Color pictures of sprites from non-dedicated observation on-board the International Space Station

The NASA Crew Earth Observations is a long term program which consists in observations of human and natural phenomena from manned spacecraft. Very recently astronauts took a lot of pictures from the International Space Station during night time giving a new opportunity to observe in color lightning flashes and related Transient Luminous Events with a high spatial resolution. In about 20 hours of observations, non-directly dedicated to thunderstorm studies, about fifteen sprites have been observed from August 2011 to April 2012. The main interest of this new dataset is the opportunity to have color observations from space. Chromatic observations allow analyzing thoroughly the main components of the sprite radiation. From space, these radiations occurring in the middle and upper atmosphere are not absorbed. The diffused emission at the top of a sprite, above 75 km, is due to radiation from first positive vibrational levels of N2 (in the red). Below 75 km, a single strong and narrow filament forms the most bright sprite part. It is superimposed on diffused light. The analysis of the measured radiation through the three color filters suggests that this filament is due to ionized nitrogen. Through the blue filter, the radiation is due to the first negative band at 470.9 nm. Through the red filter, the radiation is probably due to Meinel system bands which are rarely observed. By comparison with the simultaneously observed star apparent magnitude, the sprite brightness has been evaluated equivalent to the Jupiter one.