Quantifying orbital debris lifetimes in low earth orbit using a doubly censored Weibull framework

Accurately estimating orbital-debris lifetimes is essential for ensuring the long-term sustainability of the space environment. However, many fragments either decayed before systematic tracking began or remain unobserved today, resulting in incomplete lifetime data. This study develops a doubly censored Weibull framework to model debris persistence in low Earth orbit (LEO), accounting simultaneously for early untracked re-entries and still-orbiting objects. Parameters are estimated via maximum likelihood, with uncertainty assessed using bootstrap resampling. A one-stage multiple-comparison (MCC) procedure is introduced to test altitude-dependent differences in median lifetimes under heavy censoring. Applied to fragments from the 2009 Iridium–Cosmos collision, the results reveal strong altitude dependence: debris near 700 km exhibits lifetimes below eight years, while fragments above 825 km remain quasi-stable over 16 years. The Weibull model consistently outperforms Lognormal and Exponential alternatives, capturing the gradual, altitude-driven evolution of the re-entry hazard. By coupling survival-analysis methodology with orbital-mechanics interpretation, this framework provides a reproducible, physically interpretable, and policy-relevant foundation for estimating orbital-debris persistence and guiding mitigation strategies in upper LEO.