NASA’s Orbiting Carbon Observatory-3 (OCO-3) was installed on the International Space Station in 2019 to measure carbon dioxide in Earth’s atmosphere.
OCO-3 launched on May 4, 2019, aboard a SpaceX Falcon 9 as part of the CRS-17 cargo mission. After reaching the station, robotic equipment moved it to the Japanese Experiment Module’s Exposed Facility, where it could observe Earth from orbit.
The instrument measures reflected sunlight in specific near-infrared and oxygen wavelengths. Those observations help scientists estimate atmospheric carbon dioxide and study how ecosystems, cities, and other regions absorb or release the gas. A movable pointing mirror also lets OCO-3 target selected areas and create detailed “snapshot” maps of urban carbon emissions.
A common mix-up is confusing OCO-3 with OCO-2. OCO-2 is a separate NASA satellite launched in 2014, while OCO-3 is the station-mounted instrument assembled largely from spare OCO-2 hardware. Other ISS instruments study vegetation, temperature, or forest structure, but OCO-3’s specialty is atmospheric carbon dioxide.