bluuebunny/crossref_metadata_2025 huggingface dataset:
Dawn/VIR at Vesta: correction of the spectral variations induced by CDD temperature change on the visible channel
Authors: Rousseau Batiste , De Sanctis Maria Cristina , Ciarniello Mauro , Raponi Andrea , Scarica Pietro , Ammannito Eleonora , Frigeri Alessandro , Carrozzo Filippo Giacomo , Tosi Federico , Fonte Sergio
Published: October 2020

Abstract
From July 2011 to September 2012, the Dawn spacecraft orbited the large asteroid (4) Vesta. A nearly global coverage of the surface was achieved by the Visible and InfraRed mapping spectrometer (VIR) [1]. The change of CCD temperature during the data acquisition affects the instrument spectral response. As a consequence, the acquired spectra experienced a change in spectral slope. Here we present a method to correct this issue; this method is similar to the one we applied for the VIR VIS data of Ceres [2].CCD detector temperature dependencies
The acquisition of VIR data are organized in sequences during which several hyperspectral cubes are acquired. Within a given sequence, which may last several hours, the CCD temperature increases over time, while it goes back down in the time period between two sequences. The increase of CCD temperature induces a reddening of the spectra at visible wavelengths, as displayed in Fig. 1. To avoid misinterpretation and to retrieve a coherent shape of the Vesta spectra, a correction is therefore required.Figure 1 – Median spectral variations observed for each CCD temperature recorded during the VH2 mission phase (normalized at 550nm).Spectral correction
As in [2], we defined a correction factor for the different mission phases at Vesta, considering their particularities if necessary. This correction factor requires the definition of a reference temperature, at which the spectral response is considered reliable, and a corresponding reference spectrum. A previous analysis of the same effect on Ceres observations [2], revealed a reference CCD temperature of 177K. The correction has been applied on the mission phases during which VIR acquired VIS data. It allows to obtain a globally coherent dataset. Mapping and reliable spectral studies are then possible (see Fig. 2).Figure 2 - Map of the spectral slope for the VH2 mission phase before (top) and after (bottom) the correction. The gradient observed, in each sequences, in the top panel vanishes in the bottom panel, after the application of the correction.Conclusion
The empirical method developed in [2] has now been applied to the Vesta data acquired by the VIS channel of the VIR spectrometer. This correction is mandatory to carry out reliable analysis of the Vesta surface at global and local scale.References
[1] De Sanctis, M. C., Coradini, A., et al. 2011, Space Science Reviews, 163, 329, [2] Rousseau, B., Raponi, A., Ciarniello, M., et al. 2019, Review of Scientific Instruments, 90,   
Mixing of Condensable Constituents with H/He During Formation of the Jupiter
Authors: Lissauer Jack , Bodenheimer Peter , Stevenson David , D'Angelo Gennaro
Published: October 2020

We present results of simulations of the growth of giant planets that incorporate the mixing of light gases with denser material that enters the planet as solids. We find that heavy compounds and gas begin to intimately mix when the planet is quite small, and substantial mixing occurs when the planet becomes roughly as massive as Earth, because even incoming silicates can then fully vaporize if they arrive in the form of planetesimals or smaller bodies. Nonetheless, most of the icy and rocky material accreted by a giant planet settles to a region in which vaporized ice and rock are well-mixed until the growing planet is several times as massive as Earth. Subsequently, planetesimals break up in a region that is too cool for all the silicates to vaporize, so the silicates continue to sink, but the water remains at higher altitudes. As the planet continues to grow, silicates vaporize farther out. Because the mean molecular weight decreases rapidly outward at many radii, some of the radially inhomogeneities in composition produced during the accretion era are able to survive for billions of years. After 4.57 Gyr, our model Jupiter retains compositional gradients; from the inside outwards one finds: (i) an inner core, dominantly composed of heavy elements; (ii) a density-gradient region, containing the majority of the planet's heavy elements, where H and He increase in abundance with height, reaching ~90% mass fraction at 30% of Jupiter's radius, with rocky materials enhanced relative to ices in the lower part of this gradient region and the composition transitioning to ices enhanced relative to rock at higher altitudes; (iv) a large, uniform-composition region (we do not account for He immiscibility), enriched relative to protosolar in heavy elements, especially ices, that contains the bulk of the planet's mass; and (v) an outer region where condensation of many constituents occurs. This radial compositional profile has heavy elements more broadly distributed within the planet than predicted by classical Jupiter-formation models. NASA’s Juno spacecraft's measurements of Jupiter's gravity field also implies less concentration of heavy elements near the center of the planet than classical theoretical models. However, the preferred dilution of the core found in Juno-constrained gravity models is substantially larger than what is suggested by our accretion models, requiring some modification in the heavy element distribution. The compositional gradients in the region containing the bulk of the planet’s heavy elements prevent convection, both in our models and the models that fit current gravity, probably resulting in a hot deep interior where much of the energy from the early stages of the planet's accretion remains trapped.
Rapid Formation of Super-Earths Around Low-Mass Stars
Authors: Zawadzki Brianna
Published: October 2020

