Marco, I don't know what launch site was used, but I doubt very much that the ASAT-weapon performed a high-speed U-turn, which could cause the weapon to disintegrate from high g-forces. There is of course the possibility that the ASAT-weapon was launched from a fighter jet, similar to the U.S. test launch of an ASAT-weapon from a specially instrumented F-15. I still have not found any debris pieces from the Chinese test 11 January that are traveling in the opposite direction of the target satellite (i. e. with an inclination of ca. 81.4 degrees). This leads to the conclusion that the target was indeed struck from behind and the impact between the two bodies created debris pieces in orbits with similar inclination around 98.6 degrees, as I explained in the previous message to the list. This also means that the ASAT-weapon must have had an orbital speed larger than the target at impact, leading to a majority of debris particles traveling in orbits with apogee larger than the target, Feng Yun 1C, original orbit. It's all simple mechanics of impact, really: Some pieces are the result of an elastic collision (like two billiard balls striking, but keeping the total energy maintained - the result is one piece with high apogee and perigee ca 850 km, and the other piece with apogee ca 850 km and perigee very low). Some other pieces are the result of an inelastic collision (like two pieces of clay clinging together after collision and with some energy dissipated at collision - the result is two pieces with perigee ca. 850 km, and apogee a little higher). Most collisions seen here are probably something in between the perfectly elastic and perfectly inelastic collision. The total result is a mess of debris all over the orbital plane and most pieces are still in orbit. The piece with the present largest apogee and with perigee of ca. 850 km provides an indication of the minimum limit speed of the ASAT at impact: The speed of the ASAT must have been greater than 7.1 km/s at impact in relation to Earth's surface, or more than 550 m/s faster than the target satellite speed - that's like a fast cannon projectile, only this one was much larger!. Still, it did hit the small target satellite, max 27 feet across. Christian -- Christian Kjærnet On 14-02-07 11:10, "Marco Langbroek" <marco.langbroek@wanadoo.nl> wrote: > > > Christian Kjærnet wrote: >> Given that all the debris pieces now travel in the same direction as the >> target and in about the same orbital plane, one can conclude that the ASAT >> weapon did strike from behind, with approximately a coplanar trajectory > > In that case Xichang cannot have been the launch site of the interceptor. The > missile then would have had to make a complete U-turn. > > - Marco ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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