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International audience; A trajectory optimization problem is examined to determine the most fuel-efficient rendezvous trajectory between spacecrafts in different orbits. To explore the whole range of feasible solutions, the wait time and the total time of flight are treated as free parameters while the initial and transfer orbits are not restricted to a particular one. To improve the accuracy of the numerical computation, the Kepler's time of flight equation is posed in terms of universal variables while the Lagrange coefficients are employed to obtain three-dimensional orbit information. The optimal rendezvous trajectory is then obtained enforcing the determined necessary conditions to be satisfied given only the initial state vectors of the involved spacecrafts. Two optimal rendezvous trajectories between a Sample Return Orbiter (SRO) and an Orbiting Sample Container (OS) are computed in the context of a future Mars Sample Return mission to demonstrate the reliability of the proposed solution. Finally, orbital perturbations due to the real shape of planet Mars and the solar radiation pressure are taken into account to determine the additional energy required to compensate these perturbations while performing the rendezvous manoeuvre.

Advances in lasers, optics and electronics for Satellite’s optical communication are opening the possibility of very high performance near Earth space links with data rate up to several Gbps. Being the divergence of the laser beam typically of tens of $$\mu$$ μ rad, an extremely high precision pointing is needed to correctly establish and maintain data optical link. In particular, the relative motion between the satellite and the ground station shall be accurately evaluated to estimate how to correct pointing angles for future orbital locations. This correction is made via a point-ahead mirror (PAM) mechanism, which deviates the laser beam by an angle called point-ahead angle (PAA). The purpose of this paper is evaluate the possibility of accurately estimate the point-ahead angle in advance using the two-line elements sets for the orbiting satellite, which are available before the ground station overpass. The study evaluated TLE-based orbital evolution of Sentinel-6 satellite, comparing the results with the high precision data obtained by laser ranging from the crustal dynamics data information system (CDDIS). The maximum error observed between the estimated and measured point-ahead angles was less than 1$$\mu$$ μ rad, demonstrating the possibility of this point-ahead correction technique for LEO orbiting satellites.

The number of space debris orbiting our Earth has been continuously increasing since the beginning of the space era. The space community is converging on responsible conducts and self-regulations to address this serious problem that is degrading the near-Earth environment. In this context, green deorbiting technologies and strategies alternative to the traditional chemical propulsion are under investigation, including Electrodynamic Tethers (EDTs) because they are a promising option. To increase EDT technology maturity level, some critical points shall be addressed and experimentally evaluated, including the deployment of tape tethers, to demonstrate their reliability. This paper presents results of an experimental validation of the Deployment Mechanism (DM) proposed for the H2020 FET OPEN Project E.T.PACK - Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit. We developed a mockup that hosts the DM and other elements that are on board the tip mass of a tethered system, using off-the-shelf components. The DM is tested for the first part of the tether deployment maneuver employing the SPARTANS facility of the University of Padova. This facility includes a Testing Table where the mock-up can move with almost no friction and a Motion Capture system that provides an accurate estimation of the mock-up motion during this first part of the tether deployment maneuver.

Avalanche rescue operations require quick localization of buried people. Organized rescue intervention is often not fast enough, since professional rescuers are not directly present in the avalanche area. Therefore, companion rescue remains the most effective option for rapid response, especially in case of employment of avalanche transceivers. In this context, the AVERLA project is developing avalanche localization instrumentation for small drones, to provide winter mountain recreationists, athletes and rescue teams with a fast and accurate system to improve the buried search. In this paper, a custom radiofrequency localization system, tuned on the avalanche transceivers transmission frequency, is described and its performance is assessed. Last, the integration of the instrument on an off-the-shelf drone, as baseline for further miniaturization, is presented.

The HYPerspectral Stereo Observing System (HYPSOS) is a novel remote sensing pushbroom instrument able to give simultaneously both 3D spatial and spectral information of the observed features. HYPSOS is a very compact instrument, which makes it attractive for both possible planetary observation and for its use on a nanosat, e.g. for civilian applications. This instrument collects light from two different perspectives, as a classical pushbroom stereocamera, which allows to realize the tridimensional model of the observed surface, and then to extract the spectral information from each resolved element, thus obtaining a full 4-dimensional hypercube dataset. To demonstrate the actual performance of this novel type of instrument, we are presently realizing a HYPSOS prototype, that is an instrument breadboard to be tested in a laboratory environment. For checking its performance, we setup an optical facility representative of a possible flight configuration. In this paper we provide a description of HYPSOS concept, of its optomechanical design and of the ground support equipment used to characterize the instrument. An update on the present status of the experiment is finally given.

Light pollution is recognized as an increasingly important issue not only for astronomical observations but also for the preservation of ecosystem and the quality of human life. Emission from ground sources is currently mapped using satellite images aided by local ground observations but information has limited resolution in space and time; especially now that blue “cold” LEDs, which are poorly detected from space, are being widely used for illumination, data need to be integrated with measurement from autonomous systems flying at lower altitude. MINLU (“Misurazione dell’ INquinamento LUminoso”) autonomous payload was designed and tested to provide complete and detailed aerial observations of all light pollution sources and monitor sky brightness with the capability to be integrated on stratospheric balloons, tethered balloons or drones. The payload's architecture includes three downward looking cameras with dedicated filters and two commercial Sky Quality Meter (SQM-LE) units, one pointing in horizontal direction and the other monitoring the zenith sky. The system can achieve a ground sample distance of 3 centimeter when integrated on drones flying at 200 m altitude, going up to 8 m at altitudes above 30 km in the use with balloons; this considerably improves the information provided by satellite images showing a ground resolution around 800 m. The payload was successfully launched with a sounding balloon from Tuscany on July 8th 2021 during the astronomical night window, achieving the first continuous observation of sky brightness magnitude in Earth atmosphere from ground to stratospheric altitudes. In parallel, images of on-board cameras have been used to quantify ground emission in terms of luminous intensity and power density and allowed to track sources causing the artificial luminance of the sky.

