BackForwardInstrument:  PEM/AXIS 

Instrument details
Acronym PEM/AXIS
Full name Particle Environment Monitor / Atmospheric X-ray Imaging Spectrometer
Purpose To measure X-ray spectra from the Earth atmosphere
Short description Imaging spectrometer for X-rays of energy 3-100 keV in the range 0.012-0.41 nm.
Background Component of the UARS Particle Environment Monitor (PEM)
Scanning Technique Imagery at 8-degree intervals across the nadir from a drifting LEO
Resolution 80 km at s.s.p.
Coverage / Cycle Global daily. Sampling at 60 s intervals
Mass Power Data Rate


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1991 to 2005
Last update: 2017-05-21
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
  • Space radiometer or spectrometer
WIGOS Subcomponents
  • Subcomponent 3
  • UV spectral imagery (e.g. GEO, HEO, MEO, LEO)
  • X-ray spectrometer [from GEO, HEO, MEO, LEO]
Mission objectives
Primary mission objectives
  • X-ray flux 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
X-ray flux spectrum*3 - highNo specific limitation.Earth's limb observed, high spectral resolution
X-ray flux3 - highNo specific limitation.X-ray imager observing the Earth's surface to detect Terrestrial Gamma-ray Flashes (TGF)
X-ray sky image3 - highNo specific limitation.Earth's limb observed, spectrometry with high spatial resolution