There are two thermal infrared spectrometers (TIRS) taking measurements as part of the Polar Radiant Energy in the Far-InfraRed Experiment (PREFIRE), one aboard each of the two CubeSats positioned in asynchronous, near-polar orbits. The TIRS instruments measure far-infrared emissions from the Arctic and Antarctica, helping researchers better understand the Arctic energy budget and how far-infrared radiation plays a role in Arctic warming.