Re: Gravity Assist?

From: Jeff Umbarger (
Date: Fri Aug 26 2005 - 18:02:49 EDT

  • Next message: Geoffrey E Forden: "re: Gravity Assist?"

    Thanks Jim,
         So from what I gathered from the link, the only
    thing you get from a "Gravity Slingshot" is a change
    in direction and some less-than-100percent of the
    planets orbital velocity (wrt the sun). From this I
    would gather that it is better to slingshot off
    Mercury (fastest orbital velocity) than Jupiter (much
    slower), right? For instance, if you were sending a
    probe to Saturn and it was on the other side of the
    Sun from Earth at launch, you should wait until
    Mercury is ahead of Earth by 90 degrees around the sun
    and "bank off" Mercury to go on to Saturn, right?
    - Jeff
    --- Jim King <> wrote:
    > Try this Wikipedia article: 
    > Jim
    > Jeff Umbarger wrote:
    > >Hey All,
    > >     I know that this is somewhat off thread but
    > can
    > >someone explain how a planet can "slingshot" a
    > >satellite that has come near it at a *higher*
    > velocity
    > >than before the satellite reached the planet? Here
    > is
    > >where I struggle with this idea: if satellite is
    > >approaching a planet, then that planets gravity
    > should
    > >begin to accelerate that satellite towards it. But
    > as
    > >the satellite *departs* the planet after making
    > >closest approach that same gravity should
    > decelerate
    > >the satellite by just as much - with no net
    > positive
    > >gain, right???
    > >
    > >     Regards,
    > >          Jeff Umbarger
    > >
    > >  
    > >
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