NASA's TESS mission is expected to discover hundreds of M dwarf planets. However, few studies focus on how planets form around low-mass stars. We aim to better characterize the formation process of M dwarf planets to fill this gap and aid in the interpretation of TESS results. We use six sets of N-body planet formation simulations which vary in whether a gas disc is present, initial range of embryo semi-major axes, and initial solid surface density profile. Each simulation begins with 147 equal-mass embryos around a 0.2 solar mass star and runs for 100 Myr. We find that planets form rapidly, with most collisions occurring within the first 1 Myr. The presence of a gas disc reduces the final number of planets relative to a gas-free environment and causes planets to migrate inward. Because planet formation occurs significantly faster than the disc lifetime, super-Earths have plenty of time to accrete extended gaseous envelopes, though these may later be removed by collisions or a secondary process like photo-evaporation. In addition, we find that the final distribution of planets does not retain a memory of the slope of the initial surface density profile, regardless of whether or not a gas disc is present. Thus, our results suggest that present-day observations are unlikely to provide sufficient information to accurately reverse-engineer the initial distribution of solids.
The NASA Lucy Mission: Surveying the Diversity of Trojan Asteroids
Authors: Marchi Simone , Levison Hal , Olkin Cathy , Noll Keith
Published: October 2020

The Lucy Mission is a NASA Discovery class mission to send a highly capable and robust spacecraft to investigate seven Jupiter Trojan asteroids; a class of stable, primitive bodies near both the L4 and L5 Lagrange points with Jupiter. It is believed that Jupiter Trojan asteroids are leftover planetesimals from the outer planetary system that have been preserved since early in Solar System history, and represent the last of all of the stable populations of the Solar System to be visited by spacecraft. Lucy is slated to launch in October 2021, reach its first Trojan asteroid in 2027, and have its final encounter in 2033. During its lifetime, Lucy will perform five Trojan encounters closely studying at least seven objects (one encounter is of a nearly equal mass binary and another is an asteroid with a known satellite). The science goals include determining the surface composition, assessing the geology, determining the bulk properties and searching for satellites around all of Lucy’s targets. The payload suite consists of a color camera and infrared imaging spectrometer, a high resolution panchromatic imager, and a thermal infrared spectrometer. Additionally, two spacecraft subsystems will also contribute to the science investigations: the terminal tracking cameras and the telecommunication subsystem to measure the mass of the Trojan asteroids. Lucy’s Trojan targets include one C-type (Eurybates, 64 km in diameter), three P-types (Menoetius, Patroclus, and Polymele; 105, 114, 21 km in diameter, respectively), and two D-types (Leucus and Orus; 41 and 52 km in diameter, respectively), thereby covering a wide range of spectral types and sizes. Lucy will be the first spacecraft to observe the largest remnant of a catastrophic collision up close (Eurybates), and the first to visit a near-equal mass binary (Patroclus and Menoetius). In addition, on its way to L4, Lucy will fly by DonaldJohanson in 2025, a 4 km in diameter Main Belt asteroid named in honor of the discoverer of the Lucy fossil. In this talk, recent results from an international observational campaign of some of the Lucy’s targets will be presented, including the detection of a small satellite (1-2 km) orbiting Eurybates, and a detailed characterization of Leucus’s shape and rotational axis orientation.
Nano to Mini satellite and dedicated instruments: a new opportunity for planetary exploration
Authors: Goldberg Hannah , Van wal Stefaan , Herique Alain , Rogez Yves , Karatekin Ozgur , Villa Victor Manuel Moreno
Published: October 2020

Large planetary science missions carry a suite of instruments that must negotiate observations and priorities to fulfill their scientific objectives.  A new paradigm of mission brings use of deployable nano-spacecraft as independent operating observers to provide added science.  As in the case of the Hera mission, the Hera mothercraft will carry through the cruise phase two small CubeSats and deploy them once in the vicinity of the Didymos asteroid system.  These small CubeSats are able to navigate relative to the observing planetary body and conduct meaningful science through 1-2 miniaturized instruments.  The Juventas CubeSat for Hera will be discussed along with presentation of its low frequency radar, JuRa.  Its scientific objectives and contribution to the Hera and AIDA objectives will be presented.
Long-term Cycles of Variability of Jupiter’s Atmosphere from Ground-based Infrared Observations
Authors: Antunano Arrate , Fletcher Leigh N , Orton Glenn S , Sinclair James A , Kasaba Yasumasa
Published: October 2020

