As part of NASA’s National Balloon Program, the Michigan Exploration Laboratory (MXL), in collaboration with students in the AEROSP 495 class, is deploying high-altitude balloons (HABs) in 2025 to measure the Forbush decrease expected during the solar maximum in July 2025. To establish a baseline, we conducted two HAB flights on February 22 and March 16, carrying a GQ GMC-500+ Geiger counter, which quantifies ionizing radiation (beta, gamma, and X-ray) in counts per second (CPS), counts per minute (CPM), and dose rate (µSv/h). The balloons, reaching altitudes of approximately 30 km (100,000 ft), are also equipped with APRS trackers to transmit GPS positional data. During recent flights, radiation levels peaked at 3.6 µSv/h (Figure 1), with the highest dose rate occurring near 20 km altitude, aligning with the Regener-Pfotzer Maximum (Figure 2). By combining radiation and positional data, we construct radiation-altitude profiles (Figure 2), allowing us to detect the Forbush decrease as a deviation from the baseline profile in future flights. Data analysis performed by Daniel Voloshin and team.
