Mike Massimino

 Mike Massimino is a New York Times bestselling author who served as a NASA Astronaut from 1996 to 2014.  He is a four-time spacewalker who completed two missions to the Hubble Space Telescope, including the final Hubble servicing mission which has been called the most dangerous and complex mission in space shuttle history.  Mike set a team record with his crewmates for the most cumulative spacewalking time in a single space shuttle mission, and he was also the first person to tweet from space.  Mike received his BS from Columbia University and his PhD from MIT.  He currently lives in New York City where he is a professor at Columbia, an advisor at the Intrepid Museum, an expert television commentator, and an in-demand keynote speaker.  He also had a recurring role as himself on The Big Bang Theory television series.