The line imaging orbiter for nanosatellite-enabled spectrographic surveys (LIONESS)

The Line Imaging Orbiter for Nanosatellite-Enabled Spectrographic Surveys (LIONESS) is a 6U cube satellite mission in development at Columbia University, supported for a 2027 launch by the NASA CubeSat Launch Initiative. The student-driven CubeSat will host a narrowband integral field spectrograph with a microlens field slicer, drawing inspiration from, and intending to complement Columbia's ground-based Circumgalactic Hα Spectrograph (CHαS) deployed at MDM Observatory. The circumgalactic medium (CGM) may account for up to 90% of a galaxy's mass, yet its properties are not well understood. LIONESS will observe the diffuse CGM in low-redshift galaxies, imaging hydrogen spectra to extract information about gas distribution, mass, composition, and kinematics, and aiming to provide insights into galactic formation and gas flow between the CGM and disk. As a space-based companion to CHαS, LIONESS will offer comparable narrowband H-alpha imaging over a one-degree field of view, with a significantly lower background. We present results from an initial mission concept study, flight hardware plans, and the development of an at-scale optomechanical prototype of the LIONESS spectrograph.