Stephen A. Koerner is the acting director of NASA’s Johnson Space Center, home to America’s astronaut corps, Mission Control Center, International Space Station, Orion and Gateway programs and its more than 11,000 civil service and contractor employees. In this role, he assists in overseeing a broad range of human spaceflight activities, including development and operation of human spacecraft, commercialization of low Earth orbit and Johnson’s role in returning American astronauts to the surface of the Moon.

Koerner previously served as deputy director of NASA Johnson beginning in July 2021, overseeing strategic workforce planning, serving as Designated Agency Safety Health Officer (DASHO), and supporting the Johnson Center Director in mission reviews. Before his appointment to deputy director, Koerner served as director of the Flight Operations Directorate (FOD) for two years. In that role, he was responsible for selecting and protecting astronauts, and for the planning, training, and execution of human space flight and aviation missions. He managed an annual budget of $367 million, 600 civil servants and military personnel, and 2300 contractor personnel.  He oversaw the Astronaut Office, the Flight Director Office, the Mission Control Center, human spaceflight training facilities, and Johnson’s Aviation Operations Division. During this tenure he was also responsible for FOD’s flight readiness of the first commercial human spaceflight mission, ushering in a new era of domestic launch capability and the return of American astronauts launching from American soil. 

Prior to assuming his position as director of Flight Operations, Koerner served in several senior executive roles, including:

• Johnson Space Center Associate Director from 2018 to 2019
• Johnson Space Center Chief Financial Officer (CFO) from 2017 to 2018
• Deputy Director of Flight Operations from 2014 to 2017
• Deputy Director Mission Operations from 2007 to 2014

Koerner joined Johnson full-time in 1992. He has extensive operations experience including serving as an environmental systems space shuttle flight controller, where he supported 41 space shuttle flights in Mission Control. Since that time, he has served in a series of progressively more responsible positions, including lead for two International Space Station flight control groups, chief of the space station’s Data Systems Flight Control Branch, chief of the Mission Operations Directorate’s Management Integration Office, and as the Mission Operation Directorate’s manager for International Space Station operations.

Additional special assignments throughout his career include:

• Project manager for Johnson’s Crew Exploration Vehicle Avionics Integration Lab (June 2007 –June 2008)
• Member of NASA’s Human Exploration Framework Team (April 2010 –October 2010)
• Member of NASA’s Standing Review Board that provided an independent assessment at life cycle review milestones for the Multi-Purpose Crew Vehicle Program, the Space Launch System Program and the Ground Systems Development and Operations Program (October 2011 – August 2014)
• Lead of NASA’s Mission Operations Capability Team (October 2015 –April 2017)

Koerner is a native of Stow, Ohio. He earned a bachelor’s degree in mechanical engineering from the University of Akron in Ohio, and a master’s degree in business administration from LeTourneau University in Longview, Texas.