NASA chief scientist Zurbuchen will step down at the end of this year

The Swiss-American astrophysicist has led NASA’s science mission directorate since 2016, directing the agency’s nearly 100 missions. He announced his planned departure in a memo sent Tuesday to NASA employees.

“It’s a tough decision for me, but I think it’s time for a fresh start – for management and for me,” Zurbuchen wrote.

His planned departure comes at a time when NASA is heavily focused on returning astronauts to the Moon and possibly Mars as part of the multi-billion Artemis program, which will begin in 2019.

Zurbuchen was leading the science branch when she sent NASA’s Perseverance rover to the surface of Mars, where she collected rock samples to study whether that planet had ever had conditions suitable for life. The rover’s mission also included flying a helicopter to another planet for the first time.

NASA launched the Webb Telescope, the most powerful space observatory ever built, last December, and in July it began providing spectacular images of the cosmos.

Zurbuchen’s unit played an early role in Artemis with its Commercial Lunar Payload Services program, an effort to deploy privately built lunar landers to study the lunar surface before humans land there in years to come.

He was also instrumental in launching NASA’s first known effort to investigate unidentified aerial phenomena known as UFOs, assembling a team of citizen scientists to help a Pentagon program detect and detect mysterious objects in the sky.

“From the diversity of the team he assembled, to carrying out countless successful space science missions that changed our view of the universe, to investing in new and better ways to achieve of space science and the growth of the community as a whole, Thomas has been a force for positive change throughout NASA,” said Bobby Braun, space exploration sector manager at the Johns Hopkins Applied Physics Lab.