SERENA:Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

International audienceThe ESA-JAXA BepiColombo mission to Mercury will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric particle dynamics at Mercury as well as their interactions with solar wind, solar radiation, and interplanetary dust. The particle instrument suite SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) is flying in space on-board the BepiColombo Mercury Planetary Orbiter (MPO) and is the only instrument for ion and neutral particle detection aboard the MPO. It comprises four independent sensors: ELENA for neutral particle flow detection, Strofio for neutral gas detection, PICAM for planetary ions observations, and MIPA, mostly for solar wind ion measurements. SERENA is managed by a System Control Unit located inside the ELENA box. In the present paper the scientific goals of this suite are described, and then the four units are detailed, as well as their major features and calibration results. Finally, the SERENA operational activities are shown during the orbital path around Mercury, with also some reference to the activities planned during the long cruise phase

Correction to: SERENA: Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

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Study of Radiation Enviroment for Low-Earth Orbit (LEO) Spacecraft

The design of a space mission involves study of particle fluxes and their effects on spacecraft; space environment has a strong degrading effect on materials and components, so those need to be understood and mitigated against in order to ensure the success of mission. This work focuses on the study of Low Earth Orbit (LEO) radiation environment and how the particles interact with materials for a hypotethical space mission. Mission goal is Energetic Particle Atoms (ENA) detection using gas detector (MicroMeEGAS??) on board of a CubeSat. The payload will observe phenomena due to interation between magnetosphere and solar wind measuring precipitated particles. Being gas detector sensitive to several type of radiation, it is important to evaluate both its protection in terms of charged particles, that do not contribute to the signal, and the signal-to-noise ratio, because detector must be able to separate the desired signal from the background noise. So, the choice of the orbit requires some constraints as a consequence of the set scientific objective: we want to avoid areas where radiations are more intensive (South Atlantic Anomaly and polar regions) and for this reason we analyse the environment of LEO orbit with a low inclination. We investigate the major sources of natural environmental radiation analyzing trapped electrons and protons, solar particles flux and galactic cosmic ray intensity that arrive on and inside a cubesat at different altitudes of an appropriate Low Earth Orbit (LEO). The study of the orbit and the analysis of the radiation environment around the spacecraft are done by modeling with a web simulation tool, SPENVIS (SPace ENVironment Information System), instead Monte Carlo methods are used to simulate radiation fluxes, that penetrate into the CubeSat. Simulation results will be essential to proceed to evaluate the appropriate corrections in the instrument design, with appropriate shielding studies

Venus's southern polar vortex reveals precessing circulation.

Initial images of Venus's south pole by the Venus Express mission have shown the presence of a bright, highly variable vortex, similar to that at the planet's north pole. Using high-resolution infrared measurements of polar winds from the Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, we show the vortex to have a constantly varying internal structure, with a center of rotation displaced from the geographic south pole by ~3 degrees of latitude and that drifts around the pole with a period of 5 to 10 Earth days. This is indicative of a nonsymmetric and varying precession of the polar atmospheric circulation with respect to the planetary axis

Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

International audienceOne of the striking features about Venus atmosphere is its temporal variability and dynamics, with a chaotic polar vortex, large-scale atmospheric waves, sheared features and variable winds that depend on local time and possibly orographic features. The aim of this research is to combine data accumulated over several years and obtain a global mean state of the atmosphere focusing in the global structure of the clouds using the cloud opacity and upper cloud temperatures.We have first produced global maps using the integrated radiance through the infrared atmospheric windows centred around 1.74 μm and 2.25 μm, that show the spatial variations of the cloud opacity in the lower clouds around 44–48 km altitude and also provide an indirect estimation of the possible particle size. We have also produced similar global maps using the brightness temperatures seen in the thermal region at 3.8 μm and 5.0 μm, which provide direct indication of the temperatures at the top of the clouds around 60–70 km altitude.These maps have been generated using the complete dataset of the Visible and InfraRed Thermal Imaging Spectrometer mapping channel (VIRTIS-M) on board Venus Express, with a wide spatial and long temporal coverage in the period from May 2006 until October 2008.Our results provide a global view of the cloud opacity, particle size and upper cloud temperatures at both hemispheres, showing the main different dynamical regions of the planet. The profiles obtained also provide the detailed dependencies with latitude, local time and longitude, diagnostic of the global circulation flow and dynamics at various altitude layers, from about 44 up to 70 km over the surface

