Accession Number : ADA019121

Title :   Analysis of the Orbit of 1970-114F in Its Last 20 Days.

Descriptive Note : Technical rept.,


Personal Author(s) : King-Hele,D. G.

Report Date : JUL 1975

Pagination or Media Count : 37

Abstract : The satellite 1970-114F, the final-stage rocket of the Molyniya 1S communications satellite, decayed in the atmosphere on 3 March 1973. During the last 20 days of its life the orbit suffered exceptionally rapid decay, with the apogee height decreasing from 7000km to 1000km while the perigee height remained near 110km. About 650 observations, made by visual observers in Britain and by US Navy sensors, have been used with the PROP6 orbit refinement program to determine orbits at 14 epochs. Although the decay rate was more than ten times greater than in any previous orbit determination with PROP, good orbits were obtained, the standard deviation in inclination being less than 0.002 deg on eight orbits. The combination of high drag and good accuracy allows three techniques in orbital analysis to be successfully applied for the first time. Since zonal winds have little effect on the orbit, the changes in inclination are analysed to determine meridional winds near perigee, at heights of 110-120km, latitudes of 63 deg - 65 deg S, and 6-12 hours local time. The changes in right ascension of the node are also successfully analysed for the same purpose. The two methods agree in indicating a south-to-north wind of 40 + or - 30m/s from 11 to 21 February, a geomagnetically quiet period, and a south-to-north wind averaging 150 + or - 30m/s from 22 February to March, a geomagnetically disturbed period. Thirdly, the changes in the argument of perigee are analysed to determined atmospheric oblateness, which is found to be equal to the Earth's oblateness, to within + or - 20%. Lastly, the drag coefficient in transition flow is evaluated and found to be 0.85 + or - 0.20. (Author)

Descriptors :   *Orbits, *Communication satellites, Drag, Decay, Rates, Satellite tracking systems, USSR

Subject Categories : Unmanned Spacecraft
      Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE