Overview
- A peer-reviewed paper published Tuesday found that debris decay rates in low Earth orbit rise sharply when sunspot numbers and EUV flux exceed roughly 67%–75% of a solar-cycle peak, with EUV and sunspot number tracking decay more closely than geomagnetic indices.
- The authors derived the result from long-term two-line element records spanning about 1986–2024 by selecting 17 long-lived debris objects from an initial 95 Space-Track candidates to isolate natural orbital decay.
- The finding means the same solar heating that can speed removal of dead hardware also forces active satellites to burn more propellant to hold altitude, complicating operations for large constellations and collision-avoidance planners.
- The result is tentative because the sample is small and two high-inclination debris items deviated from the model, which points to possible limits in thermosphere models at polar latitudes and the need for broader confirmation.
- The work builds on the October 2024 declaration that Solar Cycle 25 reached its peak and raises environmental and policy questions since faster reentries could inject aluminum oxide and other byproducts into the upper atmosphere, a risk noted by AGU and NOAA researchers that calls for follow-up studies and operational monitoring.