BackForwardInstrument:  NISTAR 

Instrument details
Acronym NISTAR
Full name NIST Advanced Radiometer (NIST = National Institute of Standards and Technology Advanced Radiometer)
Purpose Continuous monitoring of the Earth radiation towards space in daylight
Short description 3-cavity radiometer covering the ranges: 1) 0.2-100 μm to measure the total radiant power emerging from the Earth; 2) 0.2-4 μm to measure the total reflected solar radiance; and 0.7-4 μm to measure the fraction of solar radiance reflected in NIR, SWIR and part of MWIR
Background DSCOVR is the refurbishment of the Triana satellite stored on the ground in 2000 [named after Rodrigo de Triana, the first of Columbus's crew to sight land in the Americas]
Scanning Technique Earth pointing from the L1 Lagrange libration point observing the full disc
Resolution N/A (full viewed Earth's disc)
Coverage / Cycle Integrated over the full Earth's sun-illuminated disc, continuously over the day.
Mass 23.5 kg Power Data Rate


Providing Agency NASA
Instrument Maturity Backed by strong heritage
Utilization Period: 2015-05-28 to ≥2026
Last update: 2021-06-17
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
  • Earth observation instrument
  • Passive optical radiometer or spectrometer
  • Broadband Earth radiation radiometer
WIGOS Subcomponents
  • Subcomponent 1
  • Broadband radiometer (for ERB)
Mission objectives
Primary mission objectives
  • Upward long-wave irradiance at TOA
  • Upward short-wave irradiance at TOA
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Tentative 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
VariableRelevance for measuring this variableOperational limitationsExplanation
Upward short-wave irradiance at TOA2 - very highInformation on BRDF needed.SW and Total (SW+LW) broadband channels. Frequent sampling from the L1 position enables capturing diurnal variations, particularly due to clouds. Also, changing solar incidence angle helps with irradiance computation
Upward long-wave irradiance at TOA2 - very highNo specific limitation.SW and Total (SW+LW) broadband channels with supporting narrow-bandwidth channel(s). LW computed as difference Total - SW