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On June 23rd 2022, BepiColombo performed its second gravity assist maneuver (MFB2) at Mercury. Just like the first encounter with Mercury that took place on October 1st 2021, the spacecraft approached the planet from dusk-nightside to dawn-dayside down to an extremely close distance (within about 200 km altitude from the planet surface). Even though BepiColombo is in a so-called “stacked configuration” during cruise, meaning that the instruments cannot be fully operated yet, these instruments can still make interesting observations. Particularly, despite their limited field-of-view, the particle sensors allow us to get a hint on the ion composition and dynamics very close to the planet well before the forthcoming orbit insertion around Mercury in December 2025. In this study, we present observations of the Mass Spectrum Analyzer (MSA) at Mercury during MFB2. MSA is part of the low energy sensors of the Mercury Plasma Particle Experiment (MPPE) consortium (PI: Y. Saito), which is a comprehensive instrumental suite for plasma, high-energy particle and energetic neutral atom measurements (Saito et al., 2021) onboard the Mercury Magnetospheric Orbiter (Mio). MSA is a “reflectron” time-of-flight spectrometer that provides information on the plasma composition and the three-dimensional distribution functions of ions with energies up to ~ 38 keV/q and masses up to ~ 60 amu (Delcourt et al., 2016). In this study, we show that both H+ and He2+ ions in the 1-10 keV range are present throughout the innermost magnetosphere near closest approach. In addition, during this MFB2 sequence, MSA observations provide evidences of He+ ions with energies of several hundreds of eVs. These ions likely originate from the planet exosphere and are rapidly circulated within the magnetosphere. During the outbound sequence of MFB2, MSA measurements also reveal copious amounts of keV protons of solar wind origin that propagate upstream after being reflected from the bow shock.

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 (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.

We present the science planning tool for dust instrument observations that is currently under development within the DESTINY+ project. The JAXA-led DESTINY+ mission (Demonstration and Experiment of Space Technology for Interplanetary voyage Phaethon fLyby and dUst Science), set to launch in 2024, carries two camera instruments intended to study the active asteroid 3200 Phaethon during a flyby in 2028, as well as the Destiny+ Dust Analyzer (DDA), an impact ionization time-of-flight mass spectrometer which will sample Phaethon’s dust environment. During the 4-years voyage leading up to the flyby, DDA will also study interplanetary and interstellar dust particles as its second main science objective. For this phase, the science working team is preparing tools to produce suitable high-level science operations schedules.As DESTINY+ relies on solar-electric propulsion to expand its Earth orbit and ultimately reach interplanetary space, a highly dynamic spacecraft attitude is required to achieve an optimal thrust vector and illumination of the solar panels. To maintain some pointing autonomy, DDA has a dual-axis pointing mechanism, granting a coverage of 1pi solid angle. The dynamic attitude combined with the flexibility of a pointing mechanism warrants elaborate planning to optimize coverage of directional dust fluxes, such as interstellar dust. Here we present the DDA Observation Planning Environment (DOPE), which is a graphical tool for intuitive campaign design, including visualizations such as spacecraft orientation or instrument footprint. Under the hood DOPE uses the SPICE toolkit for all geometric or time calculations, thus import of SPICE kernels for spacecraft trajectory, attitude, and clock is required. Here we describe the DDA science planning process to provide a contextual frame for the tool and demonstrate its functionality with emphasis on the geometrical capabilities.

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).

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

International audience; The Philae lander of the Rosetta space mission made a non-nominal landing on comet 67P/Churyumov-Gerasimenko on November 12, 2014. Shortly after, using the limited power available from Philae's batteries, the COSAC instrument performed a single 18- minutes gas chromatogram, which has remained unpublished until now due to the lack of identifiable elution. We show that despite the unsuccessful drilling of the comet and deposition of surface material in the SD2 ovens, the measurements from the COSAC instrument were executed nominally. We describe an automated search for extremely small deviations from noise and discuss the possibility of a signal from ethylene glycol at m/z 31. Arguments for and against this detection are listed, but the results remain inconclusive. Still, the successful operations of an analytical chemistry laboratory on a cometary nucleus gives great hope for the future of space exploration.

International audience; The most pristine material of the Solar System is assumed to be preserved in comets in the form of dust and ice as refractory matter. ESA’s mission Rosetta and its lander Philae had been developed to investigate the nucleus of comet 67P/Churyumov-Gerasimenko in situ. Twenty-five minutes after the initial touchdown of Philae on the surface of comet 67P in November 2014, a mass spectrum was recorded by the time-of-flight mass spectrometer COSAC onboard Philae. The new characterization of this mass spectrum through non-negative least squares fitting and Monte Carlo simulations reveals the chemical composition of comet 67P. A suite of 12 organic molecules, 9 of which also found in the original analysis of this data, exhibit high statistical probability to be present in the grains sampled from the cometary nucleus. These volatile molecules are among the most abundant in the comet’s chemical composition and represent an inventory of the first raw materials present in the early Solar System.

