On the Spatial Homogeneity of the H2O Coma of 67P/C.-G. at 3.9-3.5 AU as Seen from MIRO

Thursday, 18 December 2014
Christopher Jarchow1, Ladislav Rezac1, Paul Hartogh1, Samuel Gulkis2, Mark Allen3, Paul A A Von Allmen3, Gerard Beaudin4, Nicolas Biver5, Dominique Bockelée-Morvan6, Mathieu Choukroun7, Jacques Crovisier8, Pierre Encrenaz4, Therese Encrenaz8, Margaret A. Frerking7, Mark D Hofstadter7, Wing-Huen Ip9, Michael A Janssen3, Seungwon Lee3, Emmanuel Lellouch4, Cedric Leyrat10, F. Peter Schloerb11 and Thomas R Spilker12, (1)Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, (2)California Institute of Technology, Pasadena, CA, United States, (3)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (4)Observatoire de Paris, LERMA, Paris, France, (5)Observatoire de Paris, Paris, France, (6)Paris Observatory, Paris, France, (7)Jet Propulsion Laboratory, Pasadena, CA, United States, (8)LESIA Observatoire de Paris, Meudon, France, (9)NCU National Central University of Taiwan, Jhongli, Taiwan, (10)Paris Observatory Meudon, Meudon, France, (11)University of Massachusetts Amherst, Amherst, MA, United States, (12)Retired, Monrovia, CA, United States
The Rosetta spacecraft reached the Jupiter family comet 67P/C.-G. on 6thAugust, 2014 after a ten year long journey through interstellar space. This mission will provide unique opportunity to study the comet from a near nucleus distance ( < 100 km) with multiple remote and in-situ instruments, including a landing module. One of the scientific goals of this mission is to improve our understanding of cometary activity, and distinguish the primordial features of this object from the process driven features. We use the MIRO instrument measuring the H2O rotational transitions at sub-millimeter wavelengths to investigate the spatial and temporal variability of the early developed gaseous coma. The first successful detection of water by MIRO occurred on June 6-7 2014 at the heliocentric distance of 3.9 AU. However, in this report we also include mapping mode observations to study the coma spatial and time evolution. We apply a robust retrieval approach to constrain H2O number density and expansion velocity.