The descent of Iridium 9 has changed in character. Somewhere between 22h UT Monday October 16, and 21h UT Tuesday October 17, the satellite controllers put all their effort into lowering the perigee, rather than keeping the orbit circular as they had been doing. Since then the apogee has remained near 650Km height and the perigee height has been decreased to 587Km. This averages about 14 Km/s a day, a lower rate than the 18-19Km/day acheived previously. However it probably uses less fuel, as only one period of thrusting per orbit needs to be done. A side effect is a continuous increase in the eccentricity of the ellipse. This means the long axis of the satellite wont always be exactly on the local vertical, which may effect the atitude control algorithm being used, and the ability to predict flares as the orientation wont be known as precisely as before. Tony Beresford ----------------------------------------------------------------- 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/seesat/seesatindex.html
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