PACE Satellite: A New View of Earth's Oceans and Atmosphere
NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite, launched in February 2024, is providing unprecedented detail on our planet's systems. Its primary instrument, the Ocean Color Instrument (OCI), observes Earth across a hyperspectral range from ultraviolet to shortwave infrared light. PACE also carries two polarimeter instruments designed to measure how sunlight interacts with atmospheric particles.
The satellite's data can help warn local managers of potential water quality problems and provide critical information to emergency responders during wildfires.
Tracking Atmospheric Particles and Events
PACE's ultraviolet measurements have proven adept at tracking major atmospheric events. In August 2025, the satellite tracked a large dust plume moving westward from North Africa over the Atlantic Ocean. Simultaneously, data revealed another plume to the north, which was identified as wildfire smoke originating from the United States and Canada.
The instruments can also distinguish between different particle types. During January 2025 wildfires in the greater Los Angeles area, PACE data tracked particle size and shape, differentiating between small smoke particles and larger particles like dust and sea salt. Furthermore, by combining specific wavelengths from OCI data, scientists can determine fire intensity.
Beyond natural events, PACE can observe human influence on the atmosphere. The satellite has observed "ship tracks"—streaks of brighter clouds—over the North Pacific. These are created when emissions from ships modify marine stratocumulus clouds.
Monitoring Ocean and Freshwater Health
A core mission of PACE is identifying different types of phytoplankton from space using ocean color observations. In September 2024, the satellite distinguished specific phytoplankton communities, including picoeukaryotes, Prochlorococcus, and Synechococcus, in the eastern Atlantic Ocean.
The satellite is also a powerful tool for monitoring potentially harmful blooms. During summer 2024, it detected harmful cyanobacteria blooms in the Great Lakes, with elevated concentrations in Green Bay, Saginaw Bay, and western Lake Erie. In March 2025, researchers used PACE data to track a harmful algal bloom of Karenia mikimotoi off South Australia, monitoring its expansion over several months.
Other phytoplankton blooms play vital ecological roles. Diatom blooms, like one observed off the Kamchatka Peninsula, are crucial for transferring carbon in ocean ecosystems and supporting marine life.
Revealing the Structure of Clouds
PACE's polarimeters measure sunlight reflecting off cloud droplets from multiple angles. Using machine learning, scientists can now reconstruct detailed 3D portraits of clouds from this data. These measurements provide new insight into cloud vertical structure and variability, which is key to understanding Earth's climate system.
Broader Impact and Context
The data from PACE joins a fleet of Earth-observing satellites providing a comprehensive view of our planet. In related observations, NASA also released photographs of Earth taken during the Artemis II mission, showing stunning views of auroras, city lights, and zodiacal light.
The practical applications of PACE's observations are significant, from warning of water quality issues at reservoirs and beaches to aiding emergency response during wildfires.