Accession Number : AD0714142

Title :   Optimum Integration Interval for Use in Orbit Computations with the NRL-9 Gravitational Parameter Set.

Descriptive Note : Technical rept.,

Corporate Author : NAVAL WEAPONS LAB DAHLGREN VA

Personal Author(s) : Robinson,Jane V.

Report Date : SEP 1970

Pagination or Media Count : 30

Abstract : New gravitational parameter sets, generated to produce a better model of the earth's gravitational field, include maximum degree and order of the parameters associated with the cosine and sine terms as high as 19 and 27 respectively. Using one such gravity field solution (NWL 9A), tests were conducted to determine optimum integration intervals for near polar satellites at low (100 n.m.), medium (500 n.m.), and high (11,000 n.m.) altitudes. Through comparisons of trajectories integrated at various intervals, an optimum interval of 30 seconds was selected for the 100 n.m. altitude satellite, 60 seconds for the 500 n.m. altitude satellite, and 640 seconds for the 11,000 n.m. altitude satellite. An orbit difference of approximately 0.1 meter for a span of 2 days was considered to be satisfactory for use in orbit computations. (Graphical illustrations of these comparisons for the different satellites are presented in the appendices). In the study of the 11,000 n.m. altitude satellite, instability in the numerical integration process used in orbit computations was shown to occur for integration intervals of approximately 720 seconds and larger. (Author)

Descriptors :   (*ORBITS, NUMERICAL ANALYSIS), SATELLITES(ARTIFICIAL), EQUATIONS OF MOTION, EPHEMERIDES, OPTIMIZATION, INTEGRAL EQUATIONS, GRAVITY

Subject Categories : Geodesy
      Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE