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The SIMBIO-SYS instrument (Spectrometer and Imagers for MPO BepiColombo Integrated Observatory System), devoted to Mercury surface exploration on board the BepiColombo mission, has been developed by Leonardo (formerly Selex ES) under ASI funding and coordination and in collaboration with several Italian and French research Institutes and Universities. It has been delivered to ESA and integrated in the MPO spacecraft in April 2015. The launch of BepiColombo is planned in 2018. SIMBIO-SYS is a suite of three optical channels for Mercury remote sensing which includes a High Resolution Imaging Channel (HRIC), a STereo imaging Channel (STC) and a Visual and Infrared Hyperspectral Imager (VIHI). The three channels are integrated on a single optical bench at S/C level: this solution optimizes the overall mass and allow the best co-alignment between the channels. To fulfil the scientific goals of the mission, in compliance with the limited resources available on the MPO and the harsh operative environment, several solutions and technologies have been implemented, namely: o A very compact design for HRIC o A wide spectral coverage wih a single channel instrument for VIHI o A single detector dual channel design for STC o A special coating (ITO) and baffle (Stavroudis design) for heat load rejection o Diamond turned mirrors in RSA905 Aluminum alloy o Spectral and radiometric in-flight calibration unit with no moving parts o Large use of composite materials for structural parts o Capabilities of stereo imaging In addition, an instrument architecture with three dedicated Proximity Electronics (PE) and a common Main Electronics (ME) was designed, aimed at the best use of the available electrical resources thanks to the sharing of functions among the three channels. Each channel of the SIMBIO-SYS Flight Model (FM) has been successfully tested and characterised at Leonardo SpA premises in Campi Bisenzio (FI - Italy) by means of two dedicated Optical Ground Support Equipment (OGSE) which have been developed and manufactured for this purpose. Data obtained during on-ground optical calibration campaign demonstrates the instrument suite performance and capability for the scientific purpose of the BepiColombo Mission.

The Mercury Orbiter Radio Science Experiment (MORE) of the ESA mission BepiColombo will provide an accurate estimation of Mercury’s gravity field and rotational state, improved tests of general relativity, and a novel deep space navigation system. The key experimental setup entails a highly stable, multi-frequency radio link in X and Ka band, enabling two-way range rate measurements of 3 micron/s at nearly all solar elongation angles. In addition, a high chip rate, pseudo-noise ranging system has already been tested at 1-2 cm accuracy. The tracking data will be used together with the measurements of the Italian Spring Accelerometer to provide a pseudo drag free environment for the data analysis. We summarize the existing literature published over the past years and report on the overall configuration of the experiment, its operations in cruise and at Mercury, and the expected scientific results.

This paper focuses on a new concept for spaceborne P-band radar implementation, that is distributed SAR based on formation flying. This approach can in principle allow to overcome physical constraints that limit the performance of monolithic SARs, leading in the P-band case to huge antennas and hard swath/resolution trade-offs. The proposed SAR is based on a larger transmitting satellite and a set of light-weight receiving-only platforms. This architecture also allows for multi-mission capabilities. In particular, in the P-band case forests observation and biomass estimation can be in theory combined with interferometric ice sounding. Payload concept is clarified, and a preliminary performance analysis in terms of ambiguity and coverage is proposed.

This paper deals with a spaceborne P-band mission based on an innovative distributed architecture. This mission was considered in the Phase A study for an Earth Observation Mission based on Satellite Formation funded by the Italian Space Agency (ASI). The study has been conducted under the coordination and leadership of Thales Alenia Space Italia (TAS-I), and CO.RI.S.T.A. has been in charge of assessing the scientific applications and defining the payload architecture. Low frequencies and P-band are widely considered of high interest from a scientific point of view, in particular for biosphere and bioclimatology studies, glaciology and geophysics. However, in spite of its scientific value, a spaceborne P-band radar poses significant technological challenges, which are mainly connected to the necessity to use huge antennas (order 100 m2) because of requirements on power and ambiguities. For example, full polarization (necessary to correct Faraday rotation) leads to double the PRF for given azimuth ambiguities. As a consequence, swath has to be reduced. A distributed SAR allows to overcome these constraints by exploiting the enhanced sampling capability of the system. Basically, it is made up by a number of cooperating antennas which are able to receive the radar signal sent by one of them and reflected by the Earth surface, so that global PRF depends on effective PRF and the number of satellites. The system is based on accurate positioning and synchronization among all the satellites which fly in formation. Moreover, each antenna is relatively small. While each antenna by itself is relatively useless, the combined processing of all the received signals leads to high observation performance. The paper gives an overview of the distributed system options and trade-offs, focusing on the payload related aspects. In particular, the next section is devoted to the scientific applications and the consequent performance requirements. Then, formation mission architecture is briefly presented, and details about the distributed SAR performance are provided. Different sensors architecture are traded-off against each other, in order to find a good compromise between number of satellites, antennas dimensions, global system performance. Finally, preliminary considerations on the possibility to combine biomass and ice sounding in a formation flying mission are presented.