Uosat is a series of small satellites built by the University of Surrey, England, for conducting a variety of purposes including amateur radio and educational experiments. They are launched as secondary payloads when room is available. Uosat 1 was also known as OSCAR 9 and launched together with the SME (Solar Mesosphere Explorer). Uosat 5, which weighed just 50 kg and was launched on August 15, 1991, carried a CCD (charge-coupled device) camera able to relay pictures of Earth to schools equipped with suitable receivers.