Final report on supplementary comparison COOMET.PR-S7: Laser power responsivity (COOMET 599/RU/13)

Main text The National Institute of Standards and Technology (NIST), USA and the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), Russia agreed in February 2013 to conduct a comparison on the laser power responsivity at wavelengths of 532 nm, 1.064 μm and 10.6 μm. The aim of this comparison is to assess the equivalence of the laser power responsivity between two laboratories. The comparison was conducted within the COOMET regional metrological organization (COOMET 599/RU/13) and was registered in the BIPM Key Comparison DataBase as a supplementary comparison with the identifier COOMET.PR-S7. The comparison was carried out using one detector head for measuring laser power. The detector head was supplied by VNIIOFI (OPHIR 10A). The results of this comparison essentially demonstrated agreement between the results obtained at the two participating laboratories. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The RADiation hard Electron Monitor (RADEM) for the JUICE mission

<p>The JUpiter ICy moons Explorer (JUICE) is the European Space Agency (ESA) next large class mission to the Jovian system. The mission, scheduled to launch in 2022, will investigate Jupiter and characterize its icy moons, Callisto, Europa and Ganymede for a period of 3.5 years after a 7.5-year cruise to the planet. JUICE is planned to flyby Europa and Callisto, perform a high latitude tour of the Jovian system, and finally, at the end of the mission, it will orbit Ganymede at different altitudes inside the moon’s intrinsic magnetosphere.<br /><br />While radiation is one of the major threats for all Space missions, in the Jovian system this problem is exacerbated due to the existent of very large fluxes of energetic electrons, with energies up to dozens of MeV, which can damage and eventually destroy the spacecraft systems. The existence of this electron population, and to a lesser extent of a proton and heavy ion population, is a consequence of Jupiter’s huge magnetosphere which can accelerate these particles to energies higher than those found in other known planetary magnetospheres. Although the Galileo mission, and to a lesser extent the Cassini, Pioneer and Voyager missions have provided ample information about the radiation environment in the Jovian, several questions about particle origin, acceleration mechanisms, Jovian-Solar magnetosphere coupling, and overall dynamics of the system still need to be answered with implications in magnetospheric physics, astrobiology and others, as well as in development of future manned and unmanned missions to both the inner and outer Solar System.<br /><br />For these reasons, the JUICE mission will include the RADiation hard Electron Monitor (RADEM), a low power, low mass radiation monitor, that will increase the range of long-term spectral measurements acquired by the Energetic Particle Detector (EPD) aboard the Galileo spacecraft, from 11 to 40 MeV for electrons and from 55 to 250 MeV for protons. RADEM consists of three detector heads based on traditional silicon stack detector technologies: the Electron Detector Head (EDH), the Proton Detector Head (PDH), and the Heavy Ion Detector Head (HIDH), that will measure electrons from 0.3 MeV to 40 MeV, protons from 5 MeV to 250 MeV and Heavy Ions from Helium to Oxygen with energies from 8 to 670 MeV, respectively. Because the detectors have limited Field-Of-View, a fourth detector, the Directionality Detector Head (DDH) will measure electron angular distributions which can vary greatly along the Jovian System as observed by the Galileo spacecraft.<br /><br />Although RADEM is a housekeeping instrument that will provide in-situ Total Ionizing Dose (TID) measurements and serve as a radiation level alarm, it has a broad scientific potential. Besides the Jovian system, the instrument will be fully operated during the cruise of the Solar System, which includes three Earth flybys, a Venus flyby and a Mars flyby, that offer additional scientific opportunities including but not limited to studying the cosmic ray gradient in the Solar System, characterizing Solar Energetic Particle (SEP) events, and others. In this work, we will present RADEM from a technical point-of-view, as well as the scientific opportunities that will be addressed by the radiation monitor during the JUICE mission.</p>

Mechanical Design and Analysis of Detector Head Assembly for Space bone High-Resolution Imaging Sensor

The imaging sensors employed in satellites are subjected to a wide range of vibratory loads induced during the launching phase. The effect of temperature change also needs to be looked upon while designing the structure of the imaging sensor as satellite passes through the solar and lunar phase. This project work goes into depth of challenges incurred during launching and in-orbit operation. The research includes development of lightweight structure, incorporating flexure interface to house detector head assembly (DHA) components. The design of flexural mount is a novel approach that not only arrests the deformation of the imaging sensor but also restricts structural stresses to affect the performance of the imaging sensor. This article showcases the assessment of three different mechanical designs of DHA through finite element simulation results computed in ANSYS workbench environment. The survivability of DHA structure has been checked under 55g quasi-static loading to simulate launch vibration along with 10°C thermal gradient corresponded to the in-service orbital motion. In this research work, AL6061-T6 and Kovar has been chosen for various design components of the DHA as they are space qualified materials. Though both material options showed similar performance, due to low density, ready availability and cost effectiveness leads to select Al6061-T6 material for the fabrication of DHA components.