bluuebunny/crossref_metadata_2025 huggingface dataset:
A global colour mosaic of Mars from Mars Express HRSC high altitude observations
Authors: Michael Gregory , Tirsch Daniela , Matz Klaus-Dieter , Zuschneid Wilhelm , Hauber Ernst , Gwinner Klaus , Walter Sebastian , Jaumann Ralf , Roatsch Thomas , Postberg Frank , Liu Jianzhong
Published: July 2024

The ever-changing transparency of the martian atmosphere hinders the determination of absolute surface colour from spacecraft images. While individual high-resolution images from low orbit reveal numerous colour details of the geology, the colour variation between images caused by scattering off atmospheric dust can easily be of greater magnitude. The construction of contiguous large-scale mosaics has thus required a strategy to suppress the influence of scattering, often a form of high-pass filtering, which limits their ability to convey colour variation information over distances greater than the dimensions of single images. Here we use a dedicated high altitude observation campaign with the Mars Express High Resolution Stereo Camera (HRSC), applying a novel iterative method to construct a globally self-consistent colour model. We apply the model to colour-reference a high-altitude mosaic incorporating long-range colour variation information. Using only the relative colour information internal to individual images, the influence of absolute image to image colour changes caused by scattering is minimised, while the model enables colour variations across image boundaries to be self-consistently reconstructed. The resulting mosaic shows a level of colour detail comparable to single images, while maintaining continuity of colour features over much greater distances, thereby increasing the utility of HRSC colour images in the tracing and analysis of martian surface structures.
Iron and rocky meteorites: a reservoir of prebiotic bricks of life
Authors: Pantaleone Stefano , Bancone Niccolò , Santalucia Rosangela , Corno Marta , Rimola Albert , Mino Lorenzo , Balucani Nadia , Ugliengo Piero
Published: July 2024

Asteroids are the most ancient bodies of a planetary system, mostly formed during the accretion of the protoplanetary disk. They can be made of either rocky and metallic materials, and they are sources of important species which are fundamental for the emergence of life on planets. In our history, during the heavy late bombardment (4.0−3.8 Gya ago), a large quantity of meteorites (the asteroids that impact a planet) fall onto the earth crust, bringing several interstellar complex organic molecules, as well as other species (like phosphorus), produced during the early stages of the solar system formation.1 In recent years we have carried out periodic quantum mechanical simulations on forsterite (Mg2SiO4) and schreibersite (Fe2NiP) as archetype of rocky and iron meteorites, respectively. In particular, the former was studied through a synergistic interaction between experiments (infrared spectroscopy and high-mass resolution spectrometry) and atomistic simulations, elucidating the reactivity of HCN towards its polymerization, up to the formation of adenine, one of the DNA components.2,3 The latter system is a source of reactive phosphorus that, from the interaction with water, undergoes corrosion with the formation of oxygenated phosphorus compounds. In our work, we demonstrated the favorable exergonic formation of phosphates and, moreover, that such phosphates are in turn activated by the surface to phosphorylate other molecules, like sugars and nucleobases.4,5,6[1] M. Pasek, D. Lauretta, Origins Life Evol. Biospheres 2008, 38, 5−21[2] N. Bancone, S. Pantaleone, P. Ugliengo, A. Rimola, M. Corno, Phys. Chem. Chem. Phys. 2023, 25, 26797-26812[3] R. Santalucia, M. Pazzi, F. Bonino, M. Signorile, D. Scarano, P. Ugliengo, G. Spoto, L. Mino, Phys. Chem. Chem. Phys. 2022, 24, 7224-7230[4] S. Pantaleone, M. Corno, A. Rimola, N. Balucani, P. Ugliengo, ACS Earth Space Chem.  2021, 5, 7, 1741–1751[5] S. Pantaleone, M. Corno, A. Rimola, N. Balucani, P. Ugliengo, J. Phys. Chem. C 2022, 126, 4, 2243–2252[6] S. Pantaleone, M. Corno, A. Rimola, N. Balucani, P. Ugliengo, ACS Earth Space Chem. 2023, 7, 10, 2050–2
The UMR: Uranus Multi-Experiment Radiometer for Haze and Clouds Characterization
Authors: Apéstigue Víctor , Toledo Daniel , Arruego Ignacio ,   UMR Team
Published: July 2024

