BackForwardInstrument:  EPACT 

Instrument details
Acronym EPACT
Full name Energetic Particles Acceleration, Composition, Transport
Purpose To investigate and monitor the properties of the solar wind
Short description Measurements of the elemental and isotopic abundances of the minor ions making up the solar wind with energies in excess of 20 keV. Measurements at a rate of once per minute for ions and 20 times per minute for electrons. Deduction of solar-wind velocity, density, temperature, and heat flux. Energy ranges: 0.2-10 MeV (electrons), 1.4-120 MeV (protons), 0.16-2000 MeV (alpha-particles) and 0.02-300 MeV/n (ions with Z from 3 to 26)
Background Part of a package of instruments to observe the solar wind
Scanning Technique Interplanetary space from the L1 Lagrange libration point
Resolution N/A
Coverage / Cycle Nearly full interplanetary space
Mass Power Data Rate

 

Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1995 to 2025
Last update: 2021-11-10
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 1
  • Solar wind in situ plasma and energetic particles, magnetic field, at L1
  • Solar wind at L1 - Electron sensor
  • Solar wind at L1 - Proton sensor
  • Solar wind at L1 - Alpha-particle sensor
  • Solar wind at L1 - Heavy ion sensor
  • Solar wind at L1 - Plasma density sensor
  • Solar wind at L1 - Plasma temperature sensor
  • Solar wind at L1 - Plasma velocity sensor
Mission objectives
Primary mission objectives
  • Alpha particles differential directional flux
  • Electron 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
Electron differential directional flux*3 - highNo specific limitation.Interplanetary space, medium and high energy (over 40 to over 400 keV)
Proton differential directional flux*3 - highNo specific limitation.Interplanetary space, high energy (over 1000 keV)
Alpha particles differential directional flux*2 - very highNo specific limitation.Interplanetary space. Extended energy range (<10 to >100 MeV/n)
Solar wind density1 - primaryNo specific limitation.Interplanetary space. Infrerred from Proton. Electron and Alpha-particle spectroscopy
Solar wind temperature1 - primaryNo specific limitation.Interplanetary space. Infrerred from Proton. Electron and Alpha-particle spectroscopy
Solar wind velocity1 - primaryNo specific limitation.Interplanetary space. Infrerred from Proton. Electron and Alpha-particle spectroscopy
Heavy ion flux energy and mass spectrum*4 - fairNo specific limitation.Interplanetary space. Extended energy range (<10 to >100 MeV/n)