My research is focused on small bodies in the Solar System and how these objects provide insight on processes of planetary formation and evolution. This work involves observations of Main Belt and near-Earth asteroids and numerical models for the thermal evolution of planetesimals. Here are some of those projects ...
Spectroscopy of Differentiated Asteroids
Differentiated meteorites account for the majority of all parent bodies represented in meteorite collections. On the other hand, differentiated asteroids seem to be rare in the Main Belt. I have employed visible and near-infrared spectroscopic techniques to discover and investigate the compositions and physical properties of these asteroids, with particular focus on Vesta-like objects.
Spitzer IRS Spectra of V-type Asteroids
Working with Lucy Lim (GSFC) and Joshua Emery (U. Tenn. Knoxville) I have contributed to a mid-infrared spectroscopic study of V-type asteroids with the IRS instrument onboard the Spitzer Space Telescope. The goal of this program is to address the mineralogical relationship between V-type asteroids in the Main Belt and HED meteorites here on Earth. My contribution to this project has been a ground-based campaign to obtain visible wavelength photometric light curves and near-infrared spectra for each of the Spitzer targets.
Modeling Planetesimal Differentiation
The first planetesimals to form within the Solar nebula accreted sufficient quantities of live short-lived radionuclides, such as 26Al and 60Fe, to melt and subsequently differentiate. I have developed several models to address various aspects of this process, including the timescales and the size of planetesimals for which differentiation was a likely outcome.
Results from near-infrared spectral band analysis of V-type asteroids in the inner Main Belt (black dots) and HED meteorites (shaded and outlined regions). Though the BII Centers of these objects are similar, their BII/BI Area Ratios are quite different, which may be due to alteration of the asteroid surfaces by exposure to the space environment. Figure from Moskovitz et al. (2010).
Visible wavelength light curve of basaltic asteroid 956 Elisa. The grey shaded regions correspond to the rotational phase of Elisa at the time of the Spitzer observations. There are two regions because it is unknown whether Elisa rotates in a prograde (PG) or retrograde (RG) sense. Figure from Lim et al. 2011.
Sizes of Iron Meteorite Parent Bodies
Magmatic iron meteorites are the oldest differentiated rocks in the Solar System. However the sizes of their parent bodies have remained an area of open study. I have worked on modeling the size of these parent bodies with models that account for age, isotopic, cooling rate and compositional data.
Space Weathering of Main Belt Asteroids
It is well known that the surfaces of planetary bodies are altered over time due to exposure to the space environment. However, the details of this process remain unclear, particularly with regard to the timescale on which it occurs and how weathering affects reflectance spectra. I have employed spectroscopic techniques to investigate these issues.
Result of thermal model calculations for the sizes and times of accretion that resulted in the differentiation of planetesimals. Processes such as pyroclastic volcanism, melt migration and convection influenced the thermal evolution of bodies in this parameter space. Figure from Moskovitz & Gaidos (2011).
Time at which different depths for a variety of parent body sizes reach U-Pb isotopic closure (~600 K). Based on these calculations and the measured age of the iron IVA Muonionalusta, the size of the IVA parent body could have been as small as approximately 50 km in radius. Figure from Moskovitz & Walker (2011).
Orbital Light Curves of Earth-like Exo-planets
Orbital light curves of terrestrial exo-planets will be obtained by future space-based observatories as a consequence of repeat observations to confirm and determine these planet’s orbits around their host stars. I have worked on modeling the effects of large, lunar-like satellites in the interpretation of these planet’s surface properties and inferred habitability.
Schematic of an observer’s view of an exo-Earth with a large Moon-like satellite. Disk-average thermal infrared flux from the planet is primarily modulated by seasonal temperature variability, which depends on the thermal properties of the planet. The signal from the satellite is solely dependent on its orbital phase around the host star. Figure from Moskovitz et al. (2008).
Optimizing Spectroscopic Reduction Techniques
A major challenge in performing asteroid spectroscopy is accurately correcting for variable transmission through the Earth’s atmosphere. I am developing a model to correct this telluric absorption in near-infrared spectra. This tool will be used to correct asteroid spectra taken at a variety of telescopic facilities.
Reflectance Properties of Asteroid Pairs
Recent dynamical studies have identified pairs of asteroids on nearly identical heliocentric orbits. The components in these systems are unbound and not in orbit around a common center of mass. This dynamically interesting population is almost certainly related to binary asteroids but understanding the details of their formation remains an area of active theoretical and observational research.
Near-Earth Asteroid Fly-bys
Encounters by asteroids with the Earth enable access to objects that are typically too faint for detailed observations. Thus, these events open a unique laboratory for comprehensive studies of composition, surface properties, and tidal physics due to interactions with the Earth. My work on asteroid fly-bys aims to provide information about the fundamental properties of these objects. This has implications for impact hazard assessment, for future human and spacecraft exploration, and for interpreting asteroids as vestigial building blocks of the terrestrial planets.
Geometry of the near-Earth fly-by of asteroid (308635) 2005 YU55 which occurred in early November of 2011. This event was the first time in the era of CCD astronomy that a large (~few hundred meter) near-Earth asteroid passed between the Earth and Moon. The next time that such an event occurs is not until 2028. I was involved in an extensive campaign employing a variety of ground-based telescopes to study this object during the fly-by. Ongoing analyses of these data are providing clues about the composition and surface properties of this object.
Broad-band photometric colors of the primary and secondary components in asteroid pair systems. These data show that the components in each system have the same color. Furthermore, these data suggest that the pair formation process is compositionally independent. These results support a scenario in which pairs form by rotational fission of a larger parent body. Figure from Moskovitz (2012).
Near-infrared spectrum of a C-type near-Earth asteroid (actually it is asteroid 2005 YU55 from above). The sharp increase in reflectance at the longer wavelengths is due to significant thermal emission from the asteroid. The raw uncorrected spectrum (top) shows residual telluric features around 1.4 and 1.9 microns. The corrected spectrum (bottom) shows a dramatic improvement in the quality of the final spectrum, which can have important implications for compositional analyses.