The present understanding of Uranus and Neptune has been derived primarily from terrestrial observations and observations conducted using space telescopes. Furthermore, a brief flyby conducted by the Voyager 2 spacecraft nearly three decades ago has contributed to our knowledge of these celestial bodies. Recently, the Decadal Survey [1] has identified a mission to Uranus as a high-priority objective for NASA's space exploration program and its ongoing missions to Mars and Europa.The main mission study [2] establishes the scientific priorities for an orbiter, including analyzing the planet's bulk composition and internal structure, magnetic field, atmosphere circulation, rings, and satellite system. On the other hand, the mission includes a descent probe, whose primary mission is obtaining data on the atmospheric noble gas abundances, noble gas isotope ratios, and thermal structure using a mass spectrometer and a meteorological package.Investigation of the vertically distributed aerosols (hazes and clouds) and their microphysical and scattering properties is required to comprehend the thermal structure and dynamics of Uranus' atmosphere. These aerosols play a crucial role in the absorption and reflection of solar radiation, which directly influences the planet’s energy balance. In this work, we present a lightweight radiometer instrument [3] to be included in the descent probe for studying the aerosols in the first km of the Uranus’ atmosphere.The UMR, the Uranus Multi-experiment Radiometer, takes its heritage from previous missions for Mars exploration [4-6], where its technology, including mixed-signal ASICs radiation hardened by design [7-8], has demonstrated its endurance for extreme environments of operation, using limited resources in terms of power consumption, mass and volume footprints, and data budget. These characteristics make this instrument a valuable probe’s payload for studying Uranus’ atmosphere with a high scientific return.In this contribution, we will present the actual design of the instrument and the future perspective before a possible announcement of opportunity. References:[1] National Academies of Sciences, Engineering, and Medicine 2022. Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032 [2] Simon et al. [3] Apéstigue et al 2024. Space Science Reviews. [4] I. Arruego et al. DREAMS-SIS. ASR 2017. 60 (1): 103-120. [5] Apestigue, V. et al 2022. Sensors [6] Pérez-Izquierdo, J., Sebastián, E, et al. 2018 [7] S. Sordo-Ibáñez et al 2016. [8] S. Sordo-Ibáñez et al 2015. 
Association of volatile species to the main ices in comet 67P/Churyumov-Gerasimenko
Authors: Rubin Martin , Altwegg Kathrin , Berthelier Jean-Jacques , Bonny Robin F. , Combi Michael R. , De Keyser Johan , Doriot Antea C. , Fuselier Stephen A. , Gombosi Tamas I. , Gudipati Murthy S. , Hänni Nora P. , Kipfer Kristina A. , Ligterink Niels F. W. , Müller Daniel R. , Shou Yinsi , Wampfler Susanne F.
Published: July 2024

ESA’s Rosetta mission accompanied comet 67P/Churyumov-Gerasimenko (67P) for over two years between 2014 – 2016. On board was ROSINA, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (Balsiger et al. 2007), which measured, in situ, the composition of the gaseous coma.The set of molecules monitored included highly volatile species, such as carbon monoxide and methane, together with the main coma gases, water and carbon dioxide. In our recent work (Rubin et al., 2023), we have shown that the local coma abundances of highly volatile species can be reproduced by a linear combination of H2O and CO2, indicating that they are also associated in the ices of the comet’s nucleus.In this presentation, we will report on these findings and further investigate correlations and variations between different volatile species. ReferencesBalsiger et al., ROSINA – Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, SSR, 128(1), 745–801, 2007.Rubin et al., Volatiles in the H2O and CO2 ices of comet 67P/Churyumov-Gerasimenko, MNRAS, 526, 3, 4209–4233, 2023.
International Lunar Year 2027: Advancing Lunar Science and Exploration Globally
Authors: Klima Rachel , Neal Clive , Jawin Erica , Pieters Carle , Hanlon Michelle , Keane James , Livengood Tim , Barnes Jessica , Rubio Minna , Glotch Tim , Schmidt Greg , Byrne Paul
Published: July 2024

Over the last two decades, an international program of lunar exploration has continued to pick up speed, with over ten countries launching missions towards the Moon, successful robotic landings by several of them, and plans for humans to return to the surface and begin—for the first time—to learn how to live and work on another planetary body. Multiple commercial companies are designing and launching lunar landers, heralding unprecedented public access to the lunar surface. The Moon is a celestial body with deep cultural meaning to a great number of populations across planet Earth. Thus, it is important to engage the whole world as the next fundamental science and exploration steps are taken.The importance of worldwide engagement in the science and exploration of the Moon is well established. Numerous organizations, including the International Lunar Exploration Working Group (ILEWG), the Moon Village Association, and the International Space Exploration Coordination Group (ISECG), have been developing roadmaps for international partnerships in lunar exploration, engaging countries that have not historically been a part of space exploration efforts. The International Lunar Year of 2027 (ILY2027) seeks to build on the strong foundation that these organizations have lain by forging a sustained campaign of collaborations involving scientists, policy makers, the commercial sector, educators, and the public throughout the world, to establish together new guidelines and standards for exploration and for disseminating scientific data.ILY2027 follows the tradition set by the International Geophysical Year of 1957–58, which advanced science, drove political collaborations, and caught the attention of the global public. ILY2027 seeks participation from diverse communities to collect and analyze data to understand the lunar environment, navigate challenging political issues such as resource utilization, protect the myriad historical, cultural, and scientific aspects of the Moon, and establish standards for operation as different countries and commercial companies move towards extended operations on the lunar surface. At the Europlanet Science  Congress, we will present initial high-level scientific and cultural goals for ILY2027, with the aim of broadening involvement and engaging nations and other interested parties across the world.
Detection of Carbon Dioxide and Hydrogen Peroxide on the Layered Surface of Charon Using the James Webb Space Telescope
Authors: Protopapa Silvia , Raut Ujjwal , Wong Ian , Stansberry John , Villanueva Geronimo , Cook Jason , Holler Bryan , Grundy William M. , Brunetto Rosario , Cartwright Richard J. , Mamo Bereket , Emery Joshua , Parker Alex H. , Guilbert-Lepoutre Aurélie , Pinilla-Alonso Noemi , Milam Stefanie , Hammel Heidi B.
Published: July 2024