Sounding balloons are a fast and cost-effective transport system to lift up scientific payloads to stratospheric altitudes around 30 km, where equipment can be tested in low pressure environments and extreme temperature conditions to simulate space operation or conduct investigations of atmospheric parameters.Furthermore, ascent and descent phases offer fast changing dynamic conditions which can be used to evaluate instrument sensitivity to variation of environmental parameters and to test operation of optical systems on different target areas on ground. Images acquired with changing spatial and time resolution can be correlated with mission altitude and trajectory providing information for the validation of detection algorithms and scene mosaic reconstruction methods.This paper describes two autonomous payloads for stratospheric sounding balloon designed, assembled and tested at University of Padova, one devoted to measurement of light pollution, the other to tracking and automatic identification of targets on ground. They both rely on commercial cameras and comprise all electronic boards for sensor conditioning, data acquisition, compression and storage. Acquired images, position and attitude information are saved into on board non-volatile memory and may be partially transmitted on ground through telemetry depending on available transmission capacity. Energy for at least 4-hour continuous operation is provided by rechargeable lithium battery packs, powering all subsystems through a dedicated distribution unit. Both units have been enclosed in a light weight Styrofoam insulated structure and present a final mass lower than 3 kg, staying into the limits of a "light" balloon according to International Civil Aviation Organization regulations.The payloads have been selected by HEMERA Peer Review Group for a flight in 2019 from CNES base in Aire sur l’Adour but operations have been postponed to 2020 for bad weather conditions in both available launch windows. To speed up the operative testing of the units a joint effort has been started with university of Pisa that will hopefully lead to a first launch from Italy in January 2020.Design, calibration activities, functional and thermo-mechanical tests conducted in the University lab are presented along with a rationale of the expected scientific goals when operating in the stratospheric mission.

Introduction Dust is a ubiquitous component of our galaxy and Solar System. The Earth accumulates roughly 100 tons of space dust per day, with dimensions ranging from nanometers up to millimeter [1]. Measurements of dust proper]ties and their distribution provide important information to space science in modelling the birth and growth of the Solar System [2]. The information gained from studying these small particles has been valuable for improving our understanding of the ongoing physical processes of asteroids, comets, Kuiper Belt objects, and planetary rings [3]. The dust particles majority originate within the Solar System, typically are produced by cometary activity or by impacts on planetary or asteroid surfaces. A portion of dust dates back to the birth of the Solar System and a small fraction is of interstellar origin. These particles travel with hypersonic speeds typically in the range 10–70 km/s. The interest to these particles is caused by the fact that they are (1) samples of a distant astonomical bodies, (2) major conrtibutors in the planetary surface growth, and (3) they provide information about the origin and dynamics of the early Solar System GIADA instrument onboard Rosetta/ESA space probe, an example of dust impact sensor. The Grain Impact Analyzer and Dust Accumulator (GIADA) on board the ESA Rosetta probe performed the dynamical study of the dust ejected by the comet 67P/Churyumov-Gerasimenko. [5]. GIADA measured speed, optical cross section and momentum of dust particles larger than 60 μm and the cumulative dust flux for particles smaller than 5 μm. One of the three sub-systems constituting GIADA, the Impact Sensor (IS – Figure 1) [5], measured the momentum of individual dust particle [6]. The GIADA-IS consisted in a squared aluminium plate with a sensitive area of 100 mm x 100 mm, five ceramic piezoelectric sensors (PZTs), with a resonant frequency of 200 kHz, connected to the Al plate (in the plate center and at the 4 corners). A dust particle impact generates the Lamb waves propagating over Al plate.. The PZTs detect these waves and convert them into an electric potential proportional to the particle’s momentum. We propose to include an instrument of similar concept as GIADA-IS in the scientific payload of Comet Interceptor (and cubesats) for measuring dynamical properties of dust. Figure 1 GIADA impact Sensor DISC onboard Comet Interceptor spacecrafts. DISC (Figure 2) is a dust impact sensor, part of Dust Field and Plasma instrument., This instrument will be mounted on two of the three Comet Interceptor (CI) spacecrafts, It will provide an in situ characterization of dust particles in the coma of a Dynamically New Comet or an interstellar object. In particular, it will measure the momentum of individual dust particles during the high-speed CI flyby to its target. From the momentum, knowing the speed of the S/C, individual particle speed is retrieved. DISC overall aims are to determine: dust particle mass distribution; dust particle count; dust particle impact duration; dust particle density/structure; dust coma structures. The sensor capabilities will allow to measure during CI close encounter: dust mass distribution from particles with mass 10-15–10-8 kg ejected from the nucleus (this measurement will be performed by DISC onboard 2 different CI spacecrafts to disentangle the dust flux coming directly from the nucleus and the dust flux of particles reflected by the solar radiation pressure. DISC will be able to count particles with mass >10-15 kg. Despite the difference in physical processes in the hyper speed impacts (the fly by speed of CI will be from 7 to 70 km/s) and low speed impacts (measured by GIADA-IS during Rosetta mission), DISC mechanical configuration will allow provide particles momentum measurements. In fact, the shockwaves generated by the high-speed impacts become Lamb wave (measured by GIADA-IS) in the close proximity of the particle impact point. Figure 2 DISC exploded view. Impact Particle Monitor-a proposed dust sensor for cubesat We propose to equip one of the external panels of a cubesat with PZT transducers. This external panel will act as a dust sensitive surface and will be able to detect and monitor particles impacting the cubesat (Figure 3). This configuration can be applied in different mission scenario: • Low Earth Orbit to monitor μm- to mm-sized debris (high speed impacts) Small exploration cubesat: detection of stable or transient dust structures around small bodies, planets or satellites. In situ detection of dusty or icy plumes with cubesats . Figure 3 ILP mounted on an external face of a 6U Cubesat: left) sensing surface; right) PZT transducers. Acknowledgements This research was supported by the Italian Space Agency (ASI) within the ASI-INAF agreement I/032/05/0. References [1] F.J.M. Rietmeijer, et al. 2016, Laboratory analyses of meteoric debris in the upper stratosphere from settling bolide dust clouds, Icarus, 266, 217-234. [2] M. Fulle, et al. 2016, Comet 67P/Churyumov-Gerasimenko preserved the pebbles that formed planetesimals, Monthly Notices of the Royal Astronomical Society, 462, issue Suppl 1, pp. S132-S137. [3] M. Fulle, et al. 2017, The dust-to-ices ratio in comets and Kuiper belt objects, Monthly Notices of the Royal Astronomical Society, Mon. Not. R. Astron. Soc., 469 (Suppl_2): S45-S49 [4] Della Corte et al. 2014 GIADA: its status after the Rosetta cruise phase and on ground activity in support of the encounter with comet 67P/Churyumov-Gerasimenko, Journal of Astronomical Instrumentation [5] Esposito et al. 2002, Physical aspects of an Impact Sensor for the detection of cometary dust momentum onboard the Rosetta Space mission. Adv. Space Research. [6] Della Corte, V. et al., 2016, 67P/C-G Inner Coma dust properties from 2.2 AU inbound to 2 AU outbound to the Sun, Monthly Notices of the Royal Astronomical Society, 462, pp. S210-S219.

The Earth Space Elevator is an ingenious concept aimed at providing easy access to space, eliminating the need for rockets and potentially reducing drastically the launch costs. Technical advancements that could make the Space Elevator possible, among others, would be the availability of long carbon nanotubes or other super-strong and light material. This paper aims at addressing issues related with the stability of the system when the elevator is partially deployed starting from a nucleus in geostationary orbit (GEO). As noted by various authors, the energy increase needed to keep the orbital centre (where the gravity and centrifugal forces balance out) at GEO altitude during deployment while the tether is lengthened leads to an orbit with a positive orbital energy, i.e., the circular orbit has an energy level pertaining to a hyperbolic orbit. This situation leads to the instability of the unanchored system that would tend to escape from the geostationary orbit. The paper illustrates the change in orbital energy during assembly for a system made of a cylindrical tether and then investigate the stability of the coupled orbital and attitude motion in the orbital plane before anchoring. The analysis leads to the conclusion that the orbital motion instability ensues well before the orbital energy of the unperturbed system becomes positive.

In avalanche rescues, quick operations make a real difference between survival or death. Organized search and rescue operations require large intervention time since professionals are not directly present in the distressed area. For this reason, companion rescue is still the most effective option for localizing and extracting people involved in avalanche incidents. In this context autonomous drones equipped with avalanche transceivers can assist ground operations by reducing localization time, therefore increasing the survival rate. In this paper, technologies and strategies for avalanche rescue with autonomous drones are introduced and their performances are assessed with respect to operational scenarios. In particular, avalanche transceivers operability on board of small autonomous vehicles is evaluated and optimal beacon search trajectories are investigated.

Full list of authors: Cremonese, G.; Capaccioni, F.; Capria, M. T.; Doressoundiram, A.; Palumbo, P.; Vincendon, M.; Massironi, M.; Debei, S.; Zusi, M.; Altieri, F.; Amoroso, M.; Aroldi, G.; Baroni, M.; Barucci, A.; Bellucci, G.; Benkhoff, J.; Besse, S.; Bettanini, C.; Blecka, M.; Borrelli, D.; Brucato, J. R.; Carli, C.; Carlier, V.; Cerroni, P.; Cicchetti, A.; Colangeli, L.; Dami, M.; Da Deppo, V.; Della Corte, V.; De Sanctis, M. C.; Erard, S.; Esposito, F.; Fantinel, D.; Ferranti, L.; Ferri, F.; Ficai Veltroni, I.; Filacchione, G.; Flamini, E.; Forlani, G.; Fornasier, S.; Forni, O.; Fulchignoni, M.; Galluzzi, V.; Gwinner, K.; Ip, W.; Jorda, L.; Langevin, Y.; Lara, L.; Leblanc, F.; Leyrat, C.; Li, Y.; Marchi, S.; Marinangeli, L.; Marzari, F.; Mazzotta Epifani, E.; Mendillo, M.; Mennella, V.; Mugnuolo, R.; Muinonen, K.; Naletto, G.; Noschese, R.; Palomba, E.; Paolinetti, R.; Perna, D.; Piccioni, G.; Politi, R.; Poulet, F.; Ragazzoni, R.; Re, C.; Rossi, M.; Rotundi, A.; Salemi, G.; Sgavetti, M.; Simioni, E.; Thomas, N.; Tommasi, L.; Turella, A.; Van Hoolst, T.; Wilson, L.; Zambon, F.; Aboudan, A.; Barraud, O.; Bott, N.; Borin, P.; Colombatti, G.; El Yazidi, M.; Ferrari, S.; Flahaut, J.; Giacomini, L.; Guzzetta, L.; Lucchetti, A.; Martellato, E.; Pajola, M.; Slemer, A.; Tognon, G.; Turrini, D. -- This is an open access article, The SIMBIO-SYS (Spectrometer and Imaging for MPO BepiColombo Integrated Observatory SYStem) is a complex instrument suite part of the scientific payload of the Mercury Planetary Orbiter for the BepiColombo mission, the last of the cornerstone missions of the European Space Agency (ESA) Horizon + science program. The SIMBIO-SYS instrument will provide all the science imaging capability of the BepiColombo MPO spacecraft. It consists of three channels: the STereo imaging Channel (STC), with a broad spectral band in the 400-950 nm range and medium spatial resolution (at best 58 m/px), that will provide Digital Terrain Model of the entire surface of the planet with an accuracy better than 80 m; the High Resolution Imaging Channel (HRIC), with broad spectral bands in the 400-900 nm range and high spatial resolution (at best 6 m/px), that will provide high-resolution images of about 20% of the surface, and the Visible and near-Infrared Hyperspectral Imaging channel (VIHI), with high spectral resolution (6 nm at finest) in the 400-2000 nm range and spatial resolution reaching 120 m/px, it will provide global coverage at 480 m/px with the spectral information, assuming the first orbit around Mercury with periherm at 480 km from the surface. SIMBIO-SYS will provide high-resolution images, the Digital Terrain Model of the entire surface, and the surface composition using a wide spectral range, as for instance detecting sulphides or material derived by sulphur and carbon oxidation, at resolutions and coverage higher than the MESSENGER mission with a full co-alignment of the three channels. All the data that will be acquired will allow to cover a wide range of scientific objectives, from the surface processes and cartography up to the internal structure, contributing to the libration experiment, and the surface-exosphere interaction. The global 3D and spectral mapping will allow to study the morphology and the composition of any surface feature. In this work, we describe the on-ground calibrations and the results obtained, providing an important overview of the instrument performances. The calibrations have been performed at channel and at system levels, utilizing specific setup in most of the cases realized for SIMBIO-SYS. In the case of the stereo camera (STC), it has been necessary to have a validation of the new stereo concept adopted, based on the push-frame. This work describes also the results of the Near-Earth Commissioning Phase performed few weeks after the Launch (20 October 2018). According to the calibration results and the first commissioning the three channels are working very well. © 2020, The Author(s)., We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0. The SIMBIO-SYS instrument has been developed by Leonardo under ASI contract I/054/10/0.

The paper presents the calibration activity of the imaging system of an autonomous sensor suite designed for monitoring light pollution which, thanks to its extremely compact design, can be carried by drones or small balloons. Drones and air balloons can in fact play an important role in completing light emission measurement from satellites, allowing an increased spatial and time resolution from convenient altitudes and positions. The proposed sensor suite is able to measure the luminous intensity of polluting sources and their spectral power density with a wavelength resolution which allows to identify the different lamp technology used in street lighting. By operating over a limited area, the spatial resolution can be about tenths of meter and the time evolution of the luminosity can be measured over hours. The expected performance of imaging system has been verified through an extensive laboratory test activity allowing calibration with referenced light sources. The calibration of the multi-luminance meter allows measurements with a base uncertainty of about 5% of the reading. The multispectrometer has a FWHM equal to 10 nm and is able to measure the power density of the outdoor light source in the range between 400 nm and 700 nm.

International audience; The entry, descent and landing of Schiaparelli, the ExoMars Entry, descent and landing Demonstrator Module (EDM), offered a rare (once-per-mission) opportunity for in situ investigations of the martian environment over a wide altitude range. The aim of the ExoMars AMELIA experiment was to exploit the Entry, Descent and Landing System (EDLS) engineering measurements for scientific investigations of Mars’ atmosphere and surface. Here we present the simulations, modelling and the planned investigations prior to the Entry, Descent and Landing (EDL) event that took place on 19th October 2016. Despite the unfortunate conclusion of the Schiaparelli mission, flight data recorded during the entry and the descent until the loss of signal, have been recovered. These flight data, although limited and affected by transmission interruptions and malfunctions, are essential for investigating the anomaly and validating the EDL operation, but can also contribute towards the partial achievement of AMELIA science objectives

International audience; The first of the two missions foreseen in the ExoMars program was successfully launched on 14th March 2016. It included the Trace Gas Orbiter and the Schiaparelli Entry descent and landing Demonstrator Module. Schiaparelli hosted the DREAMS instrument suite that was the only scientific payload designed to operate after the touchdown. DREAMS is a meteorological station with the capability of measuring the electric properties of the Martian atmosphere. It was a completely autonomous instrument, relying on its internal battery for the power supply. Even with low resources (mass, energy), DREAMS would be able to perform novel measurements on Mars (atmospheric electric field) and further our understanding of the Martian environment, including the dust cycle. DREAMS sensors were designed to operate in a very dusty environment, because the experiment was designed to operate on Mars during the dust storm season (October 2016 in Meridiani Planum). Unfortunately, the Schiaparelli module failed part of the descent and the landing and crashed onto the surface of Mars. Nevertheless, several seconds before the crash, the module central computer switched the DREAMS instrument on, and sent back housekeeping data indicating that the DREAMS sensors were performing nominally. This article describes the instrument in terms of scientific goals, design, working principle and performances, as well as the results of calibration and field tests. The spare model is mature and available to fly in a future mission.

On 19th October 2016 Schiaparelli module of the ExoMars 2016 mission flew through the Mars atmosphere. After successful entry and descent under parachute, the module failed the last part of the descent and crashed on the Mars surface. Nevertheless the data transmitted in real time by Schiaparelli during the entry and descent, together with the entry state vector as initial condition, have been used to reconstruct both the trajectory and the profiles of atmospheric density, pressure and temperature along the traversed path.\ud \ud The available data-set is only a small sub-set of the whole data acquired by Schiaparelli, with a limited data rate (8 kbps) and a large gap during the entry because of the plasma blackout on the communications.\ud \ud This paper presents the work done by the AMELIA (Atmospheric Mars Entry and Landing Investigations and Analysis) team in the exploitation of the available inertial and radar data. First a reference trajectory is derived by direct integration of the inertial measurements and a strategy to overcome the entry data gap is proposed. First-order covariance analysis is used to estimate the uncertainties on all the derived parameters. Then a refined trajectory is computed incorporating the measurements provided by the on-board radar altimeter.\ud \ud The derived trajectory is consistent with the events reported in the telemetry and also with the impact point identified on the high-resolution images of the landing site.\ud \ud Finally, atmospheric profiles are computed tacking into account the aerodynamic properties of the module. Derived profiles result in good agreement with both atmospheric models and available remote sensing observations.

