BackForwardInstrument:  SMAP 

Instrument details
Acronym SMAP
Full name Soil Moisture Active-Passive (intended as payload)
Purpose Soil moisture in the roots region
Short description MW radiometer, frequency 1.41 GHz, co-aligned with SAR at 1.26 GHz - Full polarisation for the radiometer, VV, HH and HV for the SAR. Single antenna of 6 m diameter
Background New development, re-designed after the previous "Hydros" project.
Scanning Technique Conical scanning, 14.6 rpm, or 30 km/scan; incidence angle 40°, swath 1000 km
Resolution Radiometer: 40 km; SAR: 30 km (unprocessed, real aperture), 3 km (processed)
Coverage / Cycle Global coverage in 1.5 days
Mass 356 kg Power 448 W Data Rate 40 Mbps


Providing Agency NASA
Instrument Maturity Demonstration pending
Utilization Period: 2015 to 2026
Last update: 2023-07-14
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 microwave radiometer
  • Conical scanning microwave radiometer
WIGOS Subcomponents
  • Subcomponent 1
  • Low-frequency MW imagery
  • Low-frequency MW imager
Mission objectives
Primary mission objectives
  • Sea surface salinity
  • Soil moisture (in the roots region)
  • Soil moisture at surface
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
Soil moisture (in the roots region)*1 - primaryCoarse spatial resolution.MW channels around 1.4 GHz
Soil moisture at surface*1 - primaryCoarse spatial resolution.MW channels around 1.4 GHz
Sea surface salinity*1 - primaryNo specific limitation.MW polarimetric L-band radiometer (1.4 GHz)