Robert M. Lightfoot Jr. is an engineer and former Acting Administrator of the National Aeronautics and Space Administration, serving from January 20, 2017 until April 23, 2018, making him the longest-serving Acting Administrator in NASA history. He is also the incumbent Associate Administrator of NASA. Succeeding Charles Bolden, Lightfoot became the space agency's acting Associate Administrator on March 5, 2012. That job became permanent on September 25, 2012. He had previously served as the eleventh Director of the NASA Marshall Space Flight Center in Huntsville, Alabama, from March 2009 until his promotion in March 2012. On March 12, 2018 he announced his retirement from NASA effective April 30, 2018.