NMSUAstronomy

I am interested in the composition and evolution of satellites of the outer solar system as well as icy "Dwarf" planets and Kuiper Belt Objects (KBOs). These primodial objects can tell us much about conditions during the formation of the solar system. I am particularly interested in moons with icy surfaces (Europa, Enceladus, Titania, Triton) and outer solar system bodies with thin atmospheres (Triton and Pluto). Both Triton and Pluto have thin (microbar) atmospheres consisting mainly of nitrogen in vapor pressure equilbrium with frozen nitrogen on their surfaces. The dynamics of such cold and thin atmospheres are as yet not well understood.

Ongoing Projects

With the support of my advisor, Dr. Nancy Chanover, I am working on several projects related to objects in the outer solar system (and one quite close to Earth):

Uranian moon occultations:
In August and December of 2007, I observed four occultations of Uranian moons with the Agile camera on the APO 3.5 meter telescope. These occultations occurred during the Uranian equinox, a once-in-42-year event when the equatorial plane appeared edge-on from Earth. By comparing the observed lightcurves to simulated lightcurves derived from an occultation model, I have determined the pricise midpoint time and the relative satellite positions and velocities during each event. These results, when compared against the predicted values, constrain Uranus satellite orbital simulation models.

Phoebe opposition surge:
I am also analyzing data taken during a zero-phase opposition of Saturn's moon Phoebe to verify the presence of an expected "opposition surge" in brightness. The shape of the resulting solar phase lightcurve depends on surface properties such as particle size and thus the lightcurve may provide insight into the make-up of Phoebe's surface. I have compared Phoebe's solar phase lightcurve observed in four broadband filters to results from a simulated phase curve model and am now analyzing the relative contribution of two effects contributing to the opposition surge - shadow hiding and coherent backscatter.

Neptune atmosphere studies:
On July 23, 2009, I observed an occultation of a background star by Neptune with the Apache Point Observatory 3.5 meter telescope. Stellar occultation provide insight into the density variations in the upper atmosphere of Neptune. This ongoing study is part of a collaboration of several astronomers to study the upper atmospheres of Uranus and Neptune.

LCROSS observations:
On the morning of October 9, 2009, the Lunar CRater Observation and Sensing Satellite (LCROSS) will strike the moon in a permanently shadowed crater on the south pole of the Moon. The purpose is to search for the spectral signature of water in the lunar regolith that is thrown up by the impact. I am part of a team of NMSU faculty, students, and members of APO and NASA Marshall Space light Center that will observe the impact with three telescopes simulataneously in visible and infrared wavelengths. We plan to use these observations to characterize the dynamics (plume expansion velocity) and mass of the ejecta.

Pluto/Triton atmosphere studies:
I have begun work on modifying a General Circulation Model (GCM) that has been used to simulate the Martian atmosphere to conditions found on Pluto and Triton. Although much thinner, both Pluto and Triton's atmospheres are similar to that of Mars in that the major atmospheric constituent (nitrogen on Triton & Pluto, carbon dioxide on Mars) condenses and sublimes on the surface as seasons change. The behavior of Triton's atmsophere is of interest as a possible predictor of the state of Pluto's atmosphere when the New Horizons spacecraft makes its closest approach to the Pluto/Charon system in July, 2015.

Publications

Resolving dynamical parameters of the August 2007 Titania and Ariel occultation by Umbriel
C. Miller, N. J. Chanover 2009, Icarus, 200, 343-346.

Meetings

October, 2007: AAS Division for Planetary Sciences meeting, Orlando, FL Observations of Time Variable Magnitude Events of Phoebe, Ariel, and Titania
C. Miller, N. J. Chanover, J. A. Holtzman, A. J. Verbiscer

June, 2008: International Planetary Probe Workshop, Atlanta, GA Wirtanen Analysis and Surface Probe: Concept for a New Frontiers Comet Surface Sample Return Mission
C. Miller, K. Block, S. Byram, B. M. Karpowicz, N. Lanza, J. Masiero, S. Singer, B. Smith, M. Smith, A. Winfield, L. Wye, T. Balint

October, 2008: AAS Division for Planetary Sciences meeting, Ithaca, NY Resolving Dynamical Properties for Four 2007 Uranus Satellite Mutual Events
C. Miller, N. J. Chanover

Workshops

In July 2007, I spent a week at NASA's Jet Propulsion Laboratory participating in the Planetary Science Summer School. I was part of a team of 11 Astronomy and Engineering graduate students who with support of JPL engineers created a mission design for a comet sample return mission.

In February 2008, I attended a one day workshop at NASA Ames Research Center for astronomers planning to observe the impact of the LCROSS mission upper stage booster at the south pole of the Moon currently scheduled for October 9, 2009. Following the successful launch of LRO/LCROSS on June 18, 2009, I attended a follow-up workshop for astronomers to plan impact observations.

Awards

NASA Earth and Space Science Fellowship [2009]

NMSU Department of Astronomy Murrell Award [2009]

NMSU Mike Watts Outstanding Leadership Gradute Fellowship [2008]

NSF Gradaute Research Fellowship Program Honorable Mention [2008]

NMSU 21st Century Space and Aerospace Research Cluster Graduate Fellowship [2006-2009]

Support

I am pleased to thank the NMSU 21st Century Space and Areospace Cluster for a generous research fellowship. I also thank NASA for a generous Earth and Space Sciences Fellowship (NESSF).