# Impact of Mega Constellations on Geospace Safety
###### Abstract  
The extent of the impact of mega constellations on the low-orbiting geospace environment, which has not yet been assessed in more concrete quantitative terms, is an extremely important issue to consider as mega constellations are built. Satellite safety and lifetime can clearly represent the situation of space targets, and thus can reflect the impact of mega constellations on geospace security. Three target satellites with different characteristics were selected and the Accepted Collision Probability Level (ACPL) was calculated to obtain the impact of Starlink on satellite mission lifetime. Upon considering Starlink without early avoidance control, the lifetimes of the three target satellites were shortened by 56.21%, 99.09%, and 99.82%, respectively. After 10 revolutions of early avoidance control, two were shortened to 92.166% and 91.99%, while the lifetime of JILIN-01 was extended by 155.44%. After joining Starlink, the total risk became larger; even if the target satellite avoided control far more frequently than before joining Starlink, it will face a worse geospace environment. Adopting the most aggressive orbit avoidance control cannot avoid the deterioration of the geospace environment from the perspective of satellite lifetime, which is an irreversible and deteriorating process. mega constellation; geospace environment; accepted collision probability level; satellite lifetime +
Footnote †: journal: _Aerospace_  
In terms of mega constellation impact on the Earth's space environment, [PERSON] et al. discovered that the first-generation OneWeb constellation had a 35% probability of catastrophic collisions over the mission lifetime [10]. Over a 90-day period, [PERSON] et al. discovered 522 close encounters of less than one kilometer in the OneWeb constellation, with a minimum distance of only 6.4 meters, and 3676 close encounters of less than one kilometer in the Starlink constellation's five orbital planes combined, with a minimum approach distance of 16.7 meters [11]. According to [PERSON] et al. that full compliance with the Inter-Agency Space Debris Coordination Committee (IADC) mitigation guidelines and the 25-year rule will enable long-term control and basic stabilization of the LEO debris environment [12]. Given a 10% failure rate for end-of-mission disposal or satellite failure, this is still possible, but higher failure rates, such as those documented by LEO (50-60%), will result in a significant increase in debris [13], while the number of objects on LEO has been increasing due to the excessive failure rate and frequent launch activity over the year. The evolution of LEO-catalogued objects according to data on CeleTrak [14] is shown in Figure 2. [PERSON] et al. introduced a specific critical index of collision rate percentage growth to assess the environmental impact of large satellite constellations in near-Earth orbit [15]. The results of this index, which was calculated for various constellations and applied at altitudes ranging from 800 km to 1400 km, show that in regions of space where the current catalogued debris density is already high, such as around 800 km, adding 100 more abandoned satellites would increase the current collision rate by about 10%; in less-crowded low-orbit regions, such as near 1110 km and 1325 km, adding 100 more abandoned satellites would increase the current collision rate by about 10%; and in less-crowded high-orbit regions, such secondary collisions from mega constellation satellites are also a significant threat to the Earth's geospatial environment, according to [PERSON] et al., with the probability of collision for surrounding orbiting satellites exceeding the red alert threshold of \(10^{-4}\) within 30 min of a mega constellation satellite collision [16]. [PERSON] et al. found that the situation in LEO space is not yet dire if properly managed; however, both LEO and GEO have substantial and persistent collision risks, and these collision risks, along with debris events, pose far-reaching and long-lasting effects [17]. [PERSON] et al.