Dramatic aircraft chase reveals insights into satellite reentry and air pollution impacts

In early September last year, a unique observation campaign conducted by European scientists around Easter Island provided significant insights into the processes occurring during the atmospheric reentry of defunct satellites. The focus was on Salsa, one of the European Space Agency's four identical Cluster satellites, which burnt up upon reentry on September 8, 2024, with results presented at the European Conference on Space Debris this April. Using a rented business jet equipped with 26 cameras, the team tracked the brief meteor-like event lasting less than 50 seconds. Despite challenges posed by bright daylight, researchers successfully captured important data revealing that the satellite broke apart at an altitude of approximately 50 miles. The study has implications for understanding the particulate metal pollution produced during these spectacular events. "We detected lithium, potassium, and aluminum," noted Stefan Löhle, a researcher at the Institute of Space Systems in Stuttgart. This finding is pertinent as the disintegration of aluminum bodies during reentry can release aluminum oxide, an agent known to potentially trigger ozone depletion. With an increase in satellite launches, particularly from private companies like SpaceX, the atmospheric fallout from decommissioned satellites is becoming a major concern for atmospheric scientists. On average, three satellites fall back to Earth every day, and their metal remnants pose unknown risks. The research highlights that while some materials incinerate upon reentry, others may survive the journey back and potentially impact ecosystems and human health. The research team plans to continue their observations as the remaining Cluster satellites, Rumba, Tango, and Samba, reenter in 2025 and 2026. However, the persistent issue remains that daytime observations may limit data collection accuracy, particularly for spectral measurements that could provide further insights into the chemical processes at play. Additionally, the convergence of satellite debris pollution, solar activity, rising CO2 levels, and the looming threat of oxygen depletion paints a concerning picture for Earth's atmospheric health. Experts emphasize international collaboration to address these multifaceted challenges, highlighting the urgent need for responsible satellite disposal practices and robust space weather forecasting mechanisms. As these threats grow, proactive measures will be crucial to preserve the stability of the atmosphere and its vital functions, particularly with the increasing frequency of satellite reentries expected in the coming years.