BackForwardInstrument:  EIS (MSS) 

Instrument details
Acronym EIS (MSS)
Full name Energetic Ion Spectrometer
Purpose To provide ion composition measurements (protons vs. oxygen ions) and angular distributions
Short description Time-of-flight/pulse-height sensor to cover the energy range 45-500 keV/n for ions with Z from 1 to 8, with a temporal resolution of 30 s
Background Part of a package of instruments to implement the SMART (Solving Magnetospheric Acceleration, Reconnection, and Turbulence) mission
Scanning Technique 4 satellites co-flying in tetrehedral pattern, moving to different positions into the Magnetosphere for 3-D field reconstruction
Resolution N/A
Coverage / Cycle Full magnetospheric volume
Mass Power Data Rate


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2015 to 2024
Last update: 2021-12-16
Detailed characteristics
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Solar and space environment monitors
  • Energetic particle spectrometer
WIGOS Subcomponents
  • Subcomponent 2
  • Magnetospheric energetic particles and magnetometers
  • Proton sensor [cross magnetosphere]
  • Alpha-particle sensor [cross magnetosphere]
  • Heavy ion sensor [cross magnetosphere]
  • Subcomponent 3
  • Neutral and Ion Mass Spectrometer
  • Heavy ions mass spectrometer [from LEO and HEO]
Mission objectives
Primary mission objectives
  • Alpha particles differential directional flux
  • Heavy ion flux energy and mass spectrum
  • Proton differential directional flux
Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
Note: * Primary mission objective.
VariableRelevance for measuring this variableOperational limitationsExplanation
Proton differential directional flux*1 - primaryNo specific limitation.Cluster flown through the magnetosphere, low and medium energy (up to 1000 keV)
Alpha particles differential directional flux*3 - highNo specific limitation.Cross-magnetosphere satellite cluster. Low-medium energy range (<10 up to 100 MeV/n)
Heavy ion flux energy and mass spectrum*1 - primaryNo specific limitation.Cross-magnetosphere satellite cluster. Low-medium energy range (<10 up to 100 MeV/n)