###### Abstract  
Mitigation strategies to eliminate existing space debris, such as with Active Space Debris Removal (ASDR) missions, have become increasingly important. Among the considered ASDR approaches, one involves using a net as a capturing mechanism. A fundamental requirement for any ASDR mission is that the capture process itself should not give rise to new space debris. However, in simulations of net capturing, the potential for structural breaking is often overlooked. A discrete Multi-Spring-Damper net model was employed to simulate the impact of a 30 m \(\times\) 30 m net travelling at 20 m/s onto an ESA Envisat mock-up. The Envisat was modelled as a two-rigid-body system comprised of the main body and a large solar array with a hinge connection. The analysis revealed that more than two significant substructures had a notable likelihood of breaking, prompting the recommendation of limiting the impacting velocity. The generation of secondary space debris indicates that net capturing is riskier than previously assumed in the literature. active debris removal; net capturing; structural breaking; secondary space debris generation Article Generation of Secondary Space Debris Risks from Net Capturing in Active Space Debris Removal Missions  
by [PERSON] et al. [11], and validated by [PERSON] et al. [12; 13], involves the computation of nodal absolute positions along with their position gradients. This leads to an intrinsic elastic-flexible characterisation of the tether-net thread elements. In contrast to the lumped mass model, the use of the ANCF was proposed for high-precision net tracking requirements [13]. Whereas the lumped mass model was concluded to be less accurate than the ANCF, the model was still validated using a parabolic net deployment experiment with 15% bounded average relative error for a coarse mesh. Furthermore, it was found to be more efficient, presenting a 15 times better computational efficiency than the ANCF model [14]. When the discretised net contacts the space debris, the net's response has also been analysed in the literature. Two main contenders have been shown to be the most effective in appropriately modelling net contact dynamics. The impulse-based method, developed by [PERSON] [15], describes the net impact with the target in terms of a collection of multiple impulse transfers. The penalty-based method, first used for net dynamics applications by [PERSON] [16] and further developed by [PERSON] et al. [8], [PERSON] et al. [17] and [PERSON] et al. [9], computes the impact normal and friction forces by using the net node target interpenetration. Although simpler in implementation than the impulse-based formulation, the model's equations of motion were shown to be stiff with a high dependency in the initial interpenetration [15]. Whereas an essential requirement of any ASDR mission is to not generate or limit any additional or secondary space debris during the capturing process, the risk assessment of secondary space debris generation has interestingly been omitted throughout the literature. The assumption that the space debris object cannot break can be seen in many forms: whether it is by assuming that the space debris object is treated as a single rigid body [10; 15] or by simply limiting the analysis to capturing simple object shapes (cuboids, spheres and cylinders) [8; 15]. Thus, the potential for secondary structures to break during the net impact has not been yet analysed. Furthermore, the effect of net dynamics on a multi-body system is also missing in the literature. Thus, the objective of this study is to perform an investigation of the structural integrity of space debris objects' main structures at their associated weak locations [18]. This is carried out by numerically simulating a net low-velocity impact onto an Envisat mock-up and qualitatively evaluating the potential dynamic risks of structural breaking. The Envisat is chosen for its known hazardous status [2] and as a sample body with a complex and geometrical shape. This study is divided into two main parts.