NASA Science Chief, Former Astronaut John Grunsfeld Retiring

NASA science chief John Grunsfeld, a former astronaut who famously helped repair and upgrade the Hubble Space Telescope in orbit, will end his nearly quarter-century of service to the agency at the end of the month. Grunsfeld — who has headed NASA's Science Mission Directorate since January 2012, and has therefore been in charge for big moments such as the Mars rover Curiosity's Red Planet touchdown in August 2012 and the New Horizons spacecraft's epic flyby of Pluto in July 2015 — w