Temporal variations in low degree zonal harmonics from Starlette orbit analysis

The dynamical effect of temporal variations in the zonal harmonics of the earth's gravitational potential due to tidal and meteorological mass redistribution has been observed using satellite laser ranging (SLR) measurements to Starlette. The secular variations in the Earth's zonal harmonics and the year-to-year fluctuation of the even degree annual and semi-annual tides, S(a) and S(sa) have been determined from a continuous Starlette orbit spanning from 1983 through 1985. The mean values for S(a) and S(sa) tides are in good agreement with other tide solutions. The year-to-year fluctuations of the even degree S(a), deduced from Starlette node variations, are about 25 percent of the mean value obtained during the three-year Starlette orbit span.