Why is NASA Shooting Space Lasers into Forests?

Space Science, Technology

NASA is sending a shower of laser pulses to Earth from the International Space Station in order to find out the most secret things about the planet’s forests.

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The GEDI mission, which was made by NASA’s Goddard Space Flight Center and the University of Maryland, lets forested areas in even the most remote places be mapped in 3D for the first time.

The data makes it possible to study how the Earth’s forests are changing, what role they play in slowing down climate change, and the effects of planting and cutting down trees on both the local and global levels.

With the new GEDI (Global Ecosystem Dynamics Investigation) data product, scientists who study ecosystems and climates can find their areas of interest quickly and study the structure and carbon content of forests with more accuracy than before.

The launch of the new biomass product comes as GEDI’s mission is about to end in a year. It is the result of important progress in lidar (a type of laser) research in space.

GEDI is a lidar instrument with a high resolution that was made to measure plants. From its position on the International Space Station, GEDI quickly bounces laser pulses off the trees and bushes below to make detailed 3D maps of forests and landforms. When the data are processed and put on a grid with a 1 km resolution, researchers can study forest ecosystems, animal habitats, carbon content, and climate change.

GEDI has taken billions of measurements between 51.6 degrees north and south latitude in its first three years in space approximately the latitudes of London and the Falkland Islands, respectively.

The new data product combines GEDI data with data from lidars on the ground and in the air to make a global biomass map that shows how much plant life is in a certain area.

Ralph Dubayah, the lead researcher for GEDI and a professor of geographic sciences at the University of Maryland, said, “We don’t know how much carbon is stored in the world’s forests, which is a big unknown.” Trees get the carbon they need for growth from the air. But scientists need to know how much carbon is stored in forests so they can figure out how much carbon will be released by cutting down trees or having wildfires. Carbon makes up about half of a plant’s biomass.

The new GEDI tool is not the first global biomass product, but it is the first to use advanced statistical models to give a clear description of the uncertainty in its estimates. This means that GEDI’s estimates of biomass also include information about how accurate those measurements are. “That is, for every 1 kilometer estimate of average biomass, the mission knows how accurate that estimate is,” Dubayah said.

The GEDI team compared their results with forest inventories from the Food and Agriculture Organization of the United Nations and data from the US Forest Service Forest Inventory and Analysis. They found that the GEDI estimates of biomass were similar to both. When the GEDI product was different from the inventories, it showed that more research and calibration were needed.

John Armston, GEDI validation and calibration lead and research associate professor at the University of Maryland, said, “We can use this framework to estimate the biomass of whole countries. For example, many countries in the pantropical regions don’t have national forest inventories.”

“We now have the tools to provide an estimate of above-ground biomass with known uncertainty, which can be used to support climate reporting and a wide range of applications.”

Armston said that there is a lot of interest in using GEDI to look at forest definitions for carbon monitoring and to describe ecosystem structure for biodiversity assessments in many places around the world.

“Resolving the structure of different forest and woodland ecosystems with much more certainty will help not only with estimating carbon stocks, but also with understanding their ecological condition and the effects of different land management practices,” he said.

How does GEDI work?

As the International Space Station circles the blue planet, GEDI is constantly firing lasers. These pulses of energy make it possible to figure out how forests are set up and how tall trees are.

When the lasers sent out by GEDI hit Earth, they first hit the tops of the trees and then keep going until they hit the ground. Researchers also look at how the energy wave patterns change to learn about the composition of the forests.

GEDI is a NASA tool that was sent to the ISS in December 2018. It has been working there since then, and the mission was supposed to last until after this summer.