A sophisticated new tool has just launched-literally-that will be of tremendous use not only to our profession but also, in the long term, to just about everyone who depends on water.

NASA’s $916 million SMAP satellite, which went into orbit in late January, is designed to measure moisture in the soil. Pete Waydo, the system integration and test lead for SMAP, calls it “a satellite that studies the Earth’s moisture content-where it is, where it comes from, where it goes.” Every two to three days, the satellite will provide a new soil moisture map of the entire planet.

How will we be able to use this information? Predicting the weather, for one; soils with lots of moisture tend to support bigger storms. The data will also help alert communities to the likelihood of flooding. “Soils are like sponges,” explains Erika Podesta, a scientist working on the SMAP project, in a video made available by NASA. “If we know the amount of water in the soils, and we know there’s a big rainstorm coming and that the soils are near saturation, then we can predict that that area might be at risk for flooding.” Currently, flood forecasters-and also those who study drought-can map soil moisture only by relying on sparsely placed ground monitors and using models to extrapolate the data.

Information from SMAP will also help predict landslides by showing increased soil moisture in vulnerable areas. In places with high rates of malaria and other mosquito-borne diseases, high moisture levels can alert public health officials about where mosquitos are most likely breeding. Farmers in drought-stricken areas might time their planting based on soil moisture to increase their crop yields. Long-term mapping of the variations in soil moisture will ultimately help scientists understand the water, energy, and carbon cycles.

In fact, though, SMAP will be dealing with only about 1% of the Earth’s water supply; 97% of water is in the oceans and about 2% frozen in icecaps and glaciers. It’s that remaining 1% that’s involved in evapotranspiration, runoff, lake and river levels, and most things on which human activity depends.

SMAP (which stands for Soil Moisture Active and Passive) uses both radar (the active component) and a microwave radiometer (the passive). Both systems share a single reflector; only 12 inches wide when the satellite is launched, the reflector unfolds to its full 20-foot diameter once the satellite is in a stable orbit. The radiometer, more sensitive to soil moisture, has a resolution of about 40 kilometers; the radar augments the radiometer data and has a much higher resolution of about 3 kilometers. One scientist compares the use of the two systems to “looking through both lenses on a pair of bifocals at the same time” for both high accuracy and high resolution.

Once the system is fully deployed, NASA and certain “early adopters”-government agencies like the Department of Agriculture and the US Geological Survey, universities, and private companies-will begin to calibrate and validate the data. A beta version of the data products will be available in six months, and the validated data one year after launch.

More information on the system is available at www.nasa.gov/smap.

About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.