In 2018, NASA initiated a new study for the Surface Biology and Geology (SBG) Designated Observable, identified in the 2018 National Academies’ Decadal Survey entitled, "Thriving on Our Changing Planet:  A Decadal Strategy for Earth Observation from Space."

The Decadal Survey presented a clear direction on SBG Observing priorities:

• Terrestrial vegetation physiology, functional traits, and health
• Inland and coastal aquatic ecosystems physiology, functional traits, and health
• Snow and ice accumulation, melting, and albedo
• Active surface changes (eruptions, landslides, evolving landscapes, hazard risks)
• Effects of changing land use on surface energy, water, momentum, and C fluxes
• Managing agriculture, natural habitats, water use/quality, and urban development

The SBG Study has three objectives:

1. Identify and characterize a diverse set of high value SBG observing architectures
2. Assess the performance and cost effectiveness of architectures against SBG research and applications objectives
3. Perform sufficient in-depth design of one or more candidate architectures to enable near-term science return

The study integrates inputs from four Research & Applications open-invitation working groups: Applications, Algorithms, Modeling and Calibration / Validation. A parallel team is envisioning and analyzing candidate architectures for implementing observing system concepts as well as exploring capabilities from the program of record and recent opportunities.  

The study ended its first phase with more than sixty potential architecture configurations ranging from very large multi-sensor platforms to constellations of smallsats, each intended to meet the science and applications objectives in the SBG Science and Applications Traceability Matrix (SATM), developed by the study team from the 2018 Decadal Strategy document, as vetted by the community in 2019. 

In Phase 2, each of these options is being evaluated; instrument characteristics (optical performance, mass, volume, power, data rate) are being refined, cost estimates are being developed, and potential partnerships with commercial and international organization are being explored.

SBG overall assessment will include:

• Science and Applications Traceability Matrices (SATM): ESAS and HyspIRI provide well-defined observables and products
• SATM Science Objectives, required capabilities and applications are traceable and provide performance criteria in the Value Framework
• Value Framework will assess each candidate architecture by performance, cost and risk value criteria
• A small number of selected architectures from the Value Framework will then be further developed in preparation to support a Mission Concept Review (MCR) in Phases 3 and 4