NASA mission gets first snapshot of polar heat emissions

NASA’s latest climate mission has begun collecting data on the amount of heat in the form of far-infrared radiation that the Arctic and Antarctic environments are sending into space. These measurements by the Polar Radiant Energy in the Far-Infrared Experiment (PREFIRE) are essential for better predicting how climate change will affect Earth’s ice, seas and weather. Information that will help humanity better prepare for a changing world.

One of PREFIRE’s two shoebox-sized cube satellites, or CubeSats, launched from New Zealand on May 25, followed by its twin on June 5. The first CubeSat began sending back science data on July 1. The second CubeSat began collecting science data on July 25, and the mission will release the data after a problem with the GPS system on that CubeSat is resolved.

The PREFIRE mission will help researchers gain a clearer understanding of when and where the Arctic and Antarctic regions emit far infrared radiation (wavelengths greater than 15 micrometers) into space. This includes how atmospheric water vapor and clouds affect the amount of heat leaving Earth.

Because clouds and water vapor can trap far-infrared radiation near the Earth’s surface, they can raise global temperatures as part of a process known as the greenhouse effect. This is where gases in Earth’s atmosphere, such as carbon dioxide, methane, and water vapor, act as insulators, preventing heat radiated by the planet from escaping into space.

“We are constantly looking for new ways to observe the planet and fill critical gaps in our knowledge. With CubeSats like PREFIRE, we do both,” said Karen St. Germain, director of the Earth Science Division at NASA Headquarters in Washington. “The mission, part of our competitively selected Earth Venture program, is a great example of the innovative science we can achieve through collaboration with university and industry partners.”

Earth absorbs much of the sun’s energy in the tropics; weather and ocean currents transport that heat to the Arctic and Antarctic, which receive much less sunlight. The polar environment, including ice, snow, and clouds, emits much of that heat to space, much of it in the form of far infrared radiation. But those emissions have never been systematically measured, which is where PREFIRE comes in.

“It’s so exciting to see the data coming in,” said Tristan L’Ecuyer, PREFIRE’s principal investigator and a climate scientist at the University of Wisconsin, Madison. “With the addition of PREFIRE’s far-infrared measurements, we’re seeing for the first time the full spectrum of energy that Earth is radiating into space, which is critical to understanding climate change.”

This visualization of PREFIRE data shows brightness temperatures, or the intensity of radiation emitted by Earth at different wavelengths, including the far infrared. Yellow and red indicate more intense emissions originating from Earth’s surface, while blue and green represent lower emission intensities that coincide with colder regions on the surface or in the atmosphere.

The visualization starts by showing data on mid-infrared emissions (wavelengths between 4 and 15 micrometers) taken during several polar orbits by the first CubeSat to be launched in early July. It then zooms in on two passes over Greenland. The orbital trails expand vertically to show how far-infrared emissions vary through the atmosphere. The visualization ends by focusing on a region where the two passes intersect, showing how the intensity of far-infrared emissions changed in the nine hours between these two orbits.

The two PREFIRE CubeSats are in asynchronous, near-polar orbits, meaning they will fly over the same spots in the Arctic and Antarctic within hours of each other, collecting the same kind of data. This gives researchers a time series of measurements they can use to study relatively short-lived phenomena like ice sheet melting or cloud formation, and how these affect far-infrared emissions over time.