The Integral-Field Imager and Spectrometer for planetary exploration (ƒISPEx)

The fSPEx instrument is an innovative optical payload for planetary exploration which integrates a Color Camera and an Integral Field Spectrometer. The instrument uses a Three Mirror Afocal Telescope operating with a 2.4X beam reduction factor (input pupil diameter 84 mm, output pupil diameter 35 mm) to feed a collimated light beam to the camera's and spectrometers' entrance pupils. The FOVs of the two channels are aligned on a common boresight utilizing a beamsplitter and a dichroic filter. This solution, apart from saving mass by adopting a single telescope, allows operating the camera and imaging spectrometer in unison resulting in a great simplication of their operations. By selecting the polarization voltage applied to a Liquid Crystal Tunable Filter (LCTF) placed on the entrance pupil of the camera objective, it is possible to select the optical bandpass (between 0.42-0.73 μm) and the corresponding bandwidth (from 16 nm at 0.42 μm to 48 nm at 0.73 μm). This solution allows avoiding mechanical parts like in filters wheels while guaranteeing high spectral sampling. The camera optical design ensures a 3.3° x 1.6° FOV and an IFOV of 14 μrad corresponding to a spatial resolution of 0.14 m/px from a 10 km distance. The spectral channel is further divided in the VIS (0.4-1.05 μm spectral range, 3.2 nm/band sampling) and IR (0.95-5.0 μm, 8 nm/band) integral field imaging spectrometers. These channels use custom-made Coded Mask Optical Reformatters (CMOR) built from optical fibers bundles to collect the hyperspectral cube through a single acquisition. This innovative solution affords a great saving of the acquisition time with respect to instruments operating in whiskbroom or pushbroom mode. The FOV/IFOV are 0.4° (circular)/100 μrad and 0.28° x 0.28° (square)/225 μrad for the VIS and IR spectrometers, respectively. From a 10 km distance, the VIS spectrometer builds a 70 m-wide circular hyperspectral image made of 4000 pixels at 1 m/px resolution from 10 km distance; the IR channel acquires a 50x50 m image made of 484 pixels at 2.25 m/px. These requirements have been optimized for remote sensing of asteroids and comets from close distances but the instrument can be adapted also for other observation scenarios. In this respect, the ISPEx will offer the advantage to allow better exploitation of the data collected by the three channels resulting in a tremendous advantage for many scientific investigations. With this synergic approach, it will be possible to analyze high-resolution images to constrain morphology interpretation of a target, while hyperspectral data collected at the same time allow the retrieval of composition and physical properties. The availability of camera images makes it possible to apply sharpening algorithms to spectrometer ones. Apart from this, an integral-field spectrometer will keep the capabilities of more traditional whiskbroom and push broom spectrometers but it will overcome them when the target scene is rapidly evolving and changing during the acquisition: traditional instruments are limited by the fact that the cube acquisition process may take a time longer than the time scale of the investigated event. This is the case of observations enquiring into the dynamical evolution of planetary atmospheres, lightning events, outbursts, hyper-velocity impact, or fast-moving targets. By operating with fast readout detectors, an Integral Field spectrometer can adequately resolve the four dimensions of data (2D spatial, spectral and temporal) opening the possibility to perform time-resolved hyperspectral movies. Another substantial advantage of Integral Field spectrometers is their better operability during fast yby phases, where the distance from the target and illumination geometry are rapidly changing, resulting in limited periods suitable to observe the target with optimal conditions. By collecting the entire hyperspectral cube in a fraction of the time necessary to complete the scan for a traditional scanning spectrometer, an Integral Field spectrometer can reach a level of imaging exibility similar to the one achieved by a camera. Within this study, we are defining the configuration of the ISPEx5:0μm 0:4 space model operating in the 0.4-5.0 μm spectral range including optical performance analyses, and thermomechanical and electronic architecture. Moreover, we are realizing a development breadboard ISPEx1:0μm 0:4 limited to the 0.4-1.0 μm spectral range to conduct performance tests at the system level on LCTF and CMOR devices