This paper presents the concept of a dual cubesat mission designed for Moon exploration that enables scientific measurements that are not accessible by high orbital or landed missions thanks to the use of a long passive tether for orbital insertion. Due to the intrinsic characteristic of the Moon environment, low altitude orbiting spacecrafts are in fact requested for mapping key parameters such as plasma, volatiles and magnetic field. Inserting a satellite in such low trajectories from an orbiter has usually a high cost of propellant to achieve the orbit change or requires a long time to finalize the maneuver with electrical propulsive systems. Limitations are even higher for cubesats that have very limited capacity for orbital adjustment, so they cannot perform substantial orbital changes by using classical propulsive techniques. The use of a long passive tether to exchange momentum between two cubesats can eliminate such drawbacks and provide fast, far-reaching and accurate orbital changes with almost no propellant being consumed. A mission scenario is presented with the two mated cubesats released by an orbiter in circular Moon orbit at 500 km altitude. Thanks to the momentum exchanges provided by the swinging tether the upper cubesat will be left in a 520 × 737 km orbit and the lower cubesat into a 460 × 26 km orbit with a low periselenium that provides an ideal altitude for close observation of the lunar surface and monitoring of characteristic parameters of the Moon environment. With a high-inclination orbit, the low-altitude orbital passes will map the entire Moon surface in around 14 days. The upper cubesat will be transferred on a highly predictable and low-perturbation orbit and equipped with laser corner reflectors and a radio link band transponder to allow tracking both from laser stations on Earth (Matera, Italy ASI geodesy station) and from the Lunar Orbiter via radio link. The integrated analysis with radio signals between Cubesats can also be used to improve orbit determination and study perturbation effects on orbital dynamics.

Light pollution is becoming more and more an issue not only for astronomical observations but also for the quality of human life. Global light emission from surface light sources is best detected by satellites. However, drones and air ballloons can play important roles in taking local measurements from convenient altitudes and positions. The scope of this paper is to define a technique for carrying out light monitoring at relatively low altitudes with drones and airballoons. The sensor suite proposed will be able to measure the luminous intensity of polluting sources and their spectral power density with a wavelength resolution which allows to identify the different lamp technology used in street lighting. By operating over a limited area, the spatial resolution can be about tenths of meter and if tethered balloons are used, the time evolution of the luminosity can be measured over many hours. The paper discusses the sensor suite, the expected performance and issues related to operating the sensors on board drones and airballoons.

On the 19th October 2016, Schiaparelli, the Entry Demonstrator Module (EDM) of the ESA ExoMars Program entered into the martian atmosphere. Although it did not complete a safe landing on Mars, it transmitted data throughout its descent to the surface, until the loss of signal at 1 minute before the expected touch-down on Mars' surface. The main objective of the Atmospheric Mars Entry and Landing Investigations and Analysis (AMELIA) experiment was the assessment of the atmospheric science and landing site by exploiting the Entry Descent and Landing System (EDLS) sensors of Schiaparelli beyond their designed role of monitoring and evaluating the performance of the EDL technology demonstrator. Although more limited than expected, the flight data received from Schiaparelli are essential to investigate the anomaly that caused the crash landing and for the achievement of the AMELIA scientific objectives. We will present our methodology and results for the reconstruction of the dynamics of the vehicles during the EDL phases from the available flight data in order to assess the trajectory and attitude of the Schiaparelli EDM and to retrieve the atmospheric profiles.

The focus of the project is to create new approaches to the study of the past through the use of innovative aero-space technologies to measure, analyse and reconstruct the ancient landscape and its remaining natural and anthropic traces. The equipe, based at the University of Padua, is constituted by archaeologists, egyptologists, mechanical and software engineers, physicists and computer scientists and is now active on the proto-historic site of Rozto in Italy. The research includes the analysis of the historical records, as old maps and aerial photographs of the past, field use of drones and the creation of a GIS platforms to collect and see the data all together.

DREAMS (Dust Characterisation, Risk Assessment, and Environment Analyser on the Martian Surface) is a payload accommodated on the Schiaparelli Entry and Descent Module (EDM) of ExoMars 2016, the ESA - Roscosmos mission to Mars successfully launched on 14 March 2016. The DREAMS data will be archived and distributed to the scientific community through the ESA's Planetary Science Archive (PSA). All data shall be compliant with NASA's Planetary Data System (PDS4) standards for formatting and labelling files. This paper summarizes the format and content of the DREAMS data products and associated metadata. The pipeline to convert the raw telemetries to the final products for the archive is sketched as well.

After having observed the planets from his house in Padova using his telescope, in January 1611 Galileo wrote to Giuliano de Medici that Venus is moving around the Sun as Mercury. Forty years ago, Giuseppe Colombo, professor of Celestial Mechanics in Padova, made a decisive step to clarify the rotational period of Mercury. Today, scientists and engineers of the Astronomical Observatory of Padova and of the University of Padova, reunited in the Center for Space Studies and Activities (CISAS) named after Giuseppe Colombo, are busy to realize a stereo camera (STC) that will be on board the European (ESA) and Japanese (JAXA) space mission BepiColombo, devoted to the observation and exploration of the innermost planet. This paper will describe the stereo camera, which is one of the channels of the SIMBIOSYS instrument, aiming to produce the global mapping of the surface with 3D images.

