  The Galaxy Evolution Probe (GEP) is a concept for a mid- and far-infrared
space observatory to measure key properties of large samples of galaxies with
large and unbiased surveys. GEP will attempt to achieve zodiacal light and
Galactic dust emission photon background-limited observations by utilizing a 6
Kelvin, 2.0 meter primary mirror and sensitive arrays of kinetic inductance
detectors. It will have two instrument modules: a 10 - 400 micron hyperspectral
imager with spectral resolution R = 8 (GEP-I) and a 24 - 193 micron, R = 200
grating spectrometer (GEP-S). GEP-I surveys will identify star-forming galaxies
via their thermal dust emission and simultaneously measure redshifts using
polycyclic aromatic hydrocarbon emission lines. Galaxy luminosities derived
from star formation and nuclear supermassive black hole accretion will be
measured for each source, enabling the cosmic star formation history to be
measured to much greater precision than previously possible. Using optically
thin far-infrared fine-structure lines, surveys with GEP-S will measure the
growth of metallicity in the hearts of galaxies over cosmic time and
extraplanar gas will be mapped in spiral galaxies in the local universe to
investigate feedback processes. The science case and mission architecture
designed to meet the science requirements are described, and the kinetic
inductance detector and readout electronics state of the art and needed
developments are described. This paper supersedes the GEP concept study report
cited in it by providing new content, including: a summary of recent
mid-infrared KID development, a discussion of microlens array fabrication for
mid-infrared KIDs, and additional context for galaxy surveys. The reader
interested in more technical details may want to consult the concept study
report.