Jupiter’s atmosphere displays some of the most dramatic weather of any planet in our Solar System, with cycles of activity changing the upper tropospheric and stratospheric temperatures, aerosols, and cloud structures through physical processes that are not yet well understood. In the troposphere, Jupiter’s banded structure undergoes dramatic planetary-scale disturbances that can evolve over short timescales changing its appearance completely at a range of altitudes, from the cloud tops (~500 mbar) to the deeper levels (1-4 bar). Some of these tropospheric variations seem to occur randomly, like the impressive fading and revival of the South Equatorial Belt at 7°-17° S (planetocentric latitude), while others follow a periodic pattern, like the North Equatorial Belt expansions at 7°-17° N (with a ~4.5-year periodicity), the Equatorial Zone disturbances (~7-year period) within ±7° of the equator (Antuñano et al. 2018 doi:  https://doi.org/10.1029/2018GL080382) and the convective outbreaks at 21° N in the North Temperate Belt (~5-year period) (Antuñano et al., 2019 doi: https://doi.org/10.3847/1538-3881/ab2cd6). In the stratosphere, Jupiter’s equatorial and off-equatorial temperature and winds at 10-20 mbar exhibit a remarkable 4-5-year periodic oscillation with height forced by waves produced from tropospheric meteorological activity at the equatorial latitudes.Here we use almost 40 years (more than 3 jovian years) of ground-based infrared observations captured at NASA’s Infrared Telescope Facility (IRTF), the Very Large Telescope (VLT) and Subaru between 1980 and 2019 in a number of filters spanning from 7.9 to 24.5 µm.  These filters sample upper tropospheric and stratospheric temperatures and aerosols via collision-induced hydrogen and helium absorption, and emission from stratospheric hydrocarbons.  This long-term time series is used to (i) understand the impact of the previously mentioned tropospheric activity on the periodicity of the stratospheric temperature oscillations, (ii) characterize the long-term variability of Jupiter’s atmosphere at different altitudes in the upper troposphere and stratosphere, and (iii) investigate the long-term thermal, chemical and aerosol changes in Jupiter’s troposphere. In particular, we generate Lomb-Scargle periodograms and apply a Wavelet Transform analysis to our dataset to look for potential periodicities on the brightness temperature variability in different filters and compare them to previously reported cyclic activity at visible wavelengths (sensing the ammonia cloud top at ~500 mbar) and 5 µm (sensing the 1-4 bar pressure level). Finally, a Principal Component Analyses (PCA) is also performed to analyse the correlation of the brightness temperature variations at different belts and zones.
Studying the fossil meteorite Al Haggounia by X-ray Micro-CT
Authors: Manzari Paola , Tempesta Gioacchino , Mele Daniela , Agrosì Giovanna
Published: October 2020

Among the cutting-edge techniques that are being using in the meteoritics discipline to explore potential new properties, the micro-CT is useful in its potential of showing phase distribution in a 3D reconstruction and analyses of a small meteorite volume and in showing microstructures, crystal habits or grains, occurrences of vesicles or voids, melt veins and fractures. In this view, we studied a sample of Al Haggounia, a meteorite significantly porous with pore sizes from several cm to hundreds of microns. This meteorite after a complex history of classification results to be an EL-impact melt. The fragments show very different looking, from the point of view of microstructure of impact shock:  melt veins, fractures and pores and, consequently, this meteorite is particularly suitable for investigations by micro-CT coupling with SEM-EDS analyses to fit the chemical data to the textural ones. All the data obtained help us in the genetic interpretation allowing to verify the hypothesis about the origin of this meteorite developed until now.
Mars’ ionopause characterization based on MAVEN and Mars Express observations
Authors: Sanchez-Cano Beatriz , Narvaez Clara , Lester Mark , Mendillo Michael , Mayyasi Majd , Holmstrom Mats , Halekas Jasper , Andersson Laila , Fowler Christopher M. , McFadden James P. , Durward Sofija
Published: October 2020

The ionopause is a tangential discontinuity in the ionospheric thermal plasma density profile that marks the upper boundary of the ionosphere for unmagnetized planets. Since only Venus and Mars have no global “dipole” magnetic fields, ionopauses are unique to those planets. For Venus, the ionopause formation is well characterized because the thermal pressure of the ionosphere is usually larger than the solar wind dynamic pressure. For Mars, however, the maximum thermal pressure of the ionosphere is usually insufficient to balance the total pressure in the overlying magnetic pileup boundary. Therefore, the Martian ionopause is not always formed, and when it does, it is highly structured and is located at different altitudes. In this study, we characterise the Martian ionopause formation from the point of view of the electron density and electron temperature, as well as the thermal, magnetic and dynamic pressures. The objective is to investigate under which circumstances the Martian ionopause is formed, both over and far from crustal magnetic fields, and compare to the Venus’ case. We use several multi-plasma and magnetic field in-situ observations from the three deep dip campaigns of the MAVEN mission that occurred on the dayside of Mars (near subsolar point), as well as in-situ solar wind plasma observations from the Mars Express mission. We find that that 36% of the electron density profiles over strong crustal magnetic field regions had an ionopause event in contrast to the 54% of electron density profiles far from strong crustal magnetic field regions. We also find that the topside ionosphere is typically magnetized at mostly all altitudes. The ionopause, if formed, occurs where the total ionospheric pressure (magnetic+thermal) equals the upstream solar wind dynamic pressure.
OpenPlanetaryMap Updates: Planetary Basemaps and Geocoding Web Services
Authors: Manaud Nicolas , Gasperi Jérome , Nass Andrea , van Gasselt Stephan , Pio Rossi Angelo , Hare Trent
Published: October 2020

We introduce the project and present recent updates on OPM planetary basemaps, geocoding APIs and user interfaces.

OpenPlanetaryMap (OPM) is a collaborative project to build the first Open Planetary Mapping and Social platform for researchers, educators, storytellers, and the general public. We want to make it easy for anyone to create and share maps and locations on any planets or bodies in our Solar System [1].

Our platform architecture is based on four main service-oriented components: (1) an open repository of geospatial datasets; containing information used to create basemaps and to enable location-based searches, (2) basemaps that are needed to build any types of web mapping applications or geospatial data visualisation, (3) geocoding and geo-referencing APIs/web services to enable location-based searches and crowdsourcing of our datasets repository, (4) Web app, Python module and CLI interfaces to search, add and share places on planetary bodies.

Since the project started as an initiative funded by Europlanet in 2017, we have consolidated our network of collaborators and we published our first planetary basemaps and design concept [2]. Instructions on how to use our basemaps are available from our new website [3]. External projects have started to use OPM basemaps, for example: PLANMAP Stories [4] and CaSSIS Map Interface [5]. While we continue to improve our basemaps and create new ones, we have been working on providing an open planetary geocoding API/web service and user interfaces.

