Applications of UV Spatial Heterodyne Spectroscopy for High Resolution Studies of Diffuse Emission Line Sources in the Solar System

A Spatial Heterodyne Spectrometer (SHS) instrument combines high etendue and high spectral resolution in a compact package that is very effective for the study of diffuse low surface brightness emissions. SHS instruments require no telescope to achieve high sensitivity on extended sources and may be designed with fields of view exceeding 1 degree and spectral resolutions exceeding 100000. This combination makes them well suited to many solar system targets including comets, the interplanetary medium, and planetary atmospheres/coronas, using platforms from sounding rockets to remote probes. We are currently developing two variations of the SHS. The first of these is a new form of all-reflective, common-path SHS optimized for the study of FUV emission lines where transmitting optics will introduce an unacceptable attenuation of the incident beam. Secondly we are developing a multiorder variation of the SHS, where a customized high order grating is used to overlap integer orders of multiple target emission lines that can then be separated using a transform technique or with order separation filters. In this presentation we will describe the basic SHS technique, the design variations we are pursuing, and their rationale, both technical and scientific.