Deployable Reflector Research Articles

Experiment Plan of ETS-8 in orbit: Mobile communications and navigation

The experiment of mobile communications and broadcasting by S-band and the satellite navigation by L/S-band are the main objectives of Engineering Test Satellite - 8 (ETS-8), which will be launced in 2004 into geostationary orbit at 146 degree East. In this paper, the current status of ETS-8 is introduced at first and the basic experiment plan is described. For the mobile communications/broadcasting, two deployable reflectors (17 meters × 19 meters, each) and a 400 W class active phased array feeder with 31 SSPAs are installed in ETS-8. Three beams are used simultaneously to cover Japan and neighbor region. Two kinds of onboard processors are also installed, which are dedicated to voice and high-speed packet communication, respectively. The ground terminal for voice communications is as small as conventional cellular phone, and that for packet is similar size of notebook type PC. For satellite navigation, two Cesium clocks are installed. The coverage area is Asia-Pacific hemisphere. The experiment will be conducted by use of ground stations and signals from GPS. The positioning accuracy is evaluated by changing RF frequency, code pattern and chip rate. To determine the precise orbital parameters of satellite, the laser ranging method is adopted. This satellite navigation experiment will be conducted in cooperation with foreign and domestic institutes. After the funtion tests of satellite in orbit, it will be from 2005 year, the opportunity to conduct some experiment used of ETS-8 will provide. The participation of those who have interest in these experiments is welcome.

F19-(3) 大規模展開宇宙構造の地上試験検証(極限構造への機械工学の挑戦)(宇宙工学部門企画)

An essential technique to develop large-sized structures for space is design verification procedure. Ground testing is an effective and useful estimation method by comparing with analysis results. However, the effect of gravity to act upon larger structure obscures the probe into the structural characteristics per se. Especially, implementation of dynamic simulation on ground is difficult to evaluate the motion under micro-gravity. Jigs including gravity compensation system are a key point to conduct the testing. In this paper, we discuss deployment feasibility of large deployable reflector by demonstrating ground tests. Modular mesh reflector concept in which the structure consists of several basic modules is efficient to recognize gravity effect. The deployment testing results show the marginal utility for ground testing based on the modular structure.

Equilibrium paths of mechanical systems with unilateral constraints II. Deployable reflector

Restricted accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Schulz M. and Pellegrino S. 2000Equilibrium paths of mechanical systems with unilateral constraints II. Deployable reflectorProc. R. Soc. Lond. A.4562243–2262http://doi.org/10.1098/rspa.2000.0611SectionRestricted accessResearch articleEquilibrium paths of mechanical systems with unilateral constraints II. Deployable reflector M. Schulz M. Schulz Department FV/SLT2, Robert Bosch GmbH, PO Box 30 02 40, 70442 Stuttgart,, Germany () Google Scholar Find this author on PubMed Search for more papers by this author and S. Pellegrino S. Pellegrino Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK () Google Scholar Find this author on PubMed Search for more papers by this author M. Schulz M. Schulz Department FV/SLT2, Robert Bosch GmbH, PO Box 30 02 40, 70442 Stuttgart,, Germany () Google Scholar Find this author on PubMed Search for more papers by this author and S. Pellegrino S. Pellegrino Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK () Google Scholar Find this author on PubMed Search for more papers by this author Published:08 September 2000https://doi.org/10.1098/rspa.2000.0611AbstractThe paper presents a simulation of the deployment/retraction of a solid surface deployable reflector recently developed at Cambridge University. The simulation takes proper account of the contacts that can develop between panels of adjacent wings of the reflector, by implementing the theory for tracing the equilibrium path of a mechanical system with unilateral constraints that has been proposed in the companion paper. Six–fold symmetry is assumed, as experiments on a physical model of the reflector show that asymmetries do not play a significant role. During deployment, at a certain point the model shows a sudden increase in the rate of motion, although the (slow) rate of turning of the electric motors driving the model remains uniform. It is shown that the reason for this behaviour, which had not been previously explained, is the existence of a corner limit point on the equilibrium path of this structure. A corner limit point is a kind of limit point that can be encountered only in systems with unilateral constraints; the equilibrium path is non–smooth and the first–order equilibrium equations non–singular. A second limit point, of the standard type, exists on the equilibrium path. It should cause the model to jump to a configuration close to fully folded, but cannot be achieved in practice. A characteristic conical shape of the physical model is observed at the end of the retraction and is predicted by the simulation as well. Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsCited by Hu N and Burgueño R (2015) Buckling-induced smart applications: recent advances and trends, Smart Materials and Structures, 10.1088/0964-1726/24/6/063001, 24:6, (063001), Online publication date: 1-Jun-2015. Schulz M and Pellegrino S (2000) Equilibrium paths of mechanical systems with unilateral constraints I. Theory, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 456:2001, (2223-2242), Online publication date: 8-Sep-2000. This Issue08 September 2000Volume 456Issue 2001 Article InformationDOI:https://doi.org/10.1098/rspa.2000.0611Published by:Royal SocietyPrint ISSN:1364-5021Online ISSN:1471-2946History: Published online08/09/2000Published in print08/09/2000 License: Citations and impact Keywordsunilateral constraintlimit pointsolid surface deployable antennasnap throughmultibody systems