The purpose of our planetary geocoding API is to provide a common and consistent way of defining and searching for places on the surface of bodies in the Solar System, including the Earth. We are first implementing our geocoding API as a JavaScript module, along with our first web map interface that demonstrates its use. We will then focus on implementing our geocoding API as a Python module.

[1] Manaud et al. (2018). OpenPlanetaryMap: Building the first Open Planetary Mapping and Social platform for researchers, educators, storytellers, and the general public. European Planetary Science Congress 2018, 12, EPSC2018-78. [2] Nass et al. (2019). Towards a new face for Planetary Maps: Design and web- based Implementation of Planetary Basemaps. Adv. Cartogr. GIScience Int. Cartogr. Assoc., 1, 15, 2019. https://doi.org/10.5194/ica-adv-1-15-2019 [3] http://openplanetarymap.org [4] https://stories.planmap.eu/mars/gale [5] http://cassis.halimede.unibe.ch
archi: pipeline for light curve extraction of CHEOPS background stars
Authors: M. Silva André , G. Sousa Sérgio , Santos Nuno , D. S. Demangeon Olivier , X. Matos Mafalda
Published: October 2020

High precision time-series photometry from space is being used for a number of scientific cases. In this context, the recently launched CHaracterizing ExOPlanet Satellite (CHEOPS) (ESA) mission promises to bring 20 ppm precision over an exposure time of 6 h, when targeting nearby bright stars, having in mind the detailed characterization of exoplanetary systems through transit measurements. However, the official CHEOPS (ESA) mission pipeline only provides photometry for the main target (the central star in the field). In order to explore the potential of CHEOPS photometry for all stars in the field, we present archi, an additional open-source pipeline module to analyse the background stars present in the image. As archi uses the official data reduction pipeline data as input, it is not meant to be used as an independent tool to process raw CHEOPS data but, instead, to be used as an add-on to the official pipeline. We test archi using CHEOPS simulated images, and show that photometry of background stars in CHEOPS images is only slightly degraded (by a factor of 2–3) with respect to the main target. This opens a potential for the use of CHEOPS to produce photometric time-series of several close-by targets at once, as well as to use different stars in the image to calibrate systematic errors. We also show one clear scientific application where the study of the companion light curve can be important for the understanding of the contamination on the main target.
Limb-darkening reanalysis of latitudinal variation of cloud-top methane abundance in Neptune's atmosphere from VLT/MUSE-NFM
Authors: Irwin Patrick , Dobinson Jack , James Arjuna , Toledo Daniel , Teanby Nicholas , Fletcher Leigh , Orton Glenn , Perez-Hoyos Santiago
Published: October 2020

Observations of Neptune, made in 2018 with the Multi Unit Spectroscopic Explorer (MUSE) instrument (in Narrow-Field Adaptive Optics mode) at the Very Large Telescope (VLT) and covering the wavelength range 480 – 930 nm were previously reported by Irwin et al. (Icarus, 311, 2019). Here, these observations have been reanalysed to incorporate more effectively the effects of limb-darkening following a new approach based on the Minnaert limb-darkening model, after Pérez-Hoyos et al. (Icarus, under review, 2020). The 800 – 900 nm region of our observations includes similar strength absorption bands of methane and H2–H2/H2–He collision-induced absorption, which allows changes in cloud-top altitude to be discriminated from methane abundance variations. Splitting the background atmosphere (i.e., away from bright, discrete clouds) into latitude bands, the measured variation of reflectivity with observed zenith angle at each wavelength is fitted with Minnaert limb-darkening coefficients, which can then be used to reconstruct the expected spectrum at any angle that can then be fitted with our retrieval model, NEMESIS (Irwin et al., JQSRT, 109, 2008). We find that this approach: 1) provides much stronger constraints on the cloud structure and methane abundance; 2) makes better use of all the available data and; 3) is more computationally efficient. We find a very similar variation in cloud-top (at ~3 bar) methane mole fraction as previously reported, but with much better characterized errors, and with mole fractions diminishing from ~5% at equatorial latitudes to ~3% in the south polar region. The retrieved latitudinal distribution of cloud-top methane abundance in Neptune's atmosphere can be seen in the figure below, where Neptune's south pole is at bottom left. We show that, although the reduction of methane abundance is well constrained (i.e., reducing by a factor 5/3 from the equator to the south pole), the absolute abundances are not so well determined. This is because the retrieved methane abundance also depends on the assumed background cloud properties, for which a number of different combinations are found to provide equally good fits to the data, but differ in their retrieved methane abundances by ±1%. 
The Martians Moons eXploration (MMX) Rover to Phobos
Authors: Murdoch Naomi , Michel Patrick , Ulamec Stephan , Grott Matthias , Böttger Ute , Vernazza Pierre , Arrat Denis , Chalon Maxime , Tardivel Simon , Biele Jens , Grundmann Jan Thimo , Miyamoto Hirdy ,   MMX rover team
Published: October 2020

