Physical Characterization Of Small Near-Earth Asteroids Based On NEATM And WISE Data

Asteroids are metallic or rocky objects widely distributed in solar system,spanning from meters to several hundred kilometers in diameter.They contain information about the early solar system and may also rendezvous with the Earth’s orbit and impact the Earth,so study of the physical parameters,material composition and surface properties of asteroids is important for understanding formation and evolution of planets and small bodies in solar system and the defense of Near-Earth Objects(NEOs).This paper presents classification of asteroids from two perspectives,orbits and spectra,and specifically explains the classification of Near-Earth Asteroid(NEA)and the concept of Potentially Hazardous Asteroid(PHA).This paper summarizes the monitoring methods for asteroids,including observations by ground-based telescopes,space telescopes,and direct detection by probes,and focuses on Wide-field Infrared Survey Explorer(WISE)of National Aeronautics and Space Administration(NASA),and details of several internationally known asteroid detection missions,including NASA’s Double Asteroid Redirection Test(DART),Japan’s Hayabusa mission,China’s Chang’e-2 flyby of Toutatis,etc.This paper summarizes the classical infrared thermophysical models of asteroids,including STM(Standard Thermal Model)and FRM(Fast Rotating Model),as well as NEATM(Near-Earth Asteroid Thermal Model)used in this paper.In order to study the infrared thermophysical effects of small-sized NEOs,and to calculate their diameters and albedos in bulk for future deep-space asteroid detection and defense,this paper obtains small-sized NEOs with D<160 m from Minor Planet Center(MPC),including some potentially hazardous asteroids(PHAs),as study objects.Based on the NEATM(Near-Earth Asteroid Thermal Model),we used the WISE observation data in all wavelengths and the reflected light model to correct the reflected light from the Sun,and used the dynamical model to calculate the orbital data of WISE ephemeris.The diameters and albedos of 67 small-sized NEOs were calculated using a kinetic model.Fitting process was performed by Markov Chain Monte Carlo(MCMC)method,and the classification characteristics were compared with the results of WISE team and MPC data.The study provides a strong support for the observation and theory of asteroids,which can better understand the characteristics and evolution of NEOs.