E. Ammannito

Thermal analysis of unusual local-scale features on the surface of Vesta

At 525 km in mean diameter, Vesta is the second-most massive object in the main asteroid belt of our Solar System. At all scales, pyroxene absorptions are the most prominent spectral features on Vesta and overall, Vesta mineralogy indicates a complex magmatic evolution that led to a differentiated crust and mantle [1]. The thermal behavior of areas of unusual albedo seen on the surface at the local scale can be related to physical properties that can provide information about the origin of those materials. Dawns Visible and Infrared Mapping Spectrometer (VIR) [2] hyperspectral images are routinely used, by means of temperature-retrieval algorithms, to compute surface temperatures along with spectral emissivities. Here we present temperature maps of several local-scale features of Vesta that were observed by Dawn under different illumination conditions and different local solar times.

VIS-NIR imaging spectroscopy of the Mercury's surface: SIMBIO-SYS/VIHI experiment onboard the Bepi Colombo mission

VIHI (Visible and Infrared Hyperspectral Imager) is one of the three optical heads in the SIMBIO-SYS experiment onboard BepiColombo mission (the other two being STC, Stereo Camera, and HRIC, High Resolution Image Camera) [1]. The payload is designed to scan the Hermean surface from a polar orbit with the three channels to map the physical, morphological, tectonic and compositional properties of the planet. The main scientific objectives of the experiment are the study of the surface geology and stratigraphy, the surface composition, the regolith properties, the crustal differentiation, impact and volcanic processes. To fulfill these objectives the VIHI experiment uses a high performance optical layout (Schmidt telescope and spectrometer in Littrow configuration) which allows to investigate the 400–2200 nm spectral range with 256 spectral channels (6.25 nm/band sampling). The instrumental mapping capabilities are possible thanks to an IFOV of 250 °rad corresponding to a spatial scale of about 100 m/pixel at Periherm and 375 m at Apoherm. The instrument operates in pushbroom configuration, sampling the surface of Mercury with a field of view FOV of 64 × 0.25 mrad. The main technical challenges of this experiment are the focal plane design (HgCdTe thinned to improved the efficiency at visible wavelengths), the short dwell time (from about 40 msec at equator to about 100 msec at poles), thermal control, mechanical miniaturization, radiation hardening, data rate and compression. A description of the Internal Calibration Unit (ICU) concept and functionalities is given.

Calibration pipeline of VIRTIS-M onboard Venus Express

The Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) is flying on board the ESA mission Venus Express and orbiting around the planet Venus since April 11 2006, providing very valuable remote sensing data of the planet. The instrument combines a double capability: high-resolution visible and infrared imaging in the 0.28–5 µm range at moderate spectral resolution (VIRTIS-M channel) and high-resolution spectroscopy in the 2–5 µm range (VIRTIS-H channel). The scientific objectives of VIRTIS cover a large field and span from the study of the surface up to the upper atmosphere. The team is composed by people coming from institutes abroad from more than 10 countries. About 2.5 Gbit of raw compressed data are coming in average every day from the spacecraft to be further processed and distributed to the team for the data analysis. Here we described how the pipeline is structured and the various different steps performed from the telemetry to the calibrated data products but focused on VIRTIS-M. We also present some example of data product.