Dust Impact Monitor (DIM) onboard Rosetta/Philae: Tests with ice particles as comet analog materials

Flandes, A.; Krüger, Harald; Loose, Alexander; Albin, Thomas; Arnold, W.

doi:10.1016/j.pss.2014.05.014

Cited by 4 publications

(12 citation statements)

References 18 publications

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“…When a PZT segment on DIM is hit by a particle, the sensor generates a damped, closely sinusoidal electrical signal. Calibration measurements performed on the ground with different types of test particles impacting on the DIM sensor at different speeds (Péter 2002;Flandes et al 2013Flandes et al , 2014 have shown that the impacts can be described and analysed using the Hertz theory of contact mechanics (Hertz 1882;Johnson 2003). After recording the amplitude (U m ) and the width of the first half-sine pulse (T c ), it is possible to constrain the radius R and the impact speed v of the particle (Seidensticker et al 2007;Flandes et al 2013) according to Eqs.…”

Section: Measurement Techniquementioning

confidence: 99%

“…From the signal properties measured with the associated SESAME common electronics, the mass and the speed of the impacting particles could be constrained assuming given density and elastic material properties. Since the sensor sides are oriented in three mutually orthogonal directions, an assessment of the directionality of the impacting particles might be also made provided that the number of impacts is statistically sufficient (Seidensticker et al 2007;Flandes et al 2013Flandes et al , 2014.…”

Section: Introductionmentioning

confidence: 99%

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Dust Impact Monitor (SESAME-DIM) on board Rosetta/Philae: Millimetric particle flux at comet 67P/Churyumov-Gerasimenko

Hirn¹,

Albin²,

Apáthy³

et al. 2016

A&A

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Context. The Philae lander of the Rosetta mission, aimed at the in situ investigation of comet 67P/Churyumov-Gerasimenko, was deployed to the surface of the comet nucleus on 12 November 2014 at 2.99 AU heliocentric distance. The Dust Impact Monitor (DIM) as part of the Surface Electric Sounding and Acoustic Monitoring Experiment (SESAME) on the lander employed piezoelectric detectors to detect the submillimetre-and millimetre-sized dust and ice particles emitted from the nucleus. Aims. We determine the upper limit of the ambient flux of particles in the measurement range of DIM based on the measurements performed with the instrument during Philae's descent to its nominal landing site Agilkia at distances of about 22 km, 18 km, and 5 km from the nucleus barycentre and at the final landing site Abydos. Methods. The geometric factor of the DIM sensor was calculated assuming an isotropic ambient flux of the submillimetre-and millimetre-sized particles. For the measurement intervals when no particles were detected the maximum true impact rate was calculated by assuming Poisson distribution of the impacts, and it was given as the detection limit at a 95% confidence level. The shading by the comet environment at Abydos was estimated by simulating the pattern of illumination on Philae and consequently the topography around the lander. Results. Based on measurements performed with DIM, the upper limit of the flux of particles in the measurement range of the instrument was of the order of 10 −8 −10 −7 m −2 s −1 sr −1 during descent. The upper limit of the ambient flux of the submillimetreand millimetre-sized dust and ice particles at Abydos was estimated to be 1.6 × 10 −9 m −2 s −1 sr −1 on 13 and 14 November 2014. A correction factor of roughly 1/3 for the field of view of the sensors was calculated based on an analysis of the pattern of illumination on Philae. Conclusions. Considering particle speeds below escape velocity, the upper limit for the volume density of particles in the measurement range of DIM was constrained to 10 −11 m −3 −10 −12 m −3 . Results of the calculations performed with the GIPSI tool on the expected particle fluxes during the descent of Philae were compatible with the non-detection of compact particles by the DIM instrument.

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Section: Measurement Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dust Impact Monitor (SESAME-DIM) on board Rosetta/Philae: Millimetric particle flux at comet 67P/Churyumov-Gerasimenko

Hirn¹,

Albin²,

Apáthy³

et al. 2016

A&A

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“…The amplitude and the width of the first half-sine pulse are used to derive particle properties like the reduced modulus and the mass. To calibrate the instrument signals, we performed a large number of drop experiments with particles made of different materials, including water ice as a cometary analogue material (Flandes et al 2013(Flandes et al , 2014.…”

Section: Dust Impact Monitormentioning

confidence: 99%

“…Given that dust particles can hit each DIM sensor side from a large range of impact angles from almost half a hemisphere, the impact direction is only little constrained (details of the DIM detection geometry will be discussed by Hirn et al (2015b)). In addition, the speed measurement is connected with a large uncertainty as well (Flandes et al 2013(Flandes et al , 2014. It is therefore impossible to determine the particle dynamics with high accuracy for a single detected particle.…”

Section: Philae's Descent To the Comet Surfacementioning

confidence: 99%

Dust Impact Monitor (SESAME-DIM) measurements at comet 67P/Churyumov-Gerasimenko

Krüger

Seidensticker

Fischer

et al. 2015

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Context. 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 submillimeter-and millimeter-sized ice and dust particles that are emitted from the nucleus and transported into the cometary coma. Aims. The DIM sensor measures dynamical data such as flux and the directionality of the impacting particles. Mass and speed of the particles can be constrained assuming density and elastic particle properties. Methods. DIM was operated during three mission phases of Philae at the comet: (1) before the separation of Philae 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; and (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. Results. 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 kg m −3 . The particle could have been lifted off the comet's surface by sublimating water ice.

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“…properties, like its density, ρ, and Young's modulus, Y ) by means of the Hertz impact theory (Seidensticker et al 2007;Flandes et al 2014). Besides, the onboard DIM electronics is only able to store the U m and T c values.…”

Section: Introductionmentioning

confidence: 99%

A simple model for understanding the DIM dust measurement at comet 67P/Churyumov–Gerasimenko

Podolak

Flandes

Corte

et al. 2016

Planetary and Space Science

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We present a simple model for gas and dust flow from 67P/ChuryumovGerasimenko that can be used to understand the grain impact observed by the DIM instrument on Philae (Krüger et al. 2015). We show how model results when applied to the GIADA measurements Della Corte, V. et al. 2015) can be used, in conjunction with the results found by the MIRO (Schloerb et al. 2015) and VIRTIS instruments to infer surface properties such as surface temperature and surface ice fraction.

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Dust Impact Monitor (DIM) onboard Rosetta/Philae: Tests with ice particles as comet analog materials

Cited by 4 publications

References 18 publications

Dust Impact Monitor (SESAME-DIM) on board Rosetta/Philae: Millimetric particle flux at comet 67P/Churyumov-Gerasimenko

Dust Impact Monitor (SESAME-DIM) on board Rosetta/Philae: Millimetric particle flux at comet 67P/Churyumov-Gerasimenko

Dust Impact Monitor (SESAME-DIM) measurements at comet 67P/Churyumov-Gerasimenko

A simple model for understanding the DIM dust measurement at comet 67P/Churyumov–Gerasimenko

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