Understanding the surface and atmospheric conditions of Earth-size, rocky
planets in the habitable zones (HZs) of low-mass stars is currently one of the
greatest astronomical endeavors. Knowledge of the planetary effective surface
temperature alone is insufficient to accurately interpret biosignature gases
when they are observed in the coming decades. The UV stellar spectrum drives
and regulates the upper atmospheric heating and chemistry on Earth-like
planets, is critical to the definition and interpretation of biosignature
gases, and may even produce false-positives in our search for biologic
activity. This white paper briefly describes the scientific motivation for
panchromatic observations of exoplanetary systems as a whole (star and planet),
argues that a future NASA UV/Vis/near-IR space observatory is well-suited to
carry out this work, and describes technology development goals that can be
achieved in the next decade to support the development of a UV/Vis/near-IR
flagship mission in the 2020s.Comment: Submitted in response to NASA call for white papers: "Large
Astrophysics Missions to Be Studied by NASA Prior to the 2020 Decadal Survey