The Japan Aerospace Exploration Agency, JAXA, Martians Moons eXploration (MMX) mission will investigate the Martian Moons Phobos and Deimos, and return samples from Phobos to Earth. As part of this mission a small (~25 kg) rover, contributed by the Centre National d’Etudes Spatiales (CNES) and the German Aerospace Center (DLR), with additional contributions from INTA (Spain) and JAXA, will be delivered to the surface of Phobos. The rover will demonstrate the technology of locomotion on a regolith-covered, low gravity planetary surface. In addition, the rover will provide scientific data on the regolith properties (mechanical, mineralogical and thermal), provide ground truth for the MMX orbiter instruments, give context information for the returned samples, and contribute to reducing the risk of the landing and sampling operations of the MMX mission.In order to achieve these goals, the rover has a small suite of scientific instruments: a Raman spectrometer (RAX) to measure the mineralogical composition of the surface material, a radiometer (miniRAD) to measure the surface brightness temperature and determine thermal properties of both regolith and rocks (if in the field of view), a stereo pair of navigation cameras looking forwards (NAVCam) that will place constraints on the level of heterogeneity of the regolith both in terms of composition and space weathering alteration, and two cameras looking at the interface between wheel and surface (WheelCam). The WheelCams will observe the properties of the regolith compaction and flow around the wheels, and the resulting trenches in order to characterise the mechanical properties of the regolith itself.The MMX rover will be deployed from the main spacecraft from an altitude of less than 100 m above the surface of Phobos. The uprighting and deployment (legs/wheels and solar panels) sequences will be performed automatically once the rover comes to rest on the surface. The rover will then operate for 100 days covering a total distance of several meters to hundreds of meters.The MMX launch is currently planned for late 2024 with the Mars orbit insertion occurring in 2025, and the rover delivery and operations in 2026 or 2027.This presentation will provide an overview of the MMX rover and the expected science return from each of the four instruments.
Search for helium in the upper atmosphere of the hot Jupiter WASP-127 b using Phoenix/Gemini
Authors: dos Santos Leonardo A. , Ehrenreich David , Bourrier Vincent , Allart Romain , King George , Lendl Monika , Lovis Christophe , Margheim Steve , Meléndez Jorge , Seidel Julia V. , Sousa Sérgio G.
Published: October 2020

Large-scale exoplanet search surveys have shown evidence that atmospheric escape is a ubiquitous process that shapes the evolution and demographics of planets. However, we lack a detailed understanding of this process because very few exoplanets discovered to date could be probed for signatures of atmospheric escape. Recently, the metastable helium triplet at 1.083 μm has been shown to be a viable window for the presence of He-rich escaping envelopes around short-period exoplanets. Our objective is to use, for the first time, the Phoenix spectrograph to search for helium in the upper atmosphere of the inflated hot Jupiter WASP-127 b. We observed one transit and reduced the data manually since there is no pipeline available. We did not find a significant in-transit absorption signal indicative of the presence of helium around WASP-127 b, and set a 90% confidence upper limit for excess absorption at 0.87% in a 0.75 Å passband covering the He triplet. Given the large scale height of this planet, the lack of a detectable feature is likely due to unfavorable photoionization conditions to populate the metastable He I triplet. This conclusion is supported by the inferred low coronal and chromospheric activity of the host star and the old age of the system, which result in a relatively mild high-energy environment around the planet.
The Lidov-Kozai oscillation and Hugo von Zeipel
Authors: Ito Takashi , Ohtsuka Katsuhito
Published: October 2020

It is widely accepted that the theoretical framework of the so-called Lidov-Kozai oscillation was established independently in the early 1960s by a Soviet Union dynamicist (Michail L'vovich Lidov) and by a Japanese celestial mechanist (Yoshihide Kozai). A large variety of studies has stemmed from the original works by Lidov and Kozai, now having the prefix of "Lidov-Kozai" or "Kozai-Lidov." However, from a survey of past literature published in late nineteenth to early twentieth century, we have confirmed that there already existed a pioneering work using a similar analysis of this subject established in that period. This was accomplished by a Swedish astronomer, Edvard Hugo von Zeipel. In this presentation we make a brief summary of von Zeipel's work on this subject in contrast to the works of Lidov and Kozai, and show that von Zeipel's achievements in the early twentieth century (written and published in French under the title "Sur l’application des séries de M. Lindstedt à l’étudedu mouvement des comètes périodiques") already comprehended most of the fundamental and necessary formulations that the Lidov-Kozai oscillation requires. By comparing the works of Lidov, Kozai, and von Zeipel along this line of studies, we assert that the prefix "von Zeipel-Lidov-Kozai" should be used for designating this theoretical framework, and not just Lidov-Kozai or Kozai-Lidov. 
Flying through a dawn storm: a multi-instrument study of the traversal of a dawn storm by Juno on February 7th 2018
Authors: Bonfond Bertrand , Guo Ruilong , Yao Zhonghua , Denis Grodent , Gérard Jean-Claude , Randy Gladstone , Vincent Hue , Thomas Greathouse , Versteeg Maarten , Kammer Joshua , Allegrini Frederic , Ebert Robert , Kurth William , Louarn Philippe , Gershman Daniel , Connerney John , Kotsiaros Stavros , Mauk Barry
Published: October 2020

