Mainzer, Amy - Exploring the Near-Earth Objects with NEOWISE

Abstract: 
The NEOWISE project is returning radiometrically derived diameters and albedos for minor planets, including near-Earth objects (NEOs).  Using the Earth-orbiting Wide-field Infrared Survey Explorer telescope, NEOWISE measurements have been used to set constraints on the numbers, orbits, and physical properties of asteroid and comet populations.  To date, more than 700 NEOs have been observed by NEOWISE, with more to come from mining of the archival data.  By virtue of observing in the infrared near 90 degrees solar elongation, NEOWISE-detected NEOs are more likely to be large, and a larger fraction of them are potentially hazardous compared to the sample detected by ground-based telescopes observing near opposition. Population studies have shown that the NEO albedo distribution remains approximately constant with diameter down to the limit of the infrared-selected sample, 100 m. Recent results have shown that NEO albedos become brighter below this size limit, but as this sample is optically-selected, discovery biases against small, dark objects become strong and cannot be easily disentangled.  The goal of the recently reactivated NEOWISE mission is to continue physical characterization of NEOs, resulting in measurements of diameters and albedos for close to 2000 objects over the course of its 3 year survey.  NEOWISE data have enabled a wide range of solar system studies, including long- and short-period comets, Main Belt asteroids, Jovian Trojans, and Hildas, as well as the discovery of the first known Earth Trojan asteroid. Combining infrared data with shape models and rotational states determined from radar, in situ spacecraft visits, or optical lightcurves provides a powerful means for constraining properties such as thermal inertia. 

The NEOWISE project serves as a pathfinder for future space-based NEO discovery and characterization efforts such as the Near-Earth Object Camera (NEOCam).  NEOCam builds upon the knowledge gained from NEOWISE and will significantly expand the sample of NEOs with well-determined orbits and sizes, including those that may serve as the best potential destinations for future exploration.

This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This publication also makes use of data products from NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.