SMI (SPICA Mid-infrared Instrument) is one of the two focal-plane science instruments for SPICA. SMI is the Japanese led instrument proposed and managed by a nation-wide university consortium in Japan and planned to be developed in collaboration with Taiwan and the US. SMI covers the wavelength range from 12 to 36 μm with 4 separate channels: the low-resolution (R = 50-120) spectroscopy function for 17-36 μm, the broad-band (R = 5) imaging function at 34 μm, the mid-resolution (R = 1300-2300) spectroscopy function for 18-36 μm, and the high-resolution (R = 28000) spectroscopy function for 12-18 μm. In this paper, we show the results of our conceptual design and feasibility studies of SMI.
We describe the development of the focal plane detector onboard a micro-satellite aimed for observing cosmic Xray emission. Combined with an X-ray optics with focal length of approximately 40 mm, an X-ray CCD camera realizes low and stable background thanks to its capability of event classification by pulse height distribution of a event. The mission will intensively monitor a specific binary black hole to investigate periodic time variability owing to its possible binary motion. The focal plane detector adopts P-channel back-illumination type CCD. It is a miniature version of the sensors utilized in the CCD camera aboard Hitomi satellite but is upgraded in terms of the energy resolution and the prevention of visible light transmittance. We have built up an equipment for cooling and driving the device. Dark current as a function of device temperature is investigated. We see clear difference of the amount of the dark current between the imaging area and frame store area, which is probably due to the difference of the pixel size. The result indicates sufficiently low dark current can be achieved with temperature lower or equal to -80 °C. Number of pinholes in a surface aluminium layer is significantly different between devices. We identified a process with which we decrease the number of pinholes. To realize a whole instrument, we develop communication board and compact analog board.
Toward a new era of X-ray astronomy, next generation X-ray optics are indispensable. To meet a demand for telescopes lighter than the foil optics but with a better angular resolution less than 1 arcmin, we are developing micropore X-ray optics based on micromaching technologies. Using sidewalls of micropores through a thin silicon wafer, this type can be the lightest X-ray telescope ever achieved. Two new Japanese missions ORBIS and GEOX will carry this optics. ORBIS is a small X-ray astronomy mission to monitor supermassive blackholes, while GEO-X is a small exploration mission of the Earth’s magnetosphere. Both missions need a ultra light-weight (<1 kg) telescope with moderately good angular resolution (<10 arcmin) at an extremely short focal length (<30 cm). We plan to demonstrate this optics in these two missions around 2020, aiming at future other astronomy and exploration missions.
SMI (SPICA Mid-infrared Instrument) is one of the two focal-plane scientific instruments planned for new SPICA, and
the Japanese instrument proposed and managed by a university consortium in Japan. SMI covers the wavelength range of
12 to 36 μm, using the following three spectroscopic channels with unprecedentedly high sensitivities: low-resolution
spectroscopy (LRS; R = 50 - 120, 17 - 36 μm), mid-resolution spectroscopy (MRS; R = 1300 - 2300, 18 - 36 μm), and
high-resolution spectroscopy (HRS; R = 28000, 12 - 18 μm). The key functions of these channels are high-speed dustband
mapping with LRS, high-sensitivity multi-purpose spectral mapping with MRS, and high-resolution molecular-gas
spectroscopy with HRS. This paper describes the technical concept and scientific capabilities of SMI.
We present the new design of the cryogenic system of the next-generation infrared astronomy mission SPICA under the
new framework. The new design employs the V-groove design for radiators, making the best use of the Planck heritage.
The new design is based on the ESA-JAXA CDF study (NG-CryoIRTel, CDF-152(A)) with a 2 m telescope, and we
modified the CDF design to accommodate the 2.5 m telescope to meet the science requirements of SPICA. The basic
design concept of the SPICA cryogenic system is to cool the Science Instrument Assembly (SIA, which is the
combination of the telescope and focal-plane instruments) below 8K by the combination of the radiative cooling system
and mechanical cryocoolers without any cryogen.
The contamination control for the next-generation space infrared observatory SPICA is presented. The optical performance of instruments on space observatories are often degraded by particulate and/or molecular contamination. Therefore, the contamination control has a potential to produce a significant risk, and it should be investigated in the risk mitigation phase of the SPICA development. The requirements from contamination- sensitive components onborad SPICA, the telescope assembly and focal plane instruments, are summarized. Possible contamination sources inside and outside the SPICA spacecraft were investigated. Based on impact on the SPICA system design, the following contamination sources were extensively studied through simulation and measurement; (1) outgassing from the payload module surrounding the telescope mirror and focal plane instruments, (2) contamination due to the thruster plume, and (3) environmental contamination during the integration, storage and verification phases. Although the outgas from the payload module and the thruster plume were estimated to produce only a negligible influence, the environmental contamination was suggested to affect significantly the telescope and focal plane instruments. Reasonable countermeasures to reduce the environmental contamination were proposed, some of which were confirmed to be actually effective.