Eileen Ryan (New Mexico Institute of Mining and Technology), William H. Ryan (New Mexico Institute of Mining and Technology)
Keywords: near-Earth asteroid, spectroscopy, taxonomy, telescope
Abstract:
Space object identification and characterization is an important component of Space Situational Awareness (SSA). Through an Air Force collaboration that has provided a visible wavelength, low-resolution spectrometer, researchers at the Magdalena Ridge Observatory 2.4-meter telescope (located in New Mexico) have been investigating the advantages and disadvantages of using slit spectroscopy versus slitless grating methods to characterize artificial Earth-orbiting objects. The objective is to develop a method that returns useful diagnostic information with a minimal investment in observational monitoring time. However, spectral measurements are a desirable component of characterization studies of natural objects in near-Earth orbit as well. Therefore, in 2012, we began to extend this instrumentation beyond its SSA applications to the study of Near-Earth asteroids (NEAs). The typical lifetimes of NEAs are up to three orders of magnitude shorter than the typical timescales associated with the main asteroid belt. Therefore, the current NEA population is a relatively recent product that has to be continually re-supplied. Spectroscopic analysis of NEAs helps characterize their taxonomic distribution and identify potential source regions which would then enhance our understanding of the origin of the current population. Although this is of interest scientifically, it can also help estimate the magnitude of the hazard threat from still undiscovered asteroids as well as provide guidance to optimize ground-based telescope search strategies. Slit-based spectroscopy is time consuming and has limitations on how faint an object can be studied. Therefore, the goal of this current project is to determine whether a lower resolution (by a factor of 10 with respect to the slit-based spectrometer), readily available slitless grating is sufficient for rough taxonomic classification in the study of fainter target-of-opportunity NEAs. The grating provides spectral information in 20nm wavelength bands that has proven useful for material identifications of relatively bright geostationary satellites (Dao, et al. 2013). However, this arrangement results in a higher background noise. Therefore, we are testing this method among a range of lunar phases to examine the limitations of slitless spectroscopy for faint asteroid targets.
Date of Conference: September 9-12, 2014
Track: Poster