The zodiacal cloud is one of the largest structures in the solar system and strongly governed by meteoroid collisions near the Sun. Collisional erosion occurs throughout the zodiacal cloud, yet it has been historically difficult to directly measure. After transiting the inner-most regions of the solar system with Parker Solar Probe (PSP), we find that its dust impact rates are consistent with at least three distinct populations: bound zodiacal dust grains on elliptic orbits (α-meteoroids), unbound β-meteoroids on hyperbolic orbits, and a third population of impactors that may be either direct observations of discrete meteoroid streams or their collisional by-products (“β-streams”). The β-stream from the Geminids meteoroid stream is a favorable candidate for the third impactor population. β-streams of varying intensities are expected to be produced by all meteoroid streams, particularly in the inner solar system, and are a universal phenomenon in all exozodiacal disks. We discuss these recent PSP observations of the dust environment in the very inner solar system, provide constraints on their relative densities and fluxes, and discuss the erosion rate of zodiacal material.These observations are also directly relevant for understanding the impactor and space weathering environment experienced by airless bodies in the inner solar system. Since the discovery of the Moon's asymmetric ejecta cloud, the origin of its sunward-canted density enhancement has not been well understood. Ejecta is produced from β-meteoroids which impact the Moon's sunward side at similar locations to this previously unresolved asymmetry. These small grains are submicron in size, comparable to or smaller than the lunar regolith particles they hit, and can impact the Moon at very high speeds ~100 km s-1. Incorporating β-meteoroid fluxes observed by the Pioneers 8 & 9, Ulysses, and Parker Solar Probe spacecraft as a newly considered impactor source at the Moon, we find β-meteoroid impacts to the lunar surface can explain the sunward asymmetry observed by LADEE/LDEX. We discuss these observations and how this finding suggests β-meteoroids may appreciably contribute to the evolution of other airless surfaces in the inner solar system.

In this review, we summarize recent advances in the field of dusty plasmas at strong magnetic fields. Special emphasis is put on situations where experimental laboratory observations are available. These generally comprise dusty plasmas with magnetized electrons and ions, but unmagnetized dust. The fundamental parameters characterizing a magnetized (dusty) plasma are given and various effects in dusty plasmas under magnetic fields are presented. As examples, the reaction of the dust component to magnetic-field modified plasma properties, such as filamentation, imposed structures, dust rotation, nanodusty plasmas and the resulting forces on the dust are discussed. Further, the behavior of the dust charge is described and shown to be relatively unaffected by magnetic fields. Wake field formation in magnetized discharges is illustrated: the strength of the wake field is found to be reduced with increased magnetic field. The propagation of dust acoustic waves in magnetized dusty plasmas is experimentally measured and analyzed indicating that the wave dynamics are not heavily influenced by the magnetic field. Only at the highest fields ($$B> 1$$ B > 1 T) the wave activity is found to be reduced. Moreover, it is discussed how dust-cyclotron waves might be used to indicate a magnetized dust component. Finally, implications of a magnetized dusty plasma are illustrated.

Jupiter's tenuous dust ring system is embedded in the planet's inner magnetosphere, and—among other structures—contains a very tenuous protrusion called the Thebe extension. In an attempt to explain the existence of this swath of particles beyond Thebe's orbit, Hamilton and Krüger (2008), https://doi.org/10.1038/nature06886 proposed that the dust particle motion is driven by a shadow resonance caused by variable dust charging on the day and night side of Jupiter. However, the model by Divine and Garrett (1983), https://doi.org/10.1029/ja088ia09p06889 together with recent observations by the Juno spacecraft indicates a warm and rather dense inner magnetosphere of Jupiter which implies that the mechanism of the shadow resonance does not work. Instead, we argue that dust grains ejected from Thebe due to micrometeoroid bombardment become the source of dust in the Thebe extension. We show that large (grain radii of a few micrometers up to multi‐micrometers) charged dust grains having significant initial velocities oscillate in the Thebe extension. Smaller charged grains (with sub‐micrometer radii) ejected from Thebe do not spend much time in the Thebe extension and migrate into the Thebe ring. At the same time, if such grains are ejected from larger dust grains in the Thebe extension due to fragmentation, they continue to oscillate within the Thebe extension for years. We argue that fragmentation of large dust grains in the Thebe extensions could be the main source of sub‐micrometer grains detected in the Thebe extension., Key Points: In Jupiter's warm and dense inner magnetosphere dust grains acquire high negative electric charges. Dust particles ejected from Thebe with sufficient speeds contribute to the formation of the Thebe extension. Instead of shadow resonances as suggested earlier an alternative mechanism is suggested for the formation of the Thebe extension., Max Planck Institute for Solar System Research

