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BepiColombo mission will provide Digital Terrain Models of the surface of Mercury by means of the stereo channel of the SIMBIO-SYS (Spectrometer and Imaging for MPO BepiColombo Integrated Observatory SYStem) imaging package onboard. The work here described presents a novel approach for the creation of higher resolution stereo products using the high-resolution channel of SIMBIO-SYS. Being the camera rigidly integrated with the spacecraft, this latter must be tilted to acquire stereo pairs necessary for the 3D reconstruction. A new method for image simulation and stereo reconstruction is presented in this work, where the input data are chosen as closely as possible to the real mission parameters. Different simulations are executed changing the illumination conditions and the stereo angles. The Digital Terrain Models obtained are evaluated and an analysis of the best acquisition conditions is performed, helping to improve the image acquisition strategy of BepiColombo mission. In addition, a strategy for the creation of a mosaic from different images acquired with the high-resolution channel of SIMBIO-SYS is explained, giving the possibility to obtain tridimensional products of extended targets.

Landslides have been identified on several solar system bodies, and different mechanisms have been proposed to explain their runout length. We analyze images from the Rosetta mission and report the global characterization of such features on comet 67P/Churyumov‐Gerasimenko's surface. By assuming the height to runout length as an approximation for the friction coefficient of landslide material, we find that on comet 67P, this ratio falls between 0.50 and 0.97. Such unexpected high values reveal a rocky‐type mechanical behavior that is much more akin to Earth dry landslides than to icy satellites' mass movements. This behavior indicates that 67P and likely comets in general are characterized by consolidated materials possibly rejecting the idea that they are fluffy aggregates. The variability of the runout length among 67P landslides can be attributed to the different volatile content located in the top few meters of the cometary crust, which can drive the mass movement. Comet 67P Churyumov‐Gerasimenko has been imaged with unprecedented spatial detail thanks to the high‐resolution OSIRIS camera (Optical, Spectroscopic and Infrared Remote Imaging System) on board the Rosetta spacecraft. 67P is characterized by an extremely diverse morphology comprising different surface features such as rough consolidated terrains, smooth plains, unconsolidated mantles, pits, fractures, cliffs, cuestas, ubiquitous boulders, and layers. The peculiarity of 67P is also reflected by the widespread presence of landslides. By using high‐resolution images, we analyze the shape and aspect ratio of the landslides located on comet 67P finding a mechanical behavior of the cometary material that is more akin to Earth dry landslides than to icy satellites' mass movements. These results make 67P a very peculiar object, mainly composed by ices and refractory materials but characterized by rocky‐type properties rather than icy‐type characteristics. In addition, the considerable variability among the different landslides of 67P suggests that different volatile contents located in the top few meters of the cometary crust play a fundamental role on mass movement, hence being a general indicator for the subsurface cometary heterogeneities. The height to runout length (H/L) of comet 67P/Churyumov‐Gerasimenko landslides ranges between 0.50 and 0.9767P landslide reveal a rocky‐type mechanical behavior indicating that comets are made by consolidated materialsThe H/L variability is an indicator of the different volatile content located in the top few meters of the cometary crust

A future mission to return to Titan after Cassini/Huygens has now a really high priority for planetary exploration. Recent Cassini discoveries have revolutionized our understanding of the Titan system and its potential for harboring the ingredients necessary for life. These discoveries reveal that Titan is one of the most exciting places in the solar system; data show a complex environment, both for the atmosphere and for the surface. The data obtained, enriched by continuing observations from the Cassini spacecraft, show hydrocarbon lakes, river channels and drainage basins, sand dunes, cryovolcanos and sierras. All these features demonstrate that dynamic processes are present on Titan and have raised the scientific interest in a follow-up mission to Titan. A robotic lighter-than-air vehicle has been suggested as a possible platform for an extensive exploration of the moon. NASA centers and universities around the US, as well as the European Space Agency, are studying the possibility of sending, as part of the next mission to this giant moon of Saturn, a hot-air balloon or similar for further and more in-depth exploration. Several patents cover different aspects of airship subsystems, such as design, propulsion and energy production; here we discuss some critical aspects taking into account the outcomes of our work. Recent studies on airships have demonstrated the high capability of airships to be considered as scientific platforms for extended explorations, both in space and time, on planets with atmosphere. Here we analyze the dynamics of the airship in response to the encountered Titan's environment. Possible trajectories for an extended survey of the moon are investigated; these allow us to have a precise quantitative analysis of the energy necessary for a journey on the moon. Analysis on stability is performed in order to check the possible scientific slot windows available for investigations. A 1.2 km x 1.4 km region is selected as baseline: time necessary for performing a complete survey is investigated. Investigations are conducted both in a quiet situation with no wind and in wind conditions. Trajectories are followed with airship at 1.5, 3, 5 and 7 m/s velocities; surface science ( < 100 m) scenarios are proposed. Considered winds are in the range 0.0 - 1 m/s parallel and orthogonal to the ground track.

In this paper, the results of the thermo-elastic analysis performed on the stereo channel of the imaging system Integrated Observatory System for the BepiColombo European Space Agency mission to Mercury are presented. The aim of the work is to determine the effects of ambient parameter variations on the equipment performance; the optical performance is changing during the mission lifetime primarily because of the optics misalignments and deformations induced by temperature variations. The camera optics and their mountings are modeled and processed by a thermo-mechanical finite element model (FEM) program, which reproduces the expected optics and structure thermo-elastic deformations in the instrument foreseen operative temperature range, i.e., between −20?°C and 30?°C. The FEM outputs are elaborated using a MATLAB optimization routine: an algorithm based on nonlinear least square data fitting is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into a ZEMAX code for sequential ray-tracing analysis. Variations of the optical spot diagrams, modulation transfer function curves, and ensquared energy are then computed. The overall analysis shows that the preferred solution for mounting the optical elements is adopting the kinematic constraints instead of using the classical glue solution.

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.