Ron Lee scribbles in reply to Lutz: |>>Why did they choose 51.6 degrees. Why not 51 oder 60 or 50.3 ? |>>Why exactly 51.6 ? |>> |>It is likely due to the location of the Mir launch site. If it is |>at 51.6 degrees, there is your answer. They get the best performance |>by launching due east. Inclination on a due east launch equals your |>launch latitude. Baykonur/Tyuratam is actually approx 46 deg N. I suspect that 51.6 deg inclination orbit is the optimum orbit arising from azimuthal launch restrictions at the cosmodrome (eg it might not be a good idea to overfly China during ascent ;-) - that would be my guess. Perhaps Phil Clark/Chien know of the actual reason? -- Neil Clifford <neil@satellite.eu.org> http://www.satellite.eu.org/satintro.html