Ultraviolet instruments on the Habitable Worlds Observatory: considerations and capability trades on the multi-object, integral-field, and high-resolution modes of a potential ultraviolet instrument

The Habitable Worlds Observatory (HWO) is NASA’s next-generation astrophysics platform, delivering transformative capability in the search for life and study of the origins of the universe. Among the instruments under consideration for HWO is a multipurpose ultraviolet spectrograph and imager that provides a deep toolbox for some of the most pressing science investigations of the next several decades. We present a basic draft model of a potential UVI, including a multi-object spectrograph, far ultraviolet imager, high-resolution spectrograph, and integral-field spectrograph. The draft designs for these channels of the UV instrument serve as a basis for a general discussion of the instrument architecture and design challenges while also identifying potential trades, enhancements, and other considerations that the HWO project will need to address as it moves into the formulation phase. We conclude with a presentation of several scientific simulations that have helped guide the capabilities of the draft design. We intended to serve as a summary of UV instrument modes, technology, and potential design ahead of planned instrument studies in the late 2020s and then phase A in the early 2030s.