We have performed measurements of the IR absorption of $\text{SiO}_2$ nanoparticles confined in an argon radio-frequency plasma discharge using an FTIR spectrometer. By varying the gas pressure of the discharge and duty cycle of the applied radio-frequency voltage we observed a shift of the absorption peak of $\text{SiO}_2$. We attributed this shift to charge-dependent absorption features of $\text{SiO}_2$. The charge-dependent shift has been calculated for $\text{SiO}_2$ particles and from comparisons with the experiment the particle charge has been retrieved using our IRPRS (Infrared Phonon Resonance Shift) method. With the two different approaches of changing the gas pressure and altering the duty cycle we are able to deduce a relative change of the particle charge with pressure variations and an absolute estimate of the charge with the duty cycle., 10 pages, 7 figures

Dust Astronomy investigates the nature and the origin of dust particles in space. The particle size distribution ranges from nanodust to approximately 100 micrometer. The study of the elemental and/or chemical composition of the particles together with the knowledge about their origin provides insights into many disciplines. Dust Astronomy is an interdisciplinary working field, which includes Solar System Science, Interstellar Medium studies and Astrobiology. A basic tool for these studies are Dust Telescopes. Dust Telescopes are in-situ instruments to characterize individual dust particles by their velocity vector, size and composition. They are based on impact ionization used for time-of-flight compositional analysis and on charge induction for particle speed and size measurements. In this sense, already the Cassini Cosmic Dust Analyzer (CDA) was a simple Dust Telescope, which successfully characterized the dust environment at Saturn. Now, future missions go even further. In the next years the missions DESTINY+, EUROPA and IMAP will launch. In this talk, a summary is given about the capabilities of Dust Telescopes with a focus on the DESTINY+ Dust Analyser (DDA). DDA is a medium size instrument with a target diameter of 26 cm. A two-axis articulation allows to track dust RAM directions. Larger Telescopes like the record breaking LAMA instrument, developed especially for the measurement of low interstellar dust fluxes, and the instruments for the probes IMAP and EUROPA are compared with DDA. The paper will address questions about the detection of nanodust or, what is a good instrument approach for a Dust Observatory? What are the instrumental challenges for an Interstellar Probe?

Cometary meteoroid streams (also referred to as trails) exist along the orbits of comets, forming fine structures of the interplanetary dust cloud. The streams consist predominantly of the largest cometary particles (with sizes of approximately (100 micrometer to 1 cm) which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model (Soja et al., Astronomy & Astrophysics, 2015) is a universal model that simulates recently created cometary dust streams in the inner solar system, developed under ESA contract. IMEX is a physical model for dust dynamics and follows the orbital evolution of the streams of 420 comets. Particles are emitted when the comet is in the inner solar system, taking into account comet apparitions between the years 1700 and 2080. The dust ejection is described by an emission model, dust production rate and mass distribution covering the mass range from 10^-8 kg to 10^-2 kg (approximately corresponding to 100 micrometer to 1 cm particles). The dust production is calculated from the comet's absolute magnitude, the observed water production rate and dust-to-gas ratio. For each emitted particle, the trajectory is integrated individually including solar gravity, planetary perturbations as well as solar radiation pressure and Poynting-Robertson drag. The model calculates dust number density, flux and velocity. We apply the IMEX model to study comet stream traverses by the Ulysses spacecraft. Ulysses was launched in 1990 and, after a Jupiter swing-by in 1992, became the first interplanetary spacecraft orbiting the Sun on a highly inclined trajectory with an inclination of 80 degrees. The spacecraft was equipped with an impact ionization dust detector which provided the longest data set of continuous in situ dust measurements in interplanetary space existing to date, covering 17 years from 1990 to 2007. In addition to the interplanetary dust complex, several dust populations were investigated with the Ulysses dust instrument in the past: interstellar dust sweeping through our solar system, streams of approximately 10 nanometer-sized dust particles emanating from Jupiter's volcanically active moon Io, as well as sub-micrometer-sized particles driven away from the Sun by solar radiation pressure (so-called beta particles). Here we study the detection conditions for cometary meteoroid streams with the dust detector on board the Ulysses spacecraft and present first results from our attempt to identify cometary stream particles in the measured dust data set. Acknowledgements: The IMEX Dust Streams in Space model was developed under ESA funding (contract 4000106316/12/NL/AF - IMEX).

Interstellar Probe is an ambitious mission concept, to reach interstellar space (up to 1000 AU). Its launch date is between 2030 and 2042 and its goals cover different fields of science from planetary science, heliophysics (heliosphere), to astronomy. One main goal is to significantly expand our knowledge about our heliosphere, the interstellar medium, and how both interact with each other. Among many other instruments, the space probe is planned to carry a dust mass spectrometer that will be able to capture dust particles and measure their composition. This will be especially useful for measuring the interstellar dust of the local interstellar medium that continuously streams through the solar system and has been directly detected for the first time with the Ulysses spacecraft in the 1990s. The mass distributions from such in situ dust detections in the solar system so far have shown a significant discrepancy compared to the results from astronomical observations. We performed a series of simulations of the interstellar dust trajectories and distribution inside the solar system and use them to predict the ability of the Interstellar Probe to measure interstellar dust particles and how this ability is affected by different spacecraft trajectories and dust detector setups. We also discuss how the filtering of small dust particles at the boundary regions of the heliosphere affects our predictions and indicate how in situ dust measurements can be used to constrain the filtering process. In general, most of the dust particles can be measured if the spacecraft moves towards the nose of the heliosphere. However, we also find a significant correlation between the presence of small dust particles (0.1 micron and many more of the smaller particles, depending on the state of the solar magnetic field and the dust filtering at the boundary of the heliosphere. Outside the heliosphere, the absence of dust filtering should increase the detection rate of small particles (

