  We present Hyperion, a mission concept recently proposed to the December 2021
NASA Medium Explorer announcement of opportunity. Hyperion explores the
formation and destruction of molecular clouds and planet-forming disks in
nearby star-forming regions of the Milky Way. It does this using long-slit,
high-resolution spectroscopy of emission from fluorescing molecular hydrogen,
which is a powerful far-ultraviolet (FUV) diagnostic. Molecular hydrogen (H2)
is the most abundant molecule in the universe and a key ingredient for star and
planet formation, but is typically not observed directly because its symmetric
atomic structure and lack of a dipole moment mean there are no spectral lines
at visible wavelengths and few in the infrared. Hyperion uses molecular
hydrogen's wealth of FUV emission lines to achieve three science objectives:
(1) determining how star formation is related to molecular hydrogen formation
and destruction at the boundaries of molecular clouds; (2) determining how
quickly and by what process massive star feedback disperses molecular clouds;
and (3) determining the mechanism driving the evolution of planet-forming disks
around young solar-analog stars. Hyperion conducts this science using a
straightforward, highly-efficient, single-channel instrument design. Hyperion's
instrument consists of a 48 cm primary mirror, with an f/5 focal ratio. The
spectrometer has two modes, both covering 138.5-161.5 nm bandpasses. A low
resolution mode has a spectral resolution of R>10,000 with a slit length of 65
arcmin, while the high resolution mode has a spectral resolution of R>50,000
over a slit length of 5 armin. Hyperion occupies a 2 week long, high-earth,
Lunar resonance TESS-like orbit, and conducts 2 weeks of planned observations
per orbit, with time for downlinks and calibrations. Hyperion was reviewed as
Category I, which is the highest rating possible, but was not selected.