We report the first detection of carbon dioxide (CO2) and hydrogen peroxide (H2O2) on Charon’s frozen surface as revealed by JWST NIRSpec instrument. With the extended spectral range of NIRSpec, we have expanded Charon’s compositional inventory to include these two new species. Previously, the inventory primarily consisted of water ice (mostly in crystalline form), ammoniated species, and a tholin-like darkening constituent. The synergy of laboratory measurements and modeling analysis reveals a stratified surface rich in crystalline water ice with ammonia diluted in water ice at penetration depths of approximately ~100 micron. Additionally, a layer of pure crystalline CO2 is evident at shallower penetration depths of about ~1 micron. This feature is likely attributable to an endogenous source, unearthed by external impacts. This layering configuration is believed to cause a scattering effect, which may account for the peculiarly strong CO2 absorption band at longer wavelengths. Moreover, the surface is undergoing continuous alteration by photolysis and radiolysis, which are responsible for the presence of H2O2 and amorphous water ice.
Advancing Diversity within the Europlanet Society
Authors: Máté Tomasik , Piccialli Arianna , Adeli Solmaz , Opitz Andrea , Cavalazzi Barbara , Lesedi Lebogang , Pearson Victoria K. , Bonnefoy Lea E. , Dosa Melinda , Hutchinson Gerard , Heward Anita , Noack Lena , Vandaele Ann Carine , Franchi Fulvio
Published: July 2024

The Europlanet 2024 Research Infrastructure and the Europlanet Society are dedicated to creating a diverse and inclusive network that supports planetary science and industry across Europe and globally.Europlanet's efforts focus on encouraging cooperation with individuals and institutions from countries that are under-represented in this field and on increasing awareness of the challenges these countries face. However, global events in recent years have significantly impacted the planetary science community. Under-represented groups have been particularly affected, with disruptions in networking opportunities, reduced resources, and low motivation.With growing concerns about the environmental impact of conferences and the ongoing shift to hybrid meetings, we need to find new ways to network effectively. While virtual or hybrid access can reduce some barriers (like cost and travel), it also risks creating a two-tier system where the most under-represented groups could become even more marginalized.In this poster, we report participation trends from major European geoscience and planetology conferences to better understand the current situation and identify effective responses. We discuss strategies for organizing meetings and creating projects to increase the inclusion of under-represented groups in planetary science, thereby advancing a more diverse and inclusive community within Europe.
Volatiles in Jupiter-family Comets: Synergy Between Infrared Observations and Protoplanetary Disk Chemistry Models
Authors: Bonev Boncho , Willacy Karen , Gibb Erika L. , Turner Neal , Dello Russo Neil , DiSanti Michael A. , Vervack, Jr. Ronald J. , Khan Younas , Roth Nathan X. , Faggi Sara , McKay Adam J. , Saki Mohammad , Kawakita Hideyo , Villanueva Geronimo L. , Ejeta Chemeda T.
Published: July 2024

Jupiter-family comets (JFCs) are dynamically-sourced in the scattered Kuiper disk, and are generally less productive than Oort Cloud comets (OCCs). For this reason, JFCs have been underrepresented in ground-based observations of volatiles, such as C2H2, C2H6, CH3OH, HCN, H2O, NH3, H2CO, and especially CO and CH4, for which large Doppler shifts are needed to offset cometary lines from their telluric counterpart absorptions.The period since 2017 has encompassed some of the best apparitions of JFCs in modern history. These have benefitted from the availability of significantly improved instrumentation for near-IR spectroscopy, and have also coincided with increased synergy between studies of cometary volatiles and model simulations of protoplanetary disk (PPD) chemistry. This presentation will connect findings stemming from near-IR observations of JFCs and OCCs with predictions of PPD midplane ices produced by chemical models for the early solar nebula [Willacy et al. 2022; Astrophysical Journal, 931:164]. Open questions will be discussed in the context of better disentangling natal heritage in cometary volatiles from signatures of post-formative processing, as is needed to understand the comet – early solar system link.Acknowledgments: Team members gratefully acknowledge support from the following US funding programs: NSF/AAG, NASA/SSO, and NASA/EW. This work benefited from discussions at the International Space Science Institute in Bern during meetings of International Team 361, “From Qualitative to Quantitative: Exploring the Early Solar System by Connecting Comet Composition and Protoplanetary Disk Models.”
Identification and Localization of Cometary Activityin Solar System Objects with Machine Learning
Authors: Bolin Bryce
Published: July 2024

In this session, we will discuss the use of Machine Learning methods for the identification and localization of cometary activity for Solar System objects in ground and in space-based wide-field all-sky surveys. We will begin the chapter by discussing the challenges of identifying known and unknown active, extended Solar System objects in the presence of stellar-type sources and the application of classical pre-ML identification techniques and their limitations. We will then transition to the discussion of implementing ML techniques to address the challenge of extended object identification. We will finish with prospective future methods and the application to future surveys such as the Vera C. Rubin Observatory.
Studying Mercury's space weather and BepiColombo observations with global partice-based modeling
Authors: Jarvinen Riku , Honkonen Ilja , Kallio Esa
Published: July 2024

