That superhighway again

Late today ScienceDaily linked this knot-theory piece.

I'd thought we'd seen this back in 1997, from Ross and Lo (also pdf). Shane has ... come back. (One might say.) Anyway the old method was, I think, proposing solar-sails to shift one trajectory to the other. Sometimes the manifolds could find routes between us and Jupiter - which is useful for us, but also for the Comet Empire seeking to crash into us. The new "tube map" proposes to find optimal routes faster, using that knot theory. So: you're on a doomed mine on an asteroid and you need off it, to Ceres or wherever. Which is the best wherever, given fuel-reserves? The theory might work on a local computer, not requiring a supercomputer.

BACKDATE AND REWRITE 4/18 7:30 PM: Okay, I've read the thing, Danny Owen and Nicola Baresi. The press release is bad and its author should feel bad, as should ScienceDaily for not choosing a better summary.

We deal here with passageways between L1 and L2, the focal-points of (unstable) halo orbits balanced between bodies in mutual orbit. Their Jacobi Integral is similar. Once launched to that gravitational midpoint which is L1 - we should get to corresponding L2 with minimal thrust.

So: from the Earth, to (almost) the Moon which is "TLL1" - and beyond. TLL2, as the balance-point opposite the Moon from Earth, should be an easy route either to STL1 or STL2. From STL2, on to Venus (or maybe that 5:4 Laplacian); or just directly outward to anywhere. TLL2 itself is a fine shelter to fire off nukey rides to glory. So the postJacobi question is: sussing out the L1 and L2 manifolds to eject from one and inject to th'other.

Owen-Baresi, I think, shouldn't have bothered with Jupiter/Ganymede on account I suspect its L1/L2 are under severe (periodic) pressure from Europa maybe also Io. Anyway: why Ganymede? Jupiter/Callisto which is not in that resonance should make for purer maths. And that orbit interfaces better with the rest of us. Maybe the trajectory had already braked a craft into JGL1, and now's the time to get it into (less-irradiated) JGL2 . . .

Of course this blog would want to talk Sol/Venus. For all the above that counterlunar orbit L3 needs some love, as well.