Nello Vertolli

Low energy high angular resolution neutral atom detection by means of micro‐shuttering techniques: the BepiColombo SERENA/ELENA sensor

The neutral sensor ELENA (Emitted Low‐Energy Neutral Atoms) for the ESA cornerstone BepiColombo mission to Mercury (in the SERENA instrument package) is a new kind of low energetic neutral atoms instrument, mostly devoted to sputtering emission from planetary surfaces, from E∼20 eV up to E∼5 keV, within 1‐D (2°×76°). ELENA is a Time‐of‐Flight (TOF) system, based on oscillating shutter (operated at frequencies up to a 100 kHz) and mechanical gratings: the incoming neutral particles directly impinge upon the entrance with a definite timing (START) and arrive to a STOP detector after a flight path. After a brief dissertation on the achievable scientific objectives, this paper describes the instrument, with the new design techniques approached for the neutral particles identification and the nano‐techniques used for designing and manufacturing the nano‐structure shuttering core of the ELENA sensor. The expected count‐rates, based on the Hermean environment features, are shortly presented and discussed. Such d...

ELENA microchannel plate detector: absolute detection efficiency for low energy neutral atoms

Microchannel plate (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. The capability to detect non-thermal, low energy, neutral species is crucial for the Emitted Low-Energy Neutral Atoms (ELENA) sensor, which is part of the Search for Exospheric Refilling and Emitted Natural Abundances (SERENA) package on board the Mercury Planetary Orbiter (MPO) space- craft of the BepiColombo mission of European Space Agency to Mercury, which is scheduled for launch in August 2015. ELENA is a time-of-flight sensor based on a novel concept using an ultrasonic oscillating shutter (start section) and MCP detector (stop detector). The ELENA scientific objective is to monitor the emission of neutral atoms from the surface of Mercury by detecting energetic neutral atoms in the range 10 eV to 5 keV, within 76 deg FOV, perpendicular to the S/C orbital plane. The sur- face is scanned due to the spacecraft motion. In particular, processes of particle release from the surface will be investigated by identifying particles released via solar wind-induced ion sputtering (with energies >1 eV to <100 eV) as well as energetic hydrogen atoms, which are back-scattered solar wind protons, at energies of hundreds of eV. MCP absolute detection efficiency, for very low energy neutral atoms (E < 30 eV), is a crucial point for this investigation. At Messkammer fur Flugzeitinstrumente und time-of- flight facility of the University of Bern, measurements on three MCP, with different coatings, have been performed providing the first data of MCP detection efficiencies in the energy range 10 eV to 1 keV.

ELENA MCP detector: absolute detection efficiency for low-energy neutral atoms

Microchannel Plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission of ESA to Mercury to be launched in 2015. ELENA is a Time of Flight (TOF) sensor, based on a novel concept using an ultra-sonic oscillating shutter (Start section), which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop detector. The scientific objective of ELENA is to detect energetic neutral atoms in the range 10 eV – 5 keV, within 76° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the plasma environment and the planet’s surface, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles released from the surface, via solar wind-induced ion sputtering (< 1eV – < 100 eV) as well as Hydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (E < 30 eV) is a crucial point for this investigation. At the MEFISTO facility of the Physical Institute of the University of Bern (CH), measurements on three different types of MCP (with and without coating) have been performed providing the detection efficiencies in the energy range 10eV – 1keV. Outcomes from such measurements are discussed here.

Performance analysis of the GR712RC dual-core LEON3FT SPARC V8 processor in an asymmetric multi-processing environment

In this paper we present the results of a series of performance tests carried out on a prototype board mounting the Cobham Gaisler GR712RC Dual Core LEON3FT processor. The aim was the characterization of the performances of the dual core processor when used for executing a highly demanding lossless compression task, acting on data segments continuously copied from the static memory to the processor RAM. The selection of the compression activity to evaluate the performances was driven by the possibility of a comparison with previously executed tests on the Cobham/Aeroflex Gaisler UT699 LEON3FT SPARC™ V8. The results of the test activity have shown a factor 1.6 of improvement with respect to the previous tests, which can easily be improved by adopting a faster onboard board clock, and provided indications on the best size of the data chunks to be used in the compression activity.

A traffic analyzer for multiple SpaceWire links

Modern space missions are becoming increasingly complex: the interconnection of the units in a satellite is now a network of terminals linked together through routers, where devices with different level of automation and intelligence share the same data-network. The traceability of the network transactions is performed mostly at terminal level through log analysis and hence it is difficult to verify in real time the reliability of the interconnections and the interchange protocols. To improve and ease the traffic analysis in a SpaceWire network we implemented a low-level link analyzer, with the specific goal to simplify the integration and test phases in the development of space instrumentation. The traffic analyzer collects signals coming from pod probes connected in-series on the interested links between two SpaceWire terminals. With respect to the standard traffic analyzers, the design of this new tool includes the possibility to internally reshape the LVDS signal. This improvement increases the robustness of the analyzer towards environmental noise effects and guarantees a deterministic delay on all analyzed signals. The analyzer core is implemented on a Xilinx FPGA, programmed to decode the bidirectional LVDS signals at Link and Network level. Successively, the core packetizes protocol characters in homogeneous sets of time ordered events. The analyzer provides time-tagging functionality for each characters set, with a precision down to the FPGA Clock, i.e. about 20nsec in the adopted HW environment. The use of a common time reference for each character stream allows synchronous performance measurements. The collected information is then routed to an external computer for quick analysis: this is done via high-speed USB2 connection. With this analyzer it is possible to verify the link performances in terms of induced delays in the transmitted signals. A case study focused on the analysis of the Time-Code synchronization in presence of a SpaceWire Router is shown in this paper as well.