1. 1 TARANIS - a satellite project dedicated to the physics of TLEs and TGFs F. Lefeuvre 1, E. Blanc 2, J.L. Pinçon 1 and the TARANIS team* 1 LPCE /CNRS – Univ Orléans, Orléans, France, 2 CEA, DASE/LDG, Bruyères le Châtel, France * E. Blanc, J. Blecki, T. Farges, H. de Feraudy, W.C. Feldman, U.S. Inan, F. Lefeuvre, R.P. Lin, M. Parrot, T. Neubert, R. Pfaff, J.L. Pinçon, Z. Nemecek, J.L. Rauch, R. Roussel-Dupré, O. Santolik, M. Sato, D.M. Smith, M. Suzuki, Y. Takahashi

2. 2 Objective of the paper (1) to show how the TARANIS instruments may contribute to fulfill very general science objectives related to the physics of TLEs and TGFs (2) to point out required complementary measurements from - other spacecraft - ground-based stations - balloon-borne experiments

3. 3 Science Objectives Advance physical understanding of the links between TLEs, TGFs and environmental conditions (lightning activity, geomagnetic activity, atmosphere/ionosphere coupling, occurrence of Extensive Atmospheric Showers, etc.). Advance physical understanding of the links between TLEs, TGFs and environmental conditions (lightning activity, geomagnetic activity, atmosphere/ionosphere coupling, occurrence of Extensive Atmospheric Showers, etc.). Identify other potential signatures of impulsive transfers of energy (electron beams, associated electromagnetic or/and electrostatic fields) and provide inputs to test generation mechanisms Identify other potential signatures of impulsive transfers of energy (electron beams, associated electromagnetic or/and electrostatic fields) and provide inputs to test generation mechanisms Provide inputs for the modeling of the effects of TLEs, TGFs and bursts of precipitated and accelerated electrons (lightning induced electron precipitation, runaway electron beams) on the Earth’s atmosphere. Provide inputs for the modeling of the effects of TLEs, TGFs and bursts of precipitated and accelerated electrons (lightning induced electron precipitation, runaway electron beams) on the Earth’s atmosphere.

4. 4 TLEs and TGFs observationsLocate geographical positions and altitudes of TLEs and TGFs source regions Model variations with LT, season, activity indices, etc. Environmental conditionsIdentify parent lightning flashes and associated EM emissions Investigate possible correlations with cosmic rays, micrometeorites, volcanoes, etc. Transfers of energy between the radiation belts, the ionosphere and the atmosphere Detect and characterize burst of precipitated electrons (LEPs) and of accelerated electrons (RBs) TLEs and TGFs generation mechanisms Provide input data (TLEs and TGFs source regions, association with lightning activities and other environmental parameters like AES, bursts of precipitated and accelerated electrons) to test generation mechanisms Contribution to the modeling of the effects on the atmosphere and on the global electric circuit Provide information on sources of energy (TLEs, TGFs, bursts of precipitated and accelerated electrons) or/and on large scale ionospheric perturbations

5. 5 INSTRUMENTS

6. 6

7. 7 The scientific payload is operated as a single instrument The objective is: ▪ to make a low time resolution survey of the optical and field/particle events at medium and low latitudes, and field/particle events at medium and low latitudes, ▪ under alert, to record well synchronized high resolution data (Event). Alerts may be triggered by the detection of a priority event (TLEs, TGFs, electron beams, or burst of electromagnetic or electrostatic wave). A Multi EXperiment Interface Controller (MEXIC) is in charge of the on-board management ( A Multi EXperiment Interface Controller (MEXIC) is in charge of the on-board management ( M. Parrot – LPCE/CNRS (F) + CBK (P)).

