1,720,977 research outputs found
DORA Telescope Breadboard Experimental Verification
No full textThis work aims at characterizing the breadboard of the DORA telescope deployment mechanism designed to set in position the secondary mirror of a Cassegrain optical telescope. The goal of the testing campaign is the tuning of the system to match the positioning. In parallel, the forces required during the deployment have been measured, being a relevant input for the following development phases where the design of a space-qualified actuation system must be performe
Design and testing of selective laser melted structural component in AlSi9Cu3 alloy for a space dust analyser
No full textSpace is one of the most avant-garde sectors for additive manufacturing as the inherent characteristics of this technology allow the creation of complex and lightweight 3D structures. Using this brand-new design tool, it was possible to design the pumping system holder of the MicroMED instrument, a particle analyser developed for ExoMars 2022 mission. The geometry of the holder was optimized using a finite element approach. The effectiveness of the proposed solution was evaluated by comparing the performance of two different designs using the AlSi9Cu3 alloy. One solution was based on micro-milling and the other on Selective Laser Melting. In order to validate the designed SLMed holder, a mockup was produced and successfully tested in the mission's mechanical environment
Design of the optical bench for the DORA telescope
No full textPayloads miniaturization is the design rule in space-born applications and the development of space telescopes is not an exception. The research in the space field is pushing the development of deployable telescopes since the compactness of such configuration is translated into lower costs for the mission and consequently into more flight opportunities. In this framework, the goal of the paper is the development of the DORA telescope (Deployable Optics for Remote sensing Application), a project in collaboration with some Italian research institutes aiming to design space telescopes for minisatellites. The work focuses on the structural design of the main interface of the telescope, finding a compromise between the lightness and the mechanical stiffness of the designed solution. The trade-off should be assured by providing the required mechanical resistance against the expected loading at the payload launch and in the working conditions. The proposed solution satisfies the imposed requirements by limiting the allocated mass of the structural component to about 10% of the payload mass budget
Comparison of candidate mechanism concepts for a deployable space telescope
No full textThe future of spaceborne observations is strongly oriented toward miniaturization of payloads without reducing their performances. In this framework telescopes equipped with deployable structures would guarantee either an improvement of the performances or a considerable volume reduction which, due to the limitations on the launcher, translates into a lower cost of in-orbit commissioning. This paper aims at comparing possible mechanism layouts for a deployable space telescope designed for Earth observation in the infrared spectrum. The design considers a classical Cassegrain telescope and aims at packaging the secondary mirror as close as possible to the primary; the trade-off analyses among different technological solutions and configurations are presented. This is a preliminary study performed in the framework of DORA (Deployable Optics for Remote sensing Applications), a project aiming at developing a deployable telescope for minisatellites, and concludes with the assessment of the most feasible layouts which are going to be considered in the next phases of the project
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
TM4SF2, a protein involved in XLMR, interacts with PICK1 and regulates AMPAR trafficking and synapse function
No full textDORA telescope project: Preliminary characterization of the deployment mechanism
No full textThe critical conditions in a space mission depend on the task a spacecraft has to perform but generally it is the launch. Concerning mechanisms, the crucial moment is their actuation since the resting from their integration and the vibration during launch and eventual landing may have causeda degradation of the components. It is mandatory to intensivelytest the actuators to investigate any problem in the selection or the incompatibility with the system in which they have to be integrated. The DORA project aims at validating a deploymentmechanism featuring four linear actuators which shall move thesecondary mirror from a stowed position to the operational. The preliminary testing of the actuators to verify the compliance is presented and the measurement of the actuation force is directlycarried out on the DORA mockup to evaluate compatibility with the developed models of the deployment mechanism
Structural optimization of supporting structures for the DORA telescope
No full textThe mass optimization of payloads for space applications is always one of the main drivers in the design phase. This paper presents the evolution of the design from the breadboard of the DORA telescope, through a structural redesign in order to achieve competitive overall performance with minimum mass. A generative optimization technique has been applied to allow an effective distribution of the mass in the component. The optimized component has been manufactured and verification tests performed to validate the developed model
Development and characterization of a volume flow measurement system for low-pressure gases
Get PDFThis paper presents the design and validation of a volume flow measurement system developed to measure volume flowrate of gas at pressures below 1 kPa. The system had to be developed because a suitable commercial transducer was not available for the unusual working environment, where outgassing and sublimation phenomena become relevant for many materials and the rarefied atmosphere changes dramatically its heat and mass exchange parameters. The development of a low-pressure compatible measurement system comes from the need of measuring the flow rate of a rotary vane pump working under an environmental absolute pressure in the range between 600 and 1000 Pa, mostly composed by CO2 i.e. the average condition of the Martian atmosphere at the surface. The pump will be a key component of the MicroMED particle analyzer, an instrument of the ExoMars 2020 ESA-Roscosmos mission payload. The measurement system is based on a control volume, made by a stainless-steel bellow, which has been designed accounting for the environmental requirements and the expected flow rate. The measurement system has been calibrated at ambient condition and tests in low-pressure have been performed to validate the measurement system and to derive the flow rate characteristics of a pump mock-up at different environmental pressures
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