North Korea claims that its upcoming rocket launch will place a satellite in a 500 km, sun-synchronous orbit: http://www.kcna.co.jp/item/2012/201203/news28/20120328-40ee.html "It weighs 100kg and will circle along the solar synchronous orbit at 500km high altitude." The sun-synchronous claim is inconsistent with the NOTAM coordinates North Korea has issued for the impact zone of the rocket's two stages: NAVAREA NO.12-0174 Date:2012/03/19 12 UTC YELLOW SEA AND NORTH PACIFIC, LUZON. ACCORDING TO INFORMATION FROM NORTH KOREA VIA IMO, ROCKET LAUNCHING. IMPACT HOUR 2200Z TO 0300Z COMMENCING DAILY 11 TO 15 APR. IMPACT AREAS BOUNDED BY A. 35-12-25N 124-52-23E 35-12-13N 124-30-34E 35-55-20N 124-32-10E 35-55-10N 124-50-25E. B. 15-08-19N 124-46-15E 15-09-35N 123-45-27E 19-24-32N 123-54-26E 19-23-08N 124-45-13E. CANCEL THIS MSG 150400Z APR. Stage 1 would impact in zone A; stage 2 in zone B. The launch site is located at 39.660107 N, 124.705203 E. To be sun-synchronous, a 500 km orbit requires an inclination of 97.42 deg. At the latitude of the launch site, a trajectory that directly ascends to that inclination requires a launch azimuth of approximately 192.3 deg (12.3 deg west of due south). The azimuth from the launch site through the various impact zones downrange should agree closely with this value, typically within a degree or so, absent any significant yaw-steering (aka dogleg) early in the ascent. The azimuth from the launch site to the midpoint of the southern boundary of the 2nd stage's impact zone (approx. 15.15 N, 124.26 E) is 181.0 deg, which is far from the required 192.3 deg. I considered the possibility of an eastward dogleg early in the ascent, but the trajectory would have to turn toward approximately 192 deg azimuth well before the 2nd stage ceased firing, in which case the 2nd stage's impact zone should be oriented with its east and west sides pointing roughly toward azimuth 191 deg, but they do not. The west side points toward azimuth 181.8 deg, and the east side 179.8 deg - again far from the required value, and essentially identical to the azimuth calculated from the launch site. Therefore, there is no dogleg, which is not surprising, since it would involve overflying the Korean peninsula, probably including South Korea. I do not see how North Korea could reach a sun-synchronous orbit from the new launch site without risk to populated areas. Launching directly toward the required 192.3 deg azimuth would result in a trajectory that skirts China's east coast near Shanghai. The rocket's second stage would overfly Taiwan, before impacting in a zone bordering within perhaps 50 km of the west coast of the northern Philippines. To give a *very rough* idea of the effect of launching directly toward azimuth 192.3 deg, I have adjusted the longitudes of North Korea's NOTAMs: A. 35-12-25N 123-42E 35-12-13N 123-20E 35-55-20N 123-33E 35-55-10N 123-51E B. 15-08-19N 119-38E 15-09-35N 118-56E 19-24-32N 119-43E 19-23-08N 120-34E I very much doubt that North Korea plans for its rocket stages to fall in the zones I have estimated, but it is for North Korea to explain the inconsistency between the orbit it claims to be targeting and the NOTAMs it provided. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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