other magnetospheric, ionospheric, and cosmic ray experiments were also included onboard crres and supported by nasa or the office of naval research. the chemical release project was managed by nasa/msfc and utilized the release of chemicals from onboard canisters at low altitudes near dawn and dusk perigee times and at high altitudes near local midnight. the chemical releases were monitored with optical and radar instrumentation by ground-based observers to measure the bulk properties and movement of the expanding clouds of photo-ionized plasma along field lines after the releases occurred. in order to study the magnetosphere at different local times during the mission, the satellite orbit was designed to precess with respect to the earth-sun line such that the local time at apogee decreased by 2.5 minutes/day from 08:00 (lt) just after launch and returned to this position in nineteen month cycles.