Dust measurements in the coma of comet 67P/Churyumov-Gerasimenko inbound to the Sun
Alessandra Rotundi ; Holger Sierks ; Vincenzo Della Corte ; et al. ; - ASI Sponsor
Jan - 2015
DOI: 10.1126/science.aaa3905

journal : Science

Volume : 347 ; Issue : 6220
type: Article Journal

Critical measurements for understanding accretion and the dust/gas ratio in the solar nebula, where planets were forming 4.5 billion years ago, are being obtained by the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency’s Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between 3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) detected 35 outflowing grains of mass 10−10 to 10−7 kilograms, and 48 grains of mass 10−5 to 10−2 kilograms, respectively. Combined with gas data from the MIRO (Microwave Instrument for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio of 4 ± 2 averaged over the sunlit nucleus surface. A cloud of larger grains also encircles the nucleus in bound orbits from the previous perihelion. The largest orbiting clumps are meter-sized, confirming the dust/gas ratio of 3 inferred at perihelion from models of dust comae and trails.

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Notes : Support of the national funding agencies of Germany (DLR), France (Centre National d’Etudes Spatiales), Italy (Italian Space Agency), Spain (MEC), Sweden (Sweden National Science Board)