The decade of the 2020s promises to be when humanity returns to space beyond Earth orbit, with several nations trying to place astronauts on the Moon, before going further into deep space. As part of such a programme, NASA and partner organisations, propose to build a Deep Space Gateway in lunar orbit by the mid-2020s. This would be visited regularly and offer a platform for science as well as for human activity. Payloads that can be mounted externally on the Gateway offer the chance to, amongst other scientific goals, monitor and observe the dust flux in the vicinity of the Moon. This paper looks at relevant technologies to measure dust which will impact the exposed surface at high speed. Flux estimates and a model payload of detectors are described. It is predicted that the flux is sufficient to permit studies of cometary vs. asteroidal dust and their composition, and to sample interstellar dust streams. This may also be the last opportunity to measure the natural dust flux near the Moon before the current, relatively pristine environment, is contaminated by debris, as humanity’s interest in the Moon generates increased activity in that vicinity in coming decades. ISSN:0273-1177 ISSN:1879-1948

International audience

The ESA-JAXA BepiColombo mission to Mercury will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric particle dynamics at Mercury as well as their interactions with solar wind, solar radiation, and interplanetary dust. The particle instrument suite SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) is flying in space on-board the BepiColombo Mercury Planetary Orbiter (MPO) and is the only instrument for ion and neutral particle detection aboard the MPO. It comprises four independent sensors: ELENA for neutral particle flow detection, Strofio for neutral gas detection, PICAM for planetary ions observations, and MIPA, mostly for solar wind ion measurements. SERENA is managed by a System Control Unit located inside the ELENA box. In the present paper the scientific goals of this suite are described, and then the four units are detailed, as well as their major features and calibration results. Finally, the SERENA operational activities are shown during the orbital path around Mercury, with also some reference to the activities planned during the long cruise phase.

The dual spacecraft mission BepiColombo is the first joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet Mercury. BepiColombo was launched from Kourou (French Guiana) on October 20th, 2018, in its packed configuration including two spacecraft, a transfer module, and a sunshield. BepiColombo cruise trajectory is a long journey into the inner heliosphere, and it includes one flyby of the Earth (in April 2020), two of Venus (in October 2020 and August 2021), and six of Mercury (starting from 2021), before orbit insertion in December 2025. A big part of the mission instruments will be fully operational during the mission cruise phase, allowing unprecedented investigation of the different environments that will encounter during the 7-years long cruise. The present paper reviews all the planetary flybys and some interesting cruise configurations. Additional scientific research that will emerge in the coming years is also discussed, including the instruments that can contribute. Open Access funding provided by Istituto Nazionale di Astrofisica within the CRUI-CARE Agreement. Peerreview

An in-situ cosmic-dust instrument called the Mercury Dust Monitor (MDM) had been developed as a part of the science payload for the Mio (Mercury Magnetospheric Orbiter, MMO) stage of the joint European Space Agency (ESA)–JAXA Mercury-exploration mission. The BepiColombo spacecraft was successfully launched by an Ariane 5 rocket on October 20, 2018, and commissioning tests of the science payload were successfully completed in near-earth orbit before injection into a long journey to Mercury. MDM has a sensor consisting of four plates of piezoelectric lead zirconate titanate (PZT), which converts the mechanical stress (or strain) induced by dust-particle impacts into electrical signals. After the commencement of scientific operations, MDM will measure the impact momentum at which dust particles in orbit around the Sun collide with the sensor and record the arrival direction. This paper provides basic information concerning the MDM instrument and its predicted scientific operation as a future reference for scientific articles concerning the MDM’s observational data.

