Physical Characterization Studies of Near-Earth Object Spacecraft Mission Targets

摘要

Periodic asteroids and comets that come within.a perihelion distance of 1.3 AU or less are defined as Near-Earth Objects (NEOs). These small bodies are in dynamically favorable positions as potential spacecraft mission targets. As a consequence, space missions to NEOs are underway or in development by several major agencies (e.g., NASA, ESA, JAXA), and recently, a manned mission to an NEO was announced as a NASA goal to be accomplished by the year 2025. Further, NASA has selected the OSIRIS-REx unmanned spacecraft mission for launch in 2016. The spacecraft will rendezvous with and collect samples from the near-Earth asteroid 1999 RQ36. Acquiring more information about the physical nature of NEOs not only contributes to general scientific pursuits and preparation for spacecraft missions, but is important to better address the threat from dangerous NEOs having Earth-crossing orbits. We will present new data obtained by photometric, spectroscopic, and other techniques on the physical properties of several Earth-approaching asteroids that are potential mission candidates. We will discuss collaborative efforts with researchers using radar to characterize prospective targets, and outline the synergy and increased science return of such an endeavor. In addition, we will present characterization results of the photometric properties of asteroid 1999 RQ36 at visible wavelengths including its rotation rate. These data were collected during the 2011-2012 apparition of the asteroid, which is.the last opportunity for ground-based studies before OSIRIS-REx is launched.