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Instrumental characteristics of the Electron Spectrum Analyzer (ESA) onboard the Planet-B mission and observational perspectives of the electron measurements


An Electron Spectrum Analyzer (ESA) onboard the Planet-B mission to the planet Mars will measure the electron energy flux in the range of 12 eV to 15 keV in 32 energy steps. The sensor is essentially a toroidal top-hat electrostatic analyzer mounted on the surface of the spacecraft, which has a spin period of nominally 8 sec. With a 4° × 180° view angle and its spinal motion, the sensor can measure three-dimensional electron velocity distribution functions. Such distribution functions will be taken mostly during the perigee path with a high bit rate burst mode. In a nominal low bit rate mode, the reduced distribution data in the pitch-angle and energy phase space will be recorded and transmitted to Earth together with the burst mode data.

This electron measurement will provide significant information for studies on the structure of the magnetosphere and ionosphere as well as information on particle acceleration and the wave-particle interaction processes around Mars.


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Correspondence to S. Machida.

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Machida, S., Saito, Y., Ito, Y. et al. Instrumental characteristics of the Electron Spectrum Analyzer (ESA) onboard the Planet-B mission and observational perspectives of the electron measurements. Earth Planet Sp 50, 207–211 (1998).

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  • Solar Wind
  • Radio Occultation
  • Velocity Distribution Function
  • Mars Global Surveyor
  • Instrumental Characteristic