Folding and deployment of curved tape springs

This paper presents a study of a special type of tape springs, that are both longitudinally and transversely curved, as required for the ribs of a novel deployable reflector. It is shown that, although curved tape springs have much in common with straight tape springs, there is an important difference for equal-sense folds with small rotation angles. Thus, it is shown that full deployment of the reflector cannot be guaranteed if equal-sense folds are used when packaging it.

Thermal Distortion of a Modular Structure for Use a Large Reflector.

Thermal distortion of a large deployable reflector, for use on board a satellite, was evaluated using an artificial environmental chamber. The large deployable reflector, which is 15 m in diameters, was developed based on a modular concept in which the structure consists of several basic modules about 5 m in diameter. Each basic module consists of a mesh surface, a cable network, and a truss structure. The mesh used for the reflector surface reduces the weight, and the cable network is formed so that the mesh surface is parabolic in shape. The truss structure maintains the length of cable and the form of the mesh surface.

磁気冷凍の研究動向

Recent progress in magnetic refrigeration has been reviewed. Adiabatic demagnetization refrigerators (ADR) are under development at NASA for large deployable reflectors and X-ray spectrometers. The refrigerators provide temperatures of 2K at 0.027W for 165s and 0.1K at 0.01W for 13h using gadolinium gallium garnet and paramagnetic salt crystals. The Gas-Gap heat switch is used for the isothermal portion of a Carnot cycle. Active magnetic regenerator (AMR) cycles have the advantage of the Carnot cycle for larger temperature span and refrigeration capacity, in particular, above 20K. A test apparatus of the AMR demonstrated that the refrigeration capacity of 1.5-3.5W was obtainable at the temperature spans of 13-25K with a Carnot efficiency of 42%. Practical applications of magnetic refrigeration are also described.

フライトデータによるＥＴＳ‐ＶＩ搭載大形反射鏡の熱設計評価

Thermal design verification of large deployable reflectors was estimated by using flight data. The temperatures were recorded from ETS-VI, which was launched on August 28, 1994 using H-II vehicle. The reflector surfaces were coated with white paint which had low absorptivity 0.23 at begin of life (BOL) as well as high emissivity 0.87 at BOL. The back structure of the surface was covered with multi-layer insulation (MLI) blankets to shield the solar energy to the trusses. The maximum and minimum temperatures of the large reflectors were fell within the allowable temperature range. The analysis results obtained by a mathematical model agreed well with the flight data. The maximum temperature difference in the surface of the reflector using the analysis model was also evaluated within the allowable temperature.

Validation of a unique concept for a low-cost, lightweight space-deployable antenna structure

Large space-deployable antennas are needed for a variety of applications that include mobile communications, radiometry, active microwave sensing, very-long-baseline interferometry, DoD space-based radar and microspacecraft. Investigators in these fields identify the need for structures up to tens of meters in size for operation from 1 to 90 GHz, based on different aperture configurations. The selection criteria common to all of the users are low cost, lightweight, high reliability and good reflector surface precision. Fortunately, a unique class of space structures has recently emerged that offers great potential for satisfying these criteria. They are referred to as inflatable deployable structures. A good example of such a concept is under development at L'Garde Inc. Serious interest from the user community will depend on realistic demonstrations of the viability of the concept. This means that large, lightweight, low-cost structures need to be developed and used to demonstrate deployment reliability in realistic service environments. The technology data base for the L'Garde inflatable concept will accommodate the development of reflector antenna structures up to 30 m in diameter. Since the concept utilizes very low inflation pressure to maintain the required geometry on orbit, gravity-induced deflection of the structure precludes any meaningful ground-based demonstrations of functional performance. Therefore this concept has been selected for a NASA In-Space Technology Experiment Program (IN-STEP) space-based experiment. The objectives of this experiment are to validate and characterize the mechanical functional performance of a 14-m-diameter inflatable deployable reflector antenna structure in the orbital operational environment. The experiment will be carried by the NASA Spartan spacecraft, which is launched, deployed and recovered by the STS. The Spartan will provide mounting, attitude control, power and data recording for the antenna experiment. The antenna concept development will benefit from both the experiment and supporting technology developments. Results of this experiment are expected to verify the feasibility of fabricating a large space structure for only a few million dollars, demonstrate the reliability of deployment, characterize the quality of the reflector surface and correlate the analytical performance prediction models with actual measured characteristics. Technology developments in support of the experiment, to be conducted at NASA Langley Research Center and the University of Colorado, will include investigation of new and advanced flexible materials, as well as system studies to assess the adequacy of this structural concept for specific classes of applications and for the development of analytical performance production tools. These combined results will be used to advance the technology of the concept with respect to improving surface precision and performance predictability and accommodating larger size structures with different configurations in different orbits.

