Space weather conditions and spacecraft anomalies in different orbits

Abstract

A large database of anomalies, registered by 220 satellites in different orbits over the period 1971–1994, has been compiled. For the first time, data of 49 Russian Kosmos satellites have been included in a statistical analysis. The database also contains a large set of daily and hourly space weather parameters. A series of statistical analyses made it possible to quantify, for different satellite orbits, space weather conditions in the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 particles cm −2 s −1 sr −1 (pfu) at energy >10 MeV) of solar protons are linked to anomalies registered by satellites in high‐altitude (>15,000 km) near‐polar (inclination >55°) orbits typical for navigation satellites such as those used in the GPS network, NAVSTAR, etc. (the rate of anomalies increases by a factor of ∼20) and to a much smaller extent to anomalies in geostationary orbits (the rate increases by a factor of ∼4). The efficiency in producing anomalies is found to be negligible for proton fluences <100 pfu at energies >10 MeV. Elevated fluxes of energetic (>2 MeV) electrons >10 8 cm −2 d −1 sr −1 are observed by GOES on days with satellite anomalies occurring at geostationary (GOES, SCATHA, METEOSAT, MARECS A, etc.) and low‐altitude (<1500 km) near‐polar (>55°) orbits (Kosmos, SAMPEX, etc.). These elevated fluxes are not observed on days of anomalies registered in high‐altitude near‐polar orbits. Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed.