Since April 2019, a fridge-size instrument attached to the International Space Station (ISS) has tickled the treetops of much of the planet with laser light, mapping forests’ carbon stores and the wildlife habitat they provide. Yet in early 2023, the laser is set to be jettisoned into Earth’s atmosphere, where it will burn up unless NASA approves a plan to extend its tenure.
Researchers and some U.S. Congress members are now lobbying NASA to give the Global Ecosystem Dynamics Investigation (GEDI) instrument a second life so it can finish measuring the world’s tropical and temperate forests.
“To take that data source off is just madness, given that we haven’t even achieved global coverage,” says Matt Finer, a researcher for the Amazon Conservation Association. GEDI is “one of a kind,” adds Sarah Carter, a researcher at the World Resources Institute. Compared with previous instruments, it has given forest measurers “much more nuanced data.”
Imaging satellites such as Landsat can map forests, but have limitations: They can only tell whether trees are there, not how tall they are, what quality habitat they provide, or how much carbon they hold. Planes equipped with radar-like laser instruments called lidars can gather more informative forest measurements, but such flights are costly.
GEDI has used its perch on the ISS to deploy lidar over much of the globe. As the station hurtles around the planet, GEDI pings the surface with 242 pulses per second of near-infrared light and measures the reflections. The focused radiation penetrates dense canopies but bounces back from treetops, midstory branches, and the ground, enabling researchers to produce 3D forest images and estimate the wood and carbon they store.
GEDI has enabled “unquestionably the best map of canopy height that’s ever been produced,” says Ralph Dubayah, an ecologist at the University of Maryland, College Park, and leader of the GEDI team.
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