Impact of Solar Activity Cycles on ISS Orbital Decay: A Two-Decade TLE-Based Analysis (2005–2025)

This study investigates the relationship between solar activity cycles and the orbital decay of the International Space Station (ISS) over a two-decade period (2005–2025). Using thousands of real Two-Line Element (TLE) records obtained from Space-Track.org, the orbital altitude of the ISS was computed and analyzed using Python-based tools. The results clearly show that solar maxima, especially during 2011 and 2024–2025, coincide with pronounced drops in orbital altitude due to increased thermospheric drag. This empirical study validates theoretical models of space weather impact and demonstrates a reproducible method for satellite orbital analysis using open data and code. It provides valuable insights for mission planning, orbital maintenance, and atmospheric modeling.