Mathieson currently works with Northstrat Incorporated as a System Engineer. He previously served as Chief Engineer and Deputy Project Manager with Northrop Grumman Aerospace Systems. Mathieson joined Northrop Grumman in 2004, and assumed a number of roles and responsibilities, including a two-year stint in Australia, where he worked primarily as a responsible systems engineer.
In 2013, Mathieson was presented with Northrop Grumman's Innovation of the Year Award, for technical achievements on complex space systems.
While continuing his engineering work, Mathieson joined the U.S. National Track Cycling Program in 2010, and competed in multiple U.S. National Championships, Pan-American Championships, and on the UCI World Cup Circuit. He was selected to the 2012 U.S. Cycling Olympic Long Team, and earned a national title in 2012 in the team sprint event.
While at Notre Dame, Mathieson was a three-year Monogram winner as a defenseman on the Irish hockey team, including the 2004 squad, which reached the NCAA tournament for the first time in program history. Mathieson was a three-time recipient of the Knute Rockne Scholar-Athlete Award, and graduated summa cum laude in 2004 with a degree in aerospace engineering. He received honorable mention CCHA All-Academic Team in 2004, and earned Dean's List recognition in every semester at Notre Dame.
In 2008, Mathieson earned a master's degree in astronautical engineering from the University of Southern California.
T.J. and his wife, Michelle ('04), have two sons, Jack and Bowen, and live in Oak Hill, Va.