At the approach of the new millenium, we are poised at the threshold of addressing fundamental astrophysical questions about the origin and evolution of the Universe and its contents. The confluence of technological advances in telescope and spectrograph design; rapid growth in computing power; pathfinding imaging surveys on the ground and in space; and increasingly sophisticated theories of structure formation and the evolution of galaxies have inspired us to look beyond the study of a few unique objects to the systematic investigation of large samples in order to pin down their global physical properties, their formation and evolutionary history, and their cosmological significance.
In this document we argue that a National facility optimized for highly multiplexed multi-object spectroscopy is the missing element that is needed to realize this goal. We propose to develop a spectroscopic system with an integrated telescope and spectrograph design that achieves deep (22-26 mag), high-throughput, highly multiplexed (2,000-10,000 objects) spectroscopy over a wide field (1.5o) at optical and near-infrared wavelengths. This facility, SWIFT, will enable spectroscopy that is nearly two orders of magnitude more efficient than that provided by extant or planned facilities. These spectroscopic observations will probe the kinematics, chemical compositions, dynamics, ages, masses, evolutionary histories ... the very nature of astronomical objects.
The highly multiplexed multi-object spectroscopic capability of this facility will allow astronomers to contemplate and carry out ground-breaking investigations of a more mature character, larger scope, and more comprehensive nature than have been possible to date. The large-scale science enabled by SWIFT complements the high-angular-resolution science targeted by existing 8-m and 10-m class telescopes.
In the following section (S2), we discuss global astrophysical issues (large scale structure, galaxy evolution, and Galactic structure) that drive a spectroscopic need that is not met by any existing or planned instruments at large aperture telescopes. We then briefly describe the recent rapid growth in ground-based (S3) and space-based imaging capabilities (S4) that similarly require an efficient spectroscopic capability in order to achieve their astrophysical goals. Section 5 describes SWIFT, one such facility (the telescope, spectrograph, and ancillaries) which would meet this need, and compares its capabilities with those available (or soon to be) at the new generation of large aperture telescopes.