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."

Comments

it's local, folks

[gung-ho iguana]

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.

Re:3-body problem?

[LMCBoy]

You can't solve the three-body problem for a general case (meaning analytically, with the solution written as an equation). You can numerically model the behavior of a gravitational system with many bodies, given some initial conditions.

However, over time your numerical model will deviate more and more from the real evolution of the system. As long as the timescale of this error growth is much longer than a typical spacecraft's travel time, these numerical models are good enough to predict orbital trajectories accurately. Given that current models are estimated to be accurate for many thousands of years, it's no problem.

Re:Warp Theory

[Alien54]

between the stars to minimize gravitational distortions affecting their flight path

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.

Chaos theory mandates this

[WolfWithoutAClause]

The point is that the earlier you know that you are off the correct path, the earlier you can correct it, the less fuel you need to spend.

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.

Re:Chaos theory itself also rules this out...

[WolfWithoutAClause]

All the action takes place into a rotational reference frame, so you have to factor in some subtle forces like the Coriolis Force [uoregon.edu].

Actually not the coriolis force. In the frame rotating about the center of mass you only have to consider gravity and the 'centrifugal force'. If you draw a map of the overall forces you find that there are 5 points in the rotating frame where there are no overall forces acting; these are the lagrange points. It's all amazingly elegant actually.

The coriolis forces are important when you are moving around in this rotating frame however.

No not really.

[WolfWithoutAClause]

The point of the article isn't that they've calculated with more precision, more that they've worked out a way to plot courses through the solar system, more or less for free.

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 ;-)