For the first time in human history, the technological reach exists to discover and characterize planets like Earth orbiting stars other than the Sun. A space-based direct imaging mission to ultimately find and characterize other Earths is a long-term priority for space astrophysics (NRC 2010). The Exo-Starshade (Exo-S) Science and Technology Definition Team (STDT) is tasked by NASA to study the starshade-telescope mission concept under the "Probe" class of space missions, with a total cost of less than $1B (FY15 dollars). Per the STDT charter, the mission should be ready for a "new start" in 2017, with launch in 2024, and the science must be beyond the expected ground capability at the end of the mission. The Exo-S mission concept study began in May 2013 and will run until the Final Report delivery in January 2015.