# Impact of Mega Constellations on Geospace Safety
## 4 Impact of Starlink on Control Avoidance Strategies for low-orbiting Satellites in Geospace
### Impact on ACPL Values for LEO Space Target Satellites
The manipulation frequency of ACPL-\(10^{-4}\) becomes \(20.76\) times of the previous one, and the risk of known objects becomes \(62.73\) times that of the previous one before and after changes; considering Starlink before and after, the manipulation frequency of ACPL-\(10^{-6}\) compared to ACPL-\(10^{-4}\) is \(4.12\) and \(7.55\) times more frequent than before, respectively. Combining the three comparison groups, from the Figure 7 overall results, the impact of Starlink on target satellites in geospace is extremely significant, and the choice of ACPL-\(10^{-4}\) is more reasonable than ACPL-\(10^{-6}\) in terms of both economic and safety considerations. Considering Starlink before and after the change, ACPL-10\({}^{-4}\) corresponding to the operating frequency of the three target satellites in the minimum operating frequency change has doubled, and it can be clearly observed that joining Starlink to choose ACPL-10\({}^{-6}\)  
Figure 7: Comparison of ACPL values and average maneuvering coefficients for satellites with and without Starlink constellation. (**a,b**) The variation of GAOFEN satellites in the frequency and risk to different ACPL values With Starlink and Without Starlink; (**c,d**) The variation of CORVUS BC5 satellites in the frequency and risk to different ACPL values With Starlink and Without Starlink; (**e,f**) The variation of YAOGAN-35C satellites in the frequency and risk to different ACPL values With Starlink and Without Starlink. would render the risk at 0. However, as the frequency of control avoidance increases significantly, it is evident that it can not be adhered to over the long term, which means that, considering the issue of mission life, the target satellite must select a more reasonable ACPL value. However, even if the number of orbital avoidance controls vastly exceeds the number before Starlink is considered, the geospace environment will worsen. Even with the most aggressive orbital avoidance controls, the deterioration of the geospace environment is an irreversible and deteriorating process. Avoidance of controls reduces risk, and the risk relationship corresponding to the frequency of manipulation is shown in Figure 8. The Fractional Residual Risk in the figure represents the residual partial risk coefficient that varies according to the number of manipulations and is used only as a quantity to describe the degree of risk and not as a specific numerical reference. The relationship between the change in risk level and the change in the number of maneuvers can be observed visually in the graph. In order to observe the relationship and pattern of different maneuvering frequencies before and after each consideration of Starlink, the maneuvering frequencies corresponding to different ACPL values were selected in the three target satellites for comparison. In the following, risk coefficient indicates the degree of presence of risk, with a maximum value of 1. Risk indicates the probability of collision. In Figure 8a,b the risk coefficient for a manipulation frequency of 0.201 without Starlink is 1.68 \(\times\) 10\({}^{-3}\) and the risk is 6.5 \(\times\) 10\({}^{-8}\), and the risk coefficient for a manipulation frequency of 1.24 with Starlink is 3.58 \(\times\) 10\({}^{-3}\) and the risk is 2.52 \(\times\) 10\({}^{-7}\). It is obviously observed that the risk coefficient increases by 2.13 times when the manipulation frequency reaches the maximum in both comparison groups. The coefficient of risk is 2.13-times greater after considering Starlink when the manipulation frequency is 6.16-times greater than before, indicating that the coefficient of risk inevitably rises after considering Starlink, even if the manipulation frequency is doubled.