CLIMATEWIRE | With good weather and little luck, NASA’s newest Earth-observing satellite will launch early Tuesday morning from Cape Canaveral, Florida. The flight will conclude nearly a decade of mission development — and its payload could help usher in a new era of Earth science.
“It’s groundbreaking,” said Jeremy Werdell, project scientist for the PACE satellite mission. “In 25 years at NASA, it’s the first mission I feel I can grow into instead of knowing exactly what I’m going to get. It’s going to not only produce so much novel data that we don’t have in hand now, but that will effectively shine a light on so many new discoveries.”
PACE stands for Plankton, Aerosol, Cloud, ocean Ecosystem — all things the new mission will allow scientists to observe in greater detail than ever before. Pollution particles and tiny ocean organisms might not sound exciting on their own, but they are key to understanding some of the most important processes shaping the planet today, including climate change.
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Three high-tech new instruments make those observations possible.
The satellite is equipped with two polarimeters, which observe certain properties of sunlight as it bounces off objects or particles in the air below. These observations, in turn, help reveal specific characteristics of the particles the light is striking. They’re particularly useful for observing clouds and aerosols in the atmosphere, including dust, wildfire smoke and industrial air pollution.
These are some of the most advanced polarimeters in existence, according to NASA scientist Kirk Knobelspiesse, the mission’s polarimetry lead. They’re both multiangle instruments, meaning they collect images from an array of different viewpoints, giving scientists the most complete possible pictures of the clouds and particles they’re studying.
Few satellites today have that kind of capability. And PACE’s instruments will be some of the only ones collecting public data.
The mission’s flagship instrument — the only one of its kind, custom-built at NASA — is its ocean color instrument (OCI), a spectroradiometer that measures the wavelength and amplitude of emitted light. More simply, it’s an instrument that detects colors. And it’s really good at what it does: the OCI can detect more than 200 bands of color information, from the ultraviolet spectrum through visible light all the way up into the infrared.
That’s an improvement over previous satellite missions, which have been able to observe only a few different blues, greens and reds. The new capabilities will allow scientists to differentiate between various plankton communities in the ocean, giving them new insight into marine ecosystems.
“By having information across the full spectrum, then we can look at pigments we haven’t been able to do so before,” said Antonio Mannino, the mission’s deputy project scientist for oceans. “One analogy we’ve used is going from a box of eight crayons to a box of 248 or so colors.”
Clouds and climate mysteries
More detailed observations of the oceans and atmosphere can inform a variety of research, including studies on everything from toxic algae blooms to air quality to the links between clouds and global warming.
Plankton communities are a prime indicator of marine health. These tiny organisms are the cornerstone of the marine food web, and knowing what species are present in a given part of the ocean can help scientists predict how much oxygen is in the water, what kinds of fish are hanging around and how healthy their populations are. That’s valuable information for the fishing industry.
The new observations also can provide early warnings about toxic algae blooms, which can harm not only fisheries and other marine organisms but coastal human communities as well.
Plankton communities even can help scientists estimate how much carbon dioxide the ocean is absorbing from the atmosphere. That’s valuable information for climate scientists trying to make projections about how quickly the planet will warm in the coming years.
PACE also will help researchers better observe aerosols and clouds in the atmosphere — and address some of the biggest questions climate scientists are puzzling over today.
“There are two major uncertainties that are plaguing us in terms of where is our future climate heading,” said Mark Zelinka, an atmospheric scientist at Lawrence Livermore National Laboratory, who is not involved with the PACE missions. “One of them is humans — and the other one is clouds.”
Different types of clouds can warm or cool the climate, depending on physical properties such as the size, number and composition of their water droplets. Understanding the way clouds form and how they’re shifting as the planet warms is important for making accurate predictions about future climate change.
Aerosols also are closely linked to cloud research. Clouds form when water droplets condense around tiny particles in the air. And different types of aerosols can affect the size and abundance of water droplets, altering the physical properties of clouds. But scientists still have a lot of questions about exactly how these physical processes work.
“It’s still pretty uncertain just how much aerosols are affecting clouds or in what ways,” Zelinka said.
That’s why improved satellite observations are so important, he added. More data can help scientists better understand these processes and then incorporate them into the models they use to make projections about the Earth’s climate future.
“We don’t have the ability to build Earth in a laboratory,” said Knobelspiesse, PACE’s polarimetry lead. “Our only lab is the planet. But we’re not able to see the planet everywhere all the time. So having good observations of that will help us better understand and improve our models, which will help us forecast what will happen in the future.”
PACE observations also will give scientists a better picture of pollution and air quality around the world, important information for scientists and policymakers seeking to improve human health.
All three instruments and their observations combined will help give scientists the most complete understanding yet of the close connections between the Earth’s atmosphere and its oceans, Werdell said.
“Our contribution here, in terms of a grand climate sense, is to better understand how aerosols and ocean and clouds all interact, with an eye on effectively understanding their various roles in a warming atmosphere and a thus warming ocean,” he said.
‘The gold standard’
PACE is scheduled to launch no earlier than 1:33 a.m. Eastern time Tuesday, pending possible weather-related delays. The launch will turn the page on years of work.
NASA scientists first started thinking about the project about 20 years ago, according to Werdell. The idea was to develop a mission that would complement other NASA Earth-observing satellite initiatives, such as the long-running Landsat program, the ocean-observing SeaWiFS project and the Aqua mission, which focused on the Earth’s water cycle.
After more than a decade of thinking, planning and publishing reports on potential new Earth-observing systems, NASA headquarters officially green-lighted the project in December 2014, according to Werdell. Since then, various project teams have exhaustively mapped out the mission’s technical specs, its implications for scientific research and its value for ordinary human communities, including its applications for fisheries and air quality monitoring.
The project didn’t come without its challenges. The nation’s longest government shutdown in history — a 34 full days between December 2018 and January 2019 — put much of NASA’s staff on temporary furlough. The Covid-19 pandemic later caused substantial delays to the launch timeline, which was previously intended to occur some time in the fall of 2022.
But there have been good memories too, Werdell said. On Nov. 14, 2023, the PACE spacecraft was finally transported from NASA’s Goddard Space Flight Center in Maryland to the Kennedy Space Center in Florida, bringing the project into its home stretch.
“Putting it on the truck, seeing it arrive here in Florida was amazing,” Werdell said.
Once the satellite is in orbit, it will begin collecting data almost immediately — although it may take another month or two to conduct all the necessary tests to make sure everything is online and working properly.
“At the end of that 60 days, the floodgates open,” Werdell said.
The mission highlights NASA’s contributions to Earth and climate science, he added.
“There’s nothing like this mission,” he said. “A combined interdisciplinary study of sea and sky, it fills a niche that no other agency in the U.S. or abroad is pursuing. I think it’s going to become the gold standard of why NASA earth science exists.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2023. E&E News provides essential news for energy and environment professionals.