A CRITICAL ISSUE IN DEALING WITH NEAR-EARTH OBJECTS (NEO) ACCORDING TO NEOO PROGRAM GOALS AND THE PLANETARY DEFENSE COORDINATION OFFICE (PDCO) IS TO IDENTIFY POTENTIAL IMPACTORS THAT MAY STRIKE THE EARTH. GIVEN THIS PRIORITY IT IS DISTURBING THAT WE DO NOT YET HAVE AN ACCURATE MODEL OF THE ORBITS AND PHYSICAL PROPERTIES OF NEO IMPACTORS. AT BEST WE HAVE VAGUE APPROXIMATIONS FOR IMPACTOR TRAJECTORIES VELOCITIES SIZES STRENGTHS AND COMPOSITIONS. WITH AN ACCURATE MODEL WE CAN POTENTIALLY OPTIMIZE OUR GROUND- AND SPACEBASED SEARCH STRATEGIES TO FIND IMPACTORS EVALUATE THE EFFECTIVENESS OF STATE OF THE ART SURVEYS LIKE NEOCAM SENTINEL AND LSST AND DEVELOP COST EFFECTIVE EARLY WARNING SYSTEMS FOR CHELYBINSK-LIKE AND LARGER EVENTS. THE KEY PROBLEMS WITH COMPUTING AN ACCURATE IMPACTOR MODEL ARE AS FOLLOWS: 1. IMPACT PROBABILITY PROBLEMS: NEARLY ALL SYNTHETIC IMPACTORS ARE GENERATED BY RUNNING OBSERVED/MODEL NEOS THROUGH STATISTICAL OPIK -LIKE CODES WHERE IMPACT PROBABILITIES ARE DETERMINED USING GEOMETRICAL ARGUMENTS (E.G. OPIK 1951; BOTTKE ET AL. 1994; VERES ET AL. 2009). AS WE WILL SHOW HOWEVER OPIK CODES PRODUCE INACCURATE NEO IMPACTORS. THEY ASSUME THAT OVER ~1E4 YEARS THE SEMIMAJOR AXIS A ECCENTRICITY E AND INCLINATION I OF NEOS ARE UNCHANGING AND THEIR ORBIT ANGLES PRECESS UNIFORMLY. RECENT STUDIES HOWEVER SHOW THESE ASSUMPTIONS ARE FREQUENTLY VIOLATED; OVER THESE TIMESCALES PLANETARY PERTURBATIONS CAN PRODUCE NON-UNIFORM ORBIT ANGLES (E.G. JEONGAHN AND MALHOTRA 2014) AND BIG E I SWINGS (E.G. VOKROULICKY ET AL. 2012; POKORNY AND VOKROUHLICKY 2013). 2. MANY NEOS DISRUPT NEAR THE SUN. IN CONSTRUCTING A NEW NEO MODEL GRANVIK ET AL. (2016) SHOWED THAT PRIMITIVE OBJECTS BETWEEN ~100 M AND FEW KM DISRUPT WHEN THEY GET WITHIN ~0.05-0.2 AU OF THE SUN. WE ARGUE HERE THIS MAY BE TOO CONSERVATIVE; METER-SIZED BOLIDES AND LUNAR CRATERS INDICATE THAT MANY SMALL NEOS REGARDLESS OF COMPOSITION DISRUPT WITHIN ~0.17 AU OF THE SUN. NO IMPACTOR MODEL HAS YET ACCOUNTED FOR THIS EFFECT. 3. NO COLOR-ALBEDO-TAXONOMY MODEL FOR IMPACTORS. AT THIS TIME NO QUANTITATIVE MODEL OF THE LIKELY NATURE OF POTENTIAL IMPACTORS EXISTS. THIS LIMITS OUR ABILITY TO APPRAISE THE RANGE OF POTENTIAL EFFECTS PRODUCED BY THEIR BLASTS ANOTHER KEY GOAL OF NEOO AND THE PDCO. GIVEN THESE LIMITATIONS WE PROPOSE TO DEVELOP THE MOST ACCURATE NEO IMPACTOR MODEL EVER USING DIRECT NUMERICAL INTEGRATION METHODS AS WELL AS THE INSIGHTS PROVIDED BY THE NEW NEO MODEL OF GRANVIK ET AL. (2016). OUR PROPOSED TASKS ARE AS FOLLOWS: TASK 1. USING SUPERCOMPUTERS AND INITIAL CONDITIONS FROM GRANVIK ET AL. (2016) WE WILL INITIATE A LARGE NUMERICAL CAMPAIGN TO GENERATE 5E4-5E5 SYNTHETIC IMPACTORS WITH WELL-DEFINED ORBITS OVER THE NEXT THREE YEARS. THIS WILL REQUIRE US TO INTEGRATE THE ORBITS OF ~5E5-5E6 ASTEROIDS FOR ~200 MYR. IN ADDITION USING NEW CODES WRITTEN FOR THIS PROPOSAL WE WILL ALSO COMPUTE THE LOCATION IMPACT TRAJECTORIES AND COLLISION VELOCITIES FOR THE IMPACTORS. TASK 2. THE INTERNAL STRUCTURE DENSITY AND STRENGTHS OF IMPACTORS CORRELATE WITH THEIR OBSERVABLE PROPERTIES (E.G. LOW ALBEDO CCOMPLEX ASTEROIDS LIKELY SIMILAR TO CARBONACEOUS CHONDRITES). ACCORDINGLY TO PREDICT IMPACTOR PHYSICAL PROPERTIES WE WILL DEVELOP AN ALBEDO-COLOR-TAXONOMY MODEL FOR IMPACTORS BASED ON THEIR ORBITS. HERE WE WILL TAKE ADVANTAGE OF THE METHODS AND MODEL OF GRANVIK ET AL. (2016) AS WELL AS SEVERAL RICH DATASETS CONTAINING MAIN BELT AND NEO ALBEDOS (WISE/NEOWISE) COLORS (SDSS) AND TAXONOMIC CLASSES (E.G. PDS NODE). TASK 3. USING AN ESTABLISHED NEO SURVEY SIMULATOR (VERES ET AL. 2009) WE WILL EXAMINE THE EFFICIENCY OF EXISTING AND PROSPECTIVE SURVEYS AT DETECTING OUR SYNTHETIC IMPACTORS. OUR WORK WILL DETERMINE WHAT SURVEY STRATEGIES/PROPERTIES ARE NEEDED TO MEET NEOO/PDCO GOALS.