BackForwardInstrument:  SWIMS 

Instrument details
Acronym SWIMS
Full name Solar Wind Ion Mass Spectrometer
Purpose To measure solar wind composition data over a wide range of solar wind bulk speeds and for all solar wind conditions; and abundances of most of the elements and several isotopes
Short description Uses a time-of-flight (TOF) measurement technique to determine the mass of a solar wind ion with high accuracy in the range 4-60 amu (atomic mass unit), i.e. He to Ni, every few minutes. Energy range approximately 0.5-20 keV/n
Background Part of a package of instruments for solar observation
Scanning Technique Interplanetary observation from the L1 Lagrange libration point
Resolution N/A
Coverage / Cycle Large fraction of the interplanerary space, nearly continuous
Mass 8.3 kg Power 19.4 W Data Rate 505 bps


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1997 to 2027
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 - Alpha-particle sensor
  • Solar wind at L1 - Heavy ion sensor
Mission objectives
Primary mission objectives
  • Alpha particles differential directional flux
  • Heavy ion flux energy and mass spectrum
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
Alpha particles differential directional flux*2 - very highNo specific limitation.Interplanetary space. Low-medium energy range (<10 up to 100 MeV/n)
Heavy ion flux energy and mass spectrum*4 - fairNo specific limitation.Interplanetary space. Low-medium energy range (<10 up to 100 MeV/n)