IN019-11
Distributed Spacecraft with Heuristic Intelligence to Enable Logistical Decisions (D-SHIELD) for Soil Moisture Monitoring

Thursday, 10 December 2020: 11:00
Virtual
Sreeja Nag1, Mahta Moghaddam2, Daniel Selva3, Jeremy Frank4, Vinay Ravindra5, Richard Levinson4, Alan Li4, Amir Azemati6, Alan Aguilar7 and Ruzbeh Akbar8, (1)NASA Ames Research Center, Moffett Field, CA, United States, (2)University of Southern California, Ming Hsieh Department of Electrical and Computer Engineering, Los Angeles, CA, United States, (3)Texas A&M University, Department of Aerospace Engineering, College Station, TX, United States, (4)NASA Ames Research Center, Moffet Field, CA, United States, (5)NASA Ames Research Center, Moffett Field, United States, (6)University of Southern California, Los Angeles, United States, (7)Texas A&M University, College Station, United States, (8)Massachusetts Institute of Technology, Civil and Environmental Engineering, Cambridge, MA, United States
Abstract:
D-SHIELD is a suite of scalable software tools that helps schedule payload operations of a large constellation, with multiple payloads per and across spacecraft, such that the collection of observational data and their downlink, constrained by the constellation constraints (orbital mechanics), resources (e.g., power) and subsystems (e.g., attitude control), results in maximum science value for a selected use case. Constellation topology, spacecraft and ground network characteristics can be imported from design tools or existing constellations and can serve as elements of an operations design tool. D-SHIELD will include a science simulator to inform the scheduler of the predictive value of observations or operational decisions.

This presentation will summarize the development of D-SHIELD and its application to reducing global soil moisture uncertainty via responsive, intelligent scheduling. The science simulator comprises of a passive microwave simulator, a hydrologic land-surface model and a simple data assimilator to combine measurements across other third party sources – spaceborne (e.g. Sentinel-1, SMAP), airborne (e.g. P-band AirMOSS and L-band UAVSAR) or ground based sensors (e.g. SoilSCAPE). Scheduling will select, for every spacecraft, when which of its instruments will be turned on to make measurements by pointing in what direction. The scheduler can either run on the ground and schedules uplinked to the satellites, or onboard the satellites informed by Delay Tolerant Network packets routed using cross-linked communication, or a hybrid of the two depending on the size of the constellation and transiency or urgent of the phenomena being observed. In previous work, a Dynamic Programming based scheduler was applied to a simulated 24-satellite constellation monitoring urban floods with a single payload per satellite. The onboard scheduler to observe ~7% more flood magnitude than a ground-based implementation. Both onboard and offline versions performed ~98% better than constellations without agility. In this presentation, constellations with three types instruments heterogeneously distributed across the fleet - P and L band radars, radiometers and reflectometers - will use the science simulator and the scheduler to help reduce uncertainty in global soil moisture estimates.

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