TARANIS

TARANIS [CNES]

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

The payload includes numerous sensors to observe the TLEs and to perform in-situ measurements of perturbations caused on the local plasma (fields, waves and particles). The satellite uses a platform from the MYRIADE series. The upper side, which carries the payload, will be pointed towards Earth.

The payload includes the following elements:

• MCP, set of 2 cameras and 3 photometers, 30 images/s, 512 × 512 pixels and luminance measurements of the different high-resolution spectral bands;
• XGRE, set of 3 × and rays detectors, measurements of high-energy photons between 20 keV. and 10 MeV and relativistic electrons between 1 MeV to 10 MeV;
• IDEE, set of 2 electron detectors, measurements of high-energy electron spectrums between 70 keV.and 4 MeV;
• IME-BF, LF antenna to measure electric fields, measurement of an electric component between 0 and 1 MHz;
• IME-HF, HF antenna to measure electric fields, measurement of an electric component between 100 kHz and 30 MHz
• IMM, a triaxes search coil magnetometer to measure the alternative magnetic field:
  - IMM-BF, 2 mono-band coils to measure the LF field;
  - IMM-MF, 1 dual band coil to measure the LF and MF field; measure 3 components of between a few Hz to 20 kHz and of a component of 10 kHz up to 1 MHz;
• MEXIC, a set of 2 electronic boxes comprised of the 8 analyzers associated with the instruments, providing electronic power to the instruments, management of the payload modes and the interface with the Mass Storage and the platform computer.

It was launched from the Guiana Space Center in a shared launch by a Vega rocket into a quasi-sun-synchronous orbit at an altitude of 700 km in 2020, but failed to reach orbit due to an issue with the upper stage.