We study the interaction of solar wind with Mercury's magnetosphere and plasma environment with global numerical 3D hybrid plasma simulations. Ions are modeled as particles moving under the Lorentz force and electrons form a charge-neutralizing, inertialess fluid. The evoluti.on of magnetic field is self-consistently coupled with ion dynamics via Maxwell's equations in non-radiative limit. We concentrate on the formation of plasma waves, field line resonances and accelerated ion populations in the Hermean plasma environment. We analyze plasma regions and ion populations near Mercury along BepiColombo flyby trajectories prior to the orbit insertion in light of upcoming orbit phase observation of charged particles and electromagnetic fields. Further, we also discuss the new development of our Mercury model including adaptive methods and electron physics.References:Jarvinen R., Alho M., Kallio E., Pulkkinen T.I., 2020, Ultra-low frequency waves in the ion foreshock of Mercury: A global hybrid modeling study, Mon. Notices Royal Astron. Soc., 491, 3, 4147-4161, doi:10.1093/mnras/stz3257Kallio E., Jarvinen R., Massetti S., Alberti T., Milillo A., Orsini S., De Angelis E., Laky G., Slavin J., Raines J.M., Pulkkinen T.I., 2022, Ultra-low frequency waves in the Hermean magnetosphere: On the role of the morphology of the magnetic field and the foreshock, Geophys. Res. Lett. 49, 24, doi:10.1029/2022GL10185
Comparing transit spectroscopy pipelines at the catalogue level: evidence for systematic differences
Authors: Mugnai Lorenzo V.
Published: July 2024

The fidelity of data reduction pipelines significantly influences the interpretation of exoplanetary data. As we approach the operational phases of the James Webb Space Telescope (JWST) and the ARIEL space mission, addressing pipeline-induced variances is imperative due to its profound implications on our understanding of exoplanets. Our study is pioneering in its comparative analysis of pipeline results at a catalogue level, employing a robust framework to statistically evaluate outcomes from the Hubble Space Telescope’s Wide Field Camera 3 across three independent pipelines: Iraclis, EXCALIBUR, and CASCADe.Despite utilising identical data, substantial differences in extracted spectra and planetary parameters were observed. Notably, variations in detected atmospheric compositions, particularly in water and methane content, and radius and temperature estimation, exemplify significant pipeline-induced biases. These discrepancies manifest most starkly in compositional trends across the exoplanet catalogues, potentially skewing class-wide analyses and misleading interpretations of atmospheric conditions.This study highlights the urgent need for the exoplanetary science community to standardise data reduction techniques to harness the full potential of future observations. The outcome of our work is vital not only for the academic community but also for upcoming space missions, ensuring that interpretations of exoplanetary atmospheres are based on the most accurate data possible.
Latest astrometric results for the Saturnian system
Authors: Lainey Valery , Rambaux Nicolas , Tobie Gabriel , Cooper Nick , Zhang Qingfeng , Noyelles Benoit , Baillié Kevin
Published: July 2024

During the thirteen years spent in orbit around Saturn before its final plunge, the Cassini probe provided more than ten thousand astrometric observations of moons. Such a large amount of precise data has allowed us to search for extremely small signals in the orbital motion of the Saturnian satellites. These signals can be linked to key physical mechanisms at play in the system, opening the doors to a new vision of the Saturn system. Using more than a century of ground-based astrometric observations, and benefiting from Cassini imaging data, we have studied the orbital motion of all of Saturn's inner and main moons, including those recently discovered by the Cassini probe. We show how astrometry has allowed us to characterize the strong tidal effects acting among the Saturnian system, while assessing the interior characteristics of several moons and their primary, including the discovery of Mimas' ocean. Updated results are presented.
WASP-121b's transmission spectrum observed with JWST/NIRSpec G395H reveals thermal dissociation and SiO in the atmosphere
Authors: Gapp Cyril , Evans-Soma Thomas M. , Barstow Joanna K. , Lothringer Joshua D. , Sing David K. , Christie Duncan , Kreidberg Laura , Mayne Nathan J.
Published: July 2024

WASP-121b has been established as a benchmark Ultra-Hot Jupiter (UHJ), serving as a laboratory for the atmospheric chemistry and dynamics of strongly irradiated extrasolar gas giants. Here, we present and analyze WASP-121b's transmission spectrum observed with NIRSpec G395H onboard the James Webb Space Telescope (JWST) and find evidence for the thermal dissociation of H2O and H2 on the planet's permanent dayside. This finding demonstrates the importance of the thermo-chemical heterogeneity within the planet's atmosphere for the observed transmission spectrum which simultaneously probes the planet's dayside and nightside hemispheres. Additionally, we detect SiO in agreement with chemical equilibrium. Constraining the abundance of SiO and abundance ratios between Si and other atoms in WASP-121b could help discriminate between possible formation scenarios for the planet. The three-dimensional nature of thermal dissociation in WASP-121b, however, poses a challenge to constrain molecular abundances and abundance ratios from the transmission spectrum. Atmospheric models capable of grasping the thermo-chemical heterogeneity in WASP-121b's atmosphere driven by thermal dissociation on the dayside and recombination on the nightside are thus needed to explore the planet's chemical inventory.Fig. 1: WASP-121b's transmission spectrum observed using JWST/NIRSpec G395H and the model transmission spectra presented by Pluriel et al. (2020). Upper panel: The grey dots show the original data and the black dots show the data binned in wavelength. The model spectra presented by Pluriel et al. (2020) with varying degrees of molecular dissociation are plotted using lines. A wavelength-independent offset was added to the model spectra to fit the mean of the data between 2.9 µm and 3.7 µm. Lower panel: The residuals between the model spectra with added constant and the data are depicted using colored dots with the errorbars of the data propagated onto the residuals. A grey, dashed, horizontal line at 0 was added to guide the eye.Reference:  Pluriel, W., Zingales, T., Leconte, J., & Parmentier, V. 2020, A&A, 636, A66, doi: 10.1051/0004-6361/202037678
Updates on MASCS geometric calculation & Unsupervised observation clustering for photometric correction
Authors: D'Amore Mario ,   ISSI Group on Mercury Pyroclastic Deposits  (ID#552)
Published: July 2024

