The general objective of the TARANIS mission is to study magnetosphere-ionosphere-atmosphere coupling via transient processes. At the beginning of the project proposal, the transient processes considered were essentially sprites and their associated phenomena, hence the name TARANIS (Tool for the Analysis of RAdiation from lightNIng and Sprites). Today, all transient optical phenomena observed at an altitude of between 20 and 100 km (blue jets, red sprites, halos, elves, etc.) are covered by the term TLEs (Transient Luminous Events).

Furthermore, the study's reach has been extended to incorporate the transient precipitations and accelerations of energy electrons, regardless of whether they are directly linked to TLEs. The detection and the study of the gamma-ray and X-ray flashes probably associated to the TLEs, called TGFs (Terrestrial Gamma Flashes), are part of the mission objectives. In view of the satellite's orbit, emphasis is placed on medium and low latitudes, which, by definition, have been the focus of very few studies in the past.

The TARANIS mission has four main objectives:

Estimate the rate of occurrence of TLEs, TGFs and their associated emissions, highlight trigger factors
Characterise TGFs and runaway electrons that accelerate upwards in the atmosphere to the magnetosphere
Identify the effects of TLEs and TGFs on coupling between the ionosphere and the magnetosphere
Specify the role of precipitated electrons in coupling between the magnetosphere and the atmosphere.