The Destiny+ mission (Demonstration and Experiment of Space Technology for Interplanetary voyage Phaethon fLyby and dUst Science) has been selected as part of its M-class Space Science Program by the Japanese space agency JAXA/ISAS and is set to launch in 2023/2024. The mission target is the active asteroid (3200) Phaethon with a projected flyby in early 2028. The scientific payload consists of two cameras (the Telescopic Camera for Phaethon, TCAP, and the Multi-band Camera for Phaethon, MCAP), and the Destiny+ Dust Analyzer (DDA). DDA is the technological successor to the Cosmic Dust Analyzer (CDA) aboard Cassini-Huygens, which prominently investigated the dust environment of the Saturnian system. The DDA sensor is designed as a combination of impact ionization time-of-flight mass spectrometer and trajectory sensor, which will allow for the analysis of sub-micron and micron sized dust particles with respect to their composition (mass resolution m/Δm ≈ 100-150), mass, electrical charge, velocity (about 10% accuracy), and impact direction (about 10° accuracy). Besides attempting to sample the impact-generated dust cloud around Phaethon during the flyby, DDA will be actively observing the interplanetary & interstellar dust environment over the roughly four years spanning cruise phase from the Earth-Moon system through interplanetary space. After launch into a GTO-like orbit, Destiny+ will first employ its solar-electric propulsion system to spiral up to the lunar orbit within about 18 months, followed by a series of lunar swingbys and interim coasting phases in distant cislunar space, accumulating momentum to leave the Earth-Moon system at high excess velocity. The subsequent roughly 2-year interplanetary transfer to intercept Phaethon will be characterized by moderate orbital eccentricity of up to 0.1 and largely unpowered coasting phases. During these four years, the DDA sensor will benefit from a maximum pointing coverage range enabled by its dual-axis pointing mechanism and spacecraft attitude flexibility (during times of unpowered flight). This will allow for exhaustive mapping and analysis of the different interplanetary dust populations, as well as interstellar dust encountered in the region between 0.9-1.1 AU. Here, we give a progress report on the science planning efforts for the 4-year transfer phase. We present a tentative observation timeline that assigns scientific campaigns to different phases of the mission, taking into account results of various dust models, as well as operational and technical constraints.

The Cosmic Dust Analyzer (CDA) onboard Cassini characterized successfully the dust environment at Saturn from 2004 to 2017. The study of Saturn’s E ring and its interaction with the embedded moons was a major scientific goal of Cassini. After the end of the mission, the entire CDA data can be analyzed to derive the global parameters of Saturn’s E ring. The CDA instrument measured the primary charge, speed, mass and composition of individual submicron and micron sized dust grains. The instrument was continuously collecting data of dust fluxes and apparent dust densities. Therefore the data cover radial distances between 3 and 20 Saturn radii and equatorial as well as high latitudes. However, the relative impact velocities varied with the dynamical properties of the Cassini spacecraft and with the dust particles. Small relative impact speeds lead to higher mass thresholds for impact detection such that this effect has to be considered in calculating apparent dust densities. Furthermore, the pointing profile of the instrument and the related observation geometry was highly variable. This paper describes an approach to define a dust environment model at Saturn based on the entire CDA dataset.

Energetic electrons from the inner radiation belt provide significant electric charging of the surfaces of Jupiter's moons Thebe and Amalthea whose orbits are located within this radiation belt. We estimate theoretically the electric fields in the vicinity of the polar regions of Thebe and Amalthea and argue that these fields are sufficient for lofting of micron and submicron-sized dust grains from the surfaces of the moons. Thus, the lofting of charged dust grains in the electric fields can be considered as an additional source supplying dust to the gossamer rings in addition to dust ejection by micrometeoroid impacts onto the moons' surfaces. The suggested mechanism can explain qualitatively some peculiarities of the dust grain distributions within the gossamer rings., Comment: 23 pages, 2 Figures, published in Planetary and Space Science, 2020

We review the development of dust science from the first ground-based astronomical observations of dust in space to compositional analysis of individual dust particles and their source objects. A multitude of observational techniques is available for the scientific study of space dust: from meteors and interplanetary dust particles collected in the upper atmosphere to dust analyzed in situ or returned to Earth. In situ dust detectors have been developed from simple dust impact detectors determining the dust hazard in Earth orbit to dust telescopes capable of providing compositional analysis and accurate trajectory determination of individual dust particles in space. The concept of Dust Astronomy has been developed, recognizing that dust particles, like photons, carry information from remote sites in space and time. From knowledge of the dust particles' birthplace and their bulk properties, we learn about the remote environment out of which the particles were formed. Dust Observatory missions like Cassini, Stardust, and Rosetta study Saturn's satellites and rings and the dust environments of comet Wild 2 and comet Churyumov-Gerasimenko, respectively. Supplemented by simulations of dusty processes in the laboratory we are beginning to understand the dusty environments in space., 97 pages, 19 figures, 2 Tables, to be published in ISSI book Cosmic Dust from the Laboratory to the Stars, Edited by Rafael Rodrigo, J\"urgen Blum, Hsiang-Wen Hsu, Detlef Koschny, Anny-Chantal Levasseur-Regourd, Jesus Martin-Pintado, Veerle Sterken and Andrew Westphal

In order to determine whether Martian dust belts (ring or torus) actually exist and, if so, to determine the characteristics of the dust, we propose a Circum-Martian Dust Monitor (CMDM) to be deployed on the Martian Moons Exploration (MMX) project, in which JAXA plans to launch the spacecraft in 2024, investigate Phobos and Deimos, and return samples back to Earth. The CMDM is a newly developed instrument that is an impact dust detector. It weighs only 650 g and has a sensor aperture area of ∼ 1 m2, according to the conceptual design study. Detectable velocities (v) range from 0.5 km/s to more than 70 km/s, which will cover all possible dust particles: circummartian (low v), interplanetary (mid v), and interstellar (high v) particles. The measurable mass ranges from 1.3 × 10−9 g to 7.8 × 10−7 g at v = 0.5 km/s. Since the MMX spacecraft will take a quasi-circular, prograde orbit around Mars, the CMDM will be able to investigate particles from Phobos and Deimos with relative velocities lower than 1 km/s. Therefore, the CMDM will be able to determine whether or not a confined dust ring exists along Phobos' orbit and whether an extended dust torus exists along Deimos' orbit. It may also be able to clarify whether or not any such ring or torus are self-sustained.

