SNAP Radioisotope Space Programs. Quarterly Progress Report No. 8, Task 7, July 1 Through September 30, 1961

Activities in a program devoted to the safety evaluation of isotopic power systems in space applications are reported. In the study of upper atmosphere re-entry, flare and telemetry test capsules were completed for scheduled re-entry tests. The altitude of re-entry burn-through for all phase I and II test capsules and nose cone-vehicle-pod relative position data were determined. These data were used in determining the optimum positions and headings for the optical and optical-telemetry aircraft. A 100-lb test pod containing simulated SNAP 3 fuel cores was shot into space in July 1961. Two of these were flare capsules containing Na and K, and one was a telemetry capsule containing a transmitter. The flares were sighted and a telemetry signal was received in this test. The high altitude diffusion and dispersion study was concluded with the writing of equations for turbulence-induced cloud growth, wind- induced translational motion and gravity-induced vertical motion. Results of the program for predicting fuel particle size as a function of initial size and re- entry velocity and altitude are included. Work on the radioisotope shielding code was continued. (J.R.D.