How do high-altitude balloons help scientists study primary cosmic rays?

High-altitude balloons are essential for studying primary cosmic rays because they allow scientists to bypass the Earth’s atmosphere.12

When primary cosmic rays—the particles arriving from space—enter the atmosphere, they collide with atmospheric nuclei and generate "secondaries," such as muons and neutrons. Consequently, instruments located at sea level or on mountain tops only detect these secondary particles rather than the original primaries.21

By reaching altitudes of approximately 37 km (about 120,000 feet), high-altitude balloons position scientific instruments above the bulk of the atmosphere. This allows researchers to observe primary cosmic rays directly before they interact with atmospheric matter. While rockets can reach even greater heights, they are limited by smaller payload capacities and very short flight durations, whereas balloons provide a more practical platform for sustained observation.12