Luitjens Popken is an RF communication systems consultant and university lecturer for Software-Defined Radio, Electromagnetic Waves and Transmission Lines. He is a proposal evaluator for the European Commission and supports the university Space Master program of the European Union. Until March 2017, Luitjens was a Senior Staff Member at the European Space Agency (ESA). From 1994 to 2002, he served as Principal System Engineer for the ESA space project of INTEGRAL (International Gamma-Ray Astrophysics Laboratory). In 2000, Luitjens was a key member of an ESA/NASA Mission Recovery Task Force; his contribution was the vital element for the space probe of Huygens to be rescued from an almost mission-fatal implementation flaw in the communications subsystem. The recovery enabled ESA's 350 million Euro mission of Huygens to become in January 2005 the first spacecraft to land on a moon in the outer solar system (Saturn's moon Titan).