Inferring the Thermal and Electrical Properties of Comet 67P/Churyumov-Gerasimenko from the Continuum Measurements of the Microwave Instrument on the Rosetta Orbiter (MIRO)

Thursday, 18 December 2014
Stephen Joseph Keihm1, Samuel Gulkis2, Mark D Hofstadter3, Paul Von Allmen4, F. Peter Schloerb5, Mathieu Choukroun3, Seungwon Lee4 and Michael A Janssen4, (1)JPL/NASA/Caltech, Pasadena, CA, United States, (2)California Institute of Technology, Pasadena, CA, United States, (3)Jet Propulsion Laboratory, Pasadena, CA, United States, (4)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (5)University of Massachusetts Amherst, Amherst, MA, United States
ESA’s Rosetta spacecraft arrived at comet 67P/Churyumov-Gerasimenko in early August of 2013. Since the approach in June 2014, the MIRO instrument has been acquiring two types of data: continuum emission thermal data from the nucleus at the two operating wavelengths of 190 and 562 GHz, and spectroscopic data at 562 GHz on the gas present in the coma. The two continuum channels allow for probing the temperature in shallow subsurface over two effective depths on the order of a few millimeters to a few centimeters. The MIRO continuum channels can uniquely measure both dayside and night side temperatures of the comet nucleus. The measurements will be analyzed for both thermal and electrical properties of the near surface layers which in turn can be interpreted in terms of bulk density, particle size, and ice/dust ratio. Early resolved measurements of polar night regions from 100 km range will provide first estimates of the nucleus thermal inertia. Following the polar night scans, extensive measurements obtained from orbits at distances of 100, 30, 20, and 10 km will be used to map the thermal and electrical properties on a global scale.