BackForwardInstrument:  LYRA 

Instrument details
Acronym LYRA
Full name LYman-alpha RAdiometer
Purpose Observation of solar activity
Short description Small solar VUV (Vacuum Ultraviolet) 4-channel radiometer to observe the total solar irradiance at a high cadence (> 20 Hz) in four UV or EUV wavelength ranges: 115-125 nm (covering the Lyman-alpha line at 121.6 nm), 200-220 nm (Herzberg continuum), 17-80 nm (covering the He-II line at 30.4 nm) and 6-20 nm (highest solar variability)
Background Part of a package of instruments for observation of solar activity and ionospheric effects
Scanning Technique Sun pointing from a dawn-dusk orbit
Resolution N/A (full disk)
Coverage / Cycle Full solar disk each 0.05 s
Mass Power Data Rate


Providing Agency ESA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2009 to 2024
Last update: 2021-12-16
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]
  • Subcomponent 3
  • UV spectral imagery (e.g. GEO, HEO, MEO, LEO)
  • EUV spectrometer [from GEO, HEO, MEO, LEO]
Mission objectives
Primary mission objectives
  • Solar EUV flux
  • 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 EUV flux*3 - highNo specific limitation.Few channels, wide dynamic range
Solar Lyman-alpha flux*2 - very highNo specific limitation.H-Ly-alpha at 121.6 nm (EUV/UV boundary)