Japanese infrared survey mission IRIS (ASTRO-F)

Abstract

The IR Imaging Survey (IRIS) is the second IR astronomy mission of the Institute of Space and Astronomical Science (ISAS). The IRIS is a 70 cm cooled telescope dedicated for IR sky survey. This project has been approved as ISAS's 21st science mission 'ASTRO-F', and prototype model development has been ongoing since 1997. The IRIS will be launched with ISAS's launch vehicle M-V, into a sun-synchronous polar orbit with an altitude of 750 km. The IRIS telescope has a 70 cm aperture and is cooled to 6K using Stirling-cycle coolers and liquid helium. The primary and secondary mirrors are light-weight mirrors make of silicon carbide. Two focal- plane instruments are installed. One is the far-IR surveyor (FIS) which will survey the entire sky in the wavelength range from 50 to 200 micron with angular resolutions of 30- 50 arcsec. The other focal-plane instrument is the IR camera (IRC). It employs large-format detector arrays and will take deep images of selected sky regions in the near and mid IR range. The field of view of the IRC is 10 arcmin and the spatial resolution is approximately 2 arcsec. The IRIS has much higher sensitivity than that of the IRAS survey. The detection limits are 1-100 micro Jy in the near-MID IR and 10-100 mJy in the far IR. With the IRIS survey, great progress is expected in the research on evolution of galaxies, formation of stars and planets, dark matter and brown dwarfs. The IRIS is now scheduled to be launched in early 2003.