Purdue CubeSat Project Selected for Flight by NASA

SNoOPI will measure the moisture content of soil and snow from orbit

The low-cost SNoOPI CubeSat will use signals of opportunity in P-band frequencies from orbiting satellites to make remote sensing measurements.

A small satellite mission led by James Garrison, a professor in Purdue’s School of Aeronautics and Astronautics, was selected for funding by NASA's Science Mission Directorate for the In-Space Validation of Earth Science Technologies (InVEST) program.

Garrison’s project, SigNals of Opportunity: P-band Investigation (SNoOPI), will use specific radar frequencies broadcast from orbit to measure the volume of water stored in the form of accumulated snow and the water stored in soil down to the level it is absorbed by plants.

Accurate measurement of root-zone soil moisture is critical to food production. The data could help predict floods and droughts and aid in the forecasting of improved water management for agriculture, hydroelectric power, and drinkable water monitoring.

“In the general area of weather forecast, the water contained in the soil and snow is a big unknown, and improved data on these variables could greatly improve weather forecast in general,” Garrison says.

Neither root-zone soil moisture or snow water equivalent is measured directly with current technology.

But Garrison’s “Signals of Opportunity” (SoOp) in P-band is a new remote sensing technique with the capability of estimating both essential variables. Conventional P-band radar and radiometers are prone to RF spectrum access problems and require very large antennas to obtain sufficient signal-to-noise ratio or spatial resolution. SoOp reuses signals from existing telecommunications satellites, so it does not require a transmitter, in contrast with a radar measurement. Such signal efficiency makes SoOp cost effective.

Garrison’s research has advanced the P-band SoOp technique and prototype instrumentation through model development, airborne tests, and field experiments.

Further advancement of the technique requires in-space demonstration, which the grant will allow through CubeSat.

The team intends to exit the InVEST program with an instrument that will enable direct measurements of root-zone soil moisture and snow water equivalent that are not presently possible.

Garrison has partnered with NASA’s Goddard Space Flight Center and NASA’s Jet Propulsion Laboratory, which will design the instrument’s hardware, and Mississippi State assistant professor of Mehmet Kurum, who will be handling electromagnetic modeling, on the project. David Spencer, an AAE associate professor, will lead mission design and science operations, and manage the flight system contract.

Students in the Space Flight Projects Laboratory will support the project through development and operations.