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  • NASA to launch SMAP, a soil moisture satellite

NASA to launch SMAP, a soil moisture satellite

  • 29 Jan 2015
  • NASA

NASA’s Soil Moisture Active Passive (SMAP) satellite is scheduled for launch on January 29, 2015 and will produce global maps of soil moisture every 3 days at 9 km resolution. SMAP soil moisture observations will allow scientists and operational users to improve weather and climate model forecasts and flood prediction and drought monitoring capabilities. Societal benefits include improved water-resource management, agricultural productivity, and vector-borne disease control.

To make these measurements SMAP utilizes an L-band radar (3 km resolution) and an L-band radiometer (36 kilometer resolution) sharing a rotating 6-meter mesh reflector antenna. The radar and radiometer instruments will operate onboard the SMAP spacecraft in a 685 km Sun-synchronous near-polar orbit, viewing the surface at a constant 40-degree incidence angle with a 1000-km swath width.

The radar and radiometer instrument data and the derived soil moisture products will be made available free to the public through the NSIDC ( and ASF ( archive centers starting approximately six months after launch. For more information visit

Objectives: SMAP will provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. SMAP data will also be used to quantify net carbon flux in boreal landscapes and to develop improved flood prediction and drought monitoring capabilities.
Observatory: The SMAP observatory employs a dedicated spacecraft with an instrument suite that will be launched on an expendable launch vehicle into a 685-km near-polar, sun-synchronous orbit, with equator crossings at 6 am and 6 pm local time.
Instrument: The SMAP instrument includes a radiometer and a synthetic aperture radar operating at L-band (1.20-1.41 GHz). The instrument is designed to make coincident measurements of surface emission and backscatter, with the ability to sense the soil conditions through moderate vegetation cover. The instrument measurements will be analyzed to yield estimates of soil moisture and freeze/thaw state. The measurement swath width is 1000 km, providing global coverage within 3 days at the equator and 2 days at boreal latitudes (>45 degrees N).
Operations: SMAP science measurements will be acquired for a period of three years. A comprehensive validation program will be carried out after launch to assess the accuracies of the soil moisture and freeze/thaw estimates. Data products from the SMAP mission will be made available through a NASA-designated data center.

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