UoSAT-3 and UoSAT-4 Launched 1990

The primary 80C186 on-board computer failed in May 1997, and it was decided that the Store and Forward transponder operations for VITA would be taken over by the more capable PoSAT-1, rather than develop operational software for UoSAT-3’s secondary processor (based on the Zilog Z80). In 1999 the satellite was configured as an FM voice repeater (VHF to UHF) within the amateur service.

UoSAT-4 contained the scientific payloads to complement UoSAT-3, but the satellite failed due to an electrical fault after two days in orbit. The 47.5kg microsatellite was identical in shape to UoSAT-3. Most of the experiments on UoSAT-4 were re-flown in 1991 on UoSAT-5.