We report an analysis of the Comet Acoustic Surface Sounding Experiment (CASSE) acceleration signals at Philae's first touchdown site Agilkia on comet 67P/Churyumov-Gerasimenko. The signals yield the forces in the contact zone foot-sole and comet surface, and from these forces a compression strength of approximately 10 kPa can be derived. The sole's contact-resonances provide an elastic modulus of the order of 10 MPa. Our results are partially based on calibration experiments, which are described in the appendix of the current paper. Relations known in material science, linking porosity to elasticity and fracture energy, allow one to check the interdependence between compression strength and elasticity.

The so-called ‘Nebra Sky Disc’ is arguably the most important archaeological find in central Europe of the last two decades. It is a richly-decorated bronze plate with gold symbols, some of them be...

Infrared (IR) absorption spectra of melamine-formaldehyde (MF) microparticles confined in an rf plasma are studied at different plasma conditions. Several absorption peaks have been analyzed in dependence of plasma power and their temporal evolution. For comparison, the IR absorption spectra of heated MF microparticles without plasma exposition are used to determine the general influence of the temperature on the IR spectra. Measuring the temperature of the particles inside the plasma shows that the temperature is not the only process changing the particles' IR spectra. Chemical changes of the MF particles with increasing plasma power influence the absorption peak structure.

The zodiacal cloud is one of the largest structures in the solar system and strongly governed by meteoroid collisions near the Sun. Collisional erosion occurs throughout the zodiacal cloud, yet it is historically difficult to directly measure and has never been observed for discrete meteoroid streams. After six orbits with Parker Solar Probe (PSP), its dust impact rates are consistent with at least three distinct populations: bound zodiacal dust grains on elliptic orbits (α-meteoroids), unbound β-meteoroids on hyperbolic orbits, and a third population of impactors that may be either direct observations of discrete meteoroid streams or their collisional by-products (“β-streams”). The β-stream from the Geminids meteoroid stream is a favorable candidate for the third impactor population. β-streams of varying intensities are expected to be produced by all meteoroid streams, particularly in the inner solar system, and are a universal phenomenon in all exozodiacal disks. We find the majority of collisional erosion of the zodiacal cloud occurs in the range of 10–20 solar radii and expect this region to also produce the majority of pickup ions due to dust in the inner solar system. A zodiacal erosion rate of at least ∼100 kg s−1 and flux of β-meteoroids at 1 au of (0.4–0.8) × 10−4 m−2 s−1 are found to be consistent with the observed impact rates. The β-meteoroids investigated here are not found to be primarily responsible for the inner source of pickup ions, suggesting nanograins susceptible to electromagnetic forces with radii below ∼50 nm are the inner source of pickup ions. We expect the peak deposited energy flux to PSP due to dust to increase in subsequent orbits, up to 7 times that experienced during its sixth orbit.

The JAXA/ISAS spacecraft DESTINY$^+$ will be launched to the active asteroid (3200) Phaethon in 2022. Among the proposed core payload is the DESTINY+ Dust Analyzer (DDA) which is an upgrade of the Cosmic Dust Analyzer flown on the Cassini spacecraft to Saturn (Srama et al. 2011). We use two up-to-date computer models, the ESA Interplanetary Meteoroid Engineering Model (IMEM, Dikarev et al. 2005), and the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX; Sterken2013 et al., Strub et al. 2019) to study the detection conditions and fluences of interplanetary and interstellar dust with DDA. Our results show that a statistically significant number of interplanetary and interstellar dust particles will be detectable with DDA during the 4-years interplanetary cruise of DESTINY+. The particle impact direction and speed can be used to descriminate between interstellar and interplanetary particles and likely also to distinguish between cometary and asteroidal particles., Comment: 40 pages, 18 Figures, accepted for Planetary and Space Science

In the early 1990s, contemporary interstellar dust penetrating deep into the heliosphere was identified with the in-situ dust detector on board the Ulysses spacecraft. Later on, interstellar dust was also identified in the data sets measured with dust instruments on board Galileo, Cassini and Helios. Ulysses monitored the interstellar dust stream at high ecliptic latitudes for about 16 years. The three other spacecraft data sets were obtained in the ecliptic plane and cover much shorter time intervals.We compare in-situ interstellar dust measurements obtained with these four spacecrafts, published in the literature, with predictions of a state-of-the-art model for the dynamics of interstellar dust in the inner solar system (Interplanetary Meteoroid environment for EXploration, IMEX), in order to test the reliability of the model predictions. Micrometer and sub-micrometer sized dust particles are subject to solar gravity and radiation pressure as well as to the Lorentz force on a charged dust particle moving through the Interplanetary Magnetic Field. The IMEX model was calibrated with the Ulysses interstellar dust measurements and includes these relevant forces. We study the time-resolved flux and mass distribution of interstellar dust in the solar system. The IMEX model agrees with the spacecraft measurements within a factor of 2 to 3, also for time intervals and spatial regions not covered by the original model calibration with the Ulysses data set. It usually underestimates the dust fluxes measured by the space missions which were not used for the model calibration, i.e. Galileo, Cassini and Helios. IMEX is a unique time-dependent model for the prediction of interstellar dust fluxes and mass distributions for the inner and outer solar system. The model is suited to study dust detection conditions for past and future space missions., Comment: 24 pages, 7 figures, 1 table

