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Small Bodies and Dust — Open Session

The session covers contributions on dwarf planets and small solar system objects, including comets, asteroids, meteoroids, and dust. Topics include dynamics, evolution, physical properties, and interactions of dust and meteors in space as well as planetary atmospheres. Presenters are invited to highlight results obtained from recent space missions (SO, PSP, etc.), observations, laboratory studies, theoretical and numerical simulations, as well as the latest results on the physics of meteors and of dust in ionospheres, ionospheric phenomena, other atmospheric phenomena, and space weathering of surfaces. This session further provides a forum for presenting future space instrumentation on these topics. We welcome young minds and encourage the presentation of multi-disciplinarity research.

Co-organized by ST2
Convener: Jiri Pavlu | Co-convener: Maria Gritsevich
| Tue, 24 May, 10:20–11:50 (CEST), 13:20–16:40 (CEST)
Room L1

Tue, 24 May, 10:20–11:50

Chairpersons: Jakub Vaverka, Maria Gritsevich


Andrey Fedorov et al.
ESA solar observatory Solar Orbiter is expected to have flown close to a comet plasma tail two times during the mission cruise phase. It passed behind the comet C/2019 Y4(ATLAS) in the end of May 2020. The second chance occurred on December 2021 when Solar Orbiter has encountered the tail of C/2021 A1(Leonard). In the both cases the distance between the spacecraft and the comet nucleus was about 40 million km. At the time of the encounter the comet ATLAS was at just 0.3 AU from Sun, and in the second case the comet Leonard was at the Venus orbit (0.7 AU). In both cases SWA-PAS ion spectrometer has seen very clear signature of the pickup O+ ions (with the maximum at about solar wind velocity). We observed the flow of the cometary tail ions as rather sharp bursts on just several minutes of duration. The heavy ion mass-spectrometer HIS observed O+ ions (among other species of the cometary origin) during the Leonard's tail encounter. We used inter-calibrated data of both instruments to get the absolute O+ flux from both comets.

How to cite: Fedorov, A., Livi, S., Louarn, P., Owen, C., and Raines, J.: Solar Orbiter SWA-PAS and SWA-HIS observations of O+ ions in the very distant tails of the comets C/2019 Y4(ATLAS) and C/2021 A1(Leonard), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12123, https://doi.org/10.5194/egusphere-egu22-12123, 2022.


John Jørgensen et al.

During cruise from Earth to Jupiter, an attitude-sensing star camera scanned the sky in search of objects large and small. That star camera is part of the Advanced Stellar Compass (ASC), a subsystem of the Magnetometer Investigation charged with providing accurate attitude information at the end of Juno’s magnetometer boom.  The main objective of the cruise observation was to search for smaller, unregistered, solar system objects, but quite unexpectedly the system recorded a great many tiny objects ejected from the spacecraft by the impact of high velocity interplanetary dust particles (IDP). This led to the first ever comprehensive profiling of IDPs from 0.88 to 5.2 AU near the ecliptic plane. We observed a rich IDP population between 1.2AU and the 4:1 mean motion resonance with Jupiter near 2.1AU, and in the Kirkwood gaps, the IDP population drops to near zero beyond the 2:1 mean motion resonance with Jupiter at 3.3AU. However, a hundredfold increase in dust impacts with the spacecraft occurred during a 15-day period in December 2015, shortly before entering the Jovian system. We have identified this event with Juno’s passage through a Jupiter family comet tail. Detailed analysis demonstrates that the comet dust population we observed is characterized by cometary dust particles (CDPs) with a beta in the range of 2-10%. Subdued comet activity far from the Sun frustrates direct observations of the comet tail from Earth; however, our analysis shows that the tail evolution is still dominated by non-gravitational forces acting on particles of a few to tens of micrometers. We present the in-situ comet tail observations and couple these to the complex evolution of comet activity and dust tail dynamics.

How to cite: Jørgensen, J., Jørgensen, P., Benn, M., Andersen, A., Connerney, J., Toldbo, C., Bolton, S., and Levine, S.: The Juno Spacecraft Catches a Jupiter Family Comet by the Tail, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9660, https://doi.org/10.5194/egusphere-egu22-9660, 2022.


Sarah E. Anderson et al.

Comet C/2016 R2 PanSTARRS presents an unusually high N2/CO abundance ratio, as well as a heavy depletion in H2O, making it the only known comet to have this composition. Two studies have independently estimated the possible origin of this comet from building blocks formed in a peculiar region in the protoplanetary disk, near the ice line of CO and N2. Here we explore the potential fates of comets formed from these building blocks using a numerical simulation of early solar system formation and tracking the dynamics of these objects in the Jumping Neptune scenario. We find that objects formed in the region of the CO- and N2- icelines a are highly likely to be sent towards the Oort Cloud or ejected from the Solar System altogether on a relatively short timescale, thus offering a potential explanation for the scarcity of comets with R2’s unique composition.  

How to cite: Anderson, S. E., Petit, J.-M., Noyelles, B., Mousis, O., and Rousselot, P.: Peculiar Comets Ejected Early In Solar System Formation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7975, https://doi.org/10.5194/egusphere-egu22-7975, 2022.


Nicolas Thomas et al.

It was recognized in observations of the innermost coma of comet 1P/Halley by the Halley Multicolour Camera onboard Giotto, that the dayside dust coma was, on average, only around a factor 3.2 brighter than the dust coma on the nightside. This was considered surprising because the phase angle of the approach (107.2°) was not substantially different from a terminator viewing direction. The dominance of water sublimation in comets and the assumption that nightside activity should be strongly limited led to the conclusion that lateral (non-radial) flow of dust from the dayside to the nightside must be responsible. This was apparently supported qualitatively by evidence of dust gradients seen against the background of the shadowed nucleus (Keller and Thomas, 1989).

Using observations from the MICAS camera on Deep Space 1, Ho et al. (2003) found for 19P/Borrelly a dayside to nightside coma brightness ratio (DS:NS) of just 1.7 at a phase angle of 88° and rh= 1.36 AU and subsequently compared this to the results from 1P/Halley (Ho et al., 2007). The brightness ratio was even smaller despite the observation being from almost directly above the terminator. This observation has not been widely promoted, possibly in part because of the quite poor imaging quality of MICAS.

