Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 – 23 September 2022
Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 September – 23 September 2022

SB6

SB

Dust particles transport information over space and time through our solar system. Major sources are comets, asteroids and planetary rings. Planetary rings represent a special environment and the rings from Saturn have been studied extensively by Cassini. In the outer solar system, especially interstellar dust and kuiper belt sources are important. This session is open for all topics around Dust Astronomy: models and measurements about dust grain sources, sinks, dynamics and physical properties for particles from the nm to the mm size range. Simulations for the dust environment of small bodies, icy moons, or even the Earth and its moon are of interest. Predictions or measurements of dust particles by current and future missions are welcome. This might include missions like Parker Solar Probe, Solar Orbiter, Destiny+, BepiColombo, Juice and Europa. Measurement methods and related laboratory work complements the contents of this session.

Conveners: Ralf Srama, Harald Krüger, Mario Trieloff
Orals
| Wed, 21 Sep, 17:30–18:30 (CEST)|Room Albéniz+Machuca
Posters
| Attendance Thu, 22 Sep, 18:45–20:15 (CEST) | Display Wed, 21 Sep, 14:00–Fri, 23 Sep, 16:00|Poster area Level 2

Session assets

Discussion on Slack

Orals: Wed, 21 Sep | Room Albéniz+Machuca

Chairpersons: Ralf Srama, Harald Krüger
17:30–17:40
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EPSC2022-1002
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ECP
Silvan Hunziker and Veerle Sterken and the Interstellar Probe ISD Team
The Interstellar Probe is a mission concept to investigate (in situ) the heliosphere, its boundaries and its immediate surrounding interstellar space. It is a multi-purpose mission serving compelling science goals in heliosphere science, planetary science and astrophysics. One of the interdisciplinary science investigations on the Interstellar Probe concerns measurements of interstellar (and interplanetary) dust in and outside of the heliosphere. Such measurements will be unique and a major leap forward for interstellar dust research: no spacecraft ever has flown out of the heliosphere with a dedicated dust package before. This is important because the heliosphere filters out the smallest of these particles through their surface charge and coupling to magnetic fields and because the dynamics of submicron dust particles in the heliosphere are influenced by the solar cycle and the large-scale structure and dynamics of the different regions in the heliosphere. The boundary regions of the heliosphere are fairly unexplored. 
In this talk, we present the compelling and interdisciplinary science case of interstellar dust for a mission like the Interstellar Probe. We discuss interstellar dust simulation results and discuss what the mission can expect to measure, depending on different assumptions for the dust size distribution and composition. We use these simulations to illustrate how interstellar dust measurements and simulations can bring us new information about the global structure and dynamics of the heliosphere.  

How to cite: Hunziker, S. and Sterken, V. and the Interstellar Probe ISD Team: Interstellar dust as a unique and interdisciplinary science case for the Interstellar Probe, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1002, https://doi.org/10.5194/epsc2022-1002, 2022.

17:40–17:50
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EPSC2022-785
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ECP
Lennart Robin Baalmann, Silvan Hunziker, Peter Strub, David Malaspina, Urs Schroffenegger, Harald Krüger, Mark Hervig, Allison N. Jaynes, William Kurth, Lynn B. Wilson III, and Veerle J. Sterken

Interstellar dust has been and will be measured by many spacecraft, both directly (e.g. by Cassini, Ulysses, DESTINY+, IMAP) and indirectly (e.g. by Voyager, Wind). The flux of interstellar dust at these spacecraft can be enhanced, in particular for small dust grains (<0.3µm), due to the so-called focusing phase of the solar cycle (for dust), in the early 2030s.

Through their surface charges, these small particles are coupled to the solar-cycle-dependent magnetic fields inside and to interstellar fields outside of the heliosphere. By comparing the measurements to simulations of interstellar dust, inferences about the outer regions of the heliosphere and its boundary can be made. The quality of these inferences highly depends on the availability of detailed measurements of interstellar dust, highlighting the necessity of a space-based dust detector operating during the upcoming focusing phase, such as the proposed DOLPHIN mission.

