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Global Ecosystem Dynamics Investigation (GEDI, pronounced ) is a
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
mission to measure how
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...
has contributed to atmospheric CO2 concentrations.NASA probe will reveal 3D architecture of forests from space
Richard Moss, ''New Atlas''. 14 September 2014. A full-waveform
LIDAR Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is a method for determining ranges (variable distance) by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It can also be ...
was attached to the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
to provide the first global, high-resolution observations of forest vertical structure. This will allow scientists to map
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s and
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
, particularly in the tropics, providing detail on the Earth's
carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and Earth's atmosphere, atmosphere of the Earth. Carbon is the main component of biological compounds as well as ...
.NASA has a plan to take the most detailed scans of the world's forests ever
Pierre Bienaimé, ''Business Insider - UK''. 3 March 2015. The Principal Investigator is Ralph Dubayah, at the
University of Maryland The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public land-grant research university in College Park, Maryland. Founded in 1856, UMD is the flagship institution of the University System of M ...
. The Deputy Principal Investigator & Instrument Scientist is J. Bryan Blair at NASA's
Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...
.


Overview

GEDI was competitively selected as a NASA Earth Ventures Instrument (EVI) mission in 2014. Cost-capped at $94 M, GEDI is led by the
University of Maryland The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public land-grant research university in College Park, Maryland. Founded in 1856, UMD is the flagship institution of the University System of M ...
in collaboration with NASA
Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...
.
. October 9, 2018.
Climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
is closely tied to that of the carbon cycle. GEDI produces high resolution laser ranging observations of the 3D structure of the forests of Earth, which will provide answers to how deforestation has contributed to atmospheric CO2 concentrations, how much carbon forests will absorb in the future, and how
habitat degradation Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
will affect global
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
and the
water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly cons ...
. This, in turn, is also of value for
weather forecasting Weather forecasting is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather informally for millennia a ...
,
forest management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, protection, and forest regulation. This includes management for ...
,
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
and snowpack monitoring. Overall, GEDI will help to better understand how the Earth behaves as a living system. GEDI's LIDAR system provides precise geolocated elevation data that drastically improve global
Digital Elevation Models A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, moon, or asteroid. A "global DEM" refers to a discrete g ...
(DEMs). Owing to the vast number of data points that GEDI is capable of collecting it will provide a stronger baseline for DEMs and remove more system errors compared to
ICESat ICESat (Ice, Cloud, and land Elevation Satellite) was a NASA satellite mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. It operated as part of NASA's Earth Obs ...
. It launched on 5 December 2018 on board a
Falcon 9 Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX. The rocket has two stages. The first (booster) stage carries the second stage and payl ...
and it is part of the
SpaceX CRS-16 SpaceX CRS-16, also known as SpX-16, was a Commercial Resupply Service mission to the International Space Station launched on 5 December 2018 aboard a Falcon 9 launch vehicle. The mission was contracted by NASA and is flown by SpaceX. This ...
mission. It was mounted on the Japanese Experiment Module - Exposed Facility (JEM-EF) ''Kibo'' module for a two-year mission. After three month, GEDI started collecting data for scientific use on March 25, 2019. The mission is being led by Professor Ralph Dubayah of the University of Maryland. Once reaching the end of its two-year mission, GEDI will be removed from the JEM-EF and loaded into another Dragon Capsule trunk for disposal.


Instrument

The GEDI instrument is a
geodetic Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...
-class, light detection and ranging (
Lidar Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is a method for determining ranges (variable distance) by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It can also be ...
) laser system consisting of three lasers that produce eight parallel tracks of observations. Each laser fires 242 times per second and illuminates a 25 m spot (a footprint) on the surface over which 3D structure is measured. Each footprint is separated by 60 m along track, with an across-track distance of about 600 m between each of the eight tracks. GEDI is expected to produce about 10 billion cloud-free observations during its nominal 24-month mission length. Using an 80 cm telescope attached to the bottom of the instrument, GEDI will be able to receive the pulses of light that bounce back from the Earth' surface and collect information on the 3D structure of the area in question. Upon the optical bench, the instrument contains three Beam Dither Units (BDU), three beam expanders, three star trackers, and three HOMER lasers. The three HOMER lasers built and installed on GEDI were built by D. Barry Coyle, Furqan L. Chiragh, and Erich A. Frese. The GEDI instrumentation is designed to collect data between 51.6° N latitude and 51.6° S latitude. Within this area, GEDI gathers data from approximately four percent of the earth's surface, including both tropical and temperate forests. The LIDAR system can only operate effectively over relatively cloud free areas. Dense cloud cover blocks the laser pulses and prevents accurate measurements. GEDI uses an active across-track pointing system in order to help show area that is not normally covered due to the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
's orbit pattern. These occur because the ISS is not maintained in a repeating orbit and can get stuck in orbital resonances that essentially repeat orbital tracks and result in large coverage gaps.


References

{{Satellite and spacecraft instruments Kibo (ISS module) Satellite meteorology SpaceX payloads contracted by NASA Spacecraft instruments Lidar Deforestation 2018 in spaceflight Earth satellite laser altimeters