Explorer 64 (SME) & UoSAT-1

The Solar Mesosphere Explorer (SME) mission objective was primarily to investigate the processes that create and destroy ozone in the Earth's mesosphere and upper stratosphere. Some specific goals were to: determine the nature and magnitude of changes in mesospheric ozone densities resulting from changes in the solar ultraviolet flux; determine the interrelationship between solar flux, ozone, and the temperature of the upper stratosphere and mesosphere; determine the interrelationship between ozone and water vapor; and determine the interrelationship between nitrogen dioxide and ozone. All instruments on-board the SME were turned off in December 1988 because of energy considerations.

UoSAT-1 was a British amateur radio satellite which orbited Earth and was built at the University of Surrey. It exceeded its anticipated two-year orbital lifespan by six years, having received signals on 13 October 1989, before re-entering the atmosphere.