The {\it Edison} Infrared Space Observatory: Design and Status
Session 10 -- South Polar and Lunar Telescopes
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [10.04] The {\it Edison} Infrared Space Observatory: Design and Status

H. A. Thronson (Uwyo), T. G. Hawarden (JACH), A. J. Penny (RAL), J. K. Davies (ROE)

The Edison infrared space observatory was recently accepted for consideration by the European Space Agency as a candidate mission for that agency's post-2000 launch opportunities. Consequently, for the professional lifetime of most readers of this abstract, the project may be the only large-aperture observatory to operate in space over the wavelength range $\sim$ 3 -- 100+ $\mu$m.

In its current baseline configuration, Edison possesses a 1.7 m telescope within a spacecraft with overall dimensions of about 2.4 m $\times$ 5.4 m, weighing about 2360 kg. This is about the same size and mass as the ISO spacecraft and means that the observatory can be launched by vehicles available from Russia, ESA, or the US. The telescope will be cooled via radiation to about 20 K, with near-future mechanical refrigerators proposed to cool some elements of the instruments to as low as 2.5 K or less. As an alternative, small amounts of cryogens may be applied to cooling only components of the instruments. At a telescope temperature of about 20 K, photometry and broadband imaging is limited ultimately only by the celestial thermal or confusion background throughout the proposed wavelengths of operation. As an attractive alternative to purely radiative cooling, a RAL-developed Joule-Thomson/Stirling cooler, now in advanced laboratory testing, may be used to refrigerate the entire optical system. We estimate at present that this will achieve an equilibrium telescope temperature of 5 -- 10 K and will allow spectroscopic observations at the celestial thermal background throughout the infrared.

The poster paper will discuss recent design work on Edison and the status of the mission within ESA.