The Huygens Atmospheric Structure Instrument (HASI) [Fulchignoni, M., Ferri, F., Angrilli, F., Bar-Nun, A., Barucci, M.A., Bianchini, G., Borucki, W., Coradini, M., Coustenis, A., Falkner, P., Flamini, E., Grard, R., Hamelin, M., Harri, A.M., Leppelmaier, G.W., Lopez-Moreno, J.J., McDonnell, J.A.M., McKay, C.P., Neubauer, F.M., Pedersen, A., Piacardi, G., Pirronello, V., Schwingenschuh, K., Seiff, A., Svedhem, H., Vanzani, V., Zarnecki, J.C., 2002. The characterisation of Titan atmosphere physical properties. Space Sci. Rev. 104, 395–431] was a very complete instrument suite installed on board the Huygens probe, the planetary lander of the Cassini Huygens Mission to Saturn system, which successfully completed its mission in January 2005. HASI comprised a set of accelerometers, temperature sensors, pressure transducers and permittivity analysers aimed at the investigation of Titan atmosphere, which were fully operative during a several hour-long parachuted descent from an altitude of 157 km to planetary surface. Accelerometers were the only instruments activated earlier, just after Cassini separation, and recorded data during all the mission phases from atmospheric entry to landing, providing essential information for elaborating probe trajectory as well as Titan atmospheric profiles [G. Colombatti, et al. Reconstruction of the trajectory of the Huygens probe using the Huygens Atmospheric Structure Instrument, this same PSS issue]. Although not specifically designed for monitoring very fast dynamic events, HASI accelerometers have also recorded the trace of probe impact with the planetary surface, building up along with the data from Huygens Surface Science Package (SSP) instrument [ Zarnecki, J.C., Leese, M.R., Garry, J.R.C., Ghafoor, N.A.L., Hathi, B., 2002. Huygens Surface Science Package. Space Sci. Rev. 104, 593–611 ] the only set of direct measurements of the mechanical properties of the Titan soil. Though not considered secondary with respect to SSP data, HASI data provide peculiar information related to the dynamic response of the whole Huygens probe when impacting the surface, whereas the SSP data were collected mainly by sensors located on a small penetrometer below the main probe dome. Therefore, although having a sensibly lower sampling frequency, HASI Accelerometer Subsystem (ACC) data complete the information of SSP data in the study of impact deceleration profiles, which can provide key information for the estimation of the mechanical parameters of the soil and get an insight of its consistency and composition. In the analysis of Huygens mission data some unexpected features were present in the ACC data sets, so a dedicated study was needed to investigate the presence of dynamic interferences during an acquisition and correct the impact signature. The developed method is based on dynamic analysis of the impact through a three-dimensional finite-element dynamic model of the Huygens probe and the results lead to a corrected interpretation of accelerometer readings and provided an improved description of key aspects of the planetary landing. Although some aspects of probe's state after impact need some further analysis, as for final resting attitude which is to date not completely agreed on, this study disclosed that the probe experienced a vertical decelerating action which is compatible with two possible scenarios: the first one implies the penetration in a soft substrate material followed by a lateral bounce out of the generated hole and the second one suggests the displacement of pebbles from the surface into the soil. Numerical elaboration of impact data calculated a 12 cm penetration into the surface, which may have been experienced either by the lower dome of the probe or from pebbles that were situated under the dome when contacting the planet. In either case after a few seconds of motion the Huygens probe finally rested above Titan's surface with a negligible penetration. Since HASI piezo-accelerometer design was driven by the need of high full-scale values to monitor critical events during entry and descent phase, it was not possible to reconstruct horizontal motion after main deceleration phase without consistent uncertainties due to the poor overall accuracy in a low-acceleration range.

This work presents an analysis and validation of a foldable boom actuated by tape-spring foldable elastic hinges for space applications. The analytical equations of tape-springs are described, extending the classical equations for isotropic materials to orthotropic carbon-fiber composite materials. The analytical equations which describe the buckling of the hinge have been implemented in a multibody simulation software where the hinge was modeled as a nonlinear elastic bushing and the boom as a rigid body. In the experimental phase, the boom was fabricated using a thin layer carbon-fiber composite tube, and the residual vibrations after deployment were experimentally tested with a triaxial accelerometer. A direct comparison of the simulation with the physical prototype pointed out the dangerous effect of higher order vibrations which are difficult to capture in simulation. We observed that while the vibrational spectra of simulations and experiments were compatible at low frequencies during deployment, a marked difference was observed at frequencies beyond 30 Hz. While difficult to model, higher order frequencies should be carefully accounted for in the design of self-deployable space structures. Indeed, if tape-springs are used as a self-locking mechanism, the higher vibrational modes could have enough energy to unlock the structure during operation.

The Nimbus Project team, made of young engineers and university students, is developing an Autonomous Re-Entry System (ARES) based on a controlled paraglider. The target is to use the ARES to autonomously recover a reusable sounding rocket in a specific area dedicated for landing. The system is mainly divided in two parts: the paraglider wing with a traditional configuration of a ram-air parachute and the control box which houses the main control electronics. Furthermore, the sounding rocket is attached to the control box and a ground station receives telemetry or sends telecommands for both the rocket and the control box. In order to test the system in-flight independently from the launch of a rocket, a fully functional Technology Demonstrator has been developed. It is built from Commercial-Off-The-Shelf items and components and from custom composite parts. The mass of the wing is about 200g for a surface of 1.1m2 and the control box mass is 550g. The electronics communicates through telemetry and telecommands with a ground PC. Attitude and position sensors are used in the control loop and three modes of operation can be selected. The ARES has been already flight tested in direct control mode.

Sounding rockets are a widely used test bench in the aerospace field that allow the testing of a huge quantity of products, parts ed experiments. However they are often expensive and require a long development cycle before launch. In this scenario, the Nimbus project team has developed a sounding rocket with the main purpose of engineering a reusable, cost-effective test bench, which is scalable to carry heavier payloads. It has already flown multiple times and, since the first version of the rocket, many upgrades have been introduced in order to improve its performances. To demonstrate its reusability in a short time, the rocket has been launched twice in two consecutive days.

The low-frequency data collected with the antenna of the Permittivity, Wave and Altimetry experiment on board the Huygens Probe that landed on Titan on 14 January 2005 have been thoroughly analyzed considering different possible natural and artificial effects. Although a definite conclusion is still subject to the outcome of complementary inquiries, it results from our analysis that the observations can be explained, for the most part, in term of natural phenomena rather than being artifacts. Extremely-low frequency waves generated in the ionosphere of Titan, driven by the corotating Saturn's frozen plasma flow, are assumed to be the most likely source for the observation of the second eigenmode of a Schumann-like resonance at around 36 Hz in the moon-ionosphere cavity. This particular mode is thought to be enhanced with respect to other harmonics because of the particular location of the landing site with respect to that of the supposed sources. The power budget of the observed wave amplitude seems to be consistent with a rough model of the global current of the wake-ionosphere circuit. Broadband low-frequency noise events which are observed sporadically during the descent are probably due to shot noise on the antenna when the Probe is crossing aerosol clouds, an interpretation supported by post-flight ground tests. Contrary to the situation encountered on Earth, atmospheric lightning does not appear to be the source of a conventional Schumann resonance on Titan.

