Hypervelocity Impact on Whipple Shields with Varying Bumper Material at 7 KM/S: An Experimental Study

Abstract Introduction Whipple shields, first introduced in 1947 [1] to protect against meteoroids, have been widely used for protection of spacecraft against micrometeoroids and orbital debris. An impacting projectile first hits a thin sacrificial bumper, which shocks the projectile and breaks it up into a cloud of debris that expands over a standoff distance, before impacting successive layers over a larger area, thereby distributing the momentum [2]. Upon impact with the bumper, ejecta is also created, which for an impact on orbit means material is ejected into space, becoming independent pieces of debris. The behavior of various bumper materials subjected to hypervelocity impact is of high interest, as different materials show varying ability to shock and break up an incoming projectile, and produce varying amounts of ejecta on impact. Three different bumper materials (aluminum mesh, Nextel woven fabric and aluminum foam with a front face sheet) are compared to a baseline test with a traditional thin Al 6061-T6 bumper, by dimensioning all bumpers to have near equal areal density. All bumpers are impacted by spherical Al 2017-T4 projectiles at 7Ikm/s. The results are evaluated based on high-speed video footage of the debris cloud development over the standoff distance, as well as observed damage on the ejecta catcher, bumper, rear wall and witness plate.