IMPACT CRATERING IS ONE OF THE MOST UBIQUITOUS PROCESSES IN THE SOLAR SYSTEM. IN ADDITION TO ABUNDANT PRIMARY IMPACT CRATERS ON THE SURFACE OF VIRTUALLY EVERY PLANET AND SATELLITE SMALLER SECONDARY CRATERS CREATED BY ROCK FRAGMENTS EJECTED FROM THE PRIMARY CRATER ARE EVEN MORE ABUNDANT. A CONTROVERSY IS CURRENTLY RAGING IN THE CRATER DATING COMMUNITY OVER THE CONTRIBUTION OF THESE SECONDARIES TO CRATER COUNTS FOR WHICH AN UNDERSTANDING OF THE SIZE AND LOCATION OF SECONDARIES IN RELATION TO THE PRIMARY IS ESSENTIAL. IN ADDITION THE ANOMALOUSLY LARGE SECONDARY CRATERS ON MERCURY SUGGEST THAT ITS SURFACE IS DIFFERENT IN SOME YET UNDEFINED WAY FROM THAT OF THE MOON OR MARS. A FEW OF THE METEORITES THAT FALL ON EARTH ORIGINATED ON THE MOON AND MARS AND IN THE CASE OF MARS CONSTITUTE OUR ONLYSAMPLES OF THAT PLANET SO FAR. THESE METEORITES REPRESENT THE HIGH-SPEED TAIL OF THE EJECTA FROM IMPACTS ON THOSE PLANETS. EXCHANGE OF MATERIAL AND (PERHAPS) LIVING ORGANISMS BETWEEN PLANETS IS NOW RECOGNIZED TO OCCUR THROUGH SUCH HIGH-SPEED SOLID EJECTA. AT THE PRESENT TIME IT IS NOT POSSIBLE TO ACCURATELY RELATE THE SIZE OF EJECTA FRAGMENTS TO THEIR EJECTION VELOCITY THE SIZE OF THE PARENT CRATER OR THE MATERIAL PROPERTIES OF THE TARGET BODY. SEVERAL INVESTIGATIONS HAVE ESTABLISHED EMPIRICAL RELATIONS BETWEEN EJECTA FRAGMENT SIZES TO THEIR VELOCITY BUT SO FAR IT IS NOT POSSIBLE TO ACCURATELY RELATE THESE SIZES TO THE TARGET MATERIAL PROPERTIES. IN PAST WORK THEPI PROPOSED A SPALL MECHANISM FOR PRODUCING LIGHTLY SHOCKED HIGH-SPEED EJECTA AND ESTIMATED THE EJECTA SIZE-VELOCITY RELATION FROM A LINEAR ELASTIC MODEL. ALTHOUGH THIS MODEL HAS BEEN WIDELY ACCEPTED THE FOUNDATION OF THE MODEL WHILE ADEQUATE FOR THE MID-1980S HAS MANY LIMITATIONS WHEN APPLIED TO THE HIGHEST VELOCITY EJECTA. IN THE PAST THREE YEARS NUMERICAL TOOLS HAVE BEEN CREATED THAT ARECAPABLE OF ADDRESSING THESE LIMITATIONS AND PROVIDING A FIRMER UNDERSTANDING OF THE LINK BETWEEN HIGH-SPEED EJECTA AND THE INTERACTION BETWEEN THE IMPACT-GENERATED SHOCK WAVE AND THE FREE SURFACE OF THE TARGET PLANET. THE GOAL OF THE PROPOSED WORK IS TO APPLY MODERN SHOCK PHYSICS TOOLS TO EVALUATE THE RELATION BETWEEN THE PRIMARY IMPACT AND THE SIZE VELOCITY SHOCK LEVEL AND OTHER PROPERTIES (SUCHAS THE DURATION OF THE SHOCK) OF HIGH-SPEED IMPACT EJECTA. THIS RESEARCH RELIES ON THE IMPACT HYDROCODE ISALE A WELL-TESTED OPENSOURCE COMPUTER CODE DEVELOPED BY THE PI AND HIS COLLABORATORS OVER THE PAST TWO DECADES. THE CURRENT VERSION PERMITS BOTH 2D AND 3D SIMULATIONS THAT INCORPORATE DETAILED MATERIAL MODELS OF ROCK STRENGTH PORE COLLAPSE AND DILATANCY. FORMER PHD STUDENT AND THE PI PERFORMED PRELIMINARY COMPUTATIONS AT THE UNPRECEDENTEDLY HIGH RESOLUTION OF 800 CELLS PER PROJECTILE RADIUS AND CLEARLY RESOLVED THE INTERACTIONS OF THE INITIAL STRONG SHOCK WAVE WITH THE TARGET SURFACE AND TRACKED THE EVOLUTION AND SHOCK LEVEL OF EJECTA. WE PROPOSE TO FURTHER INCORPORATE THE GRADY-KIPP TENSILE FRAGMENTATION ALGORITHM INTO ISALE (THIS MODEL WAS USED IN THE OLDER LAGRANGIAN VERSIONS OF SALE BUT A NEW STRATEGY THAT DERIVES LOCAL STRAIN RATES FROM TRACER PARTICLES IS NEEDED TO IMPLEMENT IT IN THE MORE CAPABLE EULERIAN VERSION). THIS ALGORITHM PRODUCED ACCURATE ESTIMATES OF EXPERIMENTAL FRAGMENT SIZE DISTRIBUTIONS IN PAST RESEARCH AND SO IS VALIDATED. WE HOPE TO LEVERAGE ANALYTICAL SHOCK PROPAGATION MODELS IN ADDITION TO THE NUMERICAL SIMULATIONS TO PRODUCE A FLEXIBLE AND COMPREHENSIVE UNDERSTANDING OF EJECTA FRAGMENT SIZE-VELOCITY RELATIONS AND TEST THESE AGAINST THE EMPIRICAL DATA THAT IS BECOMING INCREASINGLY ABUNDANT. THIS RESEARCH IS RELEVANT TO ROSES C.3 EVOLUTION AND MODIFICATION OF SURFACES. THE RESULTS CUT ACROSS ALL ASPECTS OF IMPACT CRATERING AND ITS EFFECTS ON PLANETARY SURFACES AND THEIR EVOLUTION AS WELL AS THE INTERPRETATION OF THE PAST HISTORY OF MARS AND THE MOON FROM METEORITES.