A COMMENT ON THE USE OF SIMULTANEOUSLY LAUNCHED PROJECTILES IN THE DEVELOPMENT OF BALLISTIC LIMIT CURVES FOR MULTI-WALL TARGETS

摘要

The traditional shield design for a spacecraft that is tornoperate in the MMOD environment consists of arnbumper that is placed at a small distance from the innerrnwall. Shield performance is characterized by a ballisticrnlimit equation (BLE), which is obtained through impactrntests using light gas guns. Traditional firings employrnonly one projectile per launch package; however, somernfacilities have taken to launching multiple projectiles inrna single package. In light of the significant role playedrnby a BLE in risk assessment, a study was performed tornexamine whether this method of simultaneouslyrnlaunching projectiles would provide results consistentrnwith the traditional single-firing approach. Thisrnconcern was that multiple particle impacts, especiallyrnat oblique angles, can result in interference betweenrndebris clouds created by particles that have alreadyrnstruck the bumper, and those that have not. Thernobjectives were to attempt to duplicate a set ofrnmultiple-projectile test results using hydrocodernmodeling of test firings with single projectiles, and torndetermine if results obtained using those twornapproaches were consistent. The study focused on thernBLE used by NASA for the International Space Stationrn(ISS) Service Module (SM) small diameter cylinderrnradiator wall. This BLE was chosen because thernTsNIIMASH facility in Moscow, Russia recentlyrnperformed tests on this wall system usingrnsimultaneously launched projectiles and, based on thernresults of those tests, had suggested that somernadjustment to the NASA SM BLE may be warranted.