The Far Ultraviolet Spectroscopic Explorer Mission
Session 4 -- Instrumentation and Techniques II: Space Based
Display presentation, Monday, June 12, 1995, 9:20am - 6:30pm

## [4.01] The Far Ultraviolet Spectroscopic Explorer Mission

M.E.Perry, S.D.Friedman, D.J.Sahnow, W.Moos (JHU), J.C.Green (CU), O.H.W.Seigmund (UCB)

The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite will make high spectral resolution ($\lambda / \Delta \lambda = 30,000$) measurements in the 905-1195 \AA bandpass from low-earth orbit. Its high sensitivity and low background will permit observations of solar system, galactic, and extragalactic targets that have been too faint for previous instruments at this resolution. Lead by the Johns Hopkins University (JHU), FUSE was recently restructured as a Principal-Investigator-class mission, with a rapid development schedule and a 1998 launch. Both mission development and mission operations will be centered at JHU. About half of the observation time will be available for guest investigation.

We present a description of the FUSE mission, including details of the instrument design and its estimated performance. Although constrained by the launch-vehicle shroud and by grating technology, the optical design achieves a high effective area (30-100 cm$^2$) by using four nearly-identical channels. The optics consist of four normal incidence mirrors, four high density holographically ruled diffraction gratings, and a pair of large format double-delay-line detectors. These components are supported by a graphite-composite structure and are thermally controlled to less than one degree Celsius. The instrument and the commercially-procured spacecraft will be launched into an 800 km, 25-degree inclination orbit on a Med-Lite expendable launch vehicle.