SMAP
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| SMAP | |
|---|---|
| Name | SMAP |
| Operator | National Aeronautics and Space Administration (NASA) |
| Mission type | Earth observation |
| Launch mass | 900 kg |
| Launch date | 2015-01-31 |
| Launch vehicle | Delta II |
| Launch site | Vandenberg Air Force Base |
| Orbit reference | Geocentric orbit |
| Instrument type | Radiometer and Radar |
SMAP was a NASA Earth-observing mission designed to measure near-surface soil moisture and freeze–thaw state across the globe. Built and managed by teams at the Jet Propulsion Laboratory, the mission combined active radar and passive radiometer techniques to provide high-resolution, frequent coverage for hydrology, climate, and carbon-cycle research. SMAP data supported operational forecasting, agricultural monitoring, and scientific studies integrating observations from other platforms such as MODIS, Landsat, and Sentinel-1.
Overview
The mission employed a rotating 6-meter reflector antenna to achieve wide-swath coverage, enabling repeat observations over continental scales and polar regions. SMAP complemented programs including GRACE, ICESat-2, and GPM by providing near-surface moisture retrievals that inform water-balance assessments, river- and flood-modeling efforts, and ecosystem studies. International collaborations involved agencies such as European Space Agency, Canadian Space Agency, and research centers like CSRIO and Columbia University.
Mission Objectives
Primary objectives targeted quantifying surface soil moisture and freeze–thaw state to improve understanding of the links among terrestrial water, energy, and carbon cycles. Science goals included reducing uncertainty in hydrological flux estimates and improving parameterizations used by models operated at institutions including NOAA, European Centre for Medium-Range Weather Forecasts, and NASA Goddard Space Flight Center. Applications spanned drought and flood monitoring for stakeholders like United States Geological Survey and agricultural organizations such as Food and Agriculture Organization.
Spacecraft and Instruments
The spacecraft bus was developed by teams at Jet Propulsion Laboratory and instrument suites were provided by contractors and research labs including NASA Ames Research Center. The primary instruments were a synthetic aperture radar and a passive L-band radiometer operating near 1.4 GHz, enabling combined active-passive retrievals. Calibration and validation activities engaged field campaigns coordinated with facilities like USDA research stations, Lamont–Doherty Earth Observatory, and observatories run by Oak Ridge National Laboratory.
Operations and Data Products
SMAP operations used ground networks at facilities such as NASA Jet Propulsion Laboratory and command and control centers linked to the White Sands Complex. Data products included global soil moisture maps, freeze–thaw classification grids, and ancillary geophysical parameters distributed through archives maintained by NASA Distributed Active Archive Center and science teams at University of Michigan, University of Colorado Boulder, and California Institute of Technology. Product suites supported assimilation into numerical systems at NOAA National Centers for Environmental Prediction, hydrologic services at USGS, and integrated analyses alongside MODIS and Sentinel-1 datasets.
Science Results and Applications
SMAP enabled improvements in flood forecasting, drought monitoring, and agricultural yield estimation by providing near-surface moisture observations used in models at European Centre for Medium-Range Weather Forecasts and NOAA. Studies leveraged SMAP to refine carbon-flux estimates in boreal forests and peatlands coordinated with measurements from ICESat-2 and field plots managed by Yale University and University of Alaska Fairbanks. SMAP-derived freeze–thaw metrics advanced understanding of permafrost dynamics relevant to research at National Snow and Ice Data Center and University of Washington, and contributed to multidisciplinary projects with NOAA, NASA Goddard, and international teams from Potsdam Institute for Climate Impact Research.
Mission History and Legacy
Launched in 2015 from Vandenberg Air Force Base aboard a Delta II rocket, the mission underwent an in-orbit instrument anomaly that led to cessation of the radar transmitter; operations and science continued using the radiometer and enhanced retrieval algorithms developed by teams at Jet Propulsion Laboratory and partner institutions. SMAP’s datasets influenced operational applications at USDA and NOAA and informed successor missions and concepts pursued by NASA and ESA. Legacy outcomes include improved soil-moisture retrieval techniques adopted by research groups at Massachusetts Institute of Technology, Princeton University, and University of California, San Diego, as well as open data policies promoted by NASA and data integration efforts involving Copernicus and national agencies.