8. 8 Operations ■ ON, - 60° < lat < 60° ■ Optical measurements, night time, SAA excluded ■ X and gamma rays, SAA excluded

9. 9 Event mode triggered when a priority event is detected on 1 instrument all instruments record and transmit high resolution data Survey mode Wave instruments continuous monitoring, transmission of low resolution data Optical, particle and X& gamma ray instruments: except in excluded zones, continuous monitoring, transmission of compressed data

10. 10 MCP (Micro Cameras and Photometers) – E. MCP (Micro Cameras and Photometers) – E. Blanc -CEA/LDG (F) + Univ Tohoku-Hokkaido, Jaxa (J) Objectives - identification and characterization of TLEs - locate source regions Strategy - observations at several wavelengths at Nadir - triggering of alert signals Equipment Cameras - lightning camera : visible and near-infrared (600-900 nm) - TLE camera: band 762 ± 5 nm 30 images/second, with 512x512 pixels per image. observation zone ~ 500 km, spatial resolution at ground ~ 1 km Photometers - 762 ± 5 nm, 337 ± 5 nm, 150 to 280 nm (obs. disk of 275 km radius) - 600 to 900 nm (lightning measurements, obs. disk of 700 km). Flux of photons sampled at 20 kHz.

11. 11 XGRE (X-ray, Gamma-ray and Relativistic Electron Experiment) - XGRE (X-ray, Gamma-ray and Relativistic Electron Experiment) - D. Lawrence – JHUAPL (USA) + DNSC (D), UC Berkeley & Santa Cruz, Planetary Science Institute, SciTech Solutions (USA) Objectives - measurement of the total energy released per event - estimation of the altitude at which the burst is initiated - estimation of the latitude and LT dependent factors that control the evolution of the burst event Strategy- Measurements of photon energies 20 keV - 10 MeV - Identification of relativistic electrons (1 Mev – 10 Mev) - provide alert signals Equipment Three rectangular, 10 mm-thick CsI(Na) scintillator sheets, each having 300 cm2 area. The plastic scintillator acts as a each having 300 cm2 area. The plastic scintillator acts as a partial anticoincidence shield and a dE/dX identifier of partial anticoincidence shield and a dE/dX identifier of relativistic electrons relativistic electrons One sensor will face downward and two will face upwards

12. 12 IDEE (Energetic Electrons) - IDEE (Energetic Electrons) - J.A. Sauvaud – CESR/CNRS (F) + Univ. Prague (Cz) Objectives - - Pitch-angle Distribution of Radiation Belt Electrons - Relativistic Runaway Electrons (RRE) - Lightning-induced Electron Precipitation (LEP) ‏ Strategy - provide high resolution energetic electron spectra (70 keV - 4 MeV) in a large dynamic range of fluxes, and pitch-angle distribution, - provide alert signal for RBs Equipment Two spectrometers, one with a sight axis making an angle of 60° with the Nadir, the second making an angle of 30° with the anti-Nadir direction Angular direction better than 35°

13. 13 IME-BF (Low frequency Electric Field) - IME-BF (Low frequency Electric Field) - H. de Feraudy – CETP/CNRS (F) + GSFC (USA) Objectives - identification of the 0+ whistlers associated with the parent lightning - monitoring of the EM environment (natural and man- made emissions, EM signatures of electron beams) - estimation of the characteristic parameters of the local thermal plasma (f pe, variations in the ion density) Strategy - measurement of the E field fron DC to 1 MHz - ion probe Equipment - 1 electric (DEMETER) antenna (spheres located at the tip of 4 m booms) - 1 ion probe (C/NOFS)

14. 14 IME-HF (HF/VHF Electric Field) - IME-HF (HF/VHF Electric Field) - J.L. Rauch LPCE/CNRS (F) + Univ. Prague, IAP (Cz) Objectives - detection of HF/VHF EM signatures of lightnings - monitoring of HF/VHF natural (TIPPs) and man-made emissions (broadcast transmitters) - contribution to the estimation of polarization characteristics of HF/VHF emissions Strategy - E field measurement in the frequency band 100 kHz – 35 MHz - on-board data selection Equipment - 2 monopoles of 1 m length each (3m tip to tip distance)