On February 7th 2018, during Juno’s 11th perijove observation sequence, Juno’s ultraviolet spectrograph (Juno-UVS) unveiled the development of a dawn storm in Jupiter's aurorae. These auroral events consist of spectacular brightenings of the midnight to dawn sector of the main emissions at Jupiter. At the end of the sequence, Juno crossed the magnetic field lines connected to this dawn storm, unraveling some of the processes giving rise to these spectacular events. All in situ instruments detected a sharp transition as the spacecraft entered the dawn storm at an altitude of approximately 5RJ in the southern hemisphere. The particle fluxes detected by the JADE and JEDI instruments, including electrons and ions, increased dramatically. A strong flux of penetrating radiation was also detected by the UVS instrument. The Alfvén waves spectrograms derived from the MAG instrument also show a clear transition between a quiet and an extremely active regime as the spacecraft entered the dawn storm. Furthermore, the orientation of the magnetic field showed a very strong perturbation, associated with intense currents. And, finally, intense bKOM emissions were also observed during this time interval. Combined with the remote sensing observations of the aurora, these datasets strongly suggest that Juno witnessed a strong magnetospheric reconfiguration that started in the magneto-tail and then evolved toward dawn as the planet rotated.
Asteroid taxonomy using artificial neural networks
Authors: Penttilä Antti , Hietala Hilppa , Muinonen Karri
Published: October 2020

Asteroids are classified into different taxonomic groups according to their spectral reflectance properties in the visual and near-infrared (Vis-NIR) wavelengths. The spectral properties of the asteroid surfaces can be related to the material of the surface. There are a few taxonomic systems for asteroids, the most recent being the so-called Bus-DeMeo taxonomy (B-DM, DeMeo et al., Icarus 202, 2009). Usually, the exact wavelengths used in the taxonomic system are tied up with the particular survey data that was used to create the taxonomy. With the B-DM taxonomy, it is the SMASSII survey extended to near-infrared with the NASA IRTF telescope observations, and the wavelengths are 0.45–2.45 µm.The ESA space observatory Gaia will produce a significant number of low-resolution asteroid spectra over the 0.33–1.05 µm wavelength range in the Data Release 3 and the final data releases. There is an evident need for evaluating the surface properties of these asteroids using the Gaia data. For example, the list of taxonomic classifications for asteroids, maintained in the NASA Planetary Data System, has 2,600 asteroids with some taxonomic class (Neese, C., Ed., NASA Planetary Data System, 2010), but the Gaia data will eventually contain about 100,000 asteroid spectra.There is a plan to provide a new asteroid taxonomy using the Gaia observations (Delbo et al., PSS 73, 2012). However, a link to existing taxonomic systems such as B-DM would be highly valuable. In this work, we study the possibility to use feed-forward artificial neural network for asteroid spectral classification. We show that the classification accuracy can remain on a reasonably good level even if the B-DM classification is done with the neural network that is trained to use only data having wavelengths in the 0.45–1.05 µm range, which is the overlapping region with the Gaia and the original B-DM systems. This tool can provide the B-DM taxonomic classification for all the asteroids with Gaia spectroscopy.Acknowledgements: Research supported, in part, by the Academy of Finland (project 325805).
Ionospheric Outflow at Jupiter and Saturn
Authors: Martin Carley , Ray Licia , Constable David , Southwood David , Felici Marianna , Lorch Christopher , Kinrade Joseph , Gray Rebecca
Published: October 2020

Ionospheric outflow is the outward flow of atmospheric plasma, initiated by a loss of equilibrium along the magnetic field. Terrestrial ionospheric outflow presents as a polar wind triggered by the Dungey cycle, which drives much of Earth’s magnetospheric dynamics. At Saturn, Felici et al. [2016] observed ionospheric outflow in the lobes at 36 RS. Interestingly, at Jupiter, Valek et al. [2019] reported ionospheric outflow on magnetic field lines with invariant latitudes between Io’s auroral signatures and the main auroral emission, lower than the polar cap.At Jupiter and Saturn, the rapid rotation of the planet, coupled with an internal plasma source inside each magnetosphere, results in the Vasyliunas cycle, by which material is circulated throughout the system, eventually being lost down the magnetotail. This constant churning likely results in a system where ionospheric outflow occurs more readily at mid-to-high planetary latitudes that map to the middle magnetosphere, rather than solely at polar latitudes. Furthermore, ionospheric outflow at the Jupiter and Saturn will be affected by strong centrifugal forces and auroral currents, which are near omnipresent in each magnetosphere.Using a 1-dimensional, hydrodynamic, multi-fluid model, we determine the ionospheric outflow in the jovian and saturnian systems. Our model includes the effect of centrifugal forces and auroral field-aligned currents, both of which act to enhance outflow rates from previous studies. We find that ionospheric outflow may provide a significant contribution to the jovian and saturnian systems, with the mass source rates of 18.7 – 31.7 kg s-1and 5.5-17.7 kg s-1, respectively, where the range reflects the sensitivity to the assumed initial atmospheric conditions.
Simulating Mars D/H and atmospheric chemistry during the 2018 Global Dust Storm and comparing with NOMAD observations
Authors: Daerden Frank , Neary Lori , Villanueva Geronimo , Aoki Shohei , Viscardy Sebastien , Thomas Ian , Vandaele Ann Carine , Liuzzi Giuliano , Crismani Matteo , Khayat Alain , Smith Michael D. , Clancy R. Todd , Wolff Michael J. , Sandor Brad J. , Whiteway James A. , Mumma Michael J. , Erwin Justin , Willame Yannick , Piccialli Arianna ,   BIRA-IASB NOMAD team (continued)
Published: October 2020

