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

摘要

Very recently NASA astronauts took a new set of pictures from the International Space Station during night time in the frame of the NASA Crew Earth Observations program, giving a new opportunity to observe in color sprites and their parent lightning flashes. During about 20 h of observations, nondirectly dedicated to thunderstorm studies, 15 sprites were observed from August 2011 to April 2012. Chromatic observations allow analyzing thoroughly the main components of the sprite radiation. The red and green emissions, observed in all the sprite images, are due to the radiation of the first positive band system of molecular nitrogen N_2. The blue emission, present in only 2 out of 15 sprites, is produced by the radiation of bands of the second positive band system of N_2 and bands of the first negative band system of N_2~+ ions. It indicates the possible presence of ionization in these two sprites. The sprite brightness is equivalent to the Jupiter one.