1,582 research outputs found
Space debris mitigation, protection and remediation for a sustainable orbital environment
No full textThis thesis addresses key challenges in achieving a sustainable orbital environment through innovative approaches to space debris mitigation, protection, and remediation. The research
is structured around three primary themes: (1) the development of a docking system (DOCKS) for nanosatellite missions, (2) in-orbit inspection for 3D reconstruction of targets,
and (3) the Alba CubeSat UniPD student project.
In the first theme, the DOCKS system, designed for the Space Rider Observer Cube (SROC) mission, is introduced. DOCKS integrates ultra-close proximity navigation and
docking functionalities within a compact, standalone module, offering a scalable solution for sustainable satellite operations. Experimental validation demonstrated the system’s
robustness in managing misalignments during docking procedures.
The second theme focuses on in-orbit inspection using CubeSats to generate 3D reconstructions of resident space objects (RSOs). Experimental setups validated the use of
photogrammetry techniques for precise and scalable inspections, emphasizing the integration of active and passive sensing technologies to enhance reliability.
Lastly, the Alba CubeSat UniPD project is presented as a student-led initiative under the ESA "Fly Your Satellite! Design Booster" programme. The mission integrates advanced
payloads, including a precise orbit determination system and a debris impact sensor, aimed at supporting sustainable orbital practices while fostering education and innovation.
These contributions offer practical insights and advancements that support ongoing efforts in orbital debris management and the development of sustainable space technologies
roi samples selected
No full textThe three tables are ROIs collected data for Sentinel-2A, Landsat8-OLI, and ZYI-02D, respectively，and more data used to support the findings of this study are available from the corresponding author upon reques
Kinematic tests on a docking mechanism for microsatellites
No full textDOCKS is a smart docking system developed within the framework of the Space Rider Observer Cube mission (SROC) but suitable for use in more general scenarios. This paper presents the mechanical design of the system and the kinematic tests performed on it. The system merges a classical probe drogue configuration with a gripper-like design, to manage the connection between the parts, and it is equipped with a suite of sensors to estimate the relative pose of the target. The system is also equipped with a dedicated computer, making it a smart standalone system. A series of kinematic tests have been conducted to validate the capability of the system to passively manage misalignment during the docking manoeuvre. The final tests are presented to assess the maximum load that the system could handle, even when inactive
Development of a smart docking system for small satellites
No full textDOCKS is a smart docking system for space vehicles developed by the Department of Industrial Engineering, University of Padova, within the framework of the Space Rider Observer Cube (SROC) mission. The design and development of SROC is being conducted by a consortium of Italian entities under contract with the European Space Agency (ESA). The SROC mission is designed to be a payload on the ESA Space Rider (SR) spaceship. The main objective of the mission is to demonstrate the critical capabilities and technologies required to execute a rendezvous and docking mission in a safety-sensitive context. The space system is composed by a nanosatellite (approximately 12U CubeSat) and a deployment/retrieval mechanism mounted inside the payload bay of SR. During the mission, SROC will be released by SR, will perform inspection manoeuvres on SR and, at the end of the mission, will dock back inside the bay of SR, before reentering Earth with the mothership. The docking functionality is provided by DOCKS. DOCKS is suitable for use onboard micro- and nanosatellites and merges a classical probe drogue configuration with a gripper-like design, to manage the connection between the parts. The system is equipped with a suite of sensors to estimate the relative pose of the target and with a dedicated computer, making it a smart standalone system. A laboratory prototype has been assembled and functionally tested, aiming at the validation of the capability to passively manage misalignments during the docking manoeuvre
Tracing early stages of species differentiation: Ecological, morphological and genetic divergence of Galapagos sea lion populations
No full textBackground: Oceans are high gene flow environments that are traditionally believed to hamper the build-up of genetic divergence. Despite this, divergence appears to occur occasionally at surprisingly small scales. The Galápagos archipelago provides an ideal opportunity to examine the evolutionary processes of local divergence in an isolated marine environment. Galápagos sea lions (Zalophus wollebaeki) are top predators in this unique setting and have an essentially unlimited dispersal capacity across the entire species range. In theory, this should oppose any genetic differentiation. Results: We find significant ecological, morphological and genetic divergence between the western colonies and colonies from the central region of the archipelago that are exposed to different ecological conditions. Stable isotope analyses indicate that western animals use different food sources than those from the central area. This is likely due to niche partitioning with the second Galápagos eared seal species, the Galápagos fur seal (Arctocephalus galapagoensis) that exclusively dwells in the west. Stable isotope patterns correlate with significant differences in foraging-related skull morphology. Analyses of mitochondrial sequences as well as microsatellites reveal signs of initial genetic differentiation. Conclusion: Our results suggest a key role of intra- as well as inter-specific niche segregation in the evolution of genetic structure among populations of a highly mobile species under conditions of free movement. Given the monophyletic arrival of the sea lions on the archipelago, our study challenges the view that geographical barriers are strictly needed for the build-up of genetic divergence. The study further raises the interesting prospect that in social, colonially breeding mammals additional forces, such as social structure or feeding traditions, might bear on the genetic partitioning of populations
A lion in the house map
No full textRelated to and part of A lion in the house: a content-centered outreach strategy for public broadcasting.A Lion in the House is a 225-minute documentary that follows five racially and economically diverse young people, their families, and caregivers over six years as they confront childhood hematological cancer and the after-effects of treatment at Cincinnati’s Children’s Hospital
Fibroblastic osteosarcoma in a lion (Panthera leo)
No full textThis report describes a case of spontaneous fibroblastic osteosarcoma in the humerus of a lion from a private park in Perugia, Italy. The tumor had an irregular, smooth, brown surface and a generally firm, rubbery consistence with gritty to hard areas interspersed. The mass was poorly vascularized with areas of necrosis at the periphery. The cut surface showed a multilobulated mass that had breached the humeral cortex, with periosteal production of reactive bone. The mass invaded the epiphysis, the synovial membrane, the joint capsule and ligaments. A mild hemorrhagic effusion appeared in the joint space. Clinical signs, gross and histopathologic findings are described in this rare case of a malignant bone tumor
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