The critical density theory in LEO as analyzed by EVOLVE 4.0

The critical density theory is revisited with NASA's long-term debris environment model, EVOLVE 4.0. Previous studies were based on incomplete data and simplifying assumptions. Recent data of ground-test and on-orbit breakups and fragment decay have been utilized within the EVOLVE 4.0 structure to realistically model the projected low Earth orbit (LEO) debris environment. The EVOLVE 4.0 predictions over a 1000-year time period are shown to be consistent with the earlier predictions of simpler models; however, EVOLVE 4.0 is shown to be able to eliminate the simplifying assumptions in these earlier models and be a more accurate tool in understanding the most effective migration measures to limit future population growth.