Using the Fengyun interception as a reference, the evidence is that the interception cannot be treated as the sort of ballistic collision that we saw in school science experiments. At the point of collision, two objects will come together with a closing speed near that of orbital velocity. The catastrophic disruption of USA-193 and its interceptor will produce a debris cloud spreading evenly in all directions but, overall, still having USA-193's original orbital characterisics. Witin the cloud will be a collection of trajectories near to the original inclination but spreading either side, and there will be a range of apogees and perigees due to the vertical component of the spreading. Fragments leaving the cloud with the lowest orbital velocity will hit the upper atmosphere fairly quickly - it's a little like Soyuz or Shuttle having fired a retro-rocket. My guess (intentional word) is that the first re-entries will occur about one quarter to one half orbit after the fragmentation. The remainder will be spread over a number of days. The choice of the interception orbit ground track is a very good one. Optical observation is possible immediately after the collision, and the next three circuits of the Earth pass over very little land. The area laid out in the NOTAM is not to defined catch post-collision fragments because there will not be any heading in that direction. The SM-3 missile is three-stage so the area covers the splashdown of stages 1 and 2, and, in the event of a miss, stage 3 and it's warhead also. I have posted some expanded notes and some maps here: http://www.zarya.info/Tracking/USA193/USA193.php Bob Christy No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.20.7/1286 - Release Date: 18/02/2008 18:49 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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