Uptick in Requests Signals New Potential (Image Credits: Pixabay)
For more than five decades, Landsat satellites captured Earth’s land surfaces under the light of midmorning sun. That routine shifted as Landsat 8 and 9 began leveraging their ascending orbits over the planet’s dark side. These nighttime images, rich in thermal data, now support a surge of scientific requests, from tracking volcanic heat to probing polar ice.
Uptick in Requests Signals New Potential
Dr. Christopher Crawford, Landsat Project Scientist at the U.S. Geological Survey’s Earth Resources Observation and Science Center, observed a marked increase in demands for nighttime imagery. He oversees the program’s data acquisition strategy and noted the excitement around these observations.
“I’ve seen a noticeable uptick in the number of nighttime imaging special requests,” Crawford said. “That’s a very active and innovative measurement science area for Landsat right now.” The shortwave infrared bands detect intense heat like active fires or volcanoes, while thermal sensors measure surface temperatures across diverse features, from geysers to ice fields.
This capability proves versatile amid rising challenges such as changing ice environments and expanding wildfires that endanger lives and infrastructure. Crawford compared it to an all-purpose tool, enabling consistent monitoring where daylight falls short.
Yellowstone Yields a Thermal Surprise
A standout example emerged in Yellowstone National Park, where over 10,000 thermal features fluctuate in temperature and visibility. In April 2017, R. Greg Vaughan of the USGS Astrogeology Science Center reviewed Landsat 8’s nighttime thermal data and spotted an anomaly – a cluster of warm pixels unmatched by existing maps.
Daytime aerial views later confirmed a new hydrothermal area, marked by altered soil and dying trees, between West Tern Lake and the established Tern Lake Thermal Area. Vaughan, who serves as remote sensing lead for the Yellowstone Volcano Observatory, emphasized the instruments’ reliability.
“This is why I love Landsat 8 and 9 so much,” Vaughan said. “These instruments acquire data regularly, not just during the day, but they can also be tasked to acquire data at night on a regular basis. And this is really critical for my work.” Winter acquisitions enhance contrast against cold surroundings, making subtle changes stand out.
Crawford initiated systematic nighttime coverage of Yellowstone following Landsat 9’s 2021 launch, which doubled imaging frequency to every eight days. Vaughan’s input, including a list of active volcanoes, shaped an ongoing annual campaign.
Broader Applications in Fire and Volcano Monitoring
Wildfire researchers in the western U.S. rely on these scans, particularly the shortwave infrared bands that reveal fire edges comparable to low-altitude aircraft data. The Department of Energy’s Pacific Northwest National Laboratory has submitted requests for three consecutive seasons, aiding real-time decisions.
Volcano watchers expanded efforts post-Landsat 9, targeting global sites year-round. One campaign covered all of Iceland, assessing nationwide volcanic activity along coasts and interiors. Gas flares from liquefied natural gas sites also draw regular attention from the energy sector.
Urban areas benefit too, with requests mapping heat islands that exceed surrounding temperatures. Crawford evaluates each proposal based on scientific advancement and user needs, prioritizing underutilized regions for maximum impact.
Polar Regions Get Year-Round Coverage
The Landsat Extended Acquisition of the Poles campaign marked a leap in high-latitude monitoring. Led initially by Dr. Ted Scambos, it now delivers routine winter images where data was scarce before.
These scans track ice sheet changes, surface temperatures, and ocean-ice interactions using visible, shortwave, and thermal bands. Even at twilight, snow and ice’s high reflectivity preserves detail despite low sun angles. Data volumes stay manageable in darkness, easing transmission to ground stations.
“Snow and ice are still really bright mediums on the surface, and so even if the illumination is low, you can still see a lot of detail,” Crawford explained. Instruments run continuously, requiring only targeted recording.
Accessing and Requesting Nighttime Data
Anyone can submit special requests via the Landsat Acquisitions webpage. All resulting imagery enters the public domain through the USGS EarthExplorer site, under Landsat Collection 2 Level-1 with the “Night” criteria.
This expansion populates the archive with records essential for past, present, and future change detection. As Crawford put it, the satellites now maximize their potential for science and society alike.