BackForwardInstrument:  ULEIS 

Instrument details
Acronym ULEIS
Full name Ultra-Low Energy Isotope Spectrometer
Purpose To measure ion fluxes over the charge range from He to Ni
Short description Z ranging from 2 to 28. Time-of-flight (TOF) mass spectrometer which identifies incident ion mass and energy by simultaneously measuring the time-of-flight and the residual kinetic energy of particles which enter the telescope cone and stop in one of six detectors in the telescope. Energy range: 0.02-10 MeV/n.
Background Part of a package of instruments for solar observation
Scanning Technique Sun pointing from the L1 Lagrange libration point
Resolution N/A (full disk)
Coverage / Cycle Full Sun disk, nearly continuous
Mass 18 kg Power 30.5 W Data Rate 1 kbps


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
  • 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 flux1 - primaryNo specific limitation.Sun-pointing. Low-medium energy range (<10 up to 100 MeV/n)
Heavy ion flux energy and mass spectrum*3 - highNo specific limitation.Sun-pointing. Low-medium energy range (<10 up to 100 MeV/n)