15. 15 IMM (Low frequency magnetic field) - IMM (Low frequency magnetic field) - J.L. Pin ç on LPCE/CNRS (F) + Univ Stanford (USA) Objectives - in common with IME/BF (but for distinction between EM and ES signals) : (i) identification of the 0+ whistlers associated with the parent lightning, (ii) monitoring of the EM environment (natural and man-made emissions, EM signatures of electron beams) - below 20 kHz, estimation of the propagation characteristics of EM waves (propagation mode, k vector) - Statistical study of 0+ whistlers Strategy - B field measurement in the band 0.1 Hz – 1 MHz - automatic detection of the 0+ whistlers (from E or field) Equipment - 3 axis magnetic sensor up to 20 kHz - 1 axis magnetic sensor up to 1 MHz - 0+ whistler detector

16. 16 TARANIS contribution to major scientific issues

17. 17 Source regions of TLEs and TGFs With MCP, identification of sprites halos and elves, and of their source regions (pb for low altitude events such as blue jets ?) at given LTs. With MCP, identification of sprites halos and elves, and of their source regions (pb for low altitude events such as blue jets ?) at given LTs. With XGRE, identification of TGFs and of their source regions With XGRE, identification of TGFs and of their source regions With wave measurements, identification of 0+ whistler associated with parent lightning (MF/HF/VHF band included) With wave measurements, identification of 0+ whistler associated with parent lightning (MF/HF/VHF band included) Complementary measurements: Complementary measurements: - at ground (lightning detection network, sferics, TLEs) - on balloon borne experiments (low altitude TGFs, low altitude TLEs) - on board other spacecraft (in particular LT coverage) - etc.

18. 18 Characterization of EM signatures Monitoring of natural and man made emissions in a wide frequency bands (DC - 35 MHz) Monitoring of natural and man made emissions in a wide frequency bands (DC - 35 MHz) Discrimination between ES and EM emissions in the 0.1 Hz – 1 MHz band Discrimination between ES and EM emissions in the 0.1 Hz – 1 MHz band Estimation of the propagation characteristics up to 20 kHz Estimation of the propagation characteristics up to 20 kHz Complementary measurements : Complementary measurements : - at ground (ELF signatures, complementarities in the ELF/VLF/HF/VHF lightning detection at ground and in space) - at ground and on balloon borne experiments (characterization of the E fields above thunderstorms)

19. 19 Estimation of input parameters for generation models Characterization of the TLEs and TGFs source regions Characterization of the TLEs and TGFs source regions Estimation of the deposit of energy by EM waves in the lower layers of ionosphere Estimation of the deposit of energy by EM waves in the lower layers of ionosphere (expected) identification of runaway electron beams (expected) identification of runaway electron beams Energy and ionization sources associated with precipitated electrons Energy and ionization sources associated with precipitated electrons Complementary measurements: Complementary measurements: - at ground and on balloon born experiments, energy sources provided by Extensive Atmospheric Showers - at ground, energy released in infrasound - other spacecraft measurements - etc.

20. 20 Estimation of characteristic parameters of the D and E layers Parameters derived from the observation at the satellite altitude of: Parameters derived from the observation at the satellite altitude of: - the thermal plasma parameters - the EM power spectral density Complementary measurements Complementary measurements - at ground (EM power spectral density, ground-based ionospheric instruments)

21. 21 Estimation of input parameters for modeling effects on the atmosphere Characterization of sources of energy (TLEs, TGFs, bursts of precipitated and accelerated electrons, EMP) Characterization of sources of energy (TLEs, TGFs, bursts of precipitated and accelerated electrons, EMP) Information on local plasma parameters Information on local plasma parameters Complementary instruments: Complementary instruments: - ground-based, balloon-based and spacecraft based measurements of atmospheric species (NOx and O 3 ) variations - etc.