In 2018, new fissures from Kīlauea opened beneath a large residential development on the island of Hawai'i. From around 400 miles overhead, the Operational Land Imager and Thermal Infrared Sensor on Landsat 8 captured the fissures growing and lava moving toward the ocean — imagery both useful and stunning. Landsat's thermal bands work like an orbiting thermometer, and Hawaii, perhaps more than any other state, benefits from those data being free and open to all.
A Landsat 8 composite using infrared and near-infrared bands to show Kīlauea's volcanic activity in 2018. Credit: U.S. Geological Survey.
Hawaii stands apart from the rest of the United States: the nearest of the eight islands of the Hawaiian archipelago is 2,000 miles from the U.S. mainland. Here is how the Landsat satellites help watch it.
Lava from space
Landsat collects imagery in visible light and in bands invisible to the eye. Infrared and near-infrared bands make it easier to track the health of vegetation, burn scars or insect damage; thermal bands record surface temperature. Researchers have used Landsat to follow lava flows and the behavior of lava lakes, sometimes combining daily, coarse satellite data (pixels larger than a kilometer) with sharper Landsat images to map flows more accurately.
Cane fields to fire
In the 19th century, easy-to-mill sugarcane hybrids and irrigation turned Hawaiian cane growing from small operations into large plantations, beginning more than 100 years of agricultural prominence. High local costs and better production methods on the mainland brought a steady decline. The last cane operation, in central Maui, shut down in 2016. The fallow fields filled with dry, non-native grasses, setting the stage for one of Hawaii's largest fires: at least 19,300 acres burned in and around the former cane fields in 2019. Landsat captured the damage and continues to monitor the recovery.
Landsat 8 images showing the effect of a series of 2019 wildfires in Maui's former sugarcane fields. Credit: U.S. Geological Survey.
Landsat also underpins national land cover maps — the National Land Cover Database, LANDFIRE and USGS's Land Change Monitoring, Assessment, and Projection (LCMAP) — which classify every 30-by-30-meter plot in the country, as cultivated cropland or developed land, for example. Such maps are a starting point for urban planning, habitat restoration and land management.
Measuring forests under the clouds
The height and health of each island's tree canopy matter for water use, ecosystem health and carbon storage. On Oahu, three-dimensional lidar surveys were missing the island's notoriously cloudy peaks. Researchers at the University of Hawai'i at Mānoa combined the lidar with Landsat's steady, accurately calibrated imagery to produce a tree-height record for the entire island.
Landsat for the nation
| Users | The most widely used land remote-sensing data among federal civilian agencies; also local, state and Tribal governments, businesses and commercial imaging firms |
| Access | Free worldwide through the USGS Earth Resources Observation and Science (EROS) Center, funded by the National Land Imaging Program |
| Coverage | Landsat 8 and Landsat 9 image Earth's land every 8 days |
| Record | 50 years — the world's longest time series of Earth's land surface |
| Value | A 2017 USGS study put Landsat's annual economic benefit in the U.S. at $2.06 billion, far above its costs |
| Next | NASA and USGS are reviewing a joint study to shape Landsat Next, the successor to Landsat 9 |
Sources
Based on "Hawaii and Landsat," U.S. Geological Survey Fact Sheet 2022–3024; a work of the United States government in the public domain. It cites Flynn and others (2001), USGS (2019), Pacific Fire Exchange (2019), Chen (2022) and Straub and others (2019).
许可协议： CC0 1.0（公有领域） · 改编自 pubs.usgs.gov
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