Optical Diagnostics for the Stress Experiment Project STRESS.

A three-site television-aided tracking network was constructed and fielded for the STRESS series of barium releases. The real-time tracks of the barium-ion clouds were used to deduce the ground locations where the coverage of a communications satellite would be affected by the structured ionization in the clouds, so that an instrumented test aircraft could be vectored to these locations. Six releases were successfully tracked during the December 1976 through March 1977 test windows. The TV network acquired the barium-ion clouds as early as times corresponding to a 3 deg solar depression angle and maintained track until the sun set on the cloud 40 to 45 minutes later. The differences between cloud tracks generated by this television network and by an incoherent scatter radar that had also tracked the clouds could usually be ascribed to the two systems intentionally focusing on different regions of the amorphous ion cloud, and did not arise from inconsistencies in the tracking algorithms. Operating experience of the TV-tracking system showed that the most useful tracking procedure for experiments such as STRESS, though not necessarily the most accurate, was a single-site track that uses an empirical model for the cloud altitude after release. Projection of the second DIANNE rocket probe trajectory onto cloud photographs from various round stations showed that the rocket did not encounter the region of peak electron density in its passage through the cloud.