A SPECS update: engineering and technology requirements for a space-based far-IR imaging interferometer

TLDR: The Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) is a space-based imaging and spectral interferometer with kilometer maximum baseline lengths for imaging as mentioned in this paper.

Abstract: The Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) is a space-based imaging and spectral ("double Fourier") interferometer with kilometer maximum baseline lengths for imaging. This NASA "vision mission" will provide spatial resolution in the far-IR and submillimeter spectral range comparable to that of the Hubble Space Telescope, enabling astrophysicists to extend the legacy of current and planned far-IR observatories. The astrophysical information uniquely available with SPECS and its pathfinder mission SPIRIT will be briefly described, but that is more the focus of a companion paper in the Proceedings of the Optical, Infrared, and Millimeter Space Telescopes conference. Here we present an updated design concept for SPECS and for the pathfinder interferometer SPIRIT (Space Infrared Interferometric Telescope) and focus on the engineering and technology requirements for far-IR double Fourier interferometry. We compare the SPECS optical system requirements with those of existing ground-based and other planned space-based interferometers, such as SIM and TPF-I/Darwin.