19 Jul 2023
...and NASA’s GEDI space laser solves longstanding rainforest canopy mystery.European Southern Observatory’s Very Large Telescope (VLT) has been enhanced with a new instrument featuring an innovative concept that combines the capabilities of two flagship instruments already installed on the telescope.
The newcomer, dubbed HiRISE, will couple the SPHERE exoplanet imager and the CRIRES+ high-resolution spectrograph. While SPHERE has good resolution for direct imaging of exoplanets, CRIRES+ is 2,000 times more powerful when it comes to separating and analysing the light emitted by such planets – making it possible to determine the composition of their atmospheres.
By combining the two instruments via fiber optics, HiRISE will be able to carry out in-depth studies of known planets. It successfully captured its first light from the VLT in Chile’s Atacama Desert on July 9, 2023.
HiRISE, which was developed at the Marseille Astrophysics Laboratory (France), benefited from the expertise of teams at the Grenoble Institute of Planetology and Astrophysics and at the JL Lagrange Laboratory.
NASA space laser solves rainforest canopy mystery
GEDI – a NASA-developed space laser – has provided a detailed structure of the world’s rainforests for the first time ever, said its operational team, this week. The achievement is described in a paper in Environmental Research Ecology, entitled “Tropical forests are mainly unstratified especially in Amazonia and regions with lower fertility or higher temperatures”.
Prof. Christopher Doughty, of Northern Arizona University’s School of Informatics, Computing, and Cyber Systems, and first author on the study, commented, “Most of the world’s species live in tropical forests and most of those make use of the canopy, and yet, we know so little. Rainforest structure matters because it controls how animals access resources and escape predators, and these findings will help us understand tropical forest animal's susceptibility to climate change.”
Hao Tang, professor in the Department of Geography at the National University of Singapore and co-author, added, “A key difference between GEDI and many other satellites is its measurement of three-dimensional canopy structure,” said.
Tang, who is also a principal investigator at the NUS Center for Nature-based Climate Solutions, added, “Conventional satellites, while providing valuable data on land cover and canopy greenness, often lack the detailed vertical information offered by GEDI. This vertical information is crucial for understanding ecosystem dynamics, carbon storage and biodiversity that cannot be easily seen from typical satellite images.”
Launched in late 2018, NASA's GEDI transmits a laser beam from the International Space Station into Earth’s forests thousands of times a day. Depending on the amount of energy returned to the satellite, it can provide a detailed 3D map that shows where the leaves and branches are in a forest and how they change over time.
Doughty, Tang and the other authors of the paper analyzed GEDI data across all tropical forests and found that the structure was simpler and more exposed to sunlight than previously thought. Data also revealed that most tropical forests (80% of the Amazon and 70% of Southeast Asia and the Congo Basin) have a peak in the number of leaves at 15 meters instead of at the canopy top, debunking the fullest-at-the-top theory of early researchers.