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 curve'' by permitting more capable missions at lower cost. Most notably, this has produced a series of models for purely radiative and radiative/mechanical (''hybrid'') cooling which do not use cryogens and optical designs which are not constrained by the coolant tanks. Purely radiatively cooled models achieve equilibrium temperatures as low as about 20 K at a distance of 1 AU from the sun. More advanced Edison designs include mechanical cooling systems attached to the telescope assembly which lower the optical system temperature to similar or equal to 5K or less. Via these designs, near-cryogenic temperatures appear achievable without the limitations of cryogenic cooling. One Edison model has been proposed to the European Space Agency as the next generation infrared space observatory and is presently under consideration as a candidate ESA ''Cornerstone'' mission. The basic design is also the starting point for elements of future infrared space interferometers.