As promised, here is the link to my analysis of the USA193/LEAP interception. http://mit.edu/stgs/pdfs/Forden_Preliminary_analysis_USA_193_Shoot_down.pdf other related analyses can be found at http://mit.edu/stgs/spaceprograms.html This is based on an analysis of the debris pattern from the FY-1C collision which show that the ANGLE the debris comes off at is correlated with the direction of the interceptor (sorry, that diagram isn't shown in the paper posted but Id be glad to send it to anyone interested. seesat quite rightly doesn't allow attachments.) I believe that the LEAP interceptor will not use its third stage because that would drive the closing speed well above the announced closing speed of 9.8 km/s (my simulation gives 9.4 km/s if it does not use its third stage but I attribute that to press conference rounding error.) The second stage will splash down about 500 km way from the interception point--about 1000 km away from the ship--and the first stage much closer to the ship than that. Since the NOTAM extends about 1,500 km from the interception point I predict, which is much greater than any of the stages. If the interception point happens at the place I predict or earlier on the satellite's trajectory, observers on Oahu should be able to see it by the flash mentioned in a previous post. By the way, seeing it or not seeing it would be a great way of settling this issue! Again, my predictions for Oahu are: Az: 243.7 El: 10.5 RA: 44.5 Dec: 21.2 Unfortunately, the satellite track as it passes over the NOTAM takes well outside the angular range of any fixed optical instrument. But if is possible to control the pointing of your scope as the satellite moves, I could give you a set of RA/Dec or AZ/EL as a function of time. -----Original Message----- From: Bob Christy [mailto:rdc@zarya.info] Sent: Tuesday, February 19, 2008 9:00 AM To: SeeSat-L@satobs.org Subject: USA-193 Interception 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 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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