A CRITICAL ISSUE IN DEALING WITH NEAR-EARTH OBJECTS (NEO) ACCORDING TO NEOO PROGRAM GOALS AND THE PLANETARY…

Assistance award details

Assistance award identifier

ASST_NON_80NSSC17K0153_080

FAIN

80NSSC17K0153

Recipient

SOUTHWEST RESEARCH INSTITUTE

Awarding agency

National Aeronautics and Space Administration

Funding agency

National Aeronautics and Space Administration

Assistance listing (CFDA)

43.001

Total obligated

$453,062

Period

Aug 7, 2017 – Aug 6, 2020

Fiscal year

2017

Place of performance state

TX

Source file

FY2017_All_Assistance_Full_20261006.zip

Description

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 YE