SNOOPI: Demonstrating Earth remote sensing using P-band signals of opportunity (SoOp) on a CubeSat

Abstract

SigNals Of Opportunity: P-band Investigation (SNOOPI) will be the first in-space demonstration of P-band (240–380 MHz) signals of opportunity (SoOp) remote sensing and validation of a prototype P-band SoOp instrument. This technique has the potential to enable remote sensing of root-zone soil moisture (RZSM) and snow water equivalent (SWE). SNOOPI technology validation goals will be met by targeting observations within 9 km of SMAP calibration/validation sites in the continental United States. A second priority is collection of continuous phase data over snow-covered regions. These goals are evaluated under constraints of a limited data budget and mission lifetime, with a launch expected in early 2024. SNOOPI will capture the autocorrelation of a signal formed by the interference between the direct and reflected signals. The complex surface reflection coefficient (phase and magnitude) can be extracted from this observation. Definition of critical instrument and mission requirements for SNOOPI are described. Analyses and simulations used to justify these requirements are presented, including orbit coverage, uncertainty in the open-loop delay-Doppler prediction, observations error, and mission planning operations.