd still need to accelerate an additional 17,000 miles per hour (which would still require the solid rocket boosters and the external tank, which are the majority of the weight, which a 747 certainly couldn't carry).
The shuttle passes a speed of 56
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A cloud going mach 20.
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Obviously there major flaws in my
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You're not "wrong", you just aren't familiar enough with the numbers to rely on your intuition. Take a CD or DVD and call it the Earth. Now trace an orbit around it about 18mm out from the CD's edge. That's Low Earth Orbit (LEO has a bit of a range, I've taken 1,000km which is in the middle). Now you can see how much of a difference flying up 5-8 miles (about 0.3mm above our CD) makes. Incidentally, atmosphere is pretty much negligible more than 2mm out from your CD-Earth.
Playing with the numbers involv
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"Wing Flying" (using air resistance on wings to gain altitude) is not a particularly efficient way to gain altitude. We do it for human transportation because the altitudes we are talking about are negligible when compared to the lateral distance we want to cover. We might fly to 10,000 feet when covering 200 miles, for example, and possibly as much as 50,000 feet to cover a thousand miles. Using wings for lift are really only practical because flights are largely about covering horizontal distance, and
This is sort of a groaner (Score:3, Insightful)
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Uh, twit, this is what I do for a living. The statement, as made and stand-alone, was true of this scheme [i]and every other scheme[/i] possible for trajectory change.
Brett
Point of order (Score:2)
The BBC is not the Daily Telegraph
Concept in action (Score:2)
The Project Triangle strikes again! (Score:2)
A more technical article (Score:2)
Here's an article [caltech.edu] on this that is a bit more technical.
Massively Complex (Score:2)
To borrow a computer term, 'massively parallel', consider the 'n body problem' (down the page a bit at http://en.wikipedia.org/wiki/Three-body_problem [wikipedia.org] where the number of interactions is enormous, and all the bodies are in motion, making that enormous complexity change constantly in orientations and even numbers. computing this collection of interactions is typically done statistically since the calculations for the actual interactions would strain most computers.
Then consider the gravitational balance poin
Credit Martin Lo (Genesis) (Score:2)
Glad to see another news story about this fascinating concept not covered in the press. But since it is obviously a story that is some years old you should credit the discoverer of the superhighway, Martin Lo, whose calculations for a halo orbit around solar lagrange point IIRC made possible the GENESIS mission.
It would be very cool if someone could comprehend the math involved and make a simulation of how it would look in the solar system. I don't understand if it is the multibody problem but have an unwar
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!= Radiation Overdose (Score:2)
What? No! I didn't get the idea from watching Star-Trek movies. I'm just smarter than all the guys at NASA.
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"Putting enough radiation shielding around a spacecraft would make it far too heavy to launch,"
Or, launch it in pieces and assemble the shield in space.
Or, but a lot of water between you and the back,
Or, only heavily shield a smaller space.
Or take a nuclear power plant and creata a magnetic buble aounr the aft of the ship.
Or have two shits, one auto mated ship that stay between the lead ship and the sun.
It's an engineering problem; however pills that make people immune to radiation damage and repair them s
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Or, launch it in pieces and assemble the shield in space.
Exactly. Why do people keep talking like the only way to launch interplanetary ships is in one piece? We need to improve our orbital construction capabilities.
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So, you're one of those that can give such... :)
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In David Weber's Honor Harrington series, they use gravity waves for transport too [wikipedia.org].
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So the answer would be "No, no one has ever heard of the Anderson Drive" then... :)
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By this same logic, when our sun lines up with the plane of the milky way at 11:11am on Dec 21st, 2012, ... Who knows what will happen when we face that.
I still have high hopes for a zombie apocalypse before the end of everything at the end of 2012. *crossing my fingers*
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Somewhere, there are a group of very bright researches, clutching a very sophisticated new model for calculating optimum gravitational assists, wondering how in Hell's name a year of work got summed up by the Internet as "you fall along these tubes".
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Big deal. Gravitational assist orbits are known from the dawn of space time. It helps and guess what, yes all the probes that were sent to mars do take advantage of such orbits
You appear to have misunderstood what the article is about.