Experiments on dust clusters trapped in the sheath of a radio frequency discharge have been performed for different magnetic field strengths ranging from a few milliteslas to 5.8 T. The dynamics of the dust clusters are analyzed in terms of their normal modes. From that, various dust properties such as the kinetic temperature, the dust charge, and the screening length are derived. It is found that the kinetic temperature of the cluster rises with the magnetic field, whereas the dust charge nearly remains constant. The screening length increases slightly at intermediate magnetic field strengths. Generally, the dust properties seem to correlate with magnetization parameters of the plasma electrons and ions, however only to a small degree.

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Open Access funding provided by Max Planck Society., Before Rosetta, the space missions Giotto and Stardust shaped our view on cometary dust, supported by plentiful data from Earth based observations and interplanetary dust particles collected in the Earth's atmosphere. The Rosetta mission at comet 67P/Churyumov-Gerasimenko was equipped with a multitude of instruments designed to study cometary dust. While an abundant amount of data was presented in several individual papers, many focused on a dedicated measurement or topic. Different instruments, methods, and data sources provide different measurement parameters and potentially introduce different biases. This can be an advantage if the complementary aspect of such a complex data set can be exploited. However, it also poses a challenge in the comparison of results in the first place. The aim of this work therefore is to summarize dust results from Rosetta and before. We establish a simple classification as a common framework for intercomparison. This classification is based on the dust particle structure, porosity, and strength and also on its size. Depending on the instrumentation, these are not direct measurement parameters, but we chose them because they were the most reliable for deriving our model. The proposed classification has proved helpful in the Rosetta dust community, and we offer it here also for a broader context. In this manner, we hope to better identify synergies between different instruments and methods in the future.© C. Güttler et al. 2019

Die Rosetta-Mission ist ein Meilenstein in der Erforschung der Kometen und ihrer Entstehung. Eine der grosten Uberraschungen war die unregelmasige hantelformige Gestalt des Zielkometen 67P/Tschurjumow-Gerassimenko. Er besteht wahrscheinlich aus zwei Einzelkorpern, die durch ihre Schwerkraft aneinander gehalten werden. Seine Oberflache ist sehr rau und zeigt eine sehr vielfaltige Morphologie, die auf eine Vielzahl von ablaufenden Prozessen hindeutet. Der Kometenkern ist vermutlich auf Grosenskalen von mehr als etwa 10 bis 100 Metern homogen, Inhomogenitaten auf kleineren Skalen konnten fur seine Aktivitat verantwortlich sein. Diese ist auf kleine Gebiete konzentriert, und auch Oberflachenveranderungen, die sich innerhalb von einigen Tagen bis wenigen Wochen abspielen, sind lokal. Im Kometenmaterial wurde eine Vielzahl an organischen Substanzen gemessen, die zum Teil als Schlusselmolekule fur die Synthese der Grundbausteine des Lebens gelten, wie wir es kennen.

Cometary meteoroid trails exist in the vicinity of comets, forming fine structure of the interplanetary dust cloud. The trails consist predominantly of cometary particles with sizes of approximately 0.1 mm to 1 cm which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. When re-analysing the Helios dust data measured in the 1970s, Altobelli et al. (2006) recognized a clustering of seven impacts, detected in a very narrow region of space at a true anomaly angle of 135 deg, which the authors considered as potential cometary trail particles. We re-analyse these candidate cometary trail particles to investigate the possibility that some or all of them indeed originate from cometary trails and we constrain their source comets. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new universal model for cometary meteoroid streams in the inner solar system, developed by Soja et al. (2015). Using IMEX we study cometary trail traverses by Helios. During ten revolutions around the Sun, and in the narrow region of space where Helios detected the candidate dust particles, the spacecraft repeatedly traversed the trails of comets 45P/Honda-Mrkos-Pajduvsakova and 72P/Denning-Fujikawa. Based on the detection times and particle impact directions, four detected particles are compatible with an origin from these two comets. We find a dust spatial density in these trails of about 10^-8 to 10^-7 m^-3. The in-situ detection and analysis of meteoroid trail particles which can be traced back to their source bodies by spacecraft-based dust analysers opens a new window to remote compositional analysis of comets and asteroids without the necessity to fly a spacecraft to or even land on those celestial bodies. This provides new science opportunities for future missions like Destiny+, Europa Clipper and IMAP., Comment: 13 pages, 9 Figures, 2 Tables, accepted for pubication by Astronomy and Astrophysics

