Space Test Program Experiments

The study of satellite systems and subsystems of spacecraft components are necessary to develop sustainability and reliability of spacecraft function. They form the focus of the second type of STP experiments and logically flow from the space environment studies. The satellite systems below illustrate two of many ways these STP experiments have improved satellite function and reliability. One of the hazards associated with the operation and physical composition of a spacecraft in orbit is the phenomenon known as spacecraft charging. Spacecraft charging results from different electric potentials being built upon various spacecraft surfaces. The different potentials cause arcing and can disable a spacecraft. In 1979, STP launched the SCATHA satellite, which carried out 14 experiments related to spacecraft charging. SCATHA had operated in geosynchronous orbit for over 10 years and had returned a wealth of useful data. SCATHA provided the data base for analyzing spacecraft anomalies and was the primary source of data for military standards related to spacecraft charging. The Combined Release and Radiation Effects Satellite (CRRES) mission launched by STP in 1990 carried out two particularly useful experiments in support of military operations in space. First, CRRES demonstrated and evaluated a new high efficiency solar panel. The experiment contributed to improved space power systems. CRRES also tested and space qualified advanced microelectronic components in space and has contributed to improved military space systems. (USAF photo)