BackForwardInstrument:  SEM/SSI/ES-2 

Instrument details
Acronym SEM/SSI/ES-2
Full name SEM / Special Sensor Ionospheric Plasma Drift/Scintillation Monitor - 2
Purpose Observation of ambient electron density and temperatures, ion density, and average ion temperature and molecular weight at satellite altitude
Short description Assemblage of an electron sensor (Langmuir probe) and an ion sensor mounted on a 2.5 meter boom
Background Part of the SEM (Space Environment Monitor) package
Scanning Technique In-situ measurement in a sunsynchronous orbit
Resolution N/A
Coverage / Cycle N/A
Mass Power Data Rate


Providing Agency DoD
Instrument Maturity Flown on operational programme
Utilization Period: 1977 to 2020
Last update: 2022-07-25
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
  • Field or radiowave sensor
WIGOS Subcomponents
  • Subcomponent 1
  • In-situ plasma probes, and energetic particle spectrometers and magnetometers at GEO and LEO, and magnetic field at GEO
  • Electron sensor at LEO
  • Heavy ion sensor at LEO
Mission objectives
Primary mission objectives
  • Electron Density
  • Ionospheric plasma density
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
Electric Field4 - fairNo specific limitation.Platform. Electric field
Ionospheric plasma density*4 - fairNo specific limitation.Platform. Ionospheric plasma density
Ionospheric plasma velocity3 - highNo specific limitation.Platfgorm. Plasma velocity
Electron Density*4 - fairNo specific limitation.Platform. Electron density
Ionospheric Scintillation3 - highNo specific limitation.Platform. Scintillations detected