The MASCS instrument was an essential part of the NASA MESSENGER mission that orbited the planet Mercury between 2011 and 2015.The Visible-Infrared Spectrograph (VIRS) channels cover the visible (300–1050 nm) and near-infrared (850–1450 nm) ranges.We recomputed MASCS geometries using the NAIF SPICE toolkit's Python implementation spiceypy.While the MASCS PDS calibrated data records (CDR) contained some geometrical information, certain key parameters (such as local time) were missing.Local time serves as a useful proxy for surface temperature due to Mercury's slow rotation.A detailed digital elevation model (DTM) of the entire planet was not available, so Mercury shape was approximated as an ellipsoid.We updated this approximation with the DTM from MESSENGER/Mercury Laser Altimeter (MLA).We also included the calculation of each measurement normal direction, projected on the surface and it's angle with the local north direction. (Fig.1)lLeveraging the updated measurements, we developed a machine learning method to automatically select similar observations for photometric correction.Fig.1We extracted MDIS mosaic and DTM pixel data under each individual MASCS field of view (FOV) as proxies for geomorphological units and sub-pixel roughness.To cluster similar observations, we applied HDBSCAN, an algorithm that extends DBSCAN by creating a hierarchical clustering structure and extracting a flat clustering based on cluster stability. (fig.2)fig.2
PLATO Mission Overview
Authors: Rauer Heike , Heras Ana , Mas-Hesse Miguel , Pagano Isabella
Published: July 2024

PLATO is ESA’s M3 mission and designed to detect and characterize extrasolar planets by photometrically monitoring a large number of stars. PLATO will detect small planets around bright stars, including terrestrial planets in the habitable zone of solar-like stars. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. With the complement of radial velocity observations from ground, planets will be characterized for their radius, mass, and age with high accuracy. PLATO will provide us with a large-scale catalogue of well-characterized small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. In addition, PLATO´s Guest Observer program will allow for a number of complementary science cases, based on proposals from the community.PLATO is scheduled for a launch date end 2026. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements of a large number of stars (around 150.000 per field). This talk will present an overview of the PLATO instrument, the mission profile and its science goals.
Benchmarking the rotating jet model of cometary activity with the trajectory of comet 67P/Churyumov-Gerasimenko
Authors: Kramer Tobias , Läuter Matthias
Published: July 2024

An important tool to assess the composition and the spatial origin of cometary material is the analysis of its trajectory reflecting gravitational acceleration due to solar system bodies complemented by non-gravitational accelerations (NGA).The rotating jet model (RJM) as introduced by Chesley and Yeomans [1] reveals information about the orientation of the rotation axis and thus it contains additional parameters compared to the standard model for non-gravitational forces known from Marsden et al. [2]. The RJM is partly based on a thermophysical model of cometary activity and it usually assumes two jets (one per hemisphere) to describe the resulting NGA.We discuss the derivation of the RJM and address the jet location on the surface assuming thermophysical models. In particular we relate the total production rate of a comet to the local sublimation rate induced by known data of torques. All models are applied to the case of comet 67P/Churyumov-Gerasimenko, for which Rosetta data provides an independent data set of NGA [3].Earthbound astrometry provides another tool to study the orbital changes caused by NGA. We analyze quantitatively how the astrometry determines open parameters of the RJM for comet 67P/Churyumov-Gerasimenko.[1] S. R. Chesley and D. K. Yeomans, “Nongravitational Accelerations on Comets,” Proceedings of the International Astronomical Union, vol. 2004, no. IAUC197, pp. 289–302, 2004, doi: 10.1017/S1743921304008786.[2] B. G. Marsden, Z. Sekanina, and D. K. Yeomans, Comets and nongravitational forces. V, The Astronomical Journal, vol. 78, p. 211, 1973, doi: 10.1086/111402[3] T. Kramer and M. Läuter, “Outgassing-induced acceleration of comet 67P/Churyumov-Gerasimenko,” Astronomy & Astrophysics, vol. 630, p. A4, 2019, doi: 10.1051/0004-6361/201935229.
Abundances of trace constituents in Jupiter's atmosphere inferred from Herschel/PACS observations
Authors: Gapp Cyril , Rengel Miriam , Hartogh Paul , Sagawa Hideo , Feuchtgruber Helmut , Lellouch Emmanuel , Villanueva Geronimo L
Published: July 2024

