An oath is a solemn promise to serve a purpose greater than oneself. Now, that promise is more important than ever. In the third season of The Oath, Chuck Rosenberg speaks with people from many walks of life who served at the highest levels of public service. This season: Secretary of Defense Leon Panetta, NASA astronaut Kathryn Sullivan, and former U.S. Surgeon General Vivek Murthy. Listen to season 3 of The Oath starting on June 3.