[X] My Assistant

[hal_9000]

I can not find NH's trajectory on ssd.jpl.nasa.gov and others..
Can anyone post it here?
Thanks!!

[Greg Hullender]

dmuller: Yikes! I'm repeating myself and doing more work the second time! :-) Getting old sucks . . . :-)

Note that the hyperbolic excess doesn't actually depend on which direction NH is going; any small body with the same speed but ANY vector would end up with the same excess (unless it hit something first). That means you can compute hyperbolic excess without knowing the semimajor axis of the hyperbola, as follows:

sqrt(v^2 - 2*mu/r)

So if you know a thing's speed and its distance from the Sun, you can compute the hyperbolic excess with no other info. Of course, if the object isn't in a hyperbolic orbit, then this'll give you an imaginary result, so you should test that v^2 > 2*mu/r -- which is the same as testing that v^2/2 > mu/r which is the same as kinetic energy > -(potential energy).

Cool stuff! :-)

--Greg

[dmuller]

Getting old sucks . . . :-)

Well, at least you're not on the record for calling the mission "New Messenger" like I am