We developed a series of balloon experiments parachuting a 1:1 scale mock-up of the Huygens probe from an altitude just over 30 km to simulate at planetary scale the final part of the descent of the probe through Titan's lower atmosphere. The terrestrial atmosphere represents a natural laboratory where most of the physical parameters meet quite well the bulk condition of Titan's environment, in terms of atmosphere composition, pressure and mean density ranges, though the temperature range will be far higher. The probe mock-up consists of spares of the HASI sensor packages, housekeeping sensors and other dedicated sensors, and also incorporates the Huygens Surface Science Package (SSP) Tilt sensor and a modified version of the Beagle 2 UV sensor, for a total of 77 acquired sensor channels, sampled during ascent, drift and descent phase. An integrated data acquisition and instrument control system, simulating the HASI data-processing unit (DPU), has been developed, based on PC architecture and soft-real-time application. Sensor channels were sampled at the nominal HASI data rates, with a maximum rate of 1 kHz . Software has been developed for data acquisition, onboard storage and telemetry transmission satisfying all requests for real-time monitoring, diagnostic and redundancy. The mock-up of the Huygens probe mission was successfully launched for the second time (first launch in summer 2001, see Gaborit et al., 2001) with a stratospheric balloon from the Italian Space Agency Base “Luigi Broglio” in Sicily on May 30, 2002, and recovered with all sensors still operational. The probe was lifted to an altitude of 32 km and released to perform a parachuted descent lasting 53 min , to simulate the Huygens mission at Titan. Preliminary aerodynamic study of the probe has focused upon the achievement of a descent velocity profile reproducing the expected profile of Huygens probe descent into Titan. We present here the results of this experiment discussing their relevance in the analysis of the data which will be obtained during the Huygens mission at Titan.

The Nimbus Project team, made of young engineers and university students, has developed a sounding rocket with the main aim to engineer a reusable, cost-effective test bench. This makes it possible to field test many aerospace technologies as guidance or reentry systems, enable airborne atmospheric measurements and high altitude students' experiments. The modular architecture allows the use of different payloads, composite material structures increase lightness while off-the-shelf components reduce costs; ease of transportation and usability qualify it as an extremely versatile platform. The system is scalable to carry heavier payloads and to perform scientific tests at higher altitudes. The technology demonstrator is going to reach an altitude of 1000m with cost-effective technology and components. Demonstrator's subsystems (rocket motor, main frame, chute deploy system, etc) have been both ground and flight tested and have shown an optimal accordance between theoretical model and testing. The demonstrator launch took place on 29th March 2015.

A vision based method for position and orientation measurement of a multi body system is described. The measurement procedure comprises a combination of modern image analysis techniques such as Inverse Perspective Mapping, Normalized Cross Correlation, and Kalman filter tracking of multiple markers. The described approach is applied to measure the rapid motion of a complex system such as a deployable antenna for space applications and can easily be employed for other applications. A key feature of the described work is a detailed analysis of the main uncertainty sources and of their effects on the measurement results.

This paper describes the Electrical Ground Support Equipment (EGSE) developed for automatic tests of DREAMS (Dust characterization, Risk assessment, and Environment Analyser on the Martian Surface), that is the only surface payload package to be accommodated on the Entry, Descendent and landing Module (EDM) of the ExoMars 2016 mission to Mars, developed by the European Space Agency (ESA) in collaboration with the Russian Federal Space Agency (Roscosmos).

This paper describes the Electrical Ground Support Equipment (EGSE) of the Dust characterization, Risk assessment, and Environment Analyser on the Martian Surface (DREAMS) scientific instrument, an autonomous surface payload package to be accommodated on the Entry, Descendent and landing Module (EDM) of the ExoMars 2016 European Space Agency (ESA) mission. DREAMS will perform several kinds of measurements, such as the solar irradiance with different optical detectors in the UVA band (315-400nm), NIR band (700-1100nm) and in "total luminosity" (200 –1100 nm). It will also measure environmental parameters such as the intensity of the electric field, temperature, pressure, humidity, speed and direction of the wind. The EGSE is built to control the instrument and manage the data acquisition before the integration of DREAMS within the Entry, Descendent and landing Module (EDM) and then to retrieve data from the EDM Central Checkout System (CCS), after the integration. Finally it will support also the data management during mission operations. The EGSE is based on commercial off-the-shelf components and runs custom software. It provides power supply and simulates the spacecraft, allowing the exchange of commands and telemetry according to the protocol defined by the spacecraft prime contractor. This paper describes the architecture of the system, as well as its functionalities to test the DREAMS instrument during all development activities before the ExoMars 2016 launch.

International audience; The limited knowledge about the majority of the Mercury surface leaves many open questions regarding its geological evolution, the anomalously high metal/silicate ratio, the magnetic field generation and exosphere evolution. An integrated suite of instruments, Spectrometer and Imagers for MPO BepiColombo-Integrated Observatory SYStem (SIMBIO-SYS), which includes a stereo imaging system (STC), a high-resolution imager (HRIC) and a visible-near-infrared imaging spectrometer (VIHI), has been selected for the ESA BepiColombo mission to Mercury. SIMBIO-SYS will scan the hermean surface with the three channels and map the physical, morphological, tectonic and compositional properties of the entire planet. The availability of high-resolution images will unveil details of specific target at an unprecedented resolution. The main scientific objectives and performances along with technical characteristics of SIMBIO-SYS are described in this paper.