Lateral flow is not the only means of producing low values of DS:NS. Both slow moving particles in orbit about the nucleus and nightside outgassing can influence the observed column density ratio. Gerig et al. (2020) have investigated the observational data at 67P/Churyumov-Gerasimenko and have established both the low DS:NS ratio (as at the other comets) and an increasing DS:NS ratio with reducing heliocentric distance. Furthermore, the brightness distribution with distance in the innermost coma most closely fits radial outflow suggesting that gravitationally bound particles are not the dominant influence on DS:NS. Pinzon-Rodriguez et al. (2021) have modelled H2O and CO2 emissions from 67P in a simplified, coupled, thermal system and shown that for reasonable parameters, nightside emission of dust driven by CO2 is a promising explanation for the observations.

The presentation will provide the observational evidence for the DS:NS ratio, describe the modelling work, and demonstrate the results.


Gerig, S.-B., et al., (2020) , Icarus, 351, 113968.

Ho, T.M., et al., (2003), Advances in Space Research, 31, 2583.

Ho, T.-M., et al. (2007), Planetary and Space Science, 55, 974-985.

Keller, H.U. and N. Thomas, (1989), Astronomy and Astrophysics, 226, L9.

Pinzón-Rodríguez, O., et al., (2021), Astronomy and Astrophysics, 655, A20.

How to cite: Thomas, N., Marschall, R., Gerig, S.-B., and Pinzon-Rodriguez, O.: Dayside to nightside dust column density ratios in the inner comae of comets, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2013, https://doi.org/10.5194/egusphere-egu22-2013, 2022.


Frederik Dhooghe et al.

During the ESA/Rosetta mission more than 1.5 million individual mass spectra have been obtained in the coma of 67P/Churyumov-Gerasimenko with the ROSINA/DFMS mass spectrometer. A single spectrum at a specific mass represents the accumulation of 3000 scans with an integration time of 6.6 ms, for a 19.8 s total measuring time.

DFMS data has been a source of information on coma composition and even on refractories. Although DFMS has a high sensitivity and high dynamic range, there may still be species hidden in the spectra. One approach to improve the signal-to-noise ratio is the summation of spectra. This way, species with a low abundance, close to the limit of detection of DFMS, should become more pronounced, however, at the cost of the loss of possible time variability information.  Unfortunately, the creation of sum spectra is not straightforward. Sum spectra need a clean dataset, where all erroneous and non-cometary data have been removed. Also, instrumental effects (e.g. detector aging, changes in settings in the course of the mission) need to be taken into account.

This contribution will present the methodology and some first results for sum spectra from DFMS. It is shown how this approach can provide inputs in the search for Fe and Ni in comet 67P.

How to cite: Dhooghe, F., De Keyser, J., Hänni, N., Altwegg, K., Cessateur, G., Jehin, E., Maggiolo, R., Rubin, M., and Wurz, P.: The search for low-abundant species in the coma of comet 67P/Churyumov-Gerasimenko, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4474, https://doi.org/10.5194/egusphere-egu22-4474, 2022.


Minjae Kim et al.

Comets are thought to have preserved dust particles from the beginning of Solar System formation, providing a unique insight into dust growth mechanisms. The Rosetta mission offered the best opportunity to investigate nearly pristine cometary dust particles of comet 67P/Churyumov–Gerasimenko. Among the three in-situ dust instruments, the MIDAS (Micro-Imaging Dust Analysis System) atomic force microscope collected cometary dust particles with sizes from hundreds of nanometres to tens of micrometres on dedicated targets and recorded their 3D topographic information (Bentley et al. 2016a). However, the straightforward dust collection strategy, i.e., simply hitting the collection targets, leads to an unknown degree of collection alteration (Bentley et al. 2016b)
We aim to understand and determine which structural properties of the MIDAS dust particle remained pristine during collection. First, we generate sophisticated dust maps showing the distribution of the dust particles on the collection targets and investigate dust clustering, i.e., determination of which particles stem from a single parent particle that fragmented upon the collection impact. Additionally, in the collaboration with Longobardo et al. 2020a, we use an algorithm to determine from which cometary source regions which MIDAS particles were stemming (Longobardo et al. 2020b). Next, we develop MIDAS particle shape descriptors such as aspect ratio (i.e., height of the particle divided by the square root of area), elongation, circularity, convexity, and particle surface/volume distribution. Furthermore, we compare structures of the MIDAS dust particles and clusters to those found in the laboratory experiments (Ellerborek et al. 2017) and by COSIMA/Rosetta (Langevin et al. 2016). Finally, we combine our findings to calculate a pristinity score for MIDAS particles and determine the most pristine particles and their properties. 

Fig 1. 3D dust coverage map of target 10

We find that there is only a weak trend between shape descriptors and cometary source regions, cluster morphology, and particle characteristics. For example, particles ejected from smooth or rough terrain are similar in their shape properties, which implies that dust particle activity such as dust ejection, partial dry out, and backfall are not responsible for the structure of particles at micrometre scales. Furthermore, the aspect ratio distributions suggest that the subunits of different cluster types are similar in their shape and composition. Thus, the different cluster morphologies detected by MIDAS are not created by a change in subunit properties, but rather by different impact velocities (Lasue et al. 2019). Next, the types of clusters found in MIDAS show good agreement (Ellerbroek et al. 2017), however, there are some differences to those found by COSIMA (Lasue et al. 2019). Furthermore, we found that almost half of the MIDAS particles suffered severe alteration by impact, which indicates dust alteration was inevitable with the given dust collection strategy. Consequently, only ~ 20 particles were rated 'moderately pristine' particles, i.e., not substantially flattened by impact, not fragmented, and/or not part of a fragmentation cluster. The microphysical properties of pristine cometary materials are established in this study and can be translated into properties of laboratory analogue materials for future study.

How to cite: Kim, M., Mannel, T., Lasue, J., Longobardo, A., Bentley, M., and Moissl, R.: Primitiveness of cometary dust collected by MIDAS on-board Rosetta, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9487, https://doi.org/10.5194/egusphere-egu22-9487, 2022.


Leszek Czechowski and Konrad Kossacki


The slow ejecta (i.e., with velocity lower than escape velocity) and landslides are similar. Both are forms of gravity movement. After landing, ejecta may be still moving like a ‘regular’ landslide. On the other hand, the motion of landslides may include free fall without contact with the ground

            Observations of comets 9P/Tempe 1 and 67P/Churyumov – Gerasimenko revealed existence of various forms of mass motion [1, 2, 3]. We compare here landslides of matter from Imhotep (in the lobe Body) and from Hathemit (in the lobe Head) depressions.

