Extragalactic Science with the Orbiting Astronomical Satellite Investigating Stellar Systems (OASIS) Observatory.

The , a proposed Astrophysics MIDEX-class mission concept, has an innovative 14-meter diameter inflatable primary mirror that will provide the sensitivity to study far-infrared continuum and line emission from galaxies at all redshifts with high spectral resolution heterodyne receivers. will have the sensitivity to follow the water trail from galaxies to the comets that create oceans. It will bring an understanding of the role of water in galaxy evolution and its part of the oxygen budget, by measuring water emission from local to intermediate redshift galaxies, observations that have not been possible from the ground.