Esplorando il nostro sistema solare

ItLa comunità scientifica internazionale che si occupa dello Studio del Sistema Solare ha oggi a disposizione per le proprie attivià un'enorme quantità di dati grazie ai programmi di Esplorazione del Sistema Solare. L'uso di questi dati avviene in forte sinergia con attività teoriche numeriche e sperimentali. Ed è proprio questo coordinamento che ci ha permesso di fare enormi passi avanti nella nostra comprensione dei fenomeni atmosferici, geologici ed elettromagnetici di pianeti diversi dalla Terra. In questo articolo parleremo di due missioni missioni di esplorazione Spaziale con forte partecipazione italiana: la missione NASA/Juno verso Giove (lanciata nel 2011 e ancora attiva) e la missione NASA/Dawn verso Vesta e Ceres (lanciata nel 2007 e terminata nel 2018). Le scoperte di queste missioni ci hanno aiutato a capire meglio la storia evolutiva del nostro Sistema Solare e i meccanismi fisici determinati dalle interazioni tra i corpi planetari e gli ambienti che li circondano.EnThanks to the Solar System exploration programs, an enormous amount of data is now available to the space science community. Planetary science data exploitation, often in strong synergy with modelling and theoretical research efforts, has been essential for incrementing our knowledge on atmospheric, geological, and electromagnetic phenomena on planets other than the Earth. In this article, we discuss some recent insights from two innovative exploration missions with strong Italian participation: the NASA/Juno mission to Jupiter (launched in 2011 and still ongoing) and the NASA/Dawn mission to Vesta and Ceres (launched in 2007 and ended in 2018). The discoveries of these missions have helped us to unveil the history of our Solar System and the physical mechanisms resulting from the interactions between planetary bodies and their surrounding environments

THE GROUND-LEVEL ENHANCEMENT OF 2012 MAY 17: DERIVATION OF SOLAR PROTON EVENT PROPERTIES THROUGH THE APPLICATION OF THE NMBANGLE PPOLA MODEL

In this work, we apply an updated version of the Neutron Monitor (NM) Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model, in order to derive the characteristics of the ground-level enhancement (GLE) on 2012 May 17 (GLE71), the spectral properties of the related solar energetic particle (SEP) event, the spatial distributions of the high-energy solar cosmic ray fluxes at the top of the atmosphere, and the time evolution of the locationoftheGLEsource.Ourmodeling,baseduniquelyontheuseofground-levelNMdata,leadstothefollowing mainresults.TheSEPspectrumrelatedtoGLE71wasrathersoftduringthewholedurationoftheevent,manifesting some weak acceleration episodes only during the initial phase (at " 01:55‐02:00UT) and at " 02:30‐02:35UT and " 02:55‐03:00UT. The spectral index of the modeled SEP spectrum supports the coronal mass ejection‐shock driven particle acceleration scenario, in agreement with past results based on the analysis of satellite measurements. During the initial phase of GLE71, the solar proton source at the top of the atmosphere was located above the northernhemisphere,implyingthattheasymptoticdirectionsofviewingofthenorthernhemisphereNMsweremore favorably located for registering the event than the southern ones. The spatial distribution of the solar proton fluxes at the top of the atmosphere during the main phase manifested a large variation along longitude and latitude. At the rigidity of 1GV, the maximum primary solar protonflux resulted on the order of" 3# 10 4 part. m $2 s$ 1 sr $1 GV$ 1