Context. On October 31, 2009, the Photodetector Array Camera and Spectrometer (PACS) onboard the Herschel Space Observatory observed far infrared spectra of Jupiter in the wavelength range between 50 and 220µm as part of the program ‘Water and Related Chemistry in the Solar System’. The spectra have an effective spectral resolution between 900 and 3500, depending on wavelength and grating order.Aims. We investigate the disk-averaged chemical composition of Jupiter's atmosphere as a function of height using these observations.Methods. We used the Planetary Spectrum Generator (PSG) and the least squares fitting technique to infer the abundances of trace constituents.Results. The PACS data include numerous spectral lines attributable to ammonia (NH3), methane (CH4), phosphine (PH3), water (H2O) and deuterated hydrogen (HD) in the Jovian atmosphere and probe the chemical composition from p∼275 mbar to p∼900 mbar. From the observations, we infer an ammonia abundance profile that decreases from a mole fraction of (1.7±0.8)x10-4 at p∼900 mbar to (1.7±0.9)x10-8 at p∼275 mbar, following a fractional scale height of about 0.114. For phosphine, we find a mole fraction of (7.2±1.2)x10-7 at pressures higher than (550±100) mbar and a decrease of its abundance at lower pressures following a fractional scale height of (0.09±0.02). Our analysis delivers a methane mole fraction of (1.49±0.09)x10-3. Analyzing the HD R(0) line at 112.1 µm yields a new measurement of Jupiter's D/H ratio, D/H=(1.5±0.6)x10-5. Finally, the PACS data allow us to put the most stringent 3σ upper limits yet on the mole fractions of hydrogen halides in the Jovian troposphere. These new upper limits are
Reflected light and dayside emission from the phase curves of the ultra-hot Jupiter WASP-18 b 
Authors: Deline Adrien ,   other co-authors (incl. L. Kreidberg and the CHEOPS consortium)
Published: July 2024

The extra-solar planet WASP-18 b is placed on a very-short period (< 1 day) orbit around a F6V-type star (Teff = 6300 K), which results in a planetary dayside heated up to 3000 K. Planets with such extreme thermal conditions are called ultra-hot Jupiters (UHJs) and exhibit strong day-to-night temperature contrasts with atmospheric compositions dominated by dissociated molecules and ions. These properties make UHJs such as WASP-18 b particularly interesting for atmospheric characterisation all along their orbital phase angles through observations known as phase curves.We present our work based on the analysis of phase-curve and occultation observations with the space telescopes CHEOPS, TESS and Spitzer, including unpublished data from all three instruments. The data sets span a temporal range of 15 years and a spectral range from the visible to the mid-infrared. We model and constrain the ellipsoidal variations and Doppler boosting, obtain unprecedented precision on the ephemerides, and derive an absolute planetary radius with a precision of 0.65%, or 550 km. We include the recently published JWST data (Coulombe et al. 2023) in our atmospheric retrieval, from which we derive constraints on the structure and composition of the atmosphere of WASP-18 b. We find a thermally inverted profile with a steep temperature gradient to explain the brightness temperature in Spitzer/IRAC/Channel 2 passband. We also detect a flux excess in the CHEOPS passband (visible) that allows us to assess the presence of reflected light and compute the first constained value of the geometric albedo for this planet.
Experimental results from the CoPhyLab - determination of particle size and acceleration in comet-simulation experiments
Authors: Kreuzig Christopher , Meier Gerwin , Schuckart Christian , Goldmann Moritz , Brecher Johanna Noria , Blum Jürgen
Published: July 2024

The formation of a cometary dust tail is phenomenon that has been known for a very long time and can be seen from earth with the naked eye if the comet is close enough. The mechanism for the formation of the cometary dust tail is believed to be caused by the sublimation of volatile components, which drag away the dust particles. In the lab, we aim to reproduce this effect by placing mixtures of ice and dust in a cooled vacuum chamber and illuminating them with an artificial sun. In preparation of these experiments, we placed samples consisting entirely of µm-sized spherical water-ice grains in the chamber. As soon as the illumination is turned on, solid particles are being ejected from the surface, hence the water-ice sample ejects a fraction of its own mass in the form of solid grains, which are accelerated by the surrounding gas. We analysed the particle motion, using multiple cameras in high-speed and low-speed mode, as well as a scale, a mass spectrometer, an infrared camera, several distributed temperature sensors and a scanning line-laser system. From the high-speed camera images, we determined that most of the ejected particles are flat disks with a height of ∼ 20 µm and a diameter of ∼  80 µm. Furthermore, we performed 3D particle tracking to gain information about the trajectories and accelerations of the particles. We discovered that the speed of the particles at the first image visible in the cameras is much higher than expected. From that point on, the particle trajectories can be fit with the expected value for a gas-driven acceleration with and a gas-flow rate determined by the surface temperature using the Hertz-Knudsen equation. However, if we extrapolate the trajectory backwards in time using the same acceleration, the zero-velocity starting point of the particles would be several centimeters below the sample surface. Since this is impossible, the particles must possess an unresolved starting acceleration about tenfold higher than what could be explained by the vapour pressure of the water ice. This finding means that the initial acceleration must be driven by another process, which we aim to explain by thermal modelling and by combining data from all instruments used during the experiments.
Legacy of the DART Mission: Looking Forward to Hera
Authors: Raugh Anne , Bauer James , Barnes IV Tilden , Kolokolova Ludmilla
Published: July 2024

