Hello, > In fact, there is nothing special about the sun's gravity in a sun-synchronous > orbit. well, Mike and Ted were absolutely right in their statements! The inclination of an orbit only changes if there is a force normal to the orbital plane. In this case this force is the Sun's gravity. The Moon tries to change the inclination, too. But this force is at one time on the one side of the NOAA orbit and a "month" later on the other side. So this effect cancels out. Since the direction of a sun-synchronous orbit stays fixed to the Sun, it is the driving factor which changes the inclination. Now think of a sun-synchronous orbit with the plane exactly aligned into the Sun's direction. Then the Sun has no effect on the inclination. The same would be true if a NOAA orbit is exactly perpendicular to the Sun. In between the inclination can build up (NOAA 16) or down (NOAA 15) over time, depending on the initial nodes. Cheers, Sebastian ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/sat/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Wed Jun 26 2002 - 02:04:34 PDT