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At least 595 records · Page 33

Characterization and modeling of an advanced flexible thermal protection material for space applications

This paper describes experimental and analytical characterization of a new flexible thermal protection material known as Tailorable Advanced Blanket Insulation (TABI). This material utilizes a three-dimensional ceramic fabric core structure and an insulation filler. TABI is the leading candidate for use in deployable aeroassisted vehicle designs. Such designs require extensive structural modeling, and the most significant in-plane material properties necessary for model development are measured and analytically verified in this study. Unique test methods are developed for damping measurements. Mathematical models are developed for verification of the experimental modulus and damping data, and finally, transverse properties are described in terms of the inplane properties through use of a 12-dof finite difference model of a simple TABI configuration.

Clayton, Joseph P.↗

CHEM-Based Self-Deploying Spacecraft Radar Antennas

A document proposes self-deploying spacecraft radar antennas based on cold hibernated elastic memory (CHEM) structures. Described in a number of prior NASA Tech Briefs articles, the CHEM concept is one of utilizing open-cell shape-memory-polymer (SMP) foams to make lightweight structures that can be compressed for storage and can later be expanded, then rigidified for use. A CHEM-based antenna according to the proposal would comprise three layers of microstrip patches and transmission lines interspersed with two flat layers of SMP foam, which would serve as both dielectric spacers and as means of deployment. The SMP foam layers would be fabricated at full size at a temperature below the SMP glass-transition temperature (Tg). The layers would be assembled into a unitary structure, which, at temperature above Tg, would be compacted to much smaller thickness, then rolled up for storage. Next, the structure would be cooled to below Tg and kept there during launch. Upon reaching the assigned position in outer space, the structure would be heated above Tg to make it rebound to its original size and shape. The structure as thus deployed would then be rigidified by natural cooling to below Tg

Sokolowski, Witold↗

Advanced Composite Solar Sail System (ACS3) Mission Update

The Advanced Composite Solar Sail System (ACS3) will be the first practical solar sail for the National Aeronautics and Space Administration. [1] ACS3 will also be the first spaceflight demonstration of NASA compact deployable composite boom technology.[2] The primary mission objective of ACS3 will be to deploy and characterize an 80-m2 composite boom structure solar sail technology in low Earth orbit. Extended mission goals will be to demonstrate controlled solar sailing flight via a series of orbit raising and lowering maneuvers. Target mission orbit is a 1000 km x 1000 km midnight-noon sun-synchronous orbit. Launch of ACS3 is scheduled for July 2023 with sail deployment in September 2023. Mission duration is expected to be six to nine months. The ACS3 solar sail vehicle is a 12U Cubesat consisting of a bus module, containing flight and solar sail control avionics, and a solar sail module, containing the composite booms and metallized polymer solar sail membranes of the solar sail structure stowed within a boom deployer mechanism. A four-