to the planets on half a tank of gas
Several years back there was an awful movie with Dennis Hopper called Space Truckers. I don't really want to dignify the movie with a detailed description, it was that bad. But when I first heard someone talk about the Interplanetary Transport Network I thought of this movie and almost had an aneurism. Then I started thinking about TCP/IP over the deep space network... but then I realized I was thinking of the "Inter-Planetary Network," the SIG from the Internet Society for people interested in data networking across interplanetary distances.No... the Interplanetary Transport Network is much cooler; it's a collection of overlapping transfer orbits that allow spacecraft to move from place to place with much less fuel than they would otherwise require.
"Hmm..." you say, "I though Hohmann Transfer Orbits were the most efficient routes to other planetary bodies?" And in the general case, you would be right. However, if you look at all the meta-stable orbits that librate around the first three Lagrangian points, you can find something interesting. There are a theoretically infinite number of so-called "Lissajous" orbits that can bring you out to an orbit around L1, L2 or L3. Once you're up in one of these orbits, it doesn't take much energy to find an orbit that takes you into a libration orbit around some other system's L1, L2, L3.
Using a network of overlapping orbits, you could (in theory) get to several interesting places in interplanetary space at a fraction of the fuel cost of a typical mission. Shane Ross of CalTech (soon to be of Virginia Tech), has some great illustrations on his site of the concept. There's also a link to a 2004 presentation of the idea at CalTech.
Good Stuff.
Tags: planetary, spacecraft
