THE EDISON INFRARED SPACE-OBSERVATORY

For five years, the Edison program has had the goal of developing new designs for infrared space observatories which will ''break the cost c urve'' by permitting more capable missions at lower cost. Most notably , this has produced a series of models for purely radiative and radiat ive/mechanical (''hybrid'') cooling which do not use cryogens and opti cal designs which are not constrained by the coolant tanks. Purely rad iatively cooled models achieve equilibrium temperatures as low as abou t 20 K at a distance of 1 AU from the sun. More advanced Edison design s include mechanical cooling systems attached to the telescope assembl y which lower the optical system temperature to similar or equal to 5K or less. Via these designs, near-cryogenic temperatures appear achiev able without the limitations of cryogenic cooling. One Edison model ha s been proposed to the European Space Agency as the next generation in frared space observatory and is presently under consideration as a can didate ESA ''Cornerstone'' mission. The basic design is also the start ing point for elements of future infrared space interferometers.