The NOMAD instrument suite on the ESA-Roskosmos ExoMars Trace Gas Orbiter (TGO) observes the physical and chemical composition of the Martian atmosphere with highly resolved vertical profiles and nadir sounding in the IR and UV-vis domains. Vertically resolved profiles of, amongst other species, water vapor, HDO, ozone, CO, CO2, oxygen airglow, dust and clouds were obtained for more than one Martian year [1-5]. During its first year of operations, NOMAD witnessed the 2018 Global Dust Storm (GDS) during its onset, peak and decline. The redistribution of water vapor to high altitudes and latitudes observed during the GDS was explained using the GEM-Mars General Circulation Model (GCM) [6-8]. The GCM was driven by the dust optical depths for Mars Year 34 provided by [9]. The photolysis products of water vapor are a major driver for the atmospheric chemistry on Mars. As water vapor is redistributed over the atmosphere, it is expected to have considerable impact on many other species. GEM-Mars contains routines for atmospheric chemistry and here we present some results of the simulated impact of the GDS on atmospheric chemistry and on several of the observed species. GEM-Mars now also includes the simulation of HDO and the fractionation of water vapor upon cloud formation. The simulations will be compared with the vertical profiles of the D/H ratio obtained from NOMAD observations. The impact of the GDS on D/H can be estimated from these simulations. References [1] Vandaele, A. C. et al. (2019), Nature, 568, 7753, 521-525, doi: 10.1038/s41586-019-1097-3.[2] Aoki, S. et al. (2019), J. Geophys. Res.: Planets, 124, 3482–3497. https://doi.org/10.1029/2019JE006109[3] Gérard et al. (2020), Nature Astronomy, https://doi.org/10.1038/s41550-020-1123-2[4] Villanueva et al., submitted.[5] Korablev et al., 2020, in rev.[6] Neary, L. and F. Daerden (2018), Icarus, 300, 458–476, https://doi.org/10.1016/j.icarus.2017.09.028[7] Daerden, F. et al. (2019), Icarus, 326, 197-224, doi: 10.1016/j.icarus.2019.02.030.[8] Neary, L. et al. (2020), Geophys. Res. Lett., 47, e2019GL084354. https://doi.org/10.1029/2019GL084354[9] Montabone, L. et al. (2019), J. Geophys. Res.: Planets. doi: 10.1029/2019JE006111. 2.11.0.
Recycling of Planetary Proto-Atmospheres
Authors: Moldenhauer Tobias , Kuiper Rolf , Kley Wilhelm , Ormel Chris
Published: October 2020

Protoplanets formed by core accretion can become massive enough to accrete gas from the disk they are born in. If theplanetary proto-atmosphere exceeds a critical mass, runaway gas accretion starts and the planetary atmosphere collapses into a gasgiant. In recent years, many close-in super-Earths have been observed which raises the question on how they avoided becoming hotJupiters. We investigate the recycling hypothesis as a possible mechanism to avoid the collapse of the atmosphere.We use three-dimensional radiation-hydrodynamics to simulate the formation of proto-atmosphere in the local frame aroundthe planet. In post-processing we use tracer particles to calculate the shape of the atmosphere and determine the non-uniform recyclingtimescale in a quantitative manner. Our simulations converge to a quasi-steady state where the velocity field of the gas does not change anymore. For theparameter space explored, a = 0.1 au, m_c ∈ [1, 2, 5, 10] M_Earth, we find that recycling of the atmosphere counteracts the collapse bypreventing the gas from cooling efficiently.
Wave-particle interaction in the Io flux tube
Authors: Janser Sascha , Saur Joachim , Szalay Jamey , Clark George , Sulaiman Ali
Published: October 2020

Observations by the JUNO spacecraft revealed energetic, bidirectional particle populations with broadband energy distributions in the high-latitude region of Jupiter. These measurements indicate that an acceleration mechanism of stochastic nature plays a dominant role for the generation of the intense main auroral oval. In our current work, we investigate the acceleration of energetic electrons and protons recently observed by JUNO in the Io flux tube wake near Jupiter. We try to infer on the relevant physical acceleration process by considering a resonant as well as a non-resonant wave-particle interaction mechanism, both based on Alfven waves. We focus on necessary temporal scales to drive these mechanisms efficiently and also on the released wave energy by means of the transported Poynting flux along the flux tube.
Effects of the DART (NASA) mission collision on the structure and spin state of the secondary of the Near-Earth asteroid (65803) Didymos binary system.
Authors: Benavidez Paula , Campo Bagatin Adriano , Perez-Molina Manuel , Richardson Derek C. , Santana-Ros Antonio , Álvarez-Candal Álvaro
Published: October 2020

AIDA (Asteroid Impact & Deflection Assessment) is an international collaboration between NASA and ESA which involves both DART (Double Asteroid Redirection Test, NASA) and Hera (ESA) missions. The target is an asteroid of approximately 160 m in size, namely the secondary of the binary Near-Earth Asteroid (65803) Didymos. Little is known about the shape of the satellite, with a moderately elongated shape (b/a
Influence of Europa’s Time-Varying Electromagnetic Environment on Energetic Ion Precipitation
Authors: Addison Peter , Liuzzo Lucas , Arnold Hannes , Simon Sven
Published: October 2020

