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Space debris represent a threat to satellites in orbit around Earth. In the case of impact, satellites can be subjected to damage spanning from localized craterization to subsystem failure, to complete loss of the vehicle; large collision events may lead to fragmentation of the spacecraft. Simulating and testing debris impacts may help in understanding the physics behind these events, modelling the effects, and developing dedicated protection systems and mitigation strategies. In this context, the Space Debris group at the University of Padova investigates in-space collisions with experimental campaigns performed in a dedicated Hypervelocity Impact Facility and with numerical simulations with commercial and custom software. In this paper, an overview is given of the last 10 years of research activities performed at the University of Padova. First, the hypervelocity impact testing facility is described and the main experimental campaigns performed in the last few years are summarized. The second part of this work describes impact modelling research advances, focusing on the simulation of complex collision scenarios. [ABSTRACT FROM AUTHOR]

For impact velocities larger than a threshold velocity of 3 km/s, aluminium Whipple Shields present an enhanced protection capability with respect to monolithic protections with the same areal density. In particular, in the range between 3 and 7 km/s the projectile partially fragments and melts after impacting the bumper; modelling this transition might be complex due to the high number of parameters affecting the collision. In particular, limited data is available in literature with a systematic evaluation of such parameters. In this context, a campaign of 22 experiments was performed to assess the response of aluminium Whipple Shields to normal impacts of aluminium projectiles in the transition range up to 5 km/s. In the tests, the projectile diameter was fixed at 2.9 mm and the bumper thickness and impact velocity were systematically varied respectively at 1, 1.5, and 2 mm and between 2.6 and 5 km/s. Collected data included high-velocity videos of the debris cloud generated by the impacts at both low resolution (for all shots) and high resolution (for 19 out of 22 tests); in addition, for 10 experiments high-resolution images of both the bumper and the wall were acquired after the tests. In this paper, the experimental campaign is described and the main collected results are presented; in particular, the influence of the different impact parameters is discussed. Experimental results are finally compared with numerical simulations conducted with a smoothed particle hydrodynamics method available in IMPETUS Solver. • 22 impact experiments were performed on Aluminium Whipple Shields. • The projectile diameter was fixed at 2.9 mm for all tests. • Bumper thickness and impact velocity varied in the ranges 1–2 mm and 2.6–5 km/s. • The influence of the different impact parameters is discussed. • Experimental results are compared with numerical SPH simulations. [ABSTRACT FROM AUTHOR]