Esplorando il nostro sistema solare

ItLa comunità scientifica internazionale che si occupa dello Studio del Sistema Solare ha oggi a disposizione per le proprie attivià un'enorme quantità di dati grazie ai programmi di Esplorazione del Sistema Solare. L'uso di questi dati avviene in forte sinergia con attività teoriche numeriche e sperimentali. Ed è proprio questo coordinamento che ci ha permesso di fare enormi passi avanti nella nostra comprensione dei fenomeni atmosferici, geologici ed elettromagnetici di pianeti diversi dalla Terra. In questo articolo parleremo di due missioni missioni di esplorazione Spaziale con forte partecipazione italiana: la missione NASA/Juno verso Giove (lanciata nel 2011 e ancora attiva) e la missione NASA/Dawn verso Vesta e Ceres (lanciata nel 2007 e terminata nel 2018). Le scoperte di queste missioni ci hanno aiutato a capire meglio la storia evolutiva del nostro Sistema Solare e i meccanismi fisici determinati dalle interazioni tra i corpi planetari e gli ambienti che li circondano.EnThanks to the Solar System exploration programs, an enormous amount of data is now available to the space science community. Planetary science data exploitation, often in strong synergy with modelling and theoretical research efforts, has been essential for incrementing our knowledge on atmospheric, geological, and electromagnetic phenomena on planets other than the Earth. In this article, we discuss some recent insights from two innovative exploration missions with strong Italian participation: the NASA/Juno mission to Jupiter (launched in 2011 and still ongoing) and the NASA/Dawn mission to Vesta and Ceres (launched in 2007 and ended in 2018). The discoveries of these missions have helped us to unveil the history of our Solar System and the physical mechanisms resulting from the interactions between planetary bodies and their surrounding environments

Derivation of relativistic SEP properties through neutron monitor data modeling

The Ground Level Enhancement (GLE) data recorded by the worldwide Neutron Monitor (NM) network are useful resources for space weather modeling during solar extreme events. The derivation of Solar Energetic Particles (SEPs) properties through NM-data modeling is essential for the study of solar-terrestrial physics, providing information that cannot be obtained through the exclusive use of space techniques; an example is the derivation of the higher-energy part of the SEP spectrum. We briefly review how the application of the Neutron Monitor Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model (Plainaki et al. 2010), can provide the characteristics of the relativistic SEP flux, at a selected altitude in the Earth's atmosphere, during a GLE. Technically, the model treats the NM network as an integrated omnidirectional spectrometer and solves the inverse problem of the SEP-GLE coupling. As test cases, we present the results obtained for two different GLEs, namely GLE 60 and GLE 71, occurring at a temporal distance of ~ 11 years

The Comparative Exploration of the Ice Giant Planets with Twin Spacecraft: Unveiling the History of our Solar System

In the course of the selection of the scientific themes for the second and third L-class missions of the Cosmic Vision 2015-2025 program of the European Space Agency, the exploration of the ice giant planets Uranus and Neptune was defined "a timely milestone, fully appropriate for an L class mission". Among the proposed scientific themes, we presented the scientific case of exploring both planets and their satellites in the framework of a single L-class mission and proposed a mission scenario that could allow to achieve this result. In this work we present an updated and more complete discussion of the scientific rationale and of the mission concept for a comparative exploration of the ice giant planets Uranus and Neptune and of their satellite systems with twin spacecraft. The first goal of comparatively studying these two similar yet extremely different systems is to shed new light on the ancient past of the Solar System and on the processes that shaped its formation and evolution. This, in turn, would reveal whether the Solar System and the very diverse extrasolar systems discovered so far all share a common origin or if different environments and mechanisms were responsible for their formation. A space mission to the ice giants would also open up the possibility to use Uranus and Neptune as templates in the study of one of the most abundant type of extrasolar planets in the galaxy. Finally, such a mission would allow a detailed study of the interplanetary and gravitational environments at a range of distances from the Sun poorly covered by direct exploration, improving the constraints on the fundamental theories of gravitation and on the behaviour of the solar wind and the interplanetary magnetic field.Comment: 29 pages, 4 figures; accepted for publication on the special issue "The outer Solar System X" of the journal Planetary and Space Science. This article presents an updated and expanded discussion of the white paper "The ODINUS Mission Concept" (arXiv:1402.2472) submitted in response to the ESA call for ideas for the scientific themes of the future L2 and L3 space mission

MARCO POLO - RAMON

RAMON (Released Atoms and Ions MONitor) to be flown on board the MarcoPolo-R Mission, consists of two neutral atom sensors able to detect and characterize the neutral atoms released from the surface of a near-Earth asteroid (NEA), and an ion monitor for the characterization of the space weathering of the surface. In particular: • SHEAMON (Sputtered High-Energy Atoms MONitor) will investigate the ion-sputtering and backscattering process by detecting neutral atoms between ∼10 eV and ∼3 keV and determining their direction and velocity; • GASP (GAs SPectrometer) will analyse the mass of the low-energy (below 10 eV) neutral atoms released by different surface processes; • MIM (Miniaturized Ion Monitor) will measure the flux and energy spectra of precipitating and backscattered solar wind protons, which originate the Ion Sputtering and Backscattering processes investigated by SHEAMON. The RAMON key questions are summarized as in the following: • What processes happen on the surface of the NEA as a result of its exposure to space environment and collisions? What is the magnitude of the erosion due to space weathering at the NEA surface? • What is the efficiency of each process as a function of environment conditions? • Is the efficiency of particle release processes uniform on the NEA surface? • What is the composition of the escaping material and consequently, how it relates to the surface composition and mineralogy? • What is the role of the surface release processes in the body evolution