In this talk we give an overview of measurements and simulations of the measurements of various missions so far, and their link to interstellar dust simulations. 

How to cite: Baalmann, L. R., Hunziker, S., Strub, P., Malaspina, D., Schroffenegger, U., Krüger, H., Hervig, M., Jaynes, A. N., Kurth, W., Wilson III, L. B., and Sterken, V. J.: Investigating the outer regions of the heliosphere with measurements and simulations of interstellar dust, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-785, https://doi.org/10.5194/epsc2022-785, 2022.

17:50–18:10
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EPSC2022-82
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solicited
Bruno Sicardy, Bruno Morgado, Felipe Braga-Ribas, Jose Luis Ortiz, Josselin Desmars, Chrystian Pereira, Roberto Viera-Martins, Heikki Salo, Thamiris de Santana, Rafael Sfair, Marcelo Assafin, Gustavo Benedetti-Rossi, Julio Camargo, Estela Fernandez-Valenzuela, Altair Gomes-Júnior, Mike Kretlow, Flavia Rommel, Pablo Santos-Sanz, Damya Souami, and Frédéric Vachier and the Quaoar team

The Trans-Neptunian Object (50000) Quaoar, classified as a cubewano, is a dwarf planet candidate with a diameter of 1110 km [Br13], semi-major axis of 43.7 au and orbital eccentricity of 0.04. Its satellite Weywot orbits at 13,300 km from the primary object, and from its flux [Fr10], its diameter is about 90 km, assuming the same albedo as Quaoar. Several campaigns were conducted under the umbrella of the Lucky Star project (https://lesia.obspm.fr/lucky-star/) to observe stellar occultations by Quaoar and Weywot. Besides measuring Quaoar's and Weywot's size and shapes, those campaigns aimed at searching for material around Quaoar.

Here, we will present the results of our search for rings around Quaoar based on the following observations: 

Dates                      Places of observations
2 September 2018   Namibia
5 June 2019            Canary Islands
11 June 2020          Australia, CHEOPS satellite
27 August 2021       Australia

These campaigns were undertaken in a context where rings are already known to exists around other small bodies of the solar system: the Centaur object Chariklo [Br14] and the dwarf planet Haumea [Or17]. These two ring systems, in spite of large differences in sizes and heliocentric distances, both orbit close to the 1/3 Spin-Orbit Resonance (SOR) with the central body [Or17,Le17], meaning that the latter completes three rotations while a ring particle completes one orbital revolution. Because of their non-axisymmetric shapes, and contrarily to giant planets, Chariklo and Haumea induce strong SORs [Si19]. Theoretical calculations [Si21] and numerical simulations of collisional disks [Sa21] show that the 1/3 SOR is indeed a possible cause of confinement of a narrow ring.

If ring exists at the Quaoar 1/3 SOR, it should be close to an orbital radius of 4,200 km. This represents 7.5 Quaoar's radii, well outside the Roche limit of the central body. So, if a dense ring were to be confined near this resonance, it is expected to accrete into a satellite, and thus disappear over a short time scale. We will discuss models that could maintain a colliding disk near the Quaoar 1/3 SOR in spite of this obstacle.

Acknowledgments. The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2021 ERC Grant Agreement no. 669416 "Lucky Star"

[Br13] Braga-Ribas et al., ApJ 773, 26 (2013)
[Fr10] Fraser and Brown, ApJ, 714, 1547 (2010)
[Le17] Leiva et al., Astron. J. 154, 159 (2017)
[Or17] Ortiz et al., Nature 550, 219 (2017)
[Sa21] Salo, H. et al., European Planetary Science Congress, EPSC2021-338 (2021)
[Si19] Sicardy, B. et al., Nature Astronomy 3, 146 (2019)
[Si21] Sicardy, B. et al., European Planetary Science Congress, EPSC2021-91 (2021)

How to cite: Sicardy, B., Morgado, B., Braga-Ribas, F., Ortiz, J. L., Desmars, J., Pereira, C., Viera-Martins, R., Salo, H., de Santana, T., Sfair, R., Assafin, M., Benedetti-Rossi, G., Camargo, J., Fernandez-Valenzuela, E., Gomes-Júnior, A., Kretlow, M., Rommel, F., Santos-Sanz, P., Souami, D., and Vachier, F. and the Quaoar team: Search for rings around the large Trans-Neptunian Object (50000) Quaoar , Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-82, https://doi.org/10.5194/epsc2022-82, 2022.

