The two small satellites of the agency’s PREFIRE mission, set to launch in spring 2024, will fill in missing data from Earth’s polar regions.
Two new miniature NASA satellites will begin zipping through Earth’s atmosphere within months, detecting heat lost to space. Their observations from the most chilling regions of the planet will help predict how our ice, our seas and our climate will change in the face of global warming.
About the size of a shoebox, the cube satellites, or CubeSats, comprise a mission called PREFIRE, short for Polar radiant energy in the far infrared experiment. Equipped with technology proven on Mars, they aim to reveal for the first time the full spectrum of heat loss from Earth’s polar regions, making climate models more accurate.
PREFIRE has been developed jointly by NASA and the University of Wisconsin-Madison, with team members from the universities of Michigan and Colorado.
The mission begins with Earth’s energy budget. In a planetary balancing act, ideally the amount of thermal energy the planet receives from the Sun would be offset by the amount it radiates from the Earth system into space. The difference between incoming and outgoing energy determines the Earth’s temperature and shapes our climate.
The polar regions play a key role in the process, acting as the fins of the Earth’s radiator. The agitation of air and water, through climate and ocean currents, moves thermal energy received in the tropics toward the poles, where it is emitted as infrared thermal radiation, the same type of energy felt in a heat lamp. . About 60% of that energy flows into space at far-infrared wavelengths that have never been systematically measured.
PREFIRE can close that gap. “We have the potential to discover some fundamental things about how our planet works,” said Brian Drouin, the mission’s deputy principal investigator and scientist at NASA’s Jet Propulsion Laboratory in Southern California.
“In climate projections, much of the uncertainty comes from what we don’t know about the North and South poles and how efficiently radiation is emitted into space,” he said. “The importance of that radiation was not understood for much of the space age, but now we know and we intend to measure it.”
Each satellite, which will launch from New Zealand two weeks apart in May, will carry a thermal infrared spectrometer. Instruments designed by JPL include specially shaped mirrors and detectors to split and measure infrared light. A similar technology is used by Mars climate probe on NASA’s Mars Reconnaissance Orbiter to explore the Red Planet’s atmosphere and climate.
Miniaturizing the instruments to fit on CubeSats was a challenge for the PREFIRE engineering team. They developed a scaled-down design optimized for the comparatively warm conditions of our own planet. Weighing less than 3 kilograms (6 pounds), the instruments take readings using a device called a thermocouple, similar to the sensors found in many home thermostats.
To maximize coverage, the PREFIRE twins will orbit Earth along different paths, overlapping every few hours near the poles.
Since the 1970s, the Arctic has warmed at least three times faster than anywhere else on Earth. Winter sea ice there has shrunk by more than 15,900 square miles (41,200 square kilometers) per year, a loss of 2.6% per decade relative to the 1981-2010 average. A change is also occurring on the opposite side of the planet: Antarctica’s ice sheets are losing mass at an average rate of about 150 billion tons by year.
The implications of these changes are far-reaching. Sea ice fluctuations shape polar ecosystems and influence ocean temperature and circulation. Meltwater from kilometer-thick ice sheets in Greenland and Antarctica is responsible for about a third of the temperature rise. global mean sea level From 1993.
“If you change the polar regions, you also fundamentally change the climate around the world,” said Tristan L’Ecuyer, a professor at the University of Wisconsin-Madison and the mission’s principal investigator. “Extreme storms, flooding, coastal erosion – all of these things are influenced by what’s happening in the Arctic and Antarctica.”
To understand and project such changes, scientists use climate models that take into account many physical processes. Running the models several times (each time under slightly different conditions and assumptions) results in a set of climate projections. Assumptions about uncertain parameters, such as the efficiency with which the poles emit thermal radiation, can significantly affect the projections.
PREFIRE will provide new data on a variety of climate variables, including atmospheric temperature, surface properties, water vapor and clouds. Ultimately, more information will produce a more accurate view of an ever-changing world, L’Ecuyer said.
“As our climate models converge, we will begin to really understand what the future will look like in the Arctic and Antarctica,” he added.
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, California.
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Written by Sally Younger