tag:blogger.com,1999:blog-8304928500646903522.post7631380610830060104..comments2022-01-20T01:51:53.215-05:00Comments on bensozia: HeightJohnhttp://www.blogger.com/profile/01037215533094998996noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-8304928500646903522.post-28918704354218877802020-05-22T15:13:22.601-04:002020-05-22T15:13:22.601-04:00Out of curiosity, how are satellites supposed to b...Out of curiosity, how are satellites supposed to be meaningfully more accurate?<br /><br />Orbits can be made fairly stable, and we can in theory correct for decay over time, but they still have deviance even over the course of a single orbit, in the form of orbital eccentricity.<br /><br />The periapsis and the apoapsis of a satellite are virtually never exactly the same, and they can substantially different from each other by much, MUCH more than the ten feet of altitude deviance you complain about in your own example.<br /><br />Also, no two satellites have the same orbital paths. Even if you can exactly match the periapsis and apoapsis of two different orbits, each orbit might reach their highest and lowest altitudes at wildly different times in the orbit. Then you also need to correct for inclination and longitude of ascending node, and all the complexities that introduces.<br /><br />What about minute differences in gravity? An equatorial orbit passes over a greater mass of the planet than a polar orbit does, and is subjected to a stronger gravitational pull. A polar orbit has more deviance in the pull of gravity on the satellite, and this introduces eccentricity into the orbit.<br /><br />And how do you -zero- all of this? If we're measuring from a standardized orbital altitude, how do we even measure that altitude to begin with, if it's not based off sea level?<br /><br />Do we try to calculate distance from the center of the earth, and extrapolate out a theoretical sphere a fixed distance away from that, and then try to keep satellites within that sphere of measurement, despite the inherent difficulty of achieving a perfectly spherical orbit at an exact altitude in space?<br /><br />And even assuming we can work it all out, how much of an actual improvement in accuracy is even possible? G. Verlorennoreply@blogger.com