NASA satellites about to retire leave several gaps in Earth observation

Three NASA satelliteseach weighing approximately an elephant, are about to retire. Already in the process of gradual deactivation, they have been observing the planet for more than two decades, far exceeding initial expectations.

In addition to helping with weather forecasting, they are important in fighting forest fires, whether, for example, in monitoring oil spills. But age does not forgive, and they will soon send their last transmissions, beginning the final slow fall towards the Earth’s surface.

This is the moment scientists fear. When the three satellites – Terra, Aqua and Aura – are turned off, much of the data they are collecting will be lost.and newer satellites will not be able to meet all needs.

Fundamental data for studying the ozone layer and climate change could be lost

From that moment on, researchers will have to rely on alternative sources that may not exactly meet the requirements or look for alternative solutions to allow the continuity of records.

For some of the data recorded by these satellites, the situation is even worse: no other instrument will continue to capture this information. In a few years, the detailed features they reveal about our world will be less clear.

“Losing this irreparable data is simply tragic,” says Susan Solomon, a chemistry scientist 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 are affecting it, it seems we may be asleep at the wheel.”

The main area that will be left unattended is the stratosphere, the very important home of the ozone layer.. Through the cold, thin air of the stratosphere, ozone molecules are constantly being formed and destroyed, transported and swept away by interaction with other gases. Some of these gases have natural origin; others are there because of us – human beings.

An Aura instrument, the MLS (Microwave Limb Sounder), gives us the best view of this intense chemical activity, explains Ross J. Salawitch, a scientist at the University of Maryland. Once the Aura satellite disappears, the possible view of the planet will decrease considerably.

Impact on research: ozone layer stagnates and climate monitoring is at risk

Recently, MLS data has been demonstrating its added value in unexpected ways, according to Salawitch. The instrument showed how much bushfires in Australia in late 2019 and early 2020and the volcanic eruption near Tonga in 2022, had consequences on the ozone layer.

If it weren’t about to be shut down, the MLS could also help solve some of the problems that still persist, says Salawitch.

“The thickness of the ozone layer over populated regions in the northern hemisphere has practically not changed in the last decade,” he says. “In fact, he should be recovering. And it’s not.”

Jack Kaye, associate director of research for NASA’s Earth Science Division, acknowledges researchers’ concerns about the end of MLS. However, argues that other sourcesincluding instruments on newer satellites, on the International Space Station and here on Earth, will provide “a very good window to provide information about what is happening in the atmosphere”.

NASA launches satellites that will allow monitoring tropical cyclones in less time

For scientists studying climate change, the difference between the same and similar data can be huge. In fact, only through continuous monitoring, in an unaltered manner, over a long period, can one be sure of what is happening.

Even a small interruption in the records can create problems. For example, if an ice shelf collapses in Greenland, unless sea level rise is measured before, during and after, it will never be certain whether the sudden change was caused by the collapse.