Experiments on self-excited dust-density waves under various magnetic fields have been performed. For that purpose, different dust clouds of micrometer-sized dust particles were trapped in the sheath of a radio frequency discharge. The self-excited dust-density waves were studied for magnetic field strengths ranging from 0 mT to about 2 T. It was observed that the waves are very coherent at the lowest fields (B

We describe the use of Bayesian analysis methods applied to time-of-flight secondary ion mass spectrometer (TOF-SIMS) spectra. The method is applied to the COmetary Secondary Ion Mass Analyzer (COSIMA) TOF-SIMS mass spectra where the analysis can be broken into subgroups of lines close to integer mass values. The effects of the instrumental dead time are discussed in a new way. The method finds the joint probability density functions of measured line parameters (number of lines, and their widths, peak amplitudes, integrated amplitudes and positions). In the case of two or more lines, these distributions can take complex forms. The derived line parameters can be used to further calibrate the mass scaling of TOF-SIMS and to feed the results into other analysis methods such as multivariate analyses of spectra. We intend to use the method, first as a comprehensive tool to perform quantitative analysis of spectra, and second as a fast tool for studying interesting targets for obtaining additional TOF-SIMS measurements of the sample, a property unique to COSIMA. Finally, we point out that the Bayesian method can be thought of as a means to solve inverse problems but with forward calculations, only with no iterative corrections or other manipulation of the observed data.

The interplanetary space probe Cassini/Huygens reached Saturn in July 2004 after seven years of cruise phase. The Cosmic Dust Analyzer (CDA) measures the interplanetary, interstellar and planetary dust in our solar system since 1999 and provided unique discoveries. In 1999, CDA detected interstellar dust in the inner solar system followed by the detection of electrical charges of interplanetary dust grains during the cruise phase between Earth and Jupiter. The instrument determined the composition of interplanetary dust and the nanometre sized dust streams originating from Jupiter's moon Io. During the approach to Saturn in 2004, similar streams of submicron grains with speeds in the order of 100 km/s were detected from Saturn's inner and outer ring system and are released to the interplanetary magnetic field. Since 2004 CDA measured more than one million dust impacts characterizing the dust environment of Saturn. The instrument is one of three experiments which discovered the active ice geysers located at the south pole of Saturn's moon Enceladus in 2005. Later, a detailed compositional analysis of the water ice grains in Saturn's E ring system lead to the discovery of large reservoirs of liquid water (oceans) below the icy crust of Enceladus. Finally, the determination of the dust- magnetosphere interaction and the discovery of the extended E ring (at least twice as large as predicted) allowed the definition of a dynamical dust model of Saturn's E ring describing the observed properties. This paper summarizes the discoveries of a ten year story of success based on reliable measurements with the most advanced dust detector flown in space until today. This paper focuses on cruise results and findings achieved at Saturn with a focus on flux and density measurements., 18 pages, 12 Figures, DLRK 2011

Aims. Based on measurements by the Ulysses spacecraft and high-resolution modelling of the motion of interstellar dust (ISD) through the heliosphere we predict the ISD flow in the inner planetary system and on to the Earth. This is the third paper in a series of three about the flow and filtering of the ISD. Methods. Micrometer- and sub-micrometer-sized dust particles are subject to solar gravity and radiation pressure as well as to interactions with the interplanetary magnetic field that result in a complex size-dependent flow pattern of ISD in the planetary system. With high-resolution dynamical modelling we study the time-resolved flux and mass distribution of ISD and the requirements for detection of ISD near the Earth. Results. Along the Earth orbit the density, speed, and flow direction of ISD depend strongly on the Earth's position and the size of the interstellar grains. A broad maximum of the ISD flux (2x10^{-4}/m^2/s of particles with radii >~0.3\mu m) occurs in March when the Earth moves against the ISD flow. During this time period the relative speed with respect to the Earth is highest (~60 km/s), whereas in September when the Earth moves with the ISD flow, both the flux and the speed are lowest (, Comment: 17 pages, 17 figures

Plasmas growing or containing nanometric dust particles are widely used and proposed in plasma technological applications for production of nano-crystals and surface deposition. Here, we give a compact review of in situ methods for the diagnostics of nanodust and nanodusty plasmas, which have been developed in the framework of the SFB-TR24 to fully characterize these systems. The methods include kinetic Mie ellipsometry, angular-resolved Mie scattering, and 2D imaging Mie ellipsometry to get information about particle growth processes, particle sizes and particle size distributions. There, also the role of multiple scattering events is analyzed using radiative transfer simulations. Computed tomography and Abel inversion techniques to get the 3D dust density profiles of the particle cloud will be presented. Diagnostics of the dust dynamics yields fundamental dust and plasma properties like particle charges and electron and ion densities. Since nanodusty plasmas usually form dense dust clouds electron depletion (Havnes effect) is found to be significant.