This is the report of Ultraviolet-Optical Working Group (UVOWG) commissioned by NASA to study the scientific rationale for new missions in ultraviolet/optical space astronomy approximately ten years from now, when the Hubble Space Telescope (HST) is de-orbited. Building on scientific talks at the August 1998 Boulder meeting, the UVOWG discussed the outstanding unsolved scientific problems that can be answered by high-throughput UV spectroscopy and wide-field UV/O imaging. Following the exciting next decade of studies by HST (STIS, ACS, COS, WFC-3) and new surveys by MAP (microwave background at 1◦ scale), the Sloan Survey, and GALEX (discovery of over 106 new QSOs for background targets), the stage is set for cosmological explorations of galaxy assembly and the evolution of the intergalactic medium (IGM). Realizing that a major new UV/O mission would produce forefront science in all areas of modern astronomy, the UVOWG focused on a scientific theme, “The Emergence of the Modern Universe”, that unifies many of the unsolved problems in UV/O astronomy. We define this era as the period from redshifts z≈3→0, occupying over 80% of cosmic time and beginning after the first galaxies, quasars, and stars emerged into their present form. The exciting science to be addressed in the post-HST era includes studies of dark matter and baryons, the origin and evolution of the elements, and the major construction phase of galaxies and quasars. Key unanswered questions include: Where is the rest of the unseen universe? What is the interplay of the dark and luminous universe? How did the IGM collapse to form the galaxies and clusters? When were galaxies, clusters, and stellar populations assembled into their current form? What is the history of star formation and chemical evolution? Are massive black holes a natural part of most galaxies? A large-aperture UV/O telescope in space (ST-2010) will provide a major facility in the 21st century for solving these scientific problems. The UVOWG recommends that the first mission be a 4-m aperture, SIRTF-class mission that focuses on UV spectroscopy and wide-field imaging. In the coming decade, NASA should investigate the feasibility of an 8-m telescope, by ~2010, with deployable optics similar to NGST. The UVOWG recognizes that, like SIRTF and NGST, no high-throughput UV/Optical mission will be possible without significant NASA investments in technology, including UV detectors, gratings, mirrors, and imagers. To achieve our science goals, the ST-2010 spectrograph will need to deliver over 100-fold increase in throughput and multiplex efficiency. Likewise, the ST-2010 imagers should achieve similar gains in field of view and efficiency.

Publication Date



Also archived in: arXiv: astro-ph/9907101 v1 7 Jul 1999 Commissioned by NASA. Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Technical Report

Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus