Hybrid simulations of the proton precipitation patterns onto the upper atmosphere of Mars

We study the dependence of proton precipitation patterns onto the Martian upper atmosphere on altitude, proton energy, proton origin, and in a lesser extent, solar zenith angle, using the HYB-Mars model, a 3D quasineutral hybrid model. We find that the flux of precipitating protons has a strong altitude dependence: on the dayside, the flux of precipitating protons decreases substantially when the altitude over Mars decreases. We also find that the contribution of exospheric protons to the deposition is significant and its spatial distribution is not identical to that of the solar wind protons. In addition, the low energy proton population comes mainly from the newborn planetary protons. The energized pick-up protons and solar wind protons contribute to the higher energy proton population. The study also confirms that the proton precipitation is highly asymmetric with respect to the direction of the convection electric field in the solar wind. The study implies that the Martian induced magnetosphere protects the upper atmosphere effectively against proton precipitation

Mars Express observations of high altitude planetary ion beams and their relation to the “energetic plume” loss channel

This study presents observational evidence of high‐energy (ions >2 keV) beams of planetary ions above Mars' induced magnetospheric boundary (IMB) and relates them with the energetic plume loss channel calculated from numerical models. A systematic search of the Mars Express (MEX) ion data using an orbit filtering criteria is described, using magnetometer data from Mars Global Surveyor (MGS) to determine the solar wind motional electric field (Esw) direction. Two levels of statistical survey are presented, one focused on times when the MEX orbit was directly in line with the Esw and another for all angles between the MEX location and the Esw. For the first study, within the 3 year overlap of MGS and MEX, nine brief intervals were found with clear and unambiguous high‐energy O+ observations consistent with the energetic plume loss channel. The second survey used a point‐by‐point determination of MEX relative to the E‐field and contained many thousands of 192 s measurements. This study yielded only a weak indication for an Esw‐aligned plume. Furthermore, the y‐z components of the weighted average velocities in the bins of this y‐z spatial domain survey do not systematically point in the Esw direction. The first survey implies the existence of this plume and shows that its characteristics are seemingly consistent with the expected energy and flight direction from numerical studies; the second study softens the finding and demonstrates that there are many planetary ions beyond the IMB moving in unexpected directions. Several possible explanations for this discrepancy are discussed.Key PointsA plume of energetic (>2 keV) planetary ions is escaping from MarsThe plume is directed along the solar wind motional electric fieldClarity of plume signatures greatly depends on selected survey methodologyPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110626/1/jgra51418.pd

Flow of forces and couples to the cylindrical solids through system asymmetry thin-walled elements of varying stiffness

Задача про передачу силового і моментного навантаження до криволінійного отвору нескінченної ізотропної пластинки через систему несиметричних відносно серединної площини тонкостінних елементів змінної жорсткості зведена до системи чотирьох сингулярних інтегрально– диференціальних рівнянь з ядрами Гільберта. Методом колокації досліджується вплив на напружений стан пластинки несиметричності підсилень, способу їх розміщення на контурі отвору.The problem of flow of forces and couples to the curvilinear hole in a infinite isotropic plate through system of asymmetrical by a middle plane the thin-walled elements of varying stiffness reduce to the system of four singular integral-differential equations with cores of Hilbert. The effect of asymmetry strengthens and location mode by method of collocation does investigate

He^2+ transport in the Martian upper atmosphere with an induced magnetic field

Solar wind helium may be a significant source of neutral helium in the Martian atmosphere. The precipitating particles also transfer mass, energy, and momentum. To investigate the transport of He^2+ in the upper atmosphere of Mars, we have applied the direct simulation Monte Carlo method to solve the kinetic equation. We calculate the upward He, He^+, and He^2+ fluxes, resulting from energy spectra of the downgoing He^2+ observed below 500 km altitude by the Analyzer of Space Plasmas and Energetic Atoms 3 instrument onboard Mars Express. The particle flux of the downward moving He^2+ ions was 1–2 × 10^6 cm^–2 s^–1, and the energy flux is equal to 9–10 × 10^–3 erg cm^–2 s^–1. The calculations of the upward flux have been made for the Martian atmosphere during solar minimum. It was found, that if the induced magnetic field is not introduced in the simulations the precipitating He^2+ ions are not backscattered at all by the Martian upper atmosphere. If we include a 20 nT horizontal magnetic field, a typical field measured by Mars Global Surveyor in the altitude range of 85–500 km, we find that up to 30%–40% of the energy flux of the precipitating He^2+ ions is backscattered depending on the velocity distribution of the precipitating particles. We thus conclude that the induced magnetic field plays a crucial role in the transport of charged particles in the upper atmosphere of Mars and, therefore, that it determines the energy deposition of the solar wind

Active Experiments Beyond the Earth: Plasma Effects of Sounding Radar Operations in the Ionospheres of Venus, Mars, and the Jovian System

The operation of powerful satellite- and rocket-born sounding radars is often accompanied by a heating/acceleration of the local electrons and ions. Intense fluxes of sounder accelerated particles were detected in Earth's ionosphere when the frequency of the radar transmitter was close to one of the fundamental plasma resonances: harmonic of the electron-cyclotron frequency, plasma, or upper-hybrid frequencies. Recently it was found that running a sounder in the ionosphere of the non-magnetized Mars results in similar effects. Ion and electron sensors of the ASPERA-3 experiment (Analyzer of Space Plasma and Energetic neutral Atoms) onboard the Mars Express spacecraft discovered acceleration of the local ionospheric ions and electrons from thermal threshold energies to 100's of eV during the active sounding phase of the onboard sounder. ESA and NASA missions being studied or under development to Jupiter (JUICE- JUpiter ICy moon Explorer) in 2022, Europa Clipper in 2023 and to Venus (EnVision) in 2032 and ISRO Venus obiter in 2023 will also carry powerful sounding radars. The purpose of this study is to investigate what mechanisms can cause acceleration of the plasma particles during operations of the proposed sounding radars in the Jovian system and Venusian ionosphere. Using the results of the previous studies and characteristics of the proposed sounding radars onboard JUICE, Europa Clipper, EnVision, and ISRO Venus Obiter, we define the optimal conditions for observations of sounder accelerated particles, depending on the local conditions, such as plasma density, composition, and intensity of the magnetic field. The EnVision and ISRO Venus Obiter radar operations are expected to result in the most pronounced acceleration of ions and electrons, an effect that can be used to improve the local plasma diagnostics

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

Extremely high reflection of solar wind protons as neutral hydrogen atoms from regolith in space

We report on measurements of extremely high reflection rates of solar wind particles from regolith-covered lunar surfaces. Measurements by the Sub-keV Atom Reflecting Analyzer (SARA) instrument on the Indian Chandrayaan-1 spacecraft in orbit around the Moon show that up to 20% of the impinging solar wind protons are reflected from the lunar surface back to space as neutral hydrogen atoms. This finding, generally applicable to regolith-covered atmosphereless bodies, invalidates the widely accepted assumption that regolith almost completely absorbs the impinging solar wind.Comment: 2 figure