Mogensen finished secondary school in Copenhagen, Denmark in 1995, graduating with an International Baccalaureate from Copenhagen International School.

He received a master’s degree in aeronautical engineering from Imperial College London in the United Kingdom in 1999. As part of his studies, he spent six months at the Instituto Superior Tecnico in Lisbon, Portugal.

Mogensen received a doctorate in aerospace engineering from the University of Texas at Austin in the United States in 2007. His research interests include guidance, navigation, and control of spacecraft during entry, descent, and landing, mission analysis and design, and trajectory optimisation.

Member of the American Institute of Aeronautics and Astronautics (AIAA), the American Astronautical Society (AAS), the American Association for the Advancement of Science (AAAS), the Institute of Navigation (ION), and the Deutsche Gesellschaft für Luft- und Raumfahrt (DGLR).

Mogensen began his professional career as an engineer at Schlumberger Oilfield Services, where he worked as a drilling services engineer from 2000 to 2001. He was stationed in the Republic of Congo and the Republic of Angola for the duration of his employment, working primarily on offshore oil rigs.

From 2001 to 2003, Mogensen returned to Denmark to work at Vestas Wind Systems in Ringkøbing. He was employed as a control systems engineer in the research and development department, where he designed control systems for wind turbines.

From 2004 to 2007, whilst working towards his doctorate, Mogensen worked as a research assistant at the Center for Space Research and as a teaching assistant in the Department of Aerospace Engineering at the University of Texas at Austin, in the United States.

From 2007 to 2008, Mogensen was employed as an attitude & orbit control systems engineer by HE Space Operations. He was subcontracted to EADS Astrium in Friedrichshafen, Germany for the duration of his employment, where he worked on the ESA SWARM mission.

Prior to his selection as an astronaut in 2009, Mogensen was employed as a research fellow at the Surrey Space Centre at the University of Surrey in the United Kingdom. His research focused on spacecraft guidance, navigation and control during entry, descent and landing for lunar missions.

Mogensen has also been appointed adjunct lecturer at the National Space Institute at the Technical University of Denmark (DTU Space).