                                                        Model of ejection

A simple model of processes leading to the formation of slow ejecta is assumed [3]. The phase transition heats a certain underground volume [4, 5, 6]. It leads to vaporization of volatiles. Eventually a cavity is formed. If the pressure in the cavity exceeds some critical value then the crust could be crushed and its fragments will be ejected in the space. Note that the initial velocity of ejecta are usually approximately perpendicular to the physical surface. This assumption was used successfully in [6].


           We found that ejecta with the velocity 0.3 m s-1 (or lower) land close to the starting point for both considered depressions. Ejecta faster than 0.5 m s-1 have complex trajectories and may land far from the starting point. For the velocity  0.7 m s-1 (and higher) some of ejecta did not land during modeling even for Imhotep.

             In [6] we have found that ejecta from Hathemit fall in a wide belt mainly on the one hemisphere. For ejecta from Imhotep there is no such pattern.

             The fate of the ejecta after landing depends on many factors: the friction coefficient, the inclination of the place of landing, the vector of velocity, etc. However, often the motion is determined by small scale details. Note that the sliding grain must overcome the worst obstacle on the landing surface.

                                                 Conclusions and future plans

Determining places of deposition of the material ejected from Imhoteb or Hatmelib will allow to determine the composition of the comet's interior under these regions without the need for drilling. This would be particularly important for future missions to the comet.           


The research is partly supported by Polish National Science Centre (decision 2018/31/B/ST10/00169)


[1] Czechowski L., (2017)      Geophysical Research Abstract. EGU 2017 April, 26, 2017

[2] Jorda, L., et al. (2016) Icarus, 277, 257-278, ISSN 0019-1035, https://doi.org/10.1016/j.icarus. 2016.05.002.

[3] Auger, et al., (2015). Astronomy and Astrophysics. 583. A35. 10.1051/0004-6361/201525947.

[4] Kossacki K., Czechowski L., (2018). Icarus vol. 305, pp. 1-14, doi: 10.1016/j.icarus.2017.12.027

[5] Kossacki, K.J., Szutowicz, S., (2010). Icarus 207, 320- 340.

[6] Czechowski L. and Kossacki K.J. (2019) Planetary and Space Science 209, 105358, https://doi.org/10.1016/j.pss.2021. 105358 

How to cite: Czechowski, L. and Kossacki, K.: Ballistic landslides on comet 67P/Churyumov–Gerasimenko, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9496, https://doi.org/10.5194/egusphere-egu22-9496, 2022.


Sunny Laddha et al.

The success of the Rosetta mission to comet 67P/Churyumov–Gerasimenko has revolutionized our view of comets, while opening a plethora of new questions. In order to find the answers to them and harness the full potential of the new data, an international consortium named “Cophylab – Comet Physics Laboratory” (Cophylab.space) was launched in 2018. In this project several experiment campaigns were initialized to study cometary properties in a controlled environment. The idea was to isolate individual properties and processes in dedicated laboratory experiments. One of the experiment campaigns was designed to characterize gas flow properties of dry porous materials in a first step, with the aim of developing a model that improves our understanding of the outgassing of comets.

Before the initial model is extended to consider the sublimation of volatile components, it needs to be validated by alternative methods, such as numerical simulations. For this purpose, we chose the finite element method, to test the combination of the Darcy and Knudsen flow model, which was used in the preceding study.

Our approach was to use the results of the experiment as input in the simulations and compare the output with the measurements. This comparison confirmed the validity of the model and its assumptions. In particular, the sample is assumed to be homogenous and isotropic on a macroscopic scale, so that it can be described by a set of averaged parameters. While this description is relatively accurate for samples with well-defined grain shapes (e.g. spherical glass beads), significant discrepancies occur for inhomogeneous materials such as lunar, Asteroid or Martian analogues.

We investigated various aspects that were initially neglected in the evaluation of the measurements, such as channel building in the sample, boundary effects and non-ideal geometry of the experimental setup, which will be complemented by inhomogeneities that occur naturally in random close packing or ballistic deposition samples. Furthermore, we assessed the models range of applicability through a thorough review of the different flow regimes encountered in the measurements. Our findings indicate that boundary effects, as well as non-ideal geometry have a significant influence particularly in samples with larger grains. For finer grained samples on the other hand, inhomogeneities are the most probable cause for discrepancies. The grain size also plays an important role regarding the flow regime and its corresponding parameters.

The work for this study was performed in the framework of a master’s thesis, as part of the Cophylab project, which is funded by the D-A-CH program (DFG GU1620/3-1 and BL 298/26-1 / SNF 200021E 177964 / FWF I 3730-N36)

How to cite: Laddha, S., Macher, W., Zivithal, S., and Kargl, G.: Validation and calibration of gas flow experiments with numerical simulations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4837, https://doi.org/10.5194/egusphere-egu22-4837, 2022.


Jiri Pavlu et al.

Dust in the interstellar space is illuminated by cosmic radiation that consists of photons of different wavelengths and energetic charged particles. Whereas the photoemission is rather well understood, charging of dust grains due to interaction of with energetic charged particles was not experimentally studied in detail so far. We report the first laboratory experiment dealing with the interaction of a cosmic dust simulant with energetic charged particles emitted from a radioisotope. Measurements of the charge of micrometer silicate dust grains with an accuracy of one elementary charge revealed several processes leading to the dust charging. The observed average rate of charging events agrees well with prediction of a model based on the continuous slowing down approximation of energetic particles inside the grain. Charge steps larger than one elementary charge were attributed to emission of secondary electrons excited by the primary particle slowing down. The determined yield of secondary electron emission is approximately inversely proportional to the grain radius. The experimental results led us to the formulation of a possible scenario of interstellar dark clouds charging.

How to cite: Pavlu, J., Wild, J., Cizek, J., Nouzak, L., Vaverka, J., Safrankova, J., and Nemecek, Z.: Laboratory Simulation of the Dust Interaction with Energetic Particles and its Implication for Interstellar medium, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1363, https://doi.org/10.5194/egusphere-egu22-1363, 2022.


Michael Küppers et al.