Numerical Analyses of an Energy Loaded Joint for a Deployable Satellite Structure

Reflectors which are an integral part of space vehicles must be collapsed into the body of the vehicle for transportation to space. It is not efficient to store solid reflectors with a diameter greater than about 2.5 m in the launch vehicle and consequently deployable reflectors are used. This paper discusses the use of a flexible joint mechanism to enable a large reflector to be folded to a compact size and then deployed at geosynchronous orbit. The joint would be incorporated into the members of a skeletal truss structure and their effect on the dynamic behaviour of a single structural member and a large truss framework has been studied. It has been shown that the resonant behaviour of a structural member was significantly altered by introducing a joint into the system, but that of large trusses was not as seriously affected and resembled the equivalent of a non-jointed structure. The resonant frequencies of the jointed structure are shown to be similar to those of the non-jointed one but the amplitudes of vibration are significantly lower.

Design and Performance of the Octahedral Deployable Space Antenna (ODESA)

This paper describes the design and structural performance of a new deployable antenna reflector consisting of active and passive sub-structures based on octahedral modules made of bars and cables. A full description of the antenna structure is given, and the design and manufacture of a small scale (2 m × 2 m) physical model are discussed. The effects of finite joint size on the kinematics of folding and deployment are analysed. Structural tests have been carried out on the model to assess shape accuracy after a series of fold/deploy cycles, pre-stress accuracy and its control, and static stiffness. Results from these experiments are compared to theoretical predictions.

高精度ファンリブ型メッシュ展開鏡面

This paper describes the performance of fan rib type highly accurate, highly reproducible mesh deployable reflector with precision screw type adjustment element for surface drawing and motor and link type deployment system. Surface error and its reproducibility for repeated deployment decreased less than 1/2 of previously developed fan rib type mesh reflector with spring type deployment system. No periodic distortion which corresponds to rib arrangements can be seen and thus mesh reflector with very low gore lobe and side lobe characteristics, which is very useful for frequency reuse, is achieved in C band. This paper also presents measured higher order passive intermodulation (PIM) products of mesh developed and used for this deployable reflector with the mesh tension as a parameter.

Development of a Large Deployable Space Reflector Structure

This paper describes the selection, configuration, design and development of the 5 m diameter deployable reflector structure currently being undertaken jointly by British Aerospace Space Systems Limited and the University of Surrey. Large reflectors represent the most likely, near-term application of a large deployable space structure and offer the most promising opportunity for the development and qualification of the hardware required. Such a large, deployable reflector has to compete against other reflector designs which are not suitable for development into larger space structures but are optimized solely as reflector backing structures. These competitors provide a useful measurement of performance against which the development reflector may be compared in terms of mass, stiffness, cost and reliability. The proposed reflector comprises a radio frequency reflective surface of gold-plated molybdenum knitted wire mesh supported from the nodes of a tetrahedral truss. The development 5 m diameter reflector is made from six deployable tetrahedrons configured symmetrically around a central node. Larger reflectors are possible using the same concept with longer struts or by using an extension of this concept with extra rings of tetrahedrons. The solution is dependent upon the required reflector size and stowage volume restrictions. This design has brought together two critical items of hardware for a large deployable space structure: a simple, light, reliable self-latching hinge (developed by the Ministry of Defence and the University of Surrey) and a long, light, stiff, inexpensive carbon fibre tube (manufactured by the pultrusion technique).

