SOFIA is an airborne observatory, a Boeing 747SP modified to carry a 2.7m infrared telescope in the back of the fuselage. In the context of the preparation for my SOFIA flights, I visited the DSI in Stuttgart several times during this summer to record interviews with various DSI people about SOFIA. This episode covers these interviews, plus a recording of the visit of the instrument labs in Palmdale. The guests and topics are Alfred Krabbe, Head of the DSI, on the history and some of the science; Thomas Keilig, CEO of DSI, on the airplane and the modifications; Christian Fischer, Project Engineer of FIFI-LS, on the instrument and some of the science; Dörte Mehlert, Education and Public Outreach, on education and the flying teachers programme; and Zaheer Ali, head of the science and mission operations laboratory, on that lab.