Analysis of the orbit of ariel 1, 1962-15A, near 15th-order resonance

Ariel 1, the first international satellite, was launched on 26 April 1962, into an orbit inclined at 53.85° to the equator, with an initial perigee height near 390 km. On 8 May 1973 the orbit passed through 15th-order resonance and has been determined, with the RAE orbit refinement program PROP, at eight epochs between February and August 1973 using 500 observations. The orbital inclinations during the time of 15th-order resonance, as given by these eight orbits and 31 U.S. Navy orbits, were fitted with a theoretical curve using the THROE computer program, the best fit giving 10 ⁹C¯₁₅ = -370 ± 14 and 10 ⁹S₁₅ = -114 ± 31. The values of eccentricity were also successfully fitted using THROE, and the results are discussed.