The impact of the NASA DART spacecraft on the 160 m-diameter natural satellite called Dimorphos
of the binary asteroid 65803 Didymos on 26 September 2022 will change its orbital period around
Didymos. The change can be detected by Earth-based observers. Before impact, DART will deploy the Italian LICIACube that will
provide images of the first instants after impact. ESA’s Hera spacecraft will rendezvous Didymos four
years after the impact.

Hera will characterize in detail the properties of a Near-Earth Asteroid that are most relevant to
planetary defense:
•Measuring the mass of Dimorphos to determine the momentum transfer efficiency from DART
•Investigating in detail the crater produced by DART to improve our understanding of the cratering
process and the mechanisms by which the crater formation drives the momentum transfer
•Observing subtle dynamical effects (e.g. libration imposed by the impact, orbital and spin
excitation of Dimorphos) that are difficult to detect for remote observers.
•Characterising the surface and interior of Dimorphos to allow scaling of the momentum transfer
efficiency to different asteroids.

Hera will also provide unique asteroid science. It will rendezvous for the first
time with a binary asteroid. The secondary has a diameter of only 160 m, the smallest asteroid visited so far. Moreover, for the first time, internal and subsurface properties will be directly measured. From small asteroid internal and surface structures, through
rubble-pile evolution, impact cratering physics, to the long-term effects of space weathering in the
inner Solar System, Hera will have a major impact on many fields. How do binaries form? What is the surface composition of the asteroid pair? What are its internal properties?  What are the surface structure and regolith mobility on both Didymos and Dimorphos?
And what will be the size and the morphology of the crater left by DART? These questions and many others will be addressed by Hera as a natural outcome of its investigations focused on planetary defense.

How to cite: Küppers, M., Michel, P., Ulamec, S., Fitzsimmons, A., Green, S., Lazzarin, M., Carnelli, I., and Martino, P. and the The Hera Science Team: The ESA Hera mission to the binary asteroid (65803) Didymos:Planetary Defense and Science, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6375, https://doi.org/10.5194/egusphere-egu22-6375, 2022.


Tue, 24 May, 13:20–14:50

Chairpersons: Jiri Pavlu, Maria Gritsevich

Geraint Jones et al.

In 2019, Comet Interceptor was selected by the European Space Agency, ESA, as the first in its new class of F missions. The Japanese space agency, JAXA, is making a major contribution to the project. Comet Interceptor's primary science goal is to characterise for the first time, a yet-to-be-discovered long-period comet, preferably dynamically new, or an interstellar object. An encounter with a comet approaching the Sun for the first time will provide valuable data to complement information gathered by all previous comet missions, which through necessity all visited more evolved short period comets. The spacecraft will be launched in 2029 with the Ariel mission to the Sun-Earth Lagrange Point, L2. This relatively stable location allows a rapid response to the appearance of a suitable target comet, which will need to cross the ecliptic plane through an annulus centered on the Sun that contains Earth’s orbit. A suitable new comet would be searched for from Earth, with short period comets acting as mission backup targets. Powerful facilities such as the Vera Rubin Observatory make finding a suitable comet nearing the Sun very promising, and the spacecraft could encounter an interstellar object if one is found on a suitable trajectory. The spacecraft must cope with a wide range of target activity levels, flyby speeds, and encounter geometries. This flexibility has significant impacts on the spacecraft solar power input, thermal design, and dust shielding that can cope with dust impacts. Comet Interceptor comprises a main spacecraft and two probes, one provided by ESA, the other by JAXA, which will be released by the main spacecraft on approach to the target. The main spacecraft, which would act as the primary communication point for the whole constellation, would be targeted to pass outside the hazardous inner coma, making remote and in situ observations on the comet’s sunward side. Planned measurements of the target include its surface composition, shape, and structure, its dust environment, and the gas coma’s composition. A unique, multi-point ‘snapshot’ of the comet- solar wind interaction region will be obtained, complementing single spacecraft observations at other comets. We shall describe the science drivers, planned observations, and the mission’s instrument complement, to be provided by consortia of institutions in Europe and Japan.

How to cite: Jones, G., Snodgrass, C., and Tubiana, C. and the The Comet Interceptor Team: The Comet Interceptor Mission, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12656, https://doi.org/10.5194/egusphere-egu22-12656, 2022.


Johan De Keyser et al.

The ability to conduct multi-point measurements is a hallmark of the ESA-JAXA/Comet Interceptor mission currently in development. The mission consists of one spacecraft (A) and two probes (B1 and B2) which are expected to fly by a medium- to high-activity comet at a high relative speed (up to 70 km/s). The payload on spacecraft A and on probes B1/B2 provides different opportunities to perform multi-point in-situ data exploitation. We discuss how information about radial, solar zenith angle and latitudinal variations can be extracted from the measurements, for instance using multi-point data analysis techniques inherited from the ESA/Cluster mission. We consider different spacecraft configurations and different geometries for the spacecraft trajectory relative to the comet, as well as target comets with gas production rates between those of 67P/Churyumov-Gerasimenko and 1P/Halley. We highlight the various opportunities and limitations of the proposed algorithms. Particular attention is given to the need for data that are well intercalibrated and discuss what can be done if the intercalibration is not perfect.

How to cite: De Keyser, J., Henri, P., and Simon-Wedlund, C.: Exploiting multi-point in situ measurements during the Comet Interceptor comet flyby, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6920, https://doi.org/10.5194/egusphere-egu22-6920, 2022.


Larry W. Esposito et al.

The varying geometry of Cassini star occultations by Saturn’s rings constrains both the size and shape of structures that block starlight. Statistics of UVIS star occultations measure structures as small as meters, on times scales of minutes to decades. We calculate the excess variance, skewness and kurtosis including the effects of irregular particle shadows, along with a granola bar model of gaps, ghosts (local openings) and self-gravity wakes. In this model, the widths W and separation S of rectangular clumps play an analogous role to the  size of the particle shadows, R. In the first model considered, our calculations are based on the moments of the transparency T in the ring region sampled by the occultation, thus extending the work of  Showalter and Nicholson (1990) to larger τ  and fractional area δ, and to higher central moments, without their simplifying assumptions. We also calculate these statistics using an approach based on the autocovariance, autocoskewness and autocokurtosis.