18:10–18:20
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EPSC2022-961
Mario Trieloff, Hiroshi Kimura, Frank Postberg, Harald Krüger, Peter Strub, Jan Leitner, Veerle Sterken, Silvan Hunziker, Jon Hillier, Takayuki Hirai, Hikaru Yabuta, Motoo Ito, Nozair Khawaja, Winfried H. Schwarz, Thomas Ludwig, Jan Schmitt, Sho Sasaki, Tomoko Arai, Masanori Kobayashi, and Ralf Srama

Rare presolar grains originating by condensation in circumstellar atmospheres are known from meteorites [1]. These escaped processing in the solar nebula and are identified via their extremely diverse isotopic composition [1,2]. However, it is uncertain if such grains are representative for dust from the interstellar medium (ISM) [3–5], particular as [5] postulated a high fraction of interstellar grain population that formed directly in the ISM.

In 1992 the Ulysses spacecraft discovered a dust flow from the Local Interstellar Cloud (LIC) [6]. During the Cassini mission at Saturn, the Cosmic Dust Analyser (CDA) could identify and analyse the chemical composition of 36 individual interstellar dust (ISD) particles [7]. These grains were distinguished from Saturn bound dust by their direction and high velocity. Their mean mass is consistent with the typical size [3-5] derived from astronomical observations. As major result, each individual ISD grain contains the major rock forming elements (Mg, Si, Fe, Ca) in roughly cosmic abundances, indicating compositional homogeneity at spatial scales as small as 100 nm. In contrast, CDA did neither detect carbon-rich grains such as graphite or SiC, nor pure metal grains (upper limit of 8% at the 2 sigma confidence level) [7].

This homogeneity cannot be reconciled with isotopically and compositionally diverse populations of circumstellar dust inherited from AGB stars and supernovae found in meteorites. These grain populations consist mainly of silicates with a more diverse composition (e.g., olivine, pyroxene), however, also minor contributions (few %) of Al-oxides (e.g., corundum, hibonite), as well as carbonaceous grains (mainly silicon carbide) which contribute 20-50%, of the grains in the most primitive meteorites [2]. In contrast to circumstellar grains found in meteorites, the LIC-ISD grains detected by Cassini have a much lower variation of Mg/Si or Mg/Fe ratios [7], and appear to be a grain population homogenized by destruction, recondensation and equilibration processes in the ISM. This can be reconciled with astronomical observations of the diffuse ISM demonstrating that condensable elements of atomic mass >23 are depleted in the gas phase and hence bound in solids. Considering that the mean lifetime of ISD grains against destruction by supernova shocks is much shorter (c. 0.5 Ga) than the average residence time of ISM matter of 2.5 Ga [5], an origin of a high fraction of ISD by grain destruction followed by recondensation was suggested by [5,7]. While grain destruction most likely occurs in the hot interstellar medium, i.e., low-density cavities formed by supernova shock fronts, condensation likely occurs in the cold interstellar medium, i.e., cold molecular clouds which are also formation regions of stars and planets.

The upcoming DESTINY+ mission [8] will be equipped with an improved impact ionization mass spectrometer, the DESTINY+ Dust Analyser (DDA). During the mission, hundreds of ISD particles are expected to be measured [9]), yielding high quality mass spectra with a resolution of c. 100-200 when compared to c. 20-50 of Cassini CDA [10]. This will allow much better resolution of mass peaks at 23-28 amu (Na, Mg, Al, Si) and 39-41 (K, Ca), particularly yielding improved constraints on abundances of Al and Si. This will allow, e.g., to distinguish between Mg silicates like pyroxene and olivine or Al-rich feldspar type silicates. Also, more precise values for Na and K can be expected, particularly as some of the Cassini CDA data were compromised by alkali contamination of the Rhodium target [7]. Furthermore, the higher number of ISD particle detections will allow to better quantify the ISD fraction of non-silicate particles (oxides, SiC, graphite, metal, see [1]). This will also provide constraints on dynamic forces acting on the ISD particle flux, particularly the question if high beta particles are preferentially deflected from the inner solar system by solar radiation forces. Finally, DDA measurements will also contribute to solve the problem of apparently low or “missing” organic components in CDA detected particles, which may be caused by volatilization of refractory organic material in ISD mantles upon entering the heliosphere [11].