Loss rates of Europa's tenuous atmosphere

Loss processes in Europa's tenuous atmosphere are dominated by plasma-neutral interactions. Based on the updated data of the plasma conditions in the vicinity of Europa (Bagenal et al. 2015), we provide estimations of the atmosphere loss rates for the H2O, O2 and H2 populations. Due to the high variability of the plasma proprieties, we perform our investigation for three sample plasma environment cases identified by Bagenal et al. as hot/low density, cold/high density, and an intermediate case. The role of charge-exchange interactions between atmospheric neutrals and three different plasma populations, i.e. magnetospheric, pickup, and ionospheric ions, is examined in detail. Our assumptions related to the pickup and to the ionospheric populations are based on the model by Sittler et al. (2013). We find that O2-O2+ charge-exchange is the fastest loss process for the most abundant atmospheric species O2, though this loss process has been neglected in previous atmospheric models. Using both the revised O2 column density obtained from the EGEON model (Plainaki et al., 2013) and the current loss rate estimates, we find that the upper limit for the volume integrated loss rate due to O2-O2+ charge exchange is in the range (13-51)×1026 s-1, depending on the moon's orbital phase and illumination conditions. The results of the current study are relevant to the investigation of Europa's interaction with Jupiter's magnetospheric plasma

Planetary space weather: scientific aspects and future perspectives

International audienceIn this paper, we review the scientific aspects of planetary space weather at different regions of our Solar System, performing a comparative planetology analysis that includes a direct reference to the circum-terrestrial case. Through an interdisciplinary analysis of existing results based both on observational data and theoretical models, we review the nature of the interactions between the environment of a Solar System body other than the Earth and the impinging plasma/radiation, and we offer some considerations related to the planning of future space observations. We highlight the importance of such comparative studies for data interpretations in the context of future space missions (e.g. ESA JUICE; ESA/JAXA BEPI COLOMBO). Moreover, we discuss how the study of planetary space weather can provide feedback for better understanding the traditional circum-terrestrial space weather. Finally, a strategy for future global investigations related to this thematic is proposed

Analytical model of Europa's O2 exosphere

The origin of the exosphere of Europa is its water ice surface. The existing exosphere models, assuming either a collisionless environment (simple Monte Carlo techniques) or a kinetic approach (Direct Monte Carlo Method) both predict that the major constituent of the exosphere is molecular oxygen. Specifically, O2 is generated at the surface through radiolysis and chemical interactions of the water dissociation products. The non-escaping O2 molecules circulate around the moon impacting the surface several times, due to their long lifetime and due to their non- sticking, suffering thermalization to the surface temperature after each impact. In fact, the HST observations of the O emission lines proved the presence of an asymmetric atomic Oxygen distribution, related to a thin asymmetric molecular Oxygen atmosphere. The existing Monte Carlo models are not easily applicable as input of simulations devoted to the study of the plasma interactions with the moon. On the other hand, the simple exponential density profiles cannot well depict the higher temperature/higher altitudes component originating by radiolysis. It would thus be important to have a suitable and user-friendly model able to describe the major exospheric characteristics to use as a tool. This study presents an analytical 3D model that is able to describe the molecular Oxygen exosphere by reproducing the two-component profiles and the asymmetries due to diverse configurations among Europa, Jupiter and the Sun. This model is obtained by a non-linear fit procedure of the EGEON Monte Carlo model (Plainaki et al. 2013) to a Chamberlain density profile. Different parameters of the model are able to describe various exosphere properties thus allowing a detailed investigation of the exospheric characteristics. As an example a discussion on the exospheric temperatures in different configurations and space regions is given