These new approaches compare well to the formula for excess variance from Showalter and Nicholson in the region where all are accurate, δτ1. Skewness for small τ has a different sign for transparent and opaque structures, distinguishing gaps from clumps. The higher order central moments are calculated from higher powers of the shadow size, thus more sensitive to the extremes of the size distribution. We explain the τ dependence of the excess variance for Saturn’s background C ring by the observation of Jerousek etal(2018) that the measured optical depth is correlated with particle size in the region between 78,000 and 84,600km from Saturn.

Statistics calculated from the granola bar model give different predictions from those based on individual spherical particles. The density waves clearly show compression that triggers clump growth, as predicted by the Predator-Prey model (Esposito etal. 2012, Icarus 217, 103-114). The radial profiles and observed τ dependence suggest that the wave crests compress the gaps more than the wakes, along with broader self-gravity wakes in the wave crests, including transparent ghosts. The UVIS observations fall between the most regular and the most irregular granola bar models. Analysis of ring transparency favors irregularly-spaced elongated clumps. A closer analysis of this particular case gives H/W < 0.12, smaller than Colwell etal. (2007, Icarus 190, 127-144), suggesting wakes are more like linguine than granola bars.

How to cite: Esposito, L. W., Sremcevic, M., Colwell, J., Eckert, S., and Jerousek, R.: Shape and compression of self-gravity wakes in Saturn’s rings, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6601, https://doi.org/10.5194/egusphere-egu22-6601, 2022.


Libor Nouzak et al.

Cassini spacecraft investigated the Saturn environment more than 13 years. In course of this long period, the RPWS (Radio Plasma Wave Science) experiment not only mapped electric fields in the Saturn’s magnetosphere but also registered a large number of sharp spiky signals caused by hypervelocity dust impacts within Saturn rings. We have identified more than 140 000 such waveforms recorded by electric antennas with 10 or 80 kHz cadence in a close proximity of the ring mid-plane (up to 0.2 Rs). Among them, shapes and amplitudes of more than 100 000 non-saturated impacts were corrected on the Cassini WBR (Wide Band Receiver) transfer function.

Our laboratory experiment with the 1:20 reduced model of Cassini positioned in the test chamber of the dust accelerator allowed us to determine dependences of the signal shape and amplitude on the dust parameters (velocity and mass) and spacecraft potential. We apply these results on calculations of the mass and size distributions of dust particles detected by the electric field antennas within the Saturn ring system. The core of the paper is devoted to relation between dust characteristics (determined from impact signals and local plasma parameters) and ring mass profiles at distances ranging from 2 to 60 Rs from the surface.

How to cite: Nouzak, L., Pavlu, J., Vaverka, J., Safrankova, J., Nemecek, Z., Pisa, D., Shen, M., Sternovsky, Z., and Ye, S.: Saturn ring structure inferred from comparison of Cassini observations with laboratory simulations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1362, https://doi.org/10.5194/egusphere-egu22-1362, 2022.


Kristina Rackovic Babic et al.

Dust grains are a common constituent of the Solar system. Dust impacts have been observed using radio and wave instruments onboard spacecraft since the 1980s. Voltage waveforms show typical impulsive signals generated by dust grains. We aim at developing models of how signals are generated to be able to link observed electric signals to the physical properties of the impacting dust. To validate the model, we use the Time Domain Sampler (TDS) subsystem of the STEREO/WAVES instrument which generates high-cadence time series of voltage pulses for each monopole. A model that we propose takes into account impact-ionization-charge collection and electrostatic-influence effects. It is an analytical expression for the pulse and allows us to measure the of amount of the total ion charge, the fraction of escaping charge, the rise timescale, and the relaxation timescale. The model is simple and convenient for massive data fitting. To check our model’s accuracy, we collected all the dust events detected by STEREO/WAVES/TDS simultaneously on all three monopoles at 1AU since the beginning of the STEREO mission in 2007. Our study confirms that the rise time largely exceeds the spacecraft’s short timescale of electron collection. Our estimated rise time value allows us to determine the propagation speed of the ion cloud, which is the first time that this information has been derived from space data. Our model also makes it possible to determine properties associated with the electron dynamics, in particular the order of magnitude of the electron escape current. The obtained value gives us an estimate of the cloud’s electron temperature — a result that, as far as we know, has never been obtained before except in laboratory experiments. Furthermore, a strong correlation between the total cloud charge and the escaping charge allows us to estimate the escaping current from the amplitude of the precursor, a result that could be interesting for the study of the pulses recently observed in the magnetic waveforms of Solar Orbiter or Parker Solar Probe, for which the electric waveform is saturated.

How to cite: Rackovic Babic, K., Zaslavsky, A., Issautier, K., Meyer-Vernet, N., and Onic, D.: An analytical model for dust impact voltage signals, and its application to STEREO/WAVES data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4363, https://doi.org/10.5194/egusphere-egu22-4363, 2022.


Zoltan Sternovsky et al.

Plasma Wave antenna instruments are employed on a range of space missions and can also be used to characterize the population of cosmic dust particles. Such measurements are complementary to those made by a dedicated dust instrument and suitable for the detection of larger (> 1 micron) particles. These booms or deployed wires with receiving elements are sensitive to the plasma cloud generated by the hypervelocity impact of a dust particle on the spacecraft, or the antenna itself. The dust impact is registered as a transient voltage signal (waveform) that is due to the charging of the spacecraft/antenna, and the induced charging from the part of the plasma cloud that is expanding from the impact location. Recent advancements provide the capability of obtaining the mass of the impacting particle from the measured waveforms. The new models are based on first principles and account for the parameters of the impact plasma (in terms of effective temperatures and the geometry of the expansion), the parameters of the ambient space environment, and the geometry of the spacecraft. The latter two allow for determining the approximate impact location on the spacecraft and thus constrain the incoming direction of the dust particle. Once the expansion of the transient impact plasma is over, the spacecraft and the antennas discharge through the ambient environment and relax back to their equilibrium potentials. The analysis of the measured waveforms thus also provides information on the density of the ambient plasma and its temperature. The numerical model is applied for the reanalysis of the measurements made by the STEREO spacecraft.

How to cite: Sternovsky, Z., Garzelli, A., Horanyi, M., Malaspina, D., Pokorny, P., and Juhasz, A.: Dust detection by antenna instruments with applications to the STEREO spacecraft, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10957, https://doi.org/10.5194/egusphere-egu22-10957, 2022.


Samia Ijaz et al.