In May 2009 we have submitted to ESA a Declaration of Interest for a camera package to be place d onboard the ESA-led Jupiter Ganymede Orbiter, the JGO-WASC (JGO Wide Angle and Stereo Cameras). The camera package we are proposing includes the wide angle and the medium resolution cameras (WAC and MRC), that will be used for the scientific investigation and imaging exploration of the Jovian system and Ganymede in the visible spectral range (350-1050nm) and in stereo mode. The study will be carried out by a consortium currently led by INAF-OAPD (Italy) and including INAF-IFSI (Italy), INAF-IASF (Italy), CISAS & DEI & dep.Geosciences & dep. Physics-University of Padova (Italy), University Parthenope Napoli (Italy), INAF-OAC Napoli (Italy), IAS-Orsay (France), Free University of Berlin (Germany), IAA-CSIC Granada (Spain), DLR Berlin (Germany), Technical University Berlin (Germany), University of Muenster (Germany), University of Colorado Boulder (USA), ISAS-JAXA Kanagawa (Japan), Galileo Avionica (Italy).

A medium-power (1.5 kW) plasma thruster based on a helicon source is considered as a candidate for primary space propulsion. A high-density plasma is produced by the use of a radio frequency (RF) transmitting antenna, which produces helicon waves to ionize a neutral gas (e.g., argon, krypton, xenon, helium or hydrogen) flowing through a tube and confined by a magnetic field. The plasma is accelerated through a potential drop created by a divergent magnetic field, giving a sudden reduction in electron density (and hence plasma potential) very close to the open end of the source tube. The plasma may then expand through a "magnetic nozzle" into the vacuum. Numerical studies are conducted by CISAS in order to investigate the physics connected with the potential drop. The analysis is conducted through a combination of 1-D and 2-D numerical codes. The PPDL code is developed and used for the 1-D analysis. The main features of the code are: hybrid Boltzmann electron/drift-kinetic ion, inclusion of dominant 2-D effects, and high computational efficiency thorough implicit non linear Boltzmann solver. The 2-D analysis is performed with XOOPIC, an open source code available from Berkeley University. The combined approach is very useful since the 1-D code is used to screen many different experimental conditions and to identify the correct boundary conditions. The 2-D code is then used to refine 1-D results. The two models, combined with a global model, specifically developed to simulate the plasma reaction inside the plasma source, are run through genetic algorithms to identify an optimal thruster configuration in the 1500-W power regime. In addition, the thruster is thermally and mechanically sized.

International audience; The Huygens probe returned scientific measurements from the atmosphere and surface of Titan on 14 January 2005. Knowledge of the trajectory of Huygens is necessary for scientific analysis of those measurements. We use measurements from the Huygens Atmospheric Structure Instrument (HASI) to reconstruct the trajectory of Huygens during its mission. The HASI Accelerometer subsystem measured the axial acceleration of the probe with errors of 3E-6 m s -2, the most accurate measurements ever made by an atmospheric structure instrument on another planetary body. The atmosphere was detected at an altitude of 1498 km. Measurements of the normal acceleration of the probe, which are important for determining the probe's attitude during hypersonic entry, were significantly less accurate and limited by transverse sensitivity of the piezo sensors. Peak acceleration of 121.2 m s -2 occurred at 234.9 km altitude. The parachute deployment sequence started at 157.1 km and a speed of 342.1 m s -1. Direct measurements of pressure and temperature began shortly afterwards. The measured accelerations and equations of motion have been used to reconstruct the trajectory prior to parachute deployment. Measured pressures and temperatures, together with the equation of hydrostatic equilibrium and the equation of state, have been used to reconstruct the trajectory after parachute deployment. Uncertainties in the entry state of Huygens at the top of the atmosphere are significant, but can be reduced by requiring that the trajectory and atmospheric properties be continuous at parachute deployment.

Space robotics currently has an important role in space operations and scientists and engineers are designing new robotic systems for space servicing missions and extra-vehicular activities. In particular, free-flying robots with extended arms have compelling applications and several prototypes have recently been developed. Testing on Earth free-flying robots is a main issue as the unconstrained environment of free space must be simulated. From the experience acquired by testing a free-flying robot prototype both in a tethered facility and during a parabolic flight campaign, and after several years of experiments using air-bearing planar systems, the authors describe and discuss methods to test free-flying robots. A recent study aimed at designing a free-flying platform suitable for an under-water environment is also presented and discussed.

International audience; In the framework of the activities going on in preparation for the mission of the Huygens probe in Titan's atmosphere (January 2005), the Huygens Atmospheric Structure Instrument (HASI) team scheduled and performed several balloon campaigns to test the HASI sensors' performance in flight conditions in the Earth's atmosphere. In particular, pressure conditions reached during each test are similar to those expected in Titan's lower atmosphere. A 1:1 scaled mock-up of the Huygens probe was launched with a stratospheric balloon in 2001 (Br. Assoc. Adv. Sci. 33 (2001) 1109) and in 2002 (Br. Assoc. Adv. Sci. 34 (2002) 911; Adv. Space. Sci. (2003)) from the G. Broglio base of the Italian Space Agency, located in Trapani Milo (Sicily). In both cases the mock-up was dropped from an altitude higher than 27 and 32 km, respectively, and recovered on the ground after a parachuted descent. In this paper, we describe the results obtained in reconstructing (i) the probe descent trajectory and (ii) the profiles of the physical quantities characterizing the Earth's atmosphere, on the basis of a complete analysis of the data obtained during the HASI 2002 balloon flight experiment. Using temperature and pressure measurements, we are able to reach an accuracy of the order of 0.5% on the altitude reconstruction during the descent. We validate both the models used for trajectory reconstruction and to check the sensors' performance. We describe the problems faced in determining the Huygens probe descent trajectory in Titan's atmosphere focusing our discussion on the critical aspects of the descent reconstruction (such as the uncertainties due to measurement errors, limited knowledge of the atmospheric composition, etc.) and the validity of the adopted assumptions.