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Satellites orbiting in low Earth orbits face potential threats from space debris. To mitigate this risk, a Whipple shield is employed to shield satellites from potential hyper-velocity impacts caused by debris of varying sizes and speeds. Typically, these protective systems use spaced aluminum plates affixed to the satellite's exterior. Ongoing advancements in this field include exploring alternative materials such as foam, cellular cores, and ceramics to replace aluminum in plate construction. This study introduces a hybrid configuration featuring a Newtonian fluid-filled, high-performance fiber-reinforced polymer core positioned between the aluminum alloy plates, aiming to enhance the Whipple shield's overall shielding effectiveness. The analysis of hyper-velocity impacts was performed numerically using ANSYS Autodyn® computational software. Spherical projectiles made of stainless steel, ranging in diameter from 2 mm to 4 mm, were selected for direct collision simulations with the Whipple shield at velocities of 5 km/s, 7 km/s, and 9 km/s. The front and rear plates, each 1 mm thick, were constructed using AA6061-T6. The core, measuring 10 mm in thickness, incorporated multiple plies of Kevlar fiber-reinforced polymer (KFRP), with interplay spacing between successive KFRP plies filled with a Newtonian fluid (water). It was observed that spherical projectiles made of stainless steel with diameter ≥ 3 mm penetrated the rear plate of the whipple shield at the lower velocity of 5 km/s, with enhanced damage as the initial velocity of the projectile was increased from 5 km/s to 9 km/s. The debris cloud was found to scatter the fluid droplets, rupture the successive KFRP layers, with the initial kinetic energy playing a significant role in the severity of the damage. • Hybrid Whipple shield configuration with a Newtonian fluid-filled, high-performance fiber-reinforced polymer core. • Computation of the HVI by spherical projectiles on the shield carried out using Ansys Autodyn®. • Simulations at 5, 7 and 9 km/s with emphasis on energy variation for the projectile and Whipple shield conducted. • Perforation and debris cloud propagation captured during the simulations. [ABSTRACT FROM AUTHOR]

The space community is moving forward with the development of in-orbit servicing and removal technologies to enable the circular economy in space and improve future space missions' scientific and commercial return and space environment exploitation. The application of nanosatellites to carry out proximity operations presents an additional opportunity to support various novel and cost-effective distributed mission architectures. The SpEye CubeSat mission, funded by the Agenzia Spaziale Italiana in the framework of the Alcor Program, aims at demonstrating inspection and rendezvous guidance navigation and control capabilities of a nanosatellite in close-proximity of the satellite carrier in a low Earth orbit environment. This paper focuses on the design of the SpEye mission and on the guidance and control strategies to enable its technological demonstrations. Particular attention is placed on the safety aspects of trajectory design, considered of paramount importance for the robust autonomous operations of a low-cost CubeSat in proximity to another satellite. • CubeSat mission for proximity operations demonstration. • In-orbit experiments applicable to the In-Orbit Servicing (IOS) and Active Debris Removal (ADR) domains. • Mission design and ConOps of a nanosatellite mission released by a carrier for proximity operations purposes. • Safe inspection design considering the optimisation of information cost metric. • Close range rendezvous solved with sequential convex programming and with enhanced safety applied. [ABSTRACT FROM AUTHOR]

The regular acquisition and delivery of high-resolution, accurate elevation data has historically been provided by airborne lidar (light detection and ranging) solutions, which are costly and highly localised. Providing similar data sets globally has notable scientific and commercial applications, but comes with challenges around scale. In this work, an investigation into such a service, from low Earth orbit satellites, is presented. The suitability of different space mission architectures is analysed based on platform size and optics mirror design, with the aim of providing true global, high-resolution (5-30 m sample resolution) lidar data, annually. The technical challenges, cost implications and feasible solution sets are presented, suggesting that a small number of large platforms offers a cost-effective solution, with the optimal design (of those evaluated) being that of a micro-satellite (∼ 150 kg class) constellation with deployed optics capability. Solutions offering relatively low spatial resolution (30 m) are lower cost, with the cost rising as a square law with increasing resolution. As platform size continues to decrease, the number of satellites required to maintain global coverage scales exponentially, demanding prohibitively large constellations to ensure global coverage with smaller satellites. [Display omitted] • Global annual lidar coverage from space is technologically and financially feasible. • Deployable optics significantly increase the value potential of a space lidar mission. • Semiconductor (Diode) lasers are more promising than traditional solid-state lasers. • Fewer, larger platforms generally perform better than many, smaller platforms. • Nano-satellite platforms offer limited value due to their constrained aperture area. [ABSTRACT FROM AUTHOR]