Detection of dust grains in space is limited by a small number of dedicated dust detectors, however, we aim to study dust detection using electric field instruments usually placed on the majority of scientific spacecraft. This technique has been previously applied to detect dust impacts in space for several decades. The major advantage of this method is that entire spacecraft surface acts as a detector. We present a preliminary statistical analysis of 1-year (2015) observations of dust impacts by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. The pulses generated by dust impacts were identified in data of the Langmuir Probe and Wave instrument operating in a dipole configuration (probe to probe potential measurement). Out of all the modes we use the medium frequency burst mode, the data covers 62.5 milliseconds using 4096 measured points which gives us a sampling frequency of 66.67 kHz. First, our algorithm selected events for which the derivative exceeded a threshold value. Second, these preselected events were further categorized into groups. Several groups contained suspicious events which are most likely not related to dust impacts. In total, we find 9848 events at altitudes ranging from less than 200 to 6000 kilometers that we can interpret as dust impacts. The distribution of these dust events around the Mars orbit is discussed.

How to cite: Ijaz, S., Vaverka, J., Safrankova, J., and Nemecek, Z.: One-year analysis of dust detection using dipole electric field antennas at Mars by MAVEN, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1750, https://doi.org/10.5194/egusphere-egu22-1750, 2022.


Jakub Vaverka et al.

Hypervelocity dust impacting the spacecraft body can be either partly or totally destroyed and evaporated and then creates a cloud of charged particles. Electrons and ions generated by such impacts can consequently influence the spacecraft potential and/or measurements of on-board scientific instruments. Electric field instruments are sensitive to these disturbances and typically register signals generated by dust impacts as short pulses. Once they are distinguished from other signals, they can be used for the detection of dust grains by spacecraft (even without dedicated dust detectors). 

Solar Orbiter is equipped with the RPW (Radio and Plasma Wave) instrument including three electric field antennas allowing such detection. The time domain sampler (TDS) subsystem of RPW provides typically short electric field waveforms (62.5 ms) sampled at a rate of 262.1 kHz

We have analyzed individual electric field waveforms of dust impacts detected by Solar Orbiter RPW/TDS and sorted into different categories (typical dust impact, impacts with the complex response, misinterpreted events, and suspicious events). Typical dust impacts are compared with an expected signal based on a model of dust impacts. The reliability of dust detection (fraction of misinterpreted and suspicious events) is evaluated with respect to the distance from the Sun.

How to cite: Vaverka, J., Pavlu, J., Nouzak, L., Safrankova, J., Nemecek, Z., Pisa, D., Soucek, J., Zaslavsky, A., and Maksimovic, M.: Dust Grain Detection by the Solar Orbiter Radio and Plasma Wave instrument, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1722, https://doi.org/10.5194/egusphere-egu22-1722, 2022.


Michiko Morooka et al.

Transient electric field perturbations are commonly observed when the interplanetary dust grains impact spacecraft, and their characteristics are well-studied. The signals are interpreted as due to the plasma expansion at the impact site and last typically in the order of micro-to milli-seconds. Radio and Plasma Wave (RPW) Instrument onboard Solar Orbiter can observe grains with a dedicated mode to capture such short-lived signals by the dust in the inner Heliosphere. On the other hand, a large impact can cause electric field disturbance for a longer time in tens of seconds. The long signals are observed in the low-frequency range (<10 kHz) and found more frequently during the inbound of the Solar Orbiter excursion. We will discuss the plasma and spacecraft conditions for the long durational impact signals.

How to cite: Morooka, M., Khotyaintsev, Y., Maksimovic, M., Soucek, J., and Pisa, D.: Very long electric field disturbances induced by dust impact observed by the Solar Orbiter/RPW, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11250, https://doi.org/10.5194/egusphere-egu22-11250, 2022.


Andreas Kvammen et al.

We present results from automatic classification of dust waveforms observed by The Solar Orbiter Radio and Plasma Waves Instrument.

Every day, several dust particles impacts the Solar Orbiter as the probe travels trough the inner heliosphere. The dust impact produces a cloud of electrons and ions on the spacecraft surface and the free charge causes a sharp and characteristic voltage signal, which decays towards the equilibrium potential after a few milliseconds via interaction with the ambient plasma. Detection and analysis of the characteristic dust waveform can be used to map the density, size and velocity distribution of dust particles in the inner heliosphere, and thus enhance our understanding of the role of dust in the solar system. Such statistical analysis do however require reliable dust detection software.

It is challenging to automatically detect and separate dust waveforms from other signal shapes by "hard coded" algorithms. Both due to spacecraft charging, causing variable shapes of impact signals, and since electromagnetic waves (such as solitary waves) may induce resembling voltage signals. Here we present results of waveform classification using various supervised machine learning techniques, where manually classified data is used both to train and test the classifiers.

We investigate automatic machine learning classification as a possible tool to make statistical analysis of the distribution of dust in the inner heliosphere more reliable and easier to conduct. Furthermore, the classifier may possibly be used on data (after pre-processing) from other spacecrafts with similar instruments, such as the Parker Solar Probe (PSP), the Solar Terrestrial Relations Observatory (STEREO) and the Magnetospheric Multiscale (MMS) mission.

How to cite: Kvammen, A., Mann, I., and Kociscak, S.: Machine Learning Classification of Dust Impact Signals Observed by The Solar Orbiter Radio and Plasma Waves Instrument, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7995, https://doi.org/10.5194/egusphere-egu22-7995, 2022.


Tue, 24 May, 15:10–16:40

Chairpersons: Maria Gritsevich, Jiri Pavlu

Claire Gasque et al.

As the closest humanmade object to the sun, the Parker Solar Probe (PSP) is uniquely positioned to study inner heliospheric dust. The PSP/FIELDS instrument suite detects dust via short voltage pulses generated by the plasma clouds formed during hypervelocity dust impacts on the spacecraft. Similar dust detection methods have been used on other missions, including Voyager 1 and 2, STEREO, Wind, Cassini, and Solar Orbiter. In addition to the voltage signatures, about 2% of dust impacts captured by Time Domain Sampler (TDS) burst data on PSP/FIELDS are shown to have magnetic signatures measured by the high-frequency winding of PSP's Search Coil Magnetometer (SCM). While magnetic signatures have previously been detected in laboratory hypervelocity impact experiments, they have not been previously reported in space. The signatures are brief (lasting less than 0.1ms), and are associated with high-amplitude voltage signatures. In this work, we present statistics and case studies of dust impacts with magnetic signatures on PSP. We will discuss the TDS calibration required to interpret the measurements physically, along with potential physical mechanisms for the magnetic signatures. We will also present early modeling efforts and implications for future hypervelocity impact studies.

