Mapping Vesta: First Results from Dawn’s Survey Orbit

The geologic objectives of the Dawn Mission [1] are to derive Vesta’s shape, map the surface geology, understand the geological context and contribute to the determination of the asteroids’ origin and evolution.Geomorphology and distribution of surface features will provide evidence for impact cratering, tectonic activity, volcanism, and regolith processes. Spectral measurements of the surface will provide evidence of the compositional characteristics of geological units. Age information, as derived from crater sizefrequency distributions, provides the stratigraphic context for the structural and compositional mapping results, thus revealing the geologic history of Vesta. We present here the first results of the Dawn mission from data collected during the approach to Vesta, and its first discrete orbit phase – the Survey Orbit, which lasts 21 days after the spacecraft had established a circular polar orbit at a radius of ~3000 km with a beta angle of 10°-15°

The <i>Castalia</i> mission to Main Belt Comet 133P/Elst-Pizarro

We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC’s activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA’s highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these

THE STEREO CAMERA ON THE BEPICOLOMBO ESA/JAXA MISSION: A NOVEL APPROACH

The stereo camera (STC) is one of three channels of the spectrometer and imagers for Mercury Planet Orbiter BepiColombo Integrated Observatory SYStem (SIMBIOSYS), which will be on board the Mercury Planetary Orbiter of the ESA mission BepiColombo. SIMBIOSYS includes also an high resolution imaging channel (HRIC), providing images at spatial resolution of 5m/pixel at the periherm, and the VIS-NIR spectrometer (VIHI) that will provide the global mapping of the Mercury's surface in the spectral range 400-2200 nm, with a spectral sampling of 6.25 nm, and the spatial resolution of 400m/pixel at the periherm. The main scientific objective of STC is the global mapping of the entire surface of the Mercury in 3D and colors with a scale factor of 50m/pixel at the periherm. It will allow to generate the digital terrain model (DTM) of the entire surface improving the interpretation of morphological features at different scales and topographic relationships. The harsh environment of the Mercury will strongly affect the functionalities and performance of the instruments reducing the resources allocated to the payload. Even for the stereo camera, as for most of the instrument on board BepiColombo, a novel design had to be considered. We have implemented an original optical design, modifying a classical configurations, and a new technique of acquiring the stereo pairs for generating the DTM of the surface. The new technique will have an impact on the software chain generating the DTM and on the observation strategy. The stereo camera consists of two channels, looking at the surface at ±20° from the nadir direction, converging on the same bidimensional focal plane assembly, with no mechanical movable parts. The configuration of the focal plane assembly allows to apply the push-frame technique to acquire the stereo images

Quasi-3D model to describe topographic effects on nonspherical cometary nucleus evolution

International audienceA new quasi three-dimensional code is presented and used to explore the thermal evolution of non-spherical-shape cometary nuclei. Calculations are done for spherical nuclei with different obliquities, spherical nuclei with crater-like depressions and spheroid-shape nuclei. The results obtained for both the gas and dust fluxes agree with previous simulations. Local dust crust formation can occur when the comet is located far from the Sun (around 3.5 AU), creating active and inactive areas on the surface. For a given set of parameters, the H2O production rate is comparable to the one observed for comets. A pre–post-perihelion asymmetry exists for H2O, CO2 and CO production rates. It is shown that crater-like depressions can be erased within the lifetime of a comet and that spheroid-shape nuclei have a higher production rate than equal area spherical nuclei

The light curve of asteroid 21 Lutetia measured by VIRTIS-M during the Rosetta fly-by

International audienc

Production and 3D visualization of high-level data of minor bodies: The MATISSE tool in the framework of VESPA-Europlanet 2020 activity

International audienc