The Double Asteroid Redirection Test (DART) spacecraft successfully impacted Dimorphos, the moon of the Didymos double-asteroid system, on 26 September 2022. The resulting data sets collected and relayed to Earth from DART and its companion Light Italian Cubesat for Imaging of Asteroids (LICIACube), as well as observations from four ground-based observatories following the impact and its aftermath, have been archived with the Small Bodies Node of the Planetary Data System. In anticipation of the October 2024 launch of the ESA mission Hera, set to investigate the aftermath of the DART collision in detail, we provide an overview and guide to the data legacy the DART mission has bequeathed to its successor.
What can velocity distribution functions of warm protons at comet 67P tell us about infant bow shocks?
Authors: Stenberg Wieser Gabriella , Moeslinger Anja , Nilsson Hans , Gunell Herbert , Goetz Charlotte
Published: July 2024

The Rosetta spacecraft accompanied comet 67P/Churyumov-Gerasimenko for about two years as the comet approached the sun, passed through perihelion, and headed outwards in the solar system again. The activity level of the comet increased when the distance to the sun decreased and a cometary magnetosphere was born. Different plasma boundaries formed, separating distinct regions, such as the diamagnetic cavity or the solar wind ion cavity. A fully developed bow shock was never observed, as the spacecraft spent most the time close to the nucleus. Instead, measurements revealed what appeared to be the first stages of the formation of shock: the infant bow shock. A characteristic feature of the observations of the infant bow shock is the change of the solar wind proton velocity distribution from fast and cold to slow and warm. Such transitions of the solar wind proton populations have been observed many times at comet 67P.In this paper we focus on the details of the proton velocity distribution functions during apparent transitions between cold and warm protons. It is not obvious how the distributions look like. Protons that appear warm and slow in an energy-time spectrogram may instead be a (partial) ring distribution. Partial ring distributions were not expected at comet 67P due the small spatial scales but were recently reported. Both solar wind proton and cometary ions seem, at least occasionally, to form partial ring distributions in the cometary environment. We study the shape of the velocity distribution functions during cold proton-warm proton-transitions to confirm or reject the interpretation of the warm protons as an indication of an infant bow shock. We also try to understand the physics behind the change of the velocity distribution and, if applicable, the formation of the infant shock.
Degenerate induced magnetospheres: a distinctive mode of the solar wind interaction with non-magnetized bodies
Authors: Barabash Stas , Zhang Qi , Holmström Mats , Wang Xiao-dong , Futaana Yoshifumi , Fowler Christopher , Ramstad Robin , Nilsson Hans
Published: July 2024

Induced magnetospheres of non-magnetized atmospheric planets, like Mars and Venus, are formed by the ionospheric currents induced by the solar wind interaction with the gravitationally bound electrically conducting ionospheres. When the interplanetary magnetic field (IMF) is predominantly aligned to the solar wind velocity, the convective electric field diminishes, leading to a degeneration of the induced magnetosphere. We investigate a 4° cone angle case (angle between the solar wind velocity and the IMF) using observations from Mars Atmosphere and Volatile Evolution (MAVEN) and Mars Express (MEX), and a hybrid model of the solar wind interaction with Mars. The measurements and simulations are in agreement, allowing us to characterize the general structure of a degenerate induced magnetosphere. We find that no magnetic barrier is built. The am bipolar field defines the electrodynamics on the dayside and drives ionospheric ions up stream, forming a cloud of planetary ions. Solar wind protons propagates down to low altitudes and are lost through collisions with the neutral atmosphere, the respective magnetic field tubes deplete and a proton void form behind the planet. No bow shock is formed in the subsolar region, but shock-like structure form at the flanks. The most remarkable feature is a large cross-flow plume of planetary ions with a significant asymmetry, extending more than 10 Martian radii, driven by the ExB drift. The degenerate induced magnetospheres represent a distinctive mode in the solar wind interaction with non-magnetized planets and provide insight into the exoplanet-stellar wind interaction.
High-resolution spectroscopy of WASP-31b with ESPRESSO
Authors: Steiner Michal
Published: July 2024

Over 5500 exoplanets have been discovered, predominantly through transits on short orbits. Notably, hot Jupiters and the absence of Neptune-sized planets (Neptune desert) have been identified, thanks to missions like Kepler. These types of planets can be very different in density, mainly due to the radius-inflation effect, whose origin is unclear. This, in particular, changes the atmospheric properties and chemical composition, which can be extracted through transmission spectroscopy at both low and high resolution. Furthermore, at high resolution, we can also observe the Rossiter-McLaughlin effect, providing us with the projected spin-orbit angle, an excellent probe into the dynamical history of the system. We will show the results of high-resolution transmission spectroscopy and the Rossiter-McLaughlin effect of WASP-31 b, a Jupiter-sized planet, using the ESPRESSO spectrograph.  This planet has already been studied by a plethora of instruments. In particular, Sing+2016 found, using HST/STIS, an extremely strong signature of potassium. However, Gibson+2017 and later Gibson+2019, using VLT/FORS2 and VLT/UVES respectively, contradicted this signature. Furthermore, Flagg+2023 and later Flagg+2024 found CrH for the first time in an exoplanet's atmosphere. Brown+2017 analyzed the Rossiter-McLaughlin signature of this planet, which shows WASP-31b to be aligned (projected obliquity, λ).  In this analysis, we focused on the species sodium (Na), potassium (K), and iron (Fe). We also used the CrH template, although it is weaker in the wavelength range of ESPRESSO.
Sequential giant planet formation initiated by disc substructure
Authors: Lau Tommy Chi Ho , Birnstiel Til , Dra̧żkowska Joanna , Stammler Sebastian
Published: July 2024