The planetary fourier spectrometer (PFS) onboard the European Venus Express mission

The planetary fourier spectrometer (PFS) for the Venus Express mission is an infrared spectrometer optimized for atmospheric studies. This instrument has a short wavelength (SW) channel that covers the spectral range from 1700 to 11400 cm‑1 (0.9 5.5 μm) and a long wavelength (LW) channel that covers 250 1700 cm‑1 (5.5 45 μm). Both channels have a uniform spectral resolution of 1.3 cm‑1. The instrument field of view FOV is about 1.6 ° (FWHM) for the short wavelength channel and 2.8 ° for the LW channel which corresponds to a spatial resolution of 7 and 12 km when Venus is observed from an altitude of 250 km. PFS can provide unique data necessary to improve our knowledge not only of the atmospheric properties but also surface properties (temperature) and the surface-atmosphere interaction (volcanic activity). PFS works primarily around the pericentre of the orbit, only occasionally observing Venus from larger distances. Each measurements takes 4.5 s, with a repetition time of 11.5 s. By working roughly 1.5 h around pericentre, a total of 460 measurements per orbit will be acquired plus 60 for calibrations. PFS is able to take measurements at all local times, enabling the retrieval of atmospheric vertical temperature profiles on both the day and the night side. The PFS measures a host of atmospheric and surface phenomena on Venus. These include the:(1) thermal surface flux at several wavelengths near 1 μm, with concurrent constraints on surface temperature and emissivity (indicative of composition); (2) the abundances of several highly-diagnostic trace molecular species; (3) atmospheric temperatures from 55 to 100 km altitude; (4) cloud opacities and cloud-tracked winds in the lower-level cloud layers near 50-km altitudes; (5) cloud top pressures of the uppermost haze/cloud region near 70 80 km altitude; and (6) oxygen airglow near the 100 km level. All of these will be observed repeatedly during the 500-day nominal mission of Venus Express to yield an increased understanding of meteorological, dynamical, photochemical, and thermo-chemical processes in the Venus atmosphere. Additionally, PFS will search for and characterize current volcanic activity through spatial and temporal anomalies in both the surface thermal flux and the abundances of volcanic trace species in the lower atmosphere. Measurement of the 15 μm CO2 band is very important. Its profile gives, by means of a complex temperature profile retrieval technique, the vertical pressure-temperature relation, basis of the global atmospheric study. PFS is made of four modules called O, E, P and S being, respectively, the interferometer and proximity electronics, the digital control unit, the power supply and the pointing device

Gamma-Ray Burst Observations by the High-Energy Particle Detector on board the China Seismo-Electromagnetic Satellite between 2019 and 2021

In this paper we report the detection of five strong gamma-ray bursts (GRBs) by the High-Energy Particle Detector (HEPD-01) mounted on board the China Seismo-Electromagnetic Satellite, operational since 2018 on a Sun-synchronous polar orbit at a similar to 507 km altitude and 97 degrees inclination. HEPD-01 was designed to detect high-energy electrons in the energy range 3-100 MeV, protons in the range 30-300 MeV, and light nuclei in the range 30-300 MeV n(-1). Nonetheless, Monte Carlo simulations have shown HEPD-01 is sensitive to gamma-ray photons in the energy range 300 keV-50 MeV, even if with a moderate effective area above similar to 5 MeV. A dedicated time correlation analysis between GRBs reported in literature and signals from a set of HEPD-01 trigger configuration masks has confirmed the anticipated detector sensitivity to high-energy photons. A comparison between the simultaneous time profiles of HEPD-01 electron fluxes and photons from GRB190114C, GRB190305A, GRB190928A, GRB200826B, and GRB211211A has shown a remarkable similarity, in spite of the different energy ranges. The high-energy response, with peak sensitivity at about 2 MeV, and moderate effective area of the detector in the actual flight configuration explain why these five GRBs, characterized by a fluence above similar to 3 x 10(-5) erg cm(-2) in the energy interval 300 keV-50 MeV, have been detected