DebriSat Pre Preshot Laboratory Analyses
AEROSPACE CORP EL SEGUNDO CA PHYSICAL SCIENCES LABS
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In preparation for the DebriSat hypervelocity impact test a Pre Preshot was conducted to validate the performance of the aluminum projectile to meet the velocity goal of 7 kms and confirm operational status of test chamber and facility. The target was a multi-shock shield supplied by NASA which consisted of seven bumper panels consisting of fiberglass E-glass, 1,2,4,5, stainless steel mesh 3 and Kevlar 6,7. In contrast to the DebriSat and Debris-LV impact tests, no soft catch panels were installed. A witness plate assembly was provided by Aerospace in order to catch and sample debris for laboratory analysis, to identify materials produced by the impact and characterize the degree of darkening associated with hypervelocity collisions. The material collected on the witness plate as a result of the impact formed a thin continuous layer about 10 microns thick, solidified from molten droplets of two phases that have a complex intermixed flow structure. The material consists of a crystalline Fe-Cr-Ni rich phase and amorphous oxide phases. The relative Fe-Cr-Ni proportions in the Fe-Cr phase are not significantly different from the stainless steel bumper though it also contains significant amounts Al and Si. The Al and Si contents are about equal in early arriving Fe-Cr-Ni while the later arriving Fe-Cr is Si rich and Al is low to absent. In the later droplets there is less flow structure and individual droplets tend to retain their shape implying they were already semi-solidified when deposited. The oxide phases have a range of compositions. Significant darkening of adjacent structures, with a drop from 90-95 to 20-25 reflectance, occurred as a result of impact. The deposition on the witness plate assembly appears to be line of sight. LWIR spectral features from the deposited material are related to silicate and borate from the E-glass bumpers that were penetrated. The silicate feature shifted as a result of a change in composition.
- Operations Research
- Fluid Mechanics
- Unmanned Spacecraft