Taranis, the Celtic god of thunder and lightning, is a fitting name for a satellite set to observe gigantic luminous events 30 to 90 km high occurring above large storm clouds like those that form in the intertropical belt.

Discovered 20 years ago, such transient luminous events (TLEs)—variously called ‘elves’, ‘sprites’ and ‘blue jets’—remain shrouded in mystery. They are sometimes accompanied by terrestrial gamma-ray flashes (TGFs). The correlation between these TLEs and TGFs is one of the scientific questions the Taranis mission should have answered.

The Taranis ¹ microsatellite should have flown over thousands of TLEs and TGFs for at least two years. Its scientific instruments were to detect these events and record their luminous and radiative signatures at high resolution, as well as the electromagnetic perturbations they set off in Earth’s upper atmosphere.

Taranis should have delivered unique data to probe the mechanisms underlying lightning energy transfers between the atmosphere, ionosphere and magnetosphere, and assessed their possible impacts on Earth’s environment. The mission was initiated by CNES, which was acting as prime contractor and in charge of payload integration on the Myriade microsatellite bus and testing.

¹ Tool for the Analysis of RAdiation from lightNIng and Sprites