The five spin-stabilized (spin period = 3 seconds) probes carry identical instruments The instruments being flown are:
Development Institution: Sensors - Space Sciences Laboratory, University of California, Berkeley. Data Processing - Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder
EFI Lead: J. Bonnell(UCB)
The THEMIS Electric Field Instrument (EFI) measures the electric fields in three directions. One pair of sensors is deployed to 20 meters, the other pair to 25 meters. Two stiff telescopic booms extend sensors perpendicular to the four spinning cables and along the probe's spin axis.
Development Institutions: Technical University of Braunschweig, (TU-BS), Germany
FGM Lead: K. H. Glassmeier (TUBS)
The THEMIS Flux Gate Magnetometer (FGM) measures the background magnetic field and any low frequency (to 64 Hz) fluctuations superimposed upon it. The FGM can detect variations in the magnetic field within the accuracy of 0.01 nT. The THEMIS FGM uses an updated technology developed in Germany that digitizes the sensor signals directly and replaces the analog hardware by software. Using the digital fluxgate technology results in lower mass of the instruments and improved robustness.
Development Institution: Centre des Environements Terrestre et Planétaires (CETP), France
SCM Lead: A. Roux (CETP)
The THEMIS Search Coil Magnetometer (SCM) measures low frequency magnetic field fluctuations and waves in three directions. The SCM measures frequencies in the 0.1 Hz to 4 kHz range.
Development Institution: University of California, Berkeley (UCB)
ESA Lead: C. W. Carlson (UCB)
The THEMIS Electrostatic Analyzers (ESAs) measure the flux of thermal particles in a 360° field of view over the energy range from ~3 eV to 30 keV. There are two ESAs on each THEMIS spacecraft, one measures ions, the other electrons. The ESA measures the full 3-D distributions, as well as the density, velocity, and temperature of the ambient electrons and ions.
Development Institution: University of California, Berkeley (UCB)
SST Lead: D. Larson (UCB)
The THEMIS Solid State Telescope (SST) measures superthermal particle distribution functions, namely the number of ions and electrons coming towards the spacecraft from specified directions with specified energies within the energy range from 25 keV to 6 MeV.
Development Institution: University of California, Berkeley (UCB) and University of Calgary (UofC), Canada
ASI Leads: S. Mende (UCB) and Eric Donovan (UofC)
The THEMIS ground-based All-Sky Imager (ASI) array observes the white light aurora over the Northern American continent from Canada to Alaska. The ASI array constitute of 20 cameras covering a large section of the auroral oval with one-kilometer resolution. The array have an image repetition rate of 3 seconds.
Development Institution: University of California, Los Angeles (UCLA)
GMAG Lead: C. T. Russell (UCLA)
There are 21 THEMIS GMAG stations in the Northern United States and Canada. Ten of these systems are installed with the Ground-Based Observatory (GBO) systems for THEMIS. Eleven are installed in schools and are part of the THEMIS Education and Public Outreach (E/PO) program. These magnetometers, known as the E/PO magnetometers, are the exact same type of magnetometer as those built for the GBOs. These GMAGs measure the magnetic field with 0.01 nT resolution at 2 samples/second.
