What happens above thunderstorms: First operational concept and lessons learned from the THOR experiment during the short duration mission on-board the International Space Station

THOR, a European Space Agency experiment on the International Space Station (ISS), aims at imaging atmospheric and electric activity above thunderstorms, using optical cameras. More specific, the focus is on Cloud Turrets, mesospheric Gravity Waves, and Transient Luminous Events. This paper describes the operational concept applied for the first series of observations. The lessons learned from this first series of observations are presented, and improvements for future observation campaigns are suggested. The THOR experiment was firstly conducted during the Short Duration Mission (SDM) of Andreas Mogensen in September 2015. The observations were made using standard ISS camera equipment, following the instructions provided by ground on the targets of interest and camera settings to use. The development of the operational concept for the SDM was challenging due to the different International Partners involved, the time constraints limiting the options for technical feasibility studies and the shipping and budgetary constraints allowing only available on-board equipment to be used. Consequently, compared to the initial scenario the experiment was strongly restricted in terms of the operational setup and scientific observations. Despite these challenges the results obtained were above expectations. Among many observations of CTs and regular lightning, Andreas Mogensen managed to capture on film Sprites and for the first time a pulsing Blue Jet. Even with limited resources and non-specialised equipment, interesting observations could be made.