doctor thomas zurbuchen received his phd in physics from the university of bern in switzerland. our next witness is doctor ellen stoneman who is the director of the smithsonian arrowarrow space air and space . doctor - - is the seventh person to leave the museum since apollo 11 astronaut michael collins oversaw its founding in 1976. and is the first woman appointed to the position. doctor - - previously served as nasa's chief scientist for three years from 2013-2016. in that role, she guided the development of a long-range plan to send humans to mars. worked on strategies to expand commercial activity in earth's orbit and supported nasa's science programs and helio physics, earth science, planetary science and astrophysics. prior to that, - - served as the chief scientist for the new millenial program at the jet propulsion laboratory in california. she received her phd in geological sciences from brown university. doctor david's verbal is the charles a young professor of astrology and professor of astrophysical sciences at princeton university.my all moderate. for over two decad