Hence, interstellar dust detections by the DESTINY+ Dust Analyser will likely improve our understanding of the chemical nature of interstellar dust, its processing and lifetime in various phases of the interstellar medium, possible processing and volatile loss upon traversing our solar system to 1 AU, flux modulations upon interaction with solar electromagnetic forces, and last but not least, a tight age constraint on the LIC dust.  

 

References:

[1] E. Zinner (2014) In Meteorites and Cosmochemical Processes (ed. Davis A. M.). Elsevier, Amsterdam, pp. 181–213

[2] J. Leitner, C. Vollmer, P. Hoppe, J. Zipfel (2012) Astrophysical Journal 745, 38

[3] P. C. Frisch et al. (1999) Astrophysical Journal 525, 492

[4] H. Kimura, I. Mann, E. K. Jessberger (2003) Astrophysical Journal 583, 314

[5] S. Zhukovska, H.-P. Gail, M. Trieloff (2008) Astronomy & Astrophysics 479, 453

[6] E. Grün et al. (1993) Nature 362, 428-430

[7] N. Altobelli, F. Postberg, K. Fiege, M. Trieloff et al. (2016) Science 352, 312

[8] H. Arai, M. Kobayashi, et al. (2018) Lun. Planet. Sci. Conf. 49, abstr. #2570

[9] Krüger H., Strub P., et al. (2019) Planetary & Space Science 172, 22-42.

[10] Srama R. et al. (2004) Space Science Reviews 114, 465-518.  

[11] H. Kimura, F. Postberg, N. Altobelli, M. Trieloff (2020) Astronomy & Astrophysics 643, A50

How to cite: Trieloff, M., Kimura, H., Postberg, F., Krüger, H., Strub, P., Leitner, J., Sterken, V., Hunziker, S., Hillier, J., Hirai, T., Yabuta, H., Ito, M., Khawaja, N., Schwarz, W. H., Ludwig, T., Schmitt, J., Sasaki, S., Arai, T., Kobayashi, M., and Srama, R.: Comparing meteoritic stardust with contemporary interstellar dust measured by Cassini and DESTINY+  -  constraining models of dust processing in the interstellar medium , Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-961, https://doi.org/10.5194/epsc2022-961, 2022.

18:20–18:30
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EPSC2022-563
Peter Strub, Thomas Müller, Georg Moragas-Klostermeyer, Michael J. Freyberg, and Harald Krüger

The X-Ray Observatory eROSITA on board the Spectrum Roentgen Gamma (SRG) satellite has been operational in a halo orbit around the Sun-Earth Lagrange point L2 since summer 2019. Between December 2019 and January 2022 the eROSITA instruments registered at least seven non-nominal events which are likely related to micrometeoroid impacts, leading to permanent local defects in the X-ray CCD sensor. Each of the micrometeoroid events showed different features and effects in the CCD. In order to test the hypothesis that the defects in the CCDs are indeed related to micrometeoroid impacts, we performed numerical simulations with two interplanetary dust models, taking into account the exact times of the events, orbital position including velocity vector, and the telescope pointing and eROSITA instrument field-of-view. 

In order to identify time intervals when the SRG space telescope traversed cometary meteoroid trails, we used the IMEX dust streams in space model (Soja et al. 2015, Astron Astrophys, 583, A18). The model generates trails for 420 comets available in the JPL Small Body Database (SBDB) as of 1 August 2013, and simulates the dynamics of individual dust particles released from these comets in the size range of 100 micrometers to 1 centimeter, taking into account all relevant forces (solar and planetary gravity, solar radiation pressure, and Poynting-Robertson drag). 

