BackForwardInstrument:  LAD 

Instrument details
Acronym LAD
Full name Lyman Alpha Detector
Purpose To monitor the solar radiation at the H Lyman-alpha line
Short description Fluxmeter operating at the H Lyman-alpha line (121.6 nm)
Background Part of the payload flown on the two TWINS satellites, supporting the TWINS spectrometer for Energetic Neutral Atoms (ENA)
Scanning Technique Sun pointing from the Molniya orbit
Resolution N/A (full disk)
Coverage / Cycle Full solar disc at 0.7 s intervals
Mass Power Data Rate


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2006 to 2020
Last update: 2021-09-29
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
  • Solar activity monitor
WIGOS Subcomponents
  • Subcomponent 2
  • Solar magnetograph, solar EUV/X-ray imagery and EUV/X-ray irradiance, both on the Earth-Sun line and off the Earth-Sun line
  • Solar EUV spectrometer [from L1, GEO, LEO]
Mission objectives
Primary mission objectives
  • Solar Lyman-alpha 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
Solar Lyman-alpha flux*2 - very highNo specific limitation.H-Ly-alpha at 121.6 nm (EUV/UV boundary)