Lasers, Jedi, but no Han Solo?: How UMD Researchers’ Project is Heading to Space

By: Katelyn Newman
Publisher: Council on the Environment
Published: August 7, 2014

The University of Maryland will soon add “Instrument on International Space Station” to its list of accomplishments, thanks to the NASA-approved Global Ecosystem Dynamics Investigation (GEDI) Lidar project.

The GEDI project consists of a laser-based system that will observe the structure of forest canopy globally, examining the transformations in natural carbon storage within the carbon cycle from both anthropogenic and natural climate changes.

“We’d like to know what the biomass is of the Earth’s forest, and how that’s changed as a result of deforestation and subsequent regrowth of trees,” said Dr. Ralph Dubayah, the principal investigator of GEDI and professor for the University of Maryland Department of Geographical Sciences.

The instrument will not cost more than $94 million, and the launch will be completed by 2019, according to NASA’s press release.

“The instrument will be completed in 2017, and the time after that is just determining when we can get a ride up to the space station,” said James Bryan Blair, an instrument scientist and the deputy principal investigator of GEDI.

Blair, who helped pioneer the instrument and has been working on the measurement technique for the past 20 years, said that while they have taken similar measurements via aircraft, the space-based version would allow them to obtain a global assessment.

“Laser measurements of forests are especially unique because it’s really one of the only ways we have to peer inside the canopy and really measure the height and the vegetation of the forest, and that’s needed to measure the estimated carbon of the forest,” said Blair.

“We send out a short pulse of laser light down toward the surface, and it bounces off the trees and ground and comes back,” said Blair. “It’s been stretched out in time, and the amount that it stretches tells us how tall the trees are.”

“Over time, we can watch that structure change, either growing or, for example, if it was cut down or burned, and then we can use our measurements to estimate how much carbon was absorbed or how much was lost or emitted into the atmosphere,” said Blair, who is leading the instrument development at NASA’s Goddard Space Flight Center.

“We will be able to understand how forests contribute in terms of whether we cut them down and how they regrow, their role in the carbon cycle, and their role in putting CO2 into the atmosphere and taking it out of the atmosphere,” said Dubayah.

Dubayah, a member of the Council on the Environment, said the scientists involved would also examine how canopy structure and its changes affect habitat quality and biodiversity, specifically in biodiversity hotspots.

“We will be able to look forward in time and understand the impacts of what various policies might be. The modeling piece is critical to what we’re trying to achieve because it enables us to then ask the relevant policy questions,” said Dubayah. “It will allow us to do what we haven’t been able to do; although we can identify where we have lost the forest, we can’t analyze how much carbon has been lost.”

Dr. Matt Hansen, professor in the Department of Geographical Sciences at the university, said he looks forward to the instrument finally reaching the space station, as it’s taken 20 years to reach its current development stage. Hansen will use the measurements from the spacecraft to analyze the multidimensional domain of vegetation coverage.

“This is much more complete in application-specific vegetation,” said Hansen, who works in parallel with the GEDI project. “There is slack- you don’t know how it spans out, but the science might lead to a new opportunity after this.”

Blair said that while the laser-based instrument is being developed, NASA’s Land, Vegetation, and Ice Sensor (LVIS) will continue to take airborne measurements that will support the GEDI research.

“The more we understand the forests and the more we understand about the part they play in the global carbon cycle, we can be more informed in the ways that we manage and affect the forest,” said Blair. “Our ultimate goal is to build a generation of laser sensors after this that can measure the earth, and to do it more completely and more often.”

Reprinted from Council on the Environment with permission.