Earlier this year, Eric Hochberg, a reef systems ecologist at BIOS, was awarded two grants from the National Aeronautics and Space Administration (NASA) to continue lines of investigation stemming from the four-year NASA COral Reef Airborne Laboratory (CORAL) mission. Hochberg was principal investigator of CORAL (2015–2019), which utilized a state-of-the-art airborne sensor, called PRISM, to produce the first comprehensive assessment of reef condition for a large portion of the world’s reefs.
While CORAL met its goals—and received a 2020 NASA Honors Group Achievement Award for successful completion of its mission—there are still many areas of associated research that Hochberg and his colleagues remain interested in pursuing.
“We learned a lot from CORAL, particularly how reefs relate to the environment at the ‘whole-reef’ scale, as opposed to small-scale underwater surveys,” Hochberg said. “But, as is typical in research, our results pointed toward new and important questions, both in reef science and in remote sensing science.”
In 2020, Hochberg and Michelle Gierach, a scientist at NASA’s Jet Propulsion Laboratory (California, U.S.) and the former CORAL project manager, submitted a successful proposal to NASA’s Ocean Biology and Biogeochemistry program. They proposed to investigate how thermal stress, such as marine heatwaves that cause coral bleaching, varies over space and time, and whether this variability impacts the condition of coral reefs.
Over the next three years, Hochberg, the project’s co-principal investigator, and Gierach, the principal investigator, will use a combination of in-water, airborne, and satellite imaging spectroscopy (a new type of space-based camera that sees the earth in hundreds of colors at once, as opposed to the traditional three to five colors) in their approach. With these tools, they will study two significant bleaching events from 2016-2020 in the main Hawaiian Islands and Australia’s Great Barrier Reef. The investigation will also leverage data collected from the CORAL mission and apply CORAL algorithms—processes that convert satellite data into meaningful products, such as maps—to improve their soundness for future missions.
Also in 2020, Hochberg submitted a successful proposal to NASA’s Commercial Smallsat Data Acquisition Program, with a subaward to research professor David Wettergreen at the Robotics Institute at Carnegie Mellon University (Pennsylvania, U.S.). This proposal advances the CORAL mission by working to answer the fundamentally important reef ecology question: How much coral is there?
The PRISM sensor used in the CORAL mission was proven to be able to map coral on reefs, but because it is an airborne sensor, it can’t map the whole world at once, and it becomes prohibitively expensive to fly the plane on repeat missions. At the same time, there are hundreds of commercial satellites that take high resolution images of the earth on a daily basis, but these can’t distinguish between coral and algae the way that PRISM can. Hochberg proposed to take PRISM imagery from the CORAL mission and commercial satellite data from the same times and locations, and use deep learning (artificial neural networks) to “teach” computers to locate coral in the commercial satellite data.
“If this works, we can make a map of the world’s coral cover, which is a quantitative measure of reef health, using commercial satellite data,” Hochberg said. “That would help us answer a fundamentally important question about reefs, which is ‘How much coral is there in the world?’ That’s something we don’t know at this point.”