Hi Harro, > have somebody an information - based on actual observations -about the > rotation of our next decayer IRIDIUM 79 ( 1998 - 051D # 25470 ) ? Is it a > tumbling about all three axis ? It would be helpful to know more about this > for a reliable reentry prediction. I don't think anyone knows for sure. Last year there was some degree of regularity to Iridium 79's flashes, suggesting a spin rather than a tumble, at least over the course of a minute or so. The rotation period used to be around 8 seconds -- i.e. pretty fast. There is probably precession as well, though on a longer time scale. Without knowing how the spin axis is related to the orbital plane (e.g. the spin-axis orientation at perigee relative to the velocity vector), the drag at perigee can't be determined very accurately. Observation of the reentry does not look likely for the northern midlatitudes on this one. Perhaps off the coast of Africa near the equator. --Rob ----------------------------------------------------------------- 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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