Christopher Williams

Christopher Leigh Williams (born October 23, 1983) is an American medical physicist and NASA astronaut.

Williams holds a Ph.D. in physics from the Massachusetts Institute of Technology. Board-certified in medical physics, he has worked at Harvard Medical School, Brigham and Women's Hospital, and the Dana–Farber Cancer Institute, where he led efforts in MRI-guided radiation therapy for cancer treatment.

NASA selected Williams to be an astronaut in 2021. He flew aboard the International Space Station on his first mission: serving as a flight engineer contributing to scientific investigations and technology demonstrations for Expedition 73/74. He traveled to the space station aboard Soyuz MS-28 in November 2025 and returned in July 2026.

Early life and education Williams was born in New York City on October 23, 1983, and considers Potomac, Maryland, his hometown. He graduated from Montgomery Blair High School in Silver Spring, Maryland in 2001, and earned a Bachelor of Science degree in physics from Stanford University in 2005. He received a Ph.D. in physics from the Massachusetts Institute of Technology (MIT) in 2012, where his research focused on astrophysics and radio cosmology.

Career During high school and college, Williams worked at the United States Naval Research Laboratory in Washington, D.C., where he studied supernovae using the Very Large Array radio telescope. He also volunteered as an emergency medical technician and firefighter with the Rockville Volunteer Fire Department in Montgomery County, Maryland. He was joined by Roscosmos cosmonauts Sergey Kud-Sverchkov and Sergei Mikayev on the Soyuz flight. The mission launched from the Baikonur Cosmodrome in Kazakhstan and is expected to last about eight months.