[AR] Re: [OT] Convention for describing elliptical orbits?

  • From: Rand Simberg <simberg@xxxxxxxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Sat, 28 May 2016 13:22:08 -0700

On 2016-05-28 13:15, Henry Spencer wrote:

On Sat, 28 May 2016, Hop David wrote:
I must say I don't like this practice... But if the usual convention is altitude, that's what I'll use. If I use radii, I'll make a note to the reader that I'm not following the usual notation.

Yes, that's the sensible thing to do.  As John said, right or wrong it
is the standard practice, and you only invite confusion if you do
something different without warning people.

It makes some sense for LEO, where you really care about the
difference between altitudes of (say) 200km and 500km, and don't want
to be constantly doing multi-digit subtraction in your head to get
those numbers.  And LEO is where much of the action has been in space.
 When you go much beyond LEO, it changes from being part helpful and
part nuisance to being all nuisance, alas.

Seems helpful for any low planetary orbit, including major moons. I'd say that if periapsis altitude << radius, then use altitude, otherwise, use radius. Obviously, for most heliocentric orbits, the latter would apply.

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