  This is a white paper submitted to the Planetary Science and Astrobiology
Decadal Survey. The deep atmosphere of Venus is largely unexplored and yet may
harbor clues to the evolutionary pathways for a major silicate planet with
implications across the solar system and beyond. In situ data is needed to
resolve significant open questions related to the evolution and present-state
of Venus, including questions of Venus' possibly early habitability and current
volcanic outgassing. Deep atmosphere "probe-based" in situ missions carrying
analytical suites of instruments are now implementable in the upcoming decade
(before 2030), and will both reveal answers to fundamental questions on Venus
and help connect Venus to exoplanet analogs to be observed in the JWST era of
astrophysics.
