Evaluation of the effectiveness of 5-year rule - Impact on the orbital environment at each altitude by reducing the post-mission disposal lifetime

This paper examines the effect of shortening the post-mission disposal lifetime from 25 years to 5 or 1 year. Using NEODEEM, the debris evolutionary model developed by Kyushu University and JAXA, the change in the orbital environment at various altitude bands for long-term stability and short-term safety such as the number of collision avoidance maneuvers and collision rate are discussed. It was confirmed that the PMD compliance rate is more important than shortening the orbit lifetime for improving the long-term stability of the orbital environment. The collision rate below 700 km increased if the number of launches to high altitudes and the post-mission disposal (PMD) compliance rate increase, although the collision impact is not long-term. In the short term, the 5- or 1-year rule reduced the collision rate and collision avoidance frequency at an altitude around 600 km, more than the 25-year rule, thus shortening the PMD orbit lifetime improves short-term safety, especially at low altitudes. The paper also evaluates the effect of large constellations shows that the post-mission disposal lifetime and required compliance rate should be set according to the number and size of objects expected to be launched in the future.