Europe's Role
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Note: Hitomi (formerly ASTRO-H) was a high-energy astrophysics space observatory, developed by the Japan Aerospace Exploration Agency (JAXA) in collaboration with institutions in Japan, the US, Canada, and Europe. It carried four instruments that together spanned the energy range 0.3-600 keV. The science goals of this mission included studying the dynamics of hot gas in galaxy clusters, the accretion of matter onto supermassive black holes at the cores of distant galaxies, and the acceleration of cosmic-ray particles up to very high energies. The mission was launched on 17 February 2016 at 08:45 UTC. On 28 April 2016, JAXA announced that they would discontinue operations of Hitomi as it was no longer possible to communicate with the satellite following an anomaly which appeared to have resulted in both solar array paddles having broken off from the spacecraft body. In June 2017, ESA announced that it will participate in Japan's X-ray Astronomy Recovery Mission (XARM), designed to recover the science of the Hitomi mission. |
ESA and other European institutes contributed to Hitomi (known as ASTRO-H prior to launch) by funding some elements of the four science instruments, as well as by providing scientific support to the mission team and to the user community.
European institutes
The Netherlands Institute for Space Research (SRON) and the University of Geneva have developed a filter wheel for the Soft X-ray Spectrometer (SXS). The filters prevent strong X-ray sources from saturating the spectrometer, so that it can make accurate observations of a large range of astrophysical sources. SRON also developed the calibration source for the spectrometer, based on a novel design that can be pulsed with a voltage supply.
CEA Saclay and the AstroParticle and Cosmology laboratory (APC) at Paris Diderot University, Paris 7, have supported the Hard X-ray Imager (HXI) and the Soft Gamma-ray Detector (SGD) through radiation testing of application-specific integrated circuits and performance testing of the Cadmium Telluride (CdTe) detectors.
ESA's contribution
As a direct contribution to the project, ESA has funded the procurement of a number of items, including the Loop Heat Pipes (for the cryostat), the High Voltage Power Supplies for three of the instruments (SXS, HXI and SGD), high-purity platinum (sputtering targets for the mirror coatings), and scintillator crystals (for anti-coincidence shields on high energy detectors). The agency also provided technical support, especially on the hardware contribution and on the cryogenic chain for the detectors, and facilitated the radiation testing of key detector components at European facilities.
ESA also supports three European scientists to cover attendance at Science Working Group meetings. These scientists have been supporting the preparation of the core science programme (the performance verification phase) and they will participate in the calibration phase and the first performance demonstration observations, as well as in the analysis, scientific exploitation and interpretation of the corresponding observational data.
In addition, ESA has established the full-time presence of a scientist from ESAC to be located at JAXA's Institute of Space and Astronautical Science (ISAS), in Japan. This scientist will support in-flight calibration, science software testing and data analysis, as well as provide expert local knowledge for the community of European Hitomi users.
Support to European Users
European user activities are supported at two centres: the Science Operations Centre (SOC), located at the European Space Astronomy Centre (ESAC) in Spain, and the European Science Support Centre (ESSC), located at the ISDC Data Centre for Astrophysics, University of Geneva, (Switzerland).
The SOC will focus on supporting the European scientific community in the use of the allocated time for Hitomi, through handling annual calls for observing proposals and related activities, and by supporting users with data analysis, taking advantage of the expertise that scientists at ESAC have for calibration and cross-calibration of high-energy astronomy missions.
The tasks of the ESSC are focussed on supporting the European scientific community with respect to the utilisation of Hitomi, providing expert knowledge about the observatory, training European astronomers, and contributing to the validation of the scientific quality of the calibrations in the analysis software.
The ESSC will be staffed by scientists from the ISDC. Their role will be to provide information about Hitomi instruments, to support the preparation and distribution of documentation for the end users, to assist in testing data analysis software, and to analyse data of the in-flight calibration phase.