Our simulations reveal at least two candidate cometary trail crossings of SRG in the L2 point with predicted micrometeoroid fluxes sufficiently large that individual particle impacts have to be expected. However, a comparison of the particle impact directions predicted by the model with the telescope pointing during the impact events are in disagreement for all events, implying that none of the registered events is likely connected with dust impacts from a dedicated cometary micrometeoroid trail. However, based on these simulations, it became clear that caution is needed during time periods of cometary trail crossings when high particle fluxes are expected. Here, telescope pointings should avoid looking into the radiant direction of a meteoroid trail.

In a second analysis step, we tested the hypothesis that the events registered by eROSITA may be related to sporadic impacts of particles from the zodiacal dust cloud. To this end, we used the Interplanetary Meteoroid Environment Model 2 (IMEM2; Soja et al. 2019, Astron Astrophys, 628, A109). The model integrates the orbits of cometary and asteroidal particle distributions in the size range 1 micrometer to 1.25 millimeters over 1 Myr, including solar gravity and radiation forces, as well as particle disruptions due to mutual particle collisions. It provides the distribution of dust particles from different cometary and asteroidal sources in the inner solar system. Our results show that many of the registered events occurred when eROSITA was pointing towards directions of increased sporadic interplanetary dust flux as predicted by the model. Several of the events occurred when the telescope was pointing in the direction close to toroidal zones of the sporadic interplanetary dust flux. The modelled dust fluxes predict that approximately two to five micrometeoroid impacts of approximately 1 micrometer sized particles are expected within eROSITA’s operational timeframe of 2.5 years, in rough agreement with the number of events registered by eROSITA. 

Acknowledgements: The IMEM2 model and the IMEX Dust Streams in Space model were developed under ESA funding (contracts 4000114513/15/NL/HK and 4000106316/12/NL/AF ‐ IMEX). 

How to cite: Strub, P., Müller, T., Moragas-Klostermeyer, G., Freyberg, M. J., and Krüger, H.: Micrometeoroid Impacts on to the SRG/eROSITA X-Ray Telescope, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-563, https://doi.org/10.5194/epsc2022-563, 2022.

Display time: Wed, 21 Sep 14:00–Fri, 23 Sep 16:00

Posters: Thu, 22 Sep, 18:45–20:15 | Poster area Level 2

Chairpersons: Ralf Srama, Harald Krüger, Mario Trieloff
L2.13
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EPSC2022-367
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ECP
Simon Linti, Hsiang-Wen Hsu, Christian Fischer, Mario Trieloff, Jon Hillier, Juergen Schmidt, and Frank Postberg

Measurements during the final phase of the Cassini mission revealed the composition of individual dust particles, ejected by micrometeoroid impacts from Saturn’s main rings. These measurements were conducted with the in situ time-of-flight mass spectrometer of the Cosmic Dust Analyzer (CDA) [1] during the close planet encounters of the Grand Finale Orbits from April to September of 2017.

Here we present the compositional analysis of silicate bearing nanoparticles (about 20–100 nm in radius), that, according to our dynamical models [2], are ejected mainly from the B and C rings by micrometeoroid impacts. With an observed ice-to-silicate particle ratio of 2:1 [2], we see a much higher silicate abundance in these ring segments, compared to values constrained by remote sensing techniques [3,4,5].

In order to assess the elemental composition of individual particles, application of a deconvolution technique to the CDA mass spectra is required. This technique is based on an approach to constrain the composition of Interstellar Dust Particles (ISDs), also detected with CDA [6]. After application of the deconvolution and Relative Sensitivity Factors (RSFs) [7], elemental abundances for the individual particles are derived.

