Ariel VIA British satellite that was launched June 1979 and was the final small satellite in the Ariel series. Its three experiments were designed to measure the flux of heavy primary cosmic rays, i.e. those above iron in the periodic table, to produce a soft X-ray map of the sky (at energies 0.1–1.5 keV), and to determine the time variability and spectra of individual X-ray sources (many of which were discovered by Ariel V) by means of a proportional counter pointed for several hours toward each source. Each experiment operated successfully for most of the satellite's life (to early 1982) but the scientific returns were limited by a series of spacecraft problems, including interference, particularly over Eastern Europe, from powerful ground radars that caused random switching of both payload and spacecraft elements.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006