SigNals Of Opportunity: P-band Investigation (SNOOPI)

James Garrison ¹ Jeffrey Piepmeier ² Rashmi Shah ³ Cynthia Firman ² David Spencer ¹ Roger Banting ² Manuel Vega ² Kameron Larsen ³ Benjamin Nold ¹ Sachidananda Babu ⁴

¹School of Aeronautics and Astronautics, Purdue University, WEST LAFAYETTE, IN, USA
²Goddard Space Flight Center, NASA, MD, Greenbelt, USA
³Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
⁴Earth Science Technology Office, NASA, MD, Greenbelt, USA

SigNals Of Opportunity: P-band Investigation (SNOOPI) will demonstrate remote sensing using Signals of Opportunity (SoOp) in the frequency range from 240-380 MHz. This technique shows promise for measuring root-zone soil moisture (RZSM) and snow water equivalent (SWE) from space. Both variables were identified in the 2017-2027 Decadal Survey (ESAS 2017). P-band observations are required to penetrate into the root zone. SWE is proportional to the reflected signal phase and the longer wavelength at P-band increases intervals between phase wrapping.

Funded under the NASA In-Space Validation of Earth Science Technologies (InVEST) program, SNOOPI will verify important assumptions about reflected signal coherence, robustness to the RFI environment, and our ability to capture and process the transmitted signal from orbit. This is a necessary risk-reduction step on the path to a science mission.

The SNOOPI instrument consists of three subsystems: 1) Low Noise Front End (LNFE), developed from an airborne demonstration instrument and later redesigned in a CubeSat form factor; 2) Digital Back End (DBE), a modification of the Cion GNSS instrument flying on CICERO and 3) Commercial (COTS) antennas.

Success with SNOOPI will retire critical risks associated with a P-band SoOp satellite instrument. In addition to enabling direct measurements of RZSM and SWE, which are not presently possible, this instrument will be orders of magnitude lower in size weight, power and cost than comparable monostatic radars due to the re-utilization of powerful anthropogenic signals.