Sheffield University had experiments on both UK3 (Ariel III) and UK4. The Prinicipal Investigator for both was Professor Tom Kaiser. He had moved from Jodrell Bank to Sheffield in 1956 and became Professor of Space Science in 1966. He was one of the first to realise that space technology would be important for the study of the upper atmosphere. He built up experimental expertise at Sheffield in radio frequency impedance problems.
Ken Bullogh (1927-1994) was responsible for the design and development of the VLF receivers on both Ariel III and UK4. Both payloads worked superbly.
The Sheffield experiments measured very low frequency radiation which arises from disturbances due to the entry of charged particles into the ionosphere, from thunderstorms and man-made sources.
The studies of ELF/VLF emissions on the Ariel III and UK4 satellites indicated that man-made electromagnetic emissions, namely power-line harmonic radiation (PLHR) generated in the industrialised regions of North America and, also, VLF transmissions at 17.8 kHz (NAA) and 16.0 kHz (GBR) in the longitude sector which encompasses the South Atlantic Anomaly, were responsible, at least in part, for the formation of the electron slot between the inner and outer radiation belts in the magnetosphere.
A marked lack of PLHR induced emission in winter is attributed to the inability of the waves to become entrapped in ducts. The dependence of signal intensity on storm-time is similarly attributed to duct formation and wave-trapping therein. There was evidence of a possible association between PLHR emissions and thunderstorm activity at American longitudes.
Both experiments (Ariel III and UK4) performed well and good data recovery for 6 months was achieved with Ariel III and 8 months with UK4. The high orbital inclination and associated precession gave comprehensive coverage in geomagnetic latitude, longitude and local time in each 3-monthly period. Similar ELF/VLF narrow-band receivers were flown on both satellites and measurements were made of the peak, mean and minimum signal intensities (magnetic component) in several narrow band channels.
