SIRTF: the fourth great observatory

Abstract

The Space Infrared Telescope Facility (SIRTF) will explore the birth and evolution of the Universe with unprecedented sensitivity. SIRTF will be the first mission to combine the high sensitivity achievable from a cryogenic space telescope with the imaging and spectroscopic power of the new generation of infrared detector arrays. The scientific capabilities of this combination are so great that SIRTF was designated the highest priority major mission for all of U.S. astronomy in the 1990s. The astronomical community will use SIRTF to explore the infrared universe with a depth and precision complementary to that achieved by NASA's other great observatories -- the Hubble Space Telescope (HST), the Advanced X-ray Astrophysics Facility (AXAF), and the Compton Gamma Ray Observatory (GRO) in their respective spectral bands. The launch of SIRTF in 2001 will permit contemporaneous observations with HST to study forefront problems of astrophysics. This paper provides a comprehensive review of the SIRTF program -- the science, the mission design, the facility, the instruments, and the implementation approach. Emphasis is placed on those features of the program including the use of a solar (heliocentric) orbit and the adoption of a novel warm-launch cryogenic architecture -- which will allow us to realize the great scientific potential of SIRTF in a resource- constrained environment.