Christopher Cassidy Christopher John " Chris " Cassidy ( born January 4 , 1970 , Salem , Massachusetts , United States ) is a NASA astronaut and Navy SEAL . Chris Cassidy achieved the rank of Commander in the U . S . Navy . Cassidy attended York High School , in York , Maine . He then graduated from the Naval Academy Preparatory School in Newport , Rhode Island , in 1989 . He received a Bachelor of Science in Mathematics from the United States Naval Academy in 1993 and a Master ' s Degree in ocean engineering from MIT in 2000 . While in the Navy , Cassidy passed BUD / S and became a Navy SEAL . While a SEAL he served several tours of duty supporting the fight in the War on Terror . He resides in York , Maine with his wife , Julie Byrd , and their three children . His first spaceflight was on Space Shuttle mission STS - 127 , and his second was on Soyuz TMA - 08M . He is currently ( 31 March 2013 ) in space as a flight engineer for Expedition 35 / . Cassidy has worked as a CAPCOM for both International Space Station and Space Shuttle missions in the past . Military experience . Cassidy graduated from BUD / S Class 192 . He served for ten years as a member of the Navy SEALs . His specializations in military tactics include long range special reconnaissance ( vehicular and foot patrols ) , direct action building assaults , non - compliant ship - boardings , desert reconnaissance patrols , combat diving , underwater explosives , and a variety of air operations , including parachuting , fast roping , and rappelling . He made four six - month deployments : two to Afghanistan , and two to the Mediterranean Sea . Cassidy served as Executive Officer and Operations Officer of Special Boat Team 20 in Norfolk , Virginia , and SEAL Platoon Commander at SEAL Team 3 in Coronado , California . He deployed to the Afghanistan region two weeks after the September 11 attacks . He served as Ground Assault Force Commander for international and U . S . - only combat missions in Afghanistan . Cassidy led two months of non - compliant ship - boardings in the Northern Persian Gulf . Cassidy was also a SEAL Delivery Vehicle ( SDV ) Platoon Commander at SEAL Delivery Vehicle Team Two in Norfolk . He accumulated over 200 hours underwater as Pilot / Navigator / Mission Commander of a two - man flooded submersible ( SDV ) , which is launched and recovered from a host - ship submarine . He also served as Dry Deck Shelter Platoon Commander at SEAL Delivery Vehicle Team Two in Norfolk . Cassidy volunteered for and completed a week - long , 180 - mile charity kayak paddle from Norfolk , Virginia to Washington , D . C . to raise money and awareness for the Special Operations Warrior Foundation . NASA career . Cassidy was selected as an astronaut candidate by NASA in May 2004 . In February 2006 he completed Astronaut Candidate Training , which included scientific and technical briefings , intensive instruction in Space Shuttle and International Space Station systems , physiological training , T - 38 Talon flight training , and water and wilderness survival training . Completion of this initial training qualified him for various technical assignments within the Astronaut Office and future flight assignment as a mission specialist . He was a Mission Specialist on STS - 127 , and performed a total of three spacewalks to help install and complete components of the Japanese Experiment Module . Cassidy has been assigned to the Expedition 35 crew as a flight engineer and flew to the ISS aboard Soyuz TMA - 08M ( " US designation : 34S " ) , which launched on March 28 , 2013 . On May 11 , 2013 , Cassidy and Thomas Marshburn performed an unplanned spacewalk to replace a pump controller box suspected to be the source of an ammonia coolant leak . Cassidy participated in two US spacewalks from the ISS in June / July 2013 . Awards and honors . Cassidy is an honor graduate of Basic Underwater Demolition / SEAL training ( BUD / S ) Class 192 . He was awarded the Bronze Star with " V " device and the Presidential Unit Citation for leading a 9 - day operation at the Zhawar Kili cave complex – a national priority objective directly on the Afghan / Pakistan border during Operation Enduring Freedom . Cassidy was a guest speaker at the USNA Combat Leadership Seminar ( 2003 & 2004 ) . He was awarded a second Bronze Star for combat leadership service in 2004 during Operation Enduring Freedom in Afghanistan . Chris Cassidy is also the 500th person in space . He achieved this by being the designated crew member by the rest of his crew mates , during the STS - 127 mission . He is also the second SEAL to fly in space following William Shepherd , a veteran of four prior missions .