We model energetic and thermal ion dynamics in the perturbed electromagnetic fields at Jupiter’s moon Europa. At the location of its orbit, Europa experiences a periodic variation in background electromagnetic field strength and orientation as well as plasma conditions while Jupiter completes a synodic rotation. We use a hybrid simulation (kinetic ions, fluid electrons) to model field perturbations due to the interaction of the corotating plasma with the ionosphere and induced dipole moment under these varying background conditions. For three cases, (I) Europa at the center of the plasma sheet, (II) Europa at its maximum distance north of the plasma sheet, and (III) Europa at its maximum distance south of the plasma sheet, we calculate surface precipitation maps of energetic magnetospheric ions using a backtracing tool. The effects of the time-varying field perturbations on surface precipitation have not previously been modeled. For three of the dominant ion species (H+, O2+, and S3+), we model the spatial distribution of surface flux over the full range of ion energies observed by the Galileo spacecraft (100 eV to about 10MeV). Our results show that the field perturbations drastically affect surface fluxes. While polar regions receive consistently high particle flux, low-latitude and equatorial regions are partially shielded by draped magnetic field lines close to the moon. These shielded regions migrate in longitude and latitude across Europa’s surface as Jupiter progresses through a full synodic rotation.
Exoplanet pollution in transit spectroscopy with the next-generation of infrared space telescopes
Authors: Morello Giuseppe , Zingales Tiziano , Martin-Lagarde Marine , Gastaud Rene , Cossou Christophe , Lagage Pierre-Olivier
Published: October 2020

The next generation of space telescopes is expected to deliver transmission spectra of exoplanet atmospheres with precision down to 10 parts per million (ppm). Therefore, it is required to model the astrophysical signals with even greater precision in order not to introduce significant biases for the characterization of the planet and its atmosphere.We discuss, in particular, the contribution of the planetary flux in the analysis of transit observations. Usually, the planetary flux is assumed to be a negligible fraction of the stellar flux, so called dark planet hypothesis. However, this hypothesis is not always valid, especially at the infrared wavelengths, around the peak of thermal emission from the planet. We identify two effects, named self-blend and phase-blend, that tend to bias the measured transit depth in opposite directions (the self-blend effect was already known from Kipping & Tinetti 2010).We introduce a novel sub-package of the software ExoTETHyS that can be used to estimate the amplitude of these two effects depending on the exoplanet system parameters, along with the derivation of the mathematical formulae. In this way, it is possible to identify some priority targets to observe longer transit windows, the secondary eclipse and/or the full phase-curve in order to reduce these potential biases.We also show the impact of the self- and phase-blend effects in the analysis of simulated transit spectra taken with the James Webb Space Telescope (JWST), including the results of the atmospheric retrievals. Our analysis takes into account the possible mitigation depending on the alternative data detrending methods. 
Interplanetary Field Enhancements: An Overview
Authors: Russell Christopher , Lai Hairong , Horbury Tim
Published: October 2020

The phenomenon, dubbed the Interplanetary Field Enhancement, occurs in the solar wind near and inside of 1 AU and is attributed to collisional dust production and subsequent solar wind pickup.  The duration and strength of these events appears to depend on the heliocentric distance of the detection, the largest event was recorded by the PVO spacecraft in orbit about Venus in 1982.  It lasted 11 hours and was over 20 million km in radial extent.  While no such large structure has been seen since by PVO or Venus Express since that time observations at 1 AU by STEREO, and the flotilla of spacecraft near the L-1 Lagrangian point have continued to see smaller events.  These are now attributed to collisions of asteroidal debris, small rocks destroying each other when they collide at a mean velocity of 20 km/s at 1 AU.  Such a speed of collision with a 1 kg rock will completely destroy a 106 kg target.  Even if the number of small asteroids were constant with heliocentric distance the increased orbital speeds inside 1 AU should greatly increase the destructive power of collisions so that larger events should occur at closer distances to the Sun.  We review the statistics available from Pioneer Venus and Venus Express and compare them with 1 AU data to test this hypothesis.
On the long-term weathering of the lunar surface by the heavy minor ions of the solar wind: inputs from ion observations and SRIM simulations
Authors: Nénon Quentin , Poppe Andrew R
Published: October 2020

The lunar surface and the regolith that covers it are weathered by solar wind ions, which sputter atoms and molecules, participate to the creation of optically opaque particles, alter the regolith composition and create amorphous rims on regolith grains by displacing atoms inside the material. As protons and alpha particles dominate the density of solar wind ions, these two species may be the main contributors to ion weathering. However, the importance of solar wind minor ions heavier than alpha particles for the ion-induced alteration of airless body surfaces is an open debate. The fundamental question at stake is whether the variety of different minor ion species, their high masses, and their high charge states may overcome their low densities in the solar wind to enable them to significantly contribute to ion weathering processes.In this presentation, long-term effects which develop on geological time scales are investigated. To do so, the long-term averaged energy spectrum of thermal, suprathermal, and energetic solar wind ions is estimated by compiling and contrasting ion measurements gathered by the ACE, Wind, STEREO, ARTEMIS, and MAVEN missions. The long-term ion environment to which the lunar surface is exposed to in the solar wind is then convolved with Stopping and Range of Ions in Matter (SRIM) simulations. Combining these data and ion effect models, we find that solar wind minor ions significantly alter the lunar surface and airless body surfaces in general, as they contribute to 12% to 22% of the total sputtering and create 20% to 50% of atomic displacements at depths greater than 100 nanometers. This new approach therefore confirms that solar wind minor ions play an important role in ion weathering of airless surfaces throughout the Solar System.