Sometime in the next few years—no one knows exactly when—three NASA satellites, each as heavy as an elephant, will plunge into obscurity. They are already drifting, losing height bit by bit. They’ve been watching the planet for more than two decades, much longer than expected, helping us predict the weather, manage wildfires, monitor oil spills and much more. But age is catching up with them, and soon they will send their last transmissions and begin their slow, final fall to Earth. This is a moment scientists they are afraid.
When the three orbiters—Terra, Aqua, and Aura—are shut down, much of the data they’ve been collecting will be gone, and the newer satellites won’t be able to pick up all the work. Researchers will either have to rely on alternative sources that may not meet their exact needs or seek workarounds to allow their records to continue. With some of the data these satellites collect, the situation is even worse: no other instruments will continue to collect it.
In a few short years, the subtle characteristics they reveal about our world will become much fuzzier. “The loss of this irreplaceable data is just tragic,” said Susan Solomon, an atmospheric chemist at the Massachusetts Institute of Technology. “Just when the planet most needs us to focus on understanding how we are affected by it and how we influence it, we seem to have fallen catastrophically asleep at the wheel.”
The main area we lose sight of is the stratosphere, the most important home of the ozone layer. In the cold, rarefied air of the stratosphere, ozone molecules are constantly being formed and destroyed, shed and swept away as they interact with other gases. Some of these gases have a natural origin; others are there for us. Aura’s instrument, the Microwave Limb Probe, gives us the best line of sight into this simmering chemical drama, said Ross J. Salavitch, an atmospheric scientist at the University of Maryland. Once the aura wears off, our vision will blur considerably.
Recently, microwave limb probe data has proven its value in unexpected ways, Salavic said. It showed how much damage was done to the ozone by the devastating bushfires in Australia in late 2019 and early 2020 and by the underwater volcanic eruption near Tonga in 2022. It helped show how much ozone-depleting pollution is rising in stratosphere over East Asia from the summer monsoon in the region.
If it doesn’t go offline that soon, the beep could also help solve a big mystery, Salavic said. “The thickness of the ozone layer over populated regions in the Northern Hemisphere has barely changed over the past decade,” he said. “He has to recover. But it is not.”
Jack Kay, NASA’s associate director of Earth exploration Science Division, acknowledged researchers’ concerns about the end of the probe. But he argued that other sources, including instruments on newer satellites, on the International Space Station and here on Earth, would still provide “a pretty good window into what atmosphere does.” Financial reality compels NASA to make “tough decisions,” Kay said.
For scientists studying our changing planet, the difference between the same data and nearly identical data can be huge. They may think they understand how something develops. But only by observing it continuously, in an unchanging way, over a long period of time, can they be sure what is going on. Even a short break in recordings can cause problems.
Last year, NASA canvassed scientists for thoughts on how the end of Terra, Aqua and Aura would affect their work. Over 180 responded to the call. Even if there are alternative sources for this information, the researchers write, they may be less frequent or of lower resolution or limited to certain times of day, all factors that determine how useful the data are.
The end of Terra and Aqua will affect how we observe another important driver of our climate: how much solar radiation the planet receives, absorbs and bounces back into space. The balance between these quantities determines how much the Earth warms or cools. And to find out, scientists are relying on NASA’s Cloud and Earth’s Radiant Energy System, or CERES, instruments. Four satellites are currently flying with the CERES instruments: Terra, Aqua plus two newer ones that are nearing completion. nyt
When the three orbiters—Terra, Aqua, and Aura—are shut down, much of the data they’ve been collecting will be gone, and the newer satellites won’t be able to pick up all the work. Researchers will either have to rely on alternative sources that may not meet their exact needs or seek workarounds to allow their records to continue. With some of the data these satellites collect, the situation is even worse: no other instruments will continue to collect it.
In a few short years, the subtle characteristics they reveal about our world will become much fuzzier. “The loss of this irreplaceable data is just tragic,” said Susan Solomon, an atmospheric chemist at the Massachusetts Institute of Technology. “Just when the planet most needs us to focus on understanding how we are affected by it and how we influence it, we seem to have fallen catastrophically asleep at the wheel.”
The main area we lose sight of is the stratosphere, the most important home of the ozone layer. In the cold, rarefied air of the stratosphere, ozone molecules are constantly being formed and destroyed, shed and swept away as they interact with other gases. Some of these gases have a natural origin; others are there for us. Aura’s instrument, the Microwave Limb Probe, gives us the best line of sight into this simmering chemical drama, said Ross J. Salavitch, an atmospheric scientist at the University of Maryland. Once the aura wears off, our vision will blur considerably.
Recently, microwave limb probe data has proven its value in unexpected ways, Salavic said. It showed how much damage was done to the ozone by the devastating bushfires in Australia in late 2019 and early 2020 and by the underwater volcanic eruption near Tonga in 2022. It helped show how much ozone-depleting pollution is rising in stratosphere over East Asia from the summer monsoon in the region.
If it doesn’t go offline that soon, the beep could also help solve a big mystery, Salavic said. “The thickness of the ozone layer over populated regions in the Northern Hemisphere has barely changed over the past decade,” he said. “He has to recover. But it is not.”
Jack Kay, NASA’s associate director of Earth exploration Science Division, acknowledged researchers’ concerns about the end of the probe. But he argued that other sources, including instruments on newer satellites, on the International Space Station and here on Earth, would still provide “a pretty good window into what atmosphere does.” Financial reality compels NASA to make “tough decisions,” Kay said.
For scientists studying our changing planet, the difference between the same data and nearly identical data can be huge. They may think they understand how something develops. But only by observing it continuously, in an unchanging way, over a long period of time, can they be sure what is going on. Even a short break in recordings can cause problems.
Last year, NASA canvassed scientists for thoughts on how the end of Terra, Aqua and Aura would affect their work. Over 180 responded to the call. Even if there are alternative sources for this information, the researchers write, they may be less frequent or of lower resolution or limited to certain times of day, all factors that determine how useful the data are.
The end of Terra and Aqua will affect how we observe another important driver of our climate: how much solar radiation the planet receives, absorbs and bounces back into space. The balance between these quantities determines how much the Earth warms or cools. And to find out, scientists are relying on NASA’s Cloud and Earth’s Radiant Energy System, or CERES, instruments. Four satellites are currently flying with the CERES instruments: Terra, Aqua plus two newer ones that are nearing completion. nyt
