Author Topic: Slingshots in space  (Read 1287 times)

Offline Tom Ligon

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Re: Slingshots in space
« Reply #1 on: 02/28/2007 05:23 pm »
I came up with a Zamboni analogy, in response to seeing folks struggling with integration of the gravitational attraction going in and out of the well and coming up with no change.  That's a lot of math for doing nothing.  

Just a gravity well only changes your direction.  Picture someone sliding across the ice.  There is a rigid pole sticking out of the ice.  The slider can grab the pole and swing around it, changing direction.  But put the pole on a moving Zamboni machine and try again.  If you were moving across the direction of travel of the Zamboni, and swing into the direction it was going, you pick up speed.  If you swing to the opposite direction, you slow down.  As always, the math analysis must ask "relative to what?"

There is a second type of gravitational assist described to me by R. W. Bussard.   If you're going to do a burn, do it at perigee if at all possible.  The nature of thrust-based velocity changes is that you acquire more kinetic energy for a given amount of delta-V if you do it at high velocity.