The Carbon Mapper emissions monitoring system

Abstract. The non-profit organization Carbon Mapper has a public good mission to drive greenhouse gas (GHG) emission reductions by making methane (CH₄) and carbon dioxide (CO₂) data accessible and actionable. The Carbon Mapper emissions monitoring system contributes to the broader ecosystem of greenhouse gas observations by locating and quantifying CH₄ and CO₂ super emitters at facility scale across priority regions globally. To meet these objectives, our system includes observing platforms, an operational monitoring strategy optimized for mitigation impact, and a data platform that delivers CH₄ and CO₂ data products for diverse stakeholders. Operational scale-up of our system is centered around a new constellation of hyperspectral satellites enabled by over a decade of sustained instrument technology and algorithm advances and prototyping with aircraft surveys and recent observations by NASA’s EMIT instrument on the International Space Station. The Carbon Mapper Coalition (hereafter Tanager) satellites are each equipped with an imaging spectrometer instrument designed by NASA’s Jet Propulsion Laboratory that are assembled, launched and operated by Planet Labs. The first Tanager satellite (Tanager-1) was launched 16 August 2024, completed commissioning in January 2025, and is on track for full operational monitoring by summer 2025. Planet is currently working to expand the constellation to four Tanagers. The system is designed to balance detection limits, spatial coverage and sample frequency to optimize observational completeness for high emission CH₄ and CO₂ point sources. Each imaging spectrometer instrument has a spectral range of about 400–2500 nm, 5 nm spectral sampling, a nadir spatial resolution of 30 meters, and nadir swath width of about 19 km. Each satellite is capable of imaging up to 300,000 km² per day. By combining the results of independent controlled release testing with empirical evaluation of the radiometric, spectral, spatial performance, and retrieval noise performance of the Tanager-1 spectrometer, we predict minimum detection limits of about 66 – 144 kgCH₄/h for CH₄ point sources and about 10,400 – 19,600 kgCO₂/h for CO₂ point sources for images with 25 % albedo, 45 degree solar zenith angle, and 3 m/s wind speed. Detection limit varies with imaging mode and environmental variables. Every Tanager satellite provides multiple imaging modes with varying degrees of ground motion compensation that allow trade-offs between detection limit and spatio-temporal coverage. The Carbon Mapper monitoring strategy focuses on routine mapping of major CH₄ and CO₂ emitting regions and priority facilities around the world. With a single Tanager satellite, the cloud-free median time to access ranges from 2 to 5 days for isolated areas of interest (AOIs) at mid-latitudes. With four Tanager satellites, the cloud-free median time to access is reduced to under 10 hours for isolated AOIs, with weekly to monthly sample frequency for comprehensive mapping of contiguous regions. The constellation is designed for scale-up by launching more satellites with an ultimate goal of providing routine sub-daily monitoring of all high priority regions and 90 % observing system completeness for point sources. Additionally, the satellites are capable of sun-glint tracking over the ocean to allow monitoring of offshore oil and gas fields, a key emission sector that has largely gone unmonitored. A review of the first 7 months of Tanager-1 CH₄ and CO₂ observations including initial validation with coordinated aircraft under-flights and non-blind controlled release testing indicates that the system is meeting performance requirements and, in many cases, surpassing expectations. We also present early observational findings including the first use of Tanager data to guide the timely mitigation of a CH₄ super emitter.