Absolutely- in the case of Mercury's orbit. It demonstrates measurable relativistic orbital precession. That was the model that made me wonder about the 4-day orbital period ("year") of that newly-discovered extra-solar planet. And Kim, Huygens was exactly the spacecraft I was thinking about when I mentioned the doppler-induced frequency shift. Daniel is correct that it's non-relativistic, but it's a robust analogy. On Fri, Jun 20, 2008 at 9:21 PM, Kim <kimharch@cut.net> wrote:
Thanks - I know the difference, but I was wondering if at the "low" velocities of today's earth-based spacecraft relativistic effects are even considered when computing orbits, rendezvous, communications, etc. I my try your spreadsheet idea when I have a bit more time.