Every second, lasers mounted on the International Space Station send 242 rapid pulses of light down to Earth. These harmless beams from NASA’s Global Ecosystem Dynamics Investigation (GEDI) instrument bounce off Earth’s natural and human-made surfaces and are reflected back to the instrument. By measuring the time it takes for the signals to come back, scientists can derive the height of the surface below.
From an article in NASA’s Earth Observatory website by Emily Cassidy. NASA Earth Observatory images by Lauren Dauphin, using data from DiTommaso et al. (2021) and Landsat data from the U.S. Geological Survey.
Scientists use these light detection and ranging, or lidar, measurements to create three-dimensional profiles of Earth’s surface. GEDI’s primary mission is to measure tree heights and forest structure in order to estimate the amount of carbon stored in forests and mangroves. New research supported by NASA Harvest reveals these data also can be used to map where different types of crops are being grown.
When David Lobell, an agricultural ecologist at Stanford University, saw researchers using GEDI data to estimate tree heights, he wondered how he could use the data to study agriculture. Stefania Di Tommaso and Sherrie Wang, researchers on his team, came up with the idea of using the data to distinguish different types of crops growing on farms.
Wang reached out to the GEDI science team at the University of Maryland to see if they were using the instrument for agricultural research. They responded that they were not sure GEDI data could be used for such an application. “But they did not say it was impossible,” said Lobell, who helps lead crop yield studies for NASA Harvest.
Mapping where certain crops are grown is important for estimating the overall production of the world’s major crops. But it has been difficult to reliably map crop types from space because many plants can look the same in optical imagery.
For the complete article on the International Space Station lidar CLICK HERE.
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