On-board multibeam deployable antennas using Ka, C, andS frequency bands

The configuration, on-ground tests, and design verification results for the multibeam antenna flight model for Engineering Test Satellite-VI (ETS-VI) are described for onboard multibeam antennas with thirteen and five beams for the Ka- and S-bands, respectively. The antennas feature Ka-band frequency reuse in alternate beams through use of a cluster horn; shared use of a reflector for two frequency bands using a novel frequency selective surface (FSS); large, lightweight deployable main reflectors with diameters of 3.5 m and 2.5 m; and a highly accurate antenna-pointing control system consisting of RF sensors and an antenna-pointing mechanism to drive the subreflector. >

大型展開アンテナの試作モデルの評価と宇宙実証方法の提案

A large deployable antenna is essential for effective mobile communication satellites. This paper describes the characteristics of various scale models of the large deployable mesh reflector antennas and a study on space verification test plan using the scale models. Our ultimate goal is a deployable mesh reflector antenna with 30m diameter. Two electrical scale models of the mesh reflectors have been constructed to evaluate the electrical performance of a mesh reflector antenna. The mechanical models consist of two partial deployable models that were designed and constructed to help develop the deployable reflector with 30m diameter. One of the models is the Hexa-Link Truss structure, and the other model is the TETRUS structure. Diameter of these models are 3m. The experimental measurements and calculations of these electrical and mechanical models are also described.

Ku band electric models for large deployable mesh reflector antenna

Two scaled mesh reflector electric models have been constructed for the design of a 30 m diameter large deployable antenna. Radiation characteristics of the antennas have been measured and compared with calculated results. The similarities between measured and calculated results are very close. The cross-polarisation level especially is considerably low.

On the road to the large deployable reflector (LDR): The utility of balloon-borne platforms for far-infrared and submillimeter spectroscopy

Discussion des contributions des observations spectroscopiques dans le domaine IR-lointain et submillimetrique par ballon: revue des transitions les plus importantes entre 50 μm et 1 mm et discussion breve de la methode utilisee pour modeliser la transmission atmospherique

Technology for submillimeter wave remote sensing

The NASA research and development program in submillimeter technology is focused on the needs of major space instruments for future astrophysics, Earth and planetary science missions. Major technology programs for the fabrication of compact, rugged and low power space worthy submillimeter remote sensing instruments for keynote missions such as the Earth observing system, the large deployable reflector (submillimeter observatory) and the Mariner Mark II deep space probe. This paper will address the on-going research program to eventually enable these missions.

Aperture synthesis using orbiting telescopes

A study was carried out to determine the feasibility, with current technology, of performing aperture synthesis using two telescopes orbiting the earth in coordinated orbits separated by ∼ 10 m to 1 km. The objective was to determine whether there is a practical alternative to a very large, deployed, servo‐controlled submillimeter telescope (i.e., the Large Deployable Reflector) for obtaining high resolution submillimeter images of astronomical sources. We find that suitable classes of orbits exist which can provide good uv coverage over the entire sky and that real‐time correlation of wideband signals can be performed in orbit using current technology. The most difficult task appears to be the real‐time determination of the orientation of the baseline vector in a stable coordinate system. We have identified a plausible scheme for the determination of an arbitrary direction to within 0.003 arc sec in an astrometric coordinate system. This scheme not only makes submillimeter interferometric image reconstruction possible but should also have numerous other applications.

Large Deployable Reflector (LDR): A Concept For An Orbiting Submillimeter-Infrared Telescope For The 1990S

The history and background of the Large Deployable Reflector (LDR) are reviewed. The results of the June 1982 Asilomar (California) workshop are incorporated into the LDR science objectives and telescope concept. The areas where the LDR may have the greatest scientific impact are in the study of star formation and planetary systems in our own and nearby galaxies and in cosmological studies of the structure and evolution of the early universe. The observational requirements for these and other scientific studies give rise to a set of telescope functional requirements. These, in turn, are satisfied by an LDR configuration which is a Cassegrain design with a 20 m diameter, actively controlled, segmented, primary reflector, diffraction limited at a wavelength of 30 to 50 um. Technical challenges in the LDR development include construction of high tolerance mirror segments, surface figure measurement, figure control, vibration control, pointing, cryogenics, and coherent detectors. Project status and future plans for the LDR are discussed.

Space Infrared Astronomy: Overview Of NASA Planning

The present status and potential future direction of the NASA space infrared astronomy program is reviewed. Projects and project concepts dis-cussed include the Infrared Astronomy Satellite, Small Infrared Telescope on Spacelab 2, Cosmic Background Explorer, Shuttle Infrared Telescope Facility, Space Telescope, large deployable reflector, molecular line survey, and infrared interferometer in space. Needs for continued engineering development in critical technology areas such as detectors, cryogenics, optics, and space structures are indicated.