Cutting the cost of space travel

The Daily Telegraph : US scientists are trying to map the complex interplay of attractive forces between planets and moons in order to reduce the amount of fuel used by spacecraft. The Genesis spacecraft used this technique in 2004 to cut its fuel load by a factor of ten.Depicted by computer graphics, the optimal journey pathways look like strands of spaghetti that wrap around planetary bodies and snake between them.The pathways connect sites called Lagrange points where gravitational forces balance out. Virginia Tech’s Shane Ross said: “I like to think of [these tubes] as being similar to ocean currents, but they are gravitational currents.""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.""It’s not the same as a [gravitational] slingshot,” said Ross. “Slingshots don’t put you in orbit round a moon, whereas this does.”