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NASA Plans to Shoot Lasers at the Earth to Study Forests in 3D

Meet the newly approved, ISS-bound probe GEDI, the first probe to systematically study carbon sequestration from space.
Artist's depiction of 3D tree architecture. Image: NASA Goddard Spaceflight Center

This week, NASA released details of a newly approved project: the Global Ecosystems Dynamics Investigation (GEDI) lidar. The probe is scheduled for completion in 2018, and will eventually be launched to the International Space Station. There, from its orbital perch, the GEDI will shoot its trio of specialized lasers at the Earth.

Though that sounds like something a Bond villain will do, GEDI is most assuredly part of the effort to save the planet, not explode it. Its lasers are of the lidar variety—designed to shoot pulses, then analyze the reflected light. Its like radar but with light (thus the portmanteau lidar).

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The probe's mission is to create a three-dimensional scan of every forest on the planet between the latitudes of  50 degrees north and 50 degrees south. It's an ambitious amount of land to cover, and it includes most of the planet's temperate and tropical forests. Ultimately, the goal is to tackle one of the biggest ongoing questions in Earth sciences: the amount of carbon stored in global forests.

These trees are on the GEDI hit list. Image: ViviCam 6300/Wikipedia Commons

"GEDI will be a tremendous new resource for studying Earth's vegetation," said Piers Sellers, deputy director of Goddard's Sciences and Exploration Directorate, in a NASA statement.

"In particular, the GEDI data will provide us with global-scale insights into how much carbon is being stored in the forest biomass," he continued. "This information will be particularly powerful when combined with the historical record of changes captured by the US's long-standing program of Earth-orbiting satellites, such as Landsat and MODIS."

Normal forests store carbon at a greater rate than they release it as carbon dioxide gas, as part of the process of carbon sequestration. Though carbon dynamics can be examined with lidar-equipped drones and aircraft, it's difficult to calculate how much carbon is stored worldwide without a space-based probe.

Along those lines, not only will GEDI be able to monitor macro changes in the environment, it can detect the changing "fingerprints" of individual regions of forests. In fact, GEDI will be capable of sensing where an individual tree's canopy begins with a margin of error of only a meter.

The GEDI data will provide us with global-scale insights into how much carbon is being stored in the forest biomass

This high degree of accuracy will translate into much better estimates of the total forest biomass of the plane. It will also give researchers a clearer idea of the comparative carbon storage between established forests and newly wooded areas.

Understanding the scope of carbon sequestration in forests has never been more timely, as it profoundly affects our approach to staving off climate change. Artificial methods of carbon sequestration are being developed to reduce excess carbon dioxide emissions, but that doesn't mean preservation of forests should be taken for granted.

Indeed, last year, Motherboard's Mat McDermott reported on how most climate models underestimate the unstable future of boreal forests. If those forests shrink, massive amounts of carbon will be released back into the ecosystem. GEDI will help anticipate, if not mitigate, these potential problem areas. With lasers, no less.