NASA science chief Thomas Zurbuchen will step down by the end of the year.
As Reuters reported, Zurbuchen oversaw the successful deployment of the James Webb Space Telescope as well as the deployment of the Perseverance Mars rover.
Zurbuchen said in a statement, "This is a difficult decision for me, but I believe it is time for a new beginning - for the directorate and for me."
Zurbuchen, a Swiss-American astrophysicist, has been NASA's head of science mission directorate since 2016. He has led over 100 of the agency's missions.
Bobby Braun, the head of the Johns Hopkins Applied Physics Lab's space exploration sector, said of Zurbuchen, "From the diversity of the team he assembled to delivering countless successful space science missions that have changed our view of the universe, to investing in new and better ways of accomplishing space science goals and growing the overall community, Thomas has been a force for positive change across NASA."