Presentation Preference: 13th Hypervelocity Impact Symposium _____ Oral April 27 – May 1, 2015 __X__ Poster Boulder, Colorado (USA) MULTI-SHOCK SHIELD PERFORMANCE AT 15 MJ FOR CATALOGUED DEBRIS J. E. Miller1, B. A. Davis1, E. L. Christiansen2 and D. M. Lear2 1Jacobs, NASA Johnson Space Center, Mail Code KX, Houston, TX 77058, USA, 2 NASA Johnson Space Center, Mail Code KX, Houston, TX 77058, USA ABSTRACT While orbital debris of ten centimeters or more are tracked and catalogued, the difficulty of finding and accurately accounting for forces acting on the objects near the ten centimeter threshold results in both uncertainty of their presence and location. These challenges result in difficult decisions for operators balancing potential costly operational approaches with system loss risk. In this paper, the assessment of the feasibility of protecting a spacecraft from this cata- logued debris is described using numerical simulations and a test of a multi-shock shield system against a cylindrical projectile impacting normal to the surface with approximately 15 MJ of ki- netic energy. The hypervelocity impact test has been conducted at the Arnold Engineering Develop- ment Complex (AEDC) with a 598 g projectile at 6.905 km/s on a NASA supplied multi-shock shield. The projectile used is a hollow aluminum and nylon cylinder with an outside diameter of 8.6 cm and length of 10.3 cm. Figure 1 illustrates the multi-shock shield test article, which con- sisted of five separate bumpers, four of which are fiberglass fabric and one of steel mesh, and two rear walls, each consisting of Kevlar fabric. The overall length of the test article was 2.65 m. The test article was a 5X scaled-up version of a smaller multi-shock shield previously tested using a 1.4 cm diameter aluminum projectile for an inflatable module project. The distanc- es represented by S1 and S1/2 in the figure are 61 cm and 30.5 cm, respectively. Prior to the im- pact test, hydrodynamic simulations indicated that some enhancement to the standard multi- - 1 - shock system is needded to addresss the effectss of the cylinndrical shapee of the projectile. Basedd on the simullations, a steeel mesh bummper has beeen added to tthe shield coonfiguration to enhance tthe fragmenttation of the projectile. TThe AEDC teest occurred as planned, and the moddified NASAA multi-shocck shield succcess- fully stoppped the 5988 g projectilee using 85.5 kg/m2. The fifth bumperr layer remaained in tact, alt- hough it was torn free from its suupport structture and throown into the first rear waall. The outeer Kevlar laayer of the fiirst rear walll tore likely ffrom the imppact of the ffiifth bumper’’s support sttruc- ture, but the back of tthe rear walll was intact. No damagee occurred too the second rear wall, orr to the witneess plate behhind the targeet. Table 1 ddescribes the damage levvels observedd. Figure 1.. Diagram off multi-shockk shield arraangement Table 1. Multi-shockk shield damaage measureements Bumper 1:  Bumper 2:  Bummper 3:  BBumper 4:  Bumper 5:  Rear wall 1:  Rear wwall 2:  Fiberglasss  Fibergglass  steeel mesh  Fiberglass  Fiberglass  Kevlar  Kevllar  130 mm ddi‐ 300 mm di‐ 6000 mm di‐ 3300 mm di‐ No completee  tear on ouuter  ameter perfo‐ ameter perfo‐ ametter perfo‐ ammeter perfo‐ No dammage  penetration fabric layer  ration  ratioon  ration  ration  - 2 -