EMC aspects of turbulence heating observer (THOR) spacecraft

Turbulence Heating ObserveR (THOR) is a spacecraft mission dedicated to the study of plasma turbulence in near-Earth space. The mission is currently under study for implementation as a part of ESA Cosmic Vision program. THOR will involve a single spinning spacecraft equipped with state of the art instruments capable of sensitive measurements of electromagnetic fields and plasma particles. The sensitive electric and magnetic field measurements require that the spacecraft-generated emissions are restricted and strictly controlled; therefore a comprehensive EMC program has been put in place already during the study phase. The THOR study team and a dedicated EMC working group are formulating the mission EMC requirements state of its EMC requirements.

1. THOR Mission

Turbulence Heating ObserveR (THOR) is a candidate for an ESA Cosmic Vision medium class mission. It is one of the three candidates selected for a study for the M4 slot. If selected, it will be the first mission ever flown in space dedicated to plasma turbulence. It will explore the kinetic plasma processes that determine the basic plasma heating and particle energization processes, their efficiency for different plasma species and their relative importance in different turbulent regimes. THOR will provide closure of these fundamental astrophysical questions by making detailed in situ measurements of the closest available dilute and turbulent magnetized plasmas at unprecedented temporal and spatial resolution. THOR will focus on particular regions: solar wind, Earth's bow shock and interplanetary shocks, and compressed solar wind regions downstream of shocks — the magnetosheath. Table 1THOR payload summary

Instrument	Description	Measured quantity	Range	Max. cadence
MAG	Fluxgate magnetometer	Magnetic field	DC-50 Hz	128 sps
SCM	Search coil magnetometer	Magnetic field	1 Hz-200 kHz	524 ksps
EFI		Electric field	DC-200 kHz	524 ksps
FAR	Faraday cup	Fast ion moments		32 sps
FWP	EM field and wave receiver	Fields and waves		524 ksps
TEA	Electron spectrometer	Electron distribution	1 eV-30 keV	5 ms
IMS	Ion spectrometer with TOF	Ion distribution	5 eV-40 keV/q	150 ms
CSW	Electrostatic analyser	Cold solar wind ions	0.2 − 20 keV/q	150 ms
EPE	Solid state detector	Energetic particles	e-: 20 keV-700 keV i+: 20 keV-8MeV	7.5 s
PPU	Digital electronics for particle	Particle data products