Jacqueline Hochheiser, Corporate Communications

In January 2021, NASA will launch an exciting satellite prototype called SNoOPI (Signals of Opportunity P-band Investigation) that will be the first of its kind to detect root zone soil moisture (RZSM) from space. Getting accurate readings on soil moisture in different parts of the nation will help scientists forecast flood and drought, approximate crop yield, and regulate agricultural water consumption. Mini-Circuits played a role in bringing this revolutionary technology to life by supplying NASA with custom components that will be incorporated into the satellite system.

Current soil moisture detection technologies employ S-band (2332-2345 MHz) frequencies using a monostatic radar. This means that the transmitter and receiver share a common antenna and therefore, require a large antenna (12 to 30m) to accommodate incoming and outgoing signals and meet resolution requirements. The monostatic radar system results in a soil moisture detection resolution of only 5 cm.

Photo courtesy of Purdue University

However, SNoOPI will be launched into High Earth Orbit (HEO) and will incorporate a bistatic radar in which the satellite will have only a receiver that will interpret reflected P-band (240-270 MHz) signals from Earth. P-band signals that exist from other systems such as communication and navigation naturally reflect off the water in soil and propagate back into space where SNoOPI’s receiver will capture the signals and digest the results. In this case, the SNoOPI mission does not need a dedicated transmitter at all, but will feed off already existing signals in the environment. Using the bistatic radar method will significantly lower the weight, power consumption and cost of the satellite.

By using lower frequency radio signals such as P-band, soil moisture detection can now reach depths down to 30 cm, or what is known as the root zone soil moisture (RZSM). The root zone specifically refers to the area of soil and oxygen that surrounds the roots of plants. RZSM plays a major role in the regulation of water for agriculture in aspects such as soil saturation, evaporation rate, and plant transpiration. This information is especially useful for forecasting crop-yield and food production. The study of RZSM can also calculate the quantity of water in snowpack, as well as help forecast floods and droughts.

Mini-circuits played an important role in getting this revolutionary technology off the ground (so to speak). NASA required custom built products including a splitter and limiter that will be integrated into SNoOPI’s systems. Both the components are modifications of catalog parts that have been ruggedized to withstand space conditions such as harsh temperatures. The components were also customized to operate over P-band frequencies.

Photo Courtesy of NASA: SNoOPI Satellite

If this prototype is successful, Mini-Circuits will likely have a role to play in the subsequent launch of a constellation of these satellites to monitor soil moisture across the nation. We’re proud to support NASA’s mission to improve the sensitivity of soil moisture sensing technology, and to be a part of the next generation of satellites that will follow SNoOPI into space.

Learn more about how Mini-Circuits up-screens products for space flight!

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