Dust Impact Monitor (SESAME-DIM) Measurements at Comet 67P/Churyumov-Gerasimenko

Abstract

The Rosetta lander Philae successfully landed on the nucleus of comet 67P/Churyumov-Gerasimenko on 12 November 2014. Philae carries the Dust Impact Monitor (DIM) on board, which is part of the Surface Electric Sounding and Acoustic Monitoring Experiment (SESAME). DIM employs piezoelectric PZT sensors to detect impacts by sub-millimeter and millimeter-sized ice and dust particles that are emitted from the nucleus and transported into the cometary coma. The DIM sensor measures dynamical data like flux and the directionality of the impacting particles. Mass and speed of the particles can be constrained assuming density and elastic particle properties. DIM was operated during three mission phases of Philae at the comet: (1) Before Philae's separation from Rosetta at distances of about 9.6 km, 11.8 km, and 25.3 km from the nucleus barycenter. In this mission phase particles released from the nucleus on radial trajectories remained undetectable because of significant obscuration by the structures of Rosetta, and no dust particles were indeed detected. (2) During Philae's descent to its nominal landing site Agilkia, DIM detected one approximately millimeter-sized particle at a distance of 5.0 km from the nucleus' barycenter, corresponding to an altitude of 2.4 km from the surface. This is the closest ever dust detection at a cometary nucleus by a dedicated in-situ dust detector. (3) At Philae's final landing site, Abydos, DIM detected no dust impact which may be due to low cometary activity in the vicinity of Philae, or due to shading by obstacles close to Philae, or both. Laboratory calibration experiments showed that the material properties of the detected particle are compatible with a porous particle having a bulk density of approximately $250\mathrm{kg}{\mathrm{m}}^{-3}$. The particle could have been lifted off from the comet's surface by sublimating water ice.

arXiv comment17 pages, 5 Tables, 9 Figures, in press, Astronomy & Astrophysics 2015

References in corpus (1)

• Evolution of the Dust Coma in Comet 67P/Churyumov-Gerasimenko Before 2009 Perihelion

Cited by in corpus (11)

• Synthesis of the Morphological Description of Cometary Dust at Comet 67P
• The Rosetta mission orbiter Science overview the comet phase
• Electrical properties and porosity of the first meter of the nucleus of 67P/Churyumov-Gerasimenko. As constrained by the Permittivity Probe SESAME-PP/Philae/Rosetta
• The Dawn of Dust Astronomy
• Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras onboard Rosetta
• Helios spacecraft data revisited: Detection of cometary meteoroid trails by in-situ dust impacts
• Dust Impact Monitor (SESAME-DIM) on board Rosetta/Philae: Millimetric particle flux at comet 67P/Churyumov-Gerasimenko
• A Simple Model for Understanding the DIM Dust Measurement at Comet 67P/Churyumov-Gerasimenko
• Decay of COSAC and Ptolemy Mass Spectra at Comet 67P/Churyumov-Gerasimenko
• Cosmic dust VIII
• Small lobe of comet 67P: Characterization of the Wosret region with ROSETTA-OSIRIS