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Mission BION-M1: Results of RIBES/FOAM2 experiment on shape memory polymer foams and composites
No full textFOAM2 is an experiment in microgravity conditions which was performed on 20th of April 2013 during the BION-M1 mission of the Soyuz spacecraft. The experiment was carried out by an autonomous device contained in the BIOKON container (by Kayser Italia) which was in turn assembled in a properly designed payload (called RIBES, “Reconfigurable Incubator for Biology Experiments in Space”). The main goal of the experiment was to demonstrate shape recovery of polymer foams and composites in the space environment. A simple device for the evaluation of the actuation load during recovery of a shape memory epoxy foam was used together with an instrumented chamber for the extraction of the recovery speed of a similar sample. For the first time, also a shape memory composite was tested by observing the shape recovery of a bent thin sheet. Good results were achieved in terms of shape recovery for all the samples thanks to the adopted thermal program. The effect of microgravity is negligible if compared with recovery forces but it strongly affects performances of heating devices and has to be taken into account for designing actuators or self-deployable structures in future space applications
A Flight Demonstration of FEEP: Electric Thrusters for Microgravity Laboratories and Drag-Free Spacecraft
No full textThe scientific community's recent interest in Field Emission Electric Propulsion for drag-free spacecraft represents a major breakthrough for this technology. While FEEP was traditionally intended as a candidate for the attitude control and fine pointing of small satellites, i.e., for mN level thrust missions, this new, previously unforeseen application opportunity is due to its capabilities in the very low thrust range (about 1 μN). A major project such as LISA, presently a candidate for the next cornerstone in Horizon 2000, features FEEP as a mission-enabling technology. Several other concepts have been proposed, ranging from AU baselength interferometry, to a spaceborne constellation of antennas for syntetic aperture radiometry to be used for high accuracy weather forecasting, to noiseless microgravity laboratories. A recent proposal to the Italian Space Agency highlights the benefits of adopting a Field Emission Electric Propulsion system for a Flight Experiment on the Equivalence Principle (FEEP2).
As far as the concept is concerned, FEEP is a thoroughly proven technology. Tests in space simulators were extensively carried out at both the Electric Propulsion Laboratory of ESTEC and at Centrospazio, covering all of the thruster’s subsystems (ion emitter, propellant feeding system, neutralizer, power electronics). The basic hardware is ready to undergo a flight demonstration. This would open the way to several applications in each of three major areas: first, scientific spacecraft for fundamental physics, requiring unprecedented high performance drag-free controllers; second, microgravity laboratories; third, small satellites with accurate orbit and attitude control capabilities.
This paper summarizes the state of the art of FEEP technology and outlines the technical characteristics of the hardware for a flight experiment. The feasibility of a low cost flight demonstration is discussed and a proposed approach for a dedicated spacecraft, based on a commercially available microsatellite bus, is presented
Shape Memory Epoxy Foams and Composites: Ribes_foam2 Experiment on Spacecraft “Bion-m1” and Future Perspective
No full textAbstractShape memory epoxy foams and composites were tested in April 2013, on board the BION-M1 spacecraft through the Soyuz-2 launch vehicle, with the aim to study their behaviour in microgravity for future applications. The on-orbit Ribes_Foam2 experiment consisted in the heating of three samples in various configurations having different shapes (a prototype of actuator, a sheet of composite laminate and parallelepiped) packed on ground, to evaluate the shape recovery capabilities in the space environment. As expected, micro-gravity does not affect the ability of the samples to recover their shape in these configurations but it poses limits for the heating system design because of the difference in heat transfer on earth and on orbit. In this work, the main results of the experiment are discussed. They have provided useful information for the development of actuators and deployable structure, highlighting future perspectives
Behavior of shape memory epoxy foams in microgravity: experimental results of STS-134 mission
No full textShape memory epoxy foams were used for an experiment on the International Space Station to evaluate the feasibility of their use for building multi-functional composite structures. A small equipment was designed and built to simulate the actuation of simple devices in micro-gravity conditions: three different configurations (compression, bending and torsion) were chosen during the memory step of the foams so as to produce their recovery on ISS. Two systems were used for the experimentation to avoid damages of the flight model during laboratory tests; however a single ground experiment was performed also on the flight model before the mission. Micro-gravity does not affect the ability of the foams to recover their shape but it poses strong limits for the heating system design because of the difference in heat transfer on earth and in orbit. A full recovery of the foam samples was not achieved due to some limitations in the maximum allowable temperature on ISS for safety reasons: anyway a 70% recovery was also measured at a temperature of 110°C. Ground laboratory experiments showed that 100% recovery could be reached by increasing the maximum temperature to 120°C. Experiment results have provided many useful information for the designing of a new structural composite actuator by using shape memory foams
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
Implementation and ground validation of a facility for functional and structural analysis of proximal upper limb muscles in microgravity.
Get PDFThe study of the activity of the proximal muscles of the upper limb and in particular of
muscles acting on the gleno-humeral joint in microgravity condition has a special interest
because: 1. The upper limbs play a major role in posture and locomotion for the subject
living in the space station; 2. Muscle fatigue may have a significant effect on the hand and
upper limb, for the ordinary work on board and in particular for the extra-vehicular
activities (EVA); 3. Crewmembers may be at risk of shoulder injury during space
walks because of decreasing muscle and tendon mass during long-duration space-flight.
In this study a facility was developed to follow the changes in mass and force of proximal
upper limb muscles. The facility is composed of a dynamometer, composed of a handle
connected to a load cell, indicated as Pullgrip Dynamometer (PGD), and a specific software
able to record force measurements and to drive the testing procedure (indicated as MAAT
protocol). PGD was designed in a way to be easily mounted on the inner wall of the ISS.
The results obtained in the testing session demonstrated that PGD and MAAT can reliably:
1. Discriminate between subjects in relation to the level of muscle strength develop in a pull
effort applied on the PGD; 2. provide data for correlation between force and muscle size; 3.
Evaluate the weight of the proprioceptive feedback in comparison with visual feedback to
determine precision of force generation; 4. Evaluate muscle fatigue. The validation of the
facility based on PGD and MAAT provides support to the plans to utilize them in
experimental studies on alteration of proximal upper limb muscles on board of the
International Space Station (ISS)
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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