http://www.sciencedaily.com/releases/2002/07/020718075904.htm
Excerpt: Most missions are designed to take advantage of the way gravity pulls on a spacecraft when it swings by a body such as a planet or moon. Lo's theory mixes in another factor, the Sun's pull on the planets or a planet's pull on its nearby moons. Forces from many directions nearly cancel each other out, leaving paths through the gravity fields in which spacecraft can travel. 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. -- "Erik Reuter" <[EMAIL PROTECTED]> http://www.erikreuter.net/