We find Mg, Si and Ca similar to cosmic abundances (ISD and CI chondritic). Fe, however, is significantly depleted, for the Fe/Mg ratio on average by a factor of 2.3 compared to cosmic abundances. This observation contrasts with Fe-rich (≈ 5 w.r.t. cosmic abundances) exogenous material (IDPs), observed in the Saturnian system by CDA [8]. This drastic discrepancy in composition between ring silicates and IDPs at Saturn seems difficult to reconcile with IDPs being the main factor in polluting and darkening the rings over time [4,5,9,10]. We review several scenarios, how these compositional differences could be explained.

 

 

References

[1] R. Srama et al. (2004), Space Science Reviews 114, 465–518.

[2] H.-W. Hsu et al. (2018), Science 362.

[3] E. Epstein et al. (1984), Icarus 58, 403–411.

[4] Zhang et al. (2017a), Icarus 281, 297–321.

[5] Zhang et al. (2017b), Icarus 294, 14–42.

[6] N. Altobelli et al. (2016), Science 352, 312–318.

[7] K. Fiege et al. (2014), Icarus 241, 336–345.

[8] C. Fischer et al. (2022), this conference.

[9] J. Cuzzi and P. Estrada (1998), Icarus 132, 1–35.

[10] J. Cuzzi et al. (2009), Springer, Dordrecht, 459–509.

How to cite: Linti, S., Hsu, H.-W., Fischer, C., Trieloff, M., Hillier, J., Schmidt, J., and Postberg, F.: Iron Depletion in Silicates of Saturn’s Main Rings, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-367, https://doi.org/10.5194/epsc2022-367, 2022.

L2.14
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EPSC2022-1232
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ECP
Dynamical analysis of mineral dust in the Saturnian system
(withdrawn)
Christian Fischer, Frank Postberg, Mario Trieloff, and Jürgen Schmidt
L2.15
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EPSC2022-358
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ECP
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Artyom Aguichine, Olivier Mousis, and Bertrand Devouard

In our solar system, meteoritical matter exhibits a variety in bulk compositions that is representative of the processing history of refractory matter in the protosolar nebula (PSN). This history is usually investigated via a thermodynamic approach, where refractory grains condense out from a hot cloud. However, in the innermost regions of the PSN the migration timescale of grains can exceed the evaporation timescale of refractory species.

We investigate the role played by rocklines (condensation/sublimation lines of refractory materials) in the innermost regions of the PSN to compute the composition of drifting and evaporating grains. To do so, we compute the evolution of the PSN using a 1D viscous accretion disk model [1]. The disk is initially filled with dust that is a mixture of several refractory species of protosolar composition. This dust exists in the form of refractory grains and their vapors. The radial transport of grains is computed by solving an advection-diffusion equation, and phase transitions are accounted for by computing sublimation and condensation rates for each species. We then compare the composition of the PSN computed by our model with the composition of meteoritical bodies collected on Earth.

We find that the compositional gradient in the PSN that is created by rocklines, shown in Figures 1 and 2, matches the composition of cosmic spherules, chondrules, and chondrites. Moreover, our model shows that solid matter is concentrated in the vicinity of these sublimation/condensation fronts. Although our model only focuses on the most abundant refractory species (olivine, represented in our model by its end members forsterite and fayalite; enstatite and ferrosilite pyroxenes; kamacite and taenite metal; and iron sulfide), it suggests that rocklines heavily processed refractory matter in the PSN, which has important consequences for the composition of small and large bodies in the innermost regions of the solar system. The local increase of the iron abundance close to rocklines of iron alloys could have contributed to the high Fe-content in Mercury.



Figure 1. Composition profiles of the PSN in a Mg-Fe-Si ternary diagram (expressed in mass fraction) at different times, with composition of glass cosmic spherules (S–V type), barred olivine spherules (S-BO type), porphyritic spherules (S-P type) and C-chondrules. Protosolar and Earth’s compositions are represented by Sun’s and Earth’s symbols, respectively, and Mercury’s composition is represented by a red circle.

 

Figure 2. Same as Figure 1, but here the Fe wt% is represented as a function of heliocentric distance. Color boxes correspond to typical compositions of chondrules (0%–10%), glass cosmic spherules (10%–30%), and porphyritic and barred olivine cosmic spherules (30%–60%).