Planet formation models are necessary to understand the origins of diverse planetary systems. Circumstellar disc substructures have been proposed as preferred locations of planet formation but a complete formation scenario has not been covered by a single model so far.We aim to study the formation of giant planets facilitated by disc substructure and starting with sub-micron-sized dust. We connect dust coagulation and drift, planetesimal formation, N-body gravity, pebble accretion, planet migration, planetary gas accretion and gap opening in one consistent modelling framework. We find rapid formation of multiple gas giants from the initial disc substructure. The migration trap near the substructure allows the formation of cold gas giants. A new pressure maximum is created at the outer edge of the planetary gap, which triggers the next generation of planet formation resulting in a compact chain of giant planets. A high planet formation efficiency is achieved as the first gas giants are effective in preventing dust from drifting further inwards, which preserves materials for planet formation. Sequential planet formation is a promising framework to explain the formation of chains of gas and ice giants.
Spectrophotometric modeling of Mercury’s regolith using MESSENGER MDIS data
Authors: Björn Vesa , Muinonen Karri , Penttilä Antti , Domingue Deborah
Published: July 2024

Mercury can be modeled as an atmosphereless Solar System body. Such objects are covered by a regolith which affects how they scatter light. To deduce physical properties of Mercury’s regolith, we use spectrophotometry from the MDIS (Mercury Dual Imaging System) instrument of NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) mission. The data comes in eight colors [1] between the wavelengths of 433.2 nm and 996.2 nm, with phase angles from 20 to 130 degrees. There are 37752 data points, of which we use 26610 that are at incidence and emergence angles below 70 degrees. A theoretical particulate-medium model is used to interpret the observed reflectance. The model includes a shadowing correction that depends on three geometry parameters of the regolith. The first parameter is the packing density ν, i.e., the ratio of the particles’ volume to the total volume. The other two parameters describe the regolith’s roughness as a fractional Brownian motion (fBm) surface: the Hurst exponent H in the horizontal and the amplitude σ in the vertical direction. The numerical implementation of the model includes a set of discrete parameter values [2]. However, using trilinear interpolation, we extend the parameters to have arbitrary values within the range of the discrete values, which are 0.15–0.55 for the packing density, 0.20–0.80 for the Hurst exponent, and 0.00–0.10 for the amplitude (in units of the width of the simulated medium). We optimize the model parameters in least-squares sense using the Nelder–Mead simplex method, followed by Markov chain Monte Carlo (MCMC) sampling that uses proposed parameter values drawn from Gaussian distributions. The model parameters are solved for all wavelengths simultaneously, which means that the result is physically consistent. In the present study, the size of the regolith particles follows a uniform distribution between 0.0006 and 0.003, in units of the medium width. Our results indicate that Mercury’s regolith is densely packed (ν = 0.541 ± 0.010) with moderate horizontal variations (H = 0.529 ± 0.009) and large height variations (σ = 0.098 ± 0.002). The MCMC solution allows us to predict the spectrophotometry for differing viewing geometries. Future work includes updating the implementation of the model by increasing the range of the parameter values, especially for the packing density to ν > 0.55. Another improvement is to modify the size distribution of the regolith particles. The results of our study can be utilized in the BepiColombo mission, which will start its science mission in early 2026.  [1] Domingue et al., Icarus 257, 477 (2015)[2] Wilkman et al., Planet. Space Sci. 118, 250 (2015)[3] Nelder and Mead, Comput. J. 7(4), 308 (1965)
The electron structures in Titan’s induced1magnetosphere observed during the T36 flyby
Authors: Kim Konstantin , Edberg Niklas , Coates Andrew , Modolo Ronan
Published: July 2024

The interaction of Titan's ionosphere with Saturn's magnetosphere results in a complex region of perturbed magnetic fields, energetic and thermalized electrons and ions-induced magnetosphere (IM). Although the complexity of IM has been mentioned before, the local structure hasn't been investigated widely in the past years. In this case study we examine the origin of periodic electron plasma structures in Titan's induced magnetosphere observed during the T36 flyby. We use data from the electron and ion spectrometers CAPS/ELS and IMS, the Langmuir probe and electric antenna RPWS/LP, and the fluxgate magnetometer FGM to analyze plasma parameters, e.g. density and temperature, magnetic field fluctuations. The observed electron structures are periodic on a scale of ~ 20 seconds and possess signatures of acceleration from a few eV up to 700 eV. At the same time, the burst of low-frequency (around the ion-cyclotron and lower-hybrid frequency) and low-amplitude (~ 1 nT ) waves is observed. We propose that the observed electron structures are the result of a large-scale MHD instability as well as could possibly be a generic feature of Titan's induced magnetosphere structure. 