I agree with Tony Beresford that the thrust available to the Iridiums may be too little to force a controlled re-entry. And, like Tony, I suspect that the best they can hope for is to lower the perigee to somewhere below 300 km where they might only last a few weeks or months. At their present heights, I would guess that their lifetimes might be 20-50 years. However, I think there is little possibility of arranging for a decay at far southern latitudes. One advantage of a Molniya's orbit is that its inclination is chosen so that the perigee point does not precess around the orbit. By placing the perigee near its southern apex, the most southerly point, the Molniya is "visible" for lengthy periods as it crawls through apogee over high northern latitudes (eg above Russia). The Iridiums, on the other hand, have inclinations near 86.4 deg so their perigees rotate "backwards" around their orbits at more than 3 degrees per day. In other words, it would take less than a month for the perigee to rotate from near the N or S pole to the equator. Even if the decay can be controlled to within a few days, which I doubt, there is still no guarantee that it will drop in the vicinity of perigee. Alan -- Alan Pickup | COSPAR 2707: 55d53m48.7s N 3d11m51.2s W 156m asl Edinburgh | Tel: +44 (0)131 477 9144 Fax: +44 (0)870 0520750 Scotland | SatEvo page: http://www.wingar.demon.co.uk/satevo/ ----------------------------------------------------------------- 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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