 

[1] Aguichine, A., Mousis, O., Devouard, B., and Ronnet, T. 2020, ApJ, 901, 97.

How to cite: Aguichine, A., Mousis, O., and Devouard, B.: Processing of refractory species in the vicinity of rocklines, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-358, https://doi.org/10.5194/epsc2022-358, 2022.

L2.16
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EPSC2022-1070
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ECP
Jonas Simolka, Marcel Bauer, Ariane Exle, Patrick Fröhlich, Jan Gläser, Stephan Ingerl, Yanwei Li, Maximilian Sommer, Heiko Strack, Hartmut Henkel, Carsten Wagner, and Ralf Srama

Cosmic dust particles are important messengers. They contain information about their origin and their journey through space. The DESTINY+ mission that launches in 2024 provides the opportunity to investigate the dust populations present at 1 AU and around the active asteroid (3200) Phaethon. For this purpose, the Destiny+ Dust Analyzer (DDA) is employed. The instrument is developed under the lead of the University of Stuttgart in Germany. Its capabilities are to simultaneously analyze the dynamical and compositional properties of individual cosmic dust grains that are intersected along the mission. To gain independence from the S/C attitude a two axes pointing mechanism is developed. It provides an azimuthal range of 180° and an elevation range of 90°. The full instrument electronics is developed by the industry partner von Hoerner & Sulger GmbH in Schwetzingen, Germany while the software development takes place at the University of Stuttgart. The mass of the full instrument is ~12 kg and the power consumption is ~35 W in observation mode. The particle trajectory and grain size are determined by the trajectory sensor stage. It utilizes the fact that particles in space carry a surface charge. It consists out of a segmented plane of metal grids of which each is connected to a charge sensitive amplifier. This plane is sandwiched between two grids that are on ground potential. If a charged particle resides in between the grounded planes, it induces a mirror charge on the measurement grid segments. The incident angle, velocity and surface charge of the dust grains are reconstructed from the course and amplitude signal traces. An impact ionization time of flight mass spectrometer provides the compositional analysis of the dust grains. The sensor target is a gold surface with 300 cm² sensitive area and a field of view of 1.99 steradian. Particles collide with the sensor target with relative speeds of several km·s-1. At impact they ionize and the impact plasma is manipulated by electric fields. The cations are accelerated, reflected and focused towards an electron multiplier wich functions as an ion detector. Here the cations are detected with high temporal resolution at two sensitivity stages. This allows to identifie the presence cations in the atomic mass range of 1 – 800 u with a high dynamic range. In the relevant ion mass range of silicates, carbon and metals the mass resolution is high enough so separate the individual atomic species. As the mass spectrometer is highly sensitive to contamination the target can be heater for decontamination. A door cover protects the cleanliness of the sensor interior during launch. Additionaly to the mass spectrum the cation charge is measured by charge sensitive amplifiers at an ion grid in front of the multiplier aperture and an ion ring around it. The negative plasma charge is measured at the target. All signal channels are contiuously active and analyzed by an FPGA. A frame of the signal set is stored as soon as trigger conditions are met. This sensitive yet robust system allows to separate actual dust impacts from noise events. An uncompressed signal set from an individual impact event has a size of ~400 kbit and 2 Gbit non volatile ram is available for storage. Data processing is performed by a SAMRH71 from Microchip. Lossless and lossy compression algorithms are implemented for reducing the packet size for downlink. The talk will give an overview of the instrument functionality and design. We will present the development status and the results of first dust impact measurement will be presented, that are obtained by laboratory measurements with a dust accelerator.

 

Crossection cut through the DDA Sensor. Pointing mechanism and sensor head for measuring cosmic dust particles are depicted. A separate electronics box (not depicted) is located inside the S/C. 

How to cite: Simolka, J., Bauer, M., Exle, A., Fröhlich, P., Gläser, J., Ingerl, S., Li, Y., Sommer, M., Strack, H., Henkel, H., Wagner, C., and Srama, R.: Development of the Destiny+ Dust Telescope, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1070, https://doi.org/10.5194/epsc2022-1070, 2022.