How to cite: Gasque, C., Bale, S., Bowen, T., Dudok de Wit, T., Geotz, K., Malaspina, D., Pusack, A., and Szalay, J.: Magnetic Signatures associated with Dust Impacts on Parker Solar Probe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6496, https://doi.org/10.5194/egusphere-egu22-6496, 2022.


Jamey Szalay et al.

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.

How to cite: Szalay, J., Pokorný, P., Malaspina, D., Pusack, A., Horányi, M., DeLuca, M., Bale, S., Battams, K., Gasque, C., Goetz, K., Krüger, H., McComas, D., Schwadron, N., and Strub, P.: Collisional Evolution of the Inner Zodiacal Cloud: In-Situ observations from PSP and implications for Airless Body Surfaces, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10466, https://doi.org/10.5194/egusphere-egu22-10466, 2022.


Björn Grieger

On the 1st of January 2019, the New Horizons space probe flew by the Kuiper belt object Arrokoth. Images revealed a bilobate shape that would not allow any common map projection to display the complete surface, because multiple points have the same longitude and latitude. Arrokoth shares this feature with 67P/Churyumov-Gerasimenko, the target comet of the Rosetta mission. In order to map the complete surface of the comet, a Quincuncial Adaptive Closed Kohonen (QuACK) map has been fitted to 67P by Grieger (2019). Here, we fit a QuACK map similarly to the shape model of Arrokoth by Stern et al. (2019) and project some of the closest images acquired by the LORRI instrument onto it.

How to cite: Grieger, B.: An unambiguous global map projection for the Kuiper belt object Arrokoth by fitting a Quincuncial Adaptive Closed Kohonen (QuACK) map, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6977, https://doi.org/10.5194/egusphere-egu22-6977, 2022.


Oleksiy Golubov et al.

The Yarkovsky and YORP effects originate due to the light pressure recoil force acting on the surface of an asteroid. The Yarkovsky effect changes the asteroid's orbit, whereas the YORP effect changes its rotation state. Both effects appear to be crucially important for the long-term evolution of kilometer-sized asteroids.

The talk will review the recent successes and difficulties in the theoretical modeling of these effects, the growing body of their observational confirmations, and how these effects can alter asteroids' shapes, create binary asteroids and asteroid pairs, spread asteroid families and help asteroids to migrate from the main belt to the near-Earth orbits.

How to cite: Golubov, O., Scheeres, D. J., and Krugly, Y. N.: Yarkovsky and YORP Effects: Theoretical Models, Observational Confirmations, and Implications for Asteroid Evolution, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12609, https://doi.org/10.5194/egusphere-egu22-12609, 2022.


Ioana Lucia Boaca et al.

In this work we present the main results of the project named ‘Meteor mathematical modelling of dark flight’ (MeMATH), and current state and future work related to our project. The MeMATH project started in September 2020.

The main objectives of the MeMATH project are:

i) numerical simulation of the dark-flight trajectory;

ii) determining the search area for meteorite fragments;

iii) the study of the ablation of large bodies.

In the first stage of the project, we developed a mathematical model for the dark flight trajectory of a meteoroid. The novelty of our model is that it considers the ellipsoidal shape of the Earth, the Coriolis effect and the centrifugal force.

In the current stage of the project, we are determining the ballistic coefficient α and the mass loss parameter β based on the meteoroid height and deceleration.

The α and β parameters have a great impact in the study of meteoroids from the identification of the parent body to determining the initial and final mass and finding out weather the remnant matter after ablation could result in a meteorite on the ground.


The work of IB and MB was supported by a grant of the Romanian Ministry of Education and Research, CNCS-UEFISCDI, project number PN-III-P1-1.1-PD-2019-0784, within PNCDI III.


How to cite: Boaca, I. L., Gritsevich, M., Birlan, M., Nedelcu, A., and Boaca, T.: The interaction of meteoroids with the atmosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8746, https://doi.org/10.5194/egusphere-egu22-8746, 2022.


Oleksiy Golubov et al.

On November 7, 2020, a bright fireball was observed over Sweden, and 13.8 kg iron meteorite was later recovered. Multiple observations of the fireball were conducted from Denmark, Finland, and Norway, making it the first instrumentally documented fall of an iron meteorite.

We used the instrumental recordings of the bolide to reconstruct its preatmospheric orbit, and studied the past orbital evolution of the meteoroid. We found no close affinity of the orbit of the meteoroid with any near-Earth asteroid. The long YORP timescale suggests that the meteoroid could have arrived intact from the main asteroid belt. Our analysis of the orbit shows that the meteoroid probably entered its near-Earth orbit via either the 𝜈6 secular resonance with Saturn or the 3:1 mean motion resonance with Jupiter.

The work was partially funded by the National Research Foundation of Ukraine (project N2020.02/0371).

How to cite: Golubov, O., Kyrylenko, I., Slyusarev, I., Visuri, J., Gritsevich, M., Krugly, Y. N., Belskaya, I., and Shevchenko, V. G.: Search for the parent body of the recently fallen iron meteorite, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12472, https://doi.org/10.5194/egusphere-egu22-12472, 2022.


Karol Havrila et al.

            All-sky camera systems such as the AMOS network, record a large number of fireball events. By using multi-station triangulation method obtain information about trajectory of the body in the description change in altitude and velocity over time. Based on the characteristic of the object trajectory can determine important physical properties as the input mass of the meteoroid or the final mass of meteorites, and thus the probability of the formation and impact of particles on the Earth's surface. For this purpose, we used the method of dimensionless coefficients α (ballistic coefficient) and β (mass loss coefficient), which define the impact of the dynamical and physical properties of meteoroids on the searched input/final masses.

            Large number of recorded fireballs requires automatic data processing and their effective reduction. For this purpose, we have created a program with a user interface that works with data from all-sky fireballs cameras (in our case we focus on data from the Slovak AMOS system), defines the values of α-β coefficients and evaluates the probability of the meteorite formation with specific mass during the flight through the atmosphere. The program gives an interactive settings of physical parameters of the body and thus defines impact on the required values of body input/final masses. This algorithms was created for the purpose of user-friendly processing of scientific data, and the same time serves for the selecting suitable candidates for the formation and impact of dust particles and meteorites on the Earth's surface.

How to cite: Havrila, K., Gritsevich, M., and Tóth, J.: Identification of meteorite particles from AMOS data using the new user-friendly software interface. , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6946, https://doi.org/10.5194/egusphere-egu22-6946, 2022.


Peter A.B. Krizan et al.

Hydrothermal alteration is one of the fundamental processes by which several planetary bodies within our Solar System have been modified. The abundance of transient liquid water throughout the Solar System is increasingly recognised as playing a vital and active role in shaping the evolution of planetary surfaces. In particular, the process of hydrothermal alteration affects mineral composition on a microscopic level, simultaneously altering pre-existing minerals and allowing new mineral species to nucleate. This research reports new findings of fluid inclusions and their composition from one achondrite meteorite (Allan Hills A77256) and eight chondrite meteorites (Allan Hills 84029, Bells, Lonewolf Nunataks 94101 & 94102, Mighei, Santa Cruz, Sutter’s Mill, Sayama). We show that the presence of fluid inclusions within these meteorites is much more common than previously recognised, spanning much of the diversity of chondritic meteorite classes.

The first discovery of extraterrestrial liquid water was within halite crystals of the Zag and Monahans (1998) ordinary chondrites in 1999. Recent studies concerning extraterrestrial water and its evolution throughout the Solar System have attempted to gather inferences on the hydrothermal histories of parent asteroid bodies by utilising different proxies, including (but not limited to) magnetite grains, hydrous minerals, and degree of thermal metamorphism. These studies have highlighted a lack of direct water samples used within research and the need to determine whether further extraterrestrial liquid water fluid inclusions exist. Aside from those within the Zag and Monahans (1998) chondrites, additional claims of fluid inclusions within other meteorites have been previously reported. Until now, none have been independently confirmed or analysed further to determine whether or not they host liquid water.

Here we show that both petrographically primary and secondary in all our nine meteorites are hosted in olivine. Due to the formational nature of olivine, we predict that all petrographically primary fluid inclusions will fail to host liquid water. In contrast, petrographically secondary fluid inclusions may prove to be more plausible candidates. These inclusions are much more likely to possess liquid water as they were likely formed by subsequent and late periods of localised hydrothermal alteration, resulting in the serpentinisation of the host olivine crystals. Despite their predominance within our samples, in many cases, the analysis of secondary fluid inclusions is impeded by their sub-micron sizes and technological limitations of the instruments to operate at such a minuscule specimen size (< 1µm).

This research utilises a combination of SEM-EDS and Raman spectroscopy to target and determine the composition of the trapped fluids within suitable inclusions (diameter > 1µm). Spectra from initial Raman analyses conducted on selected fluid inclusions within olivine crystals of the Bells and Santa Cruz carbonaceous chondrites are presented. The majority of spectra from twenty-eight analysed fluid inclusions showed the fingerprint wavelength peak for olivine between 820-850 cm-1 alongside an unanticipated discovery of several cosmic diamonds embedded deep within certain olivine grains at a wavelength peak of 1320-1360 cm-1. This research highlights that numerous factors can affect the probability of a fluid inclusion hosting liquid water. 

How to cite: Krizan, P. A. B., H. -S. Chan, Q., Gough, A., and Papineau, D.: The hunt for liquid water in meteorites, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3872, https://doi.org/10.5194/egusphere-egu22-3872, 2022.


Seppe Lampe et al.

During atmospheric entry, micrometeorites experience variable degrees of (i) evaporation due to gas drag heating and (ii) mixing with atmospheric oxygen. Evaporation affects the physical properties and chemical and isotopic compositions of fully melted cosmic spherules (CSs). Oxygen isotope ratios of pristine micrometeorites are commonly used to relate these particles to their appropriate parent bodies. However, the degree of mixing with atmospheric oxygen and isotope fractionation by evaporation in CSs generally remains unclear, leading to uncertainties in their initial oxygen isotope ratios, which in turn complicates the precursor body identification. Previously, several studies have estimated the degree of evaporation based on contents of major refractory elements Ca and Al in combination with Fe/Si atomic ratios. This now commonly adopted chemical classification system has not yet been assessed with O and Fe isotope variability. As evaporation leads to both isotope and chemical fractionation, it is imperative to verify whether the predicted amounts of evaporation based on isotopic and chemical proxies converge.

Here, we measure the major and trace element compositions of 57 chondritic (mostly vitreous) CSs, along with their Fe isotope ratios. The δ56Fe isotope and chemical (K, Zn, Na or CaO and Al2O3 concentrations) fractionation in these particles show no correlation. This can be interpreted in two ways: (i) separate processes govern chemical and isotope fractionation or (ii) the selected proxies for isotope and/or chemical fractionation are inadequate. Because the initial Fe isotope ratios of chondrites display limited variation (0.005 ± 0.008‰ δ56Fe), Fe isotope ratios in CSs are assumed to only have changed through evaporation. At the same time, the chemical compositions of CSs show larger variability, so the CSs are thus often not chemically representative of their precursor bodies.

As oxygen isotope ratios are commonly used to identify the precursor bodies of (micro)meteorites, triple oxygen isotope ratios are measured in 37 of the 57 CSs. Based on the relationship between δ57Fe and δ18O, the effect of evaporation on the O isotope ratios can be corrected, which allows for a more precise precursor body reconstruction. Via this method, two 16O-poor spherules with greatly varying degrees of isotope fractionation (~1.0‰ and 29.1‰ δ56Fe, respectively) can be distinguished. Furthermore, it is observed that CSs that likely have an OC-like heritage all underwent the same degree of atmospheric mixing (~8‰ δ18O). These findings highlight the potential of including Fe isotope measurements to the regular methodologies applied to CS studies.

How to cite: Lampe, S., Soens, B., Chernonozhkin, S., González de Vega, C., van Ginneken, M., Van Maldeghem, F., Vanhaecke, F., Glass, B., Franchi, I., Terryn, H., Debaille, V., Claeys, P., and Goderis, S.: Decoupling of chemical and isotope fractionation processes during atmospheric entry of S-type micrometeorites, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5656, https://doi.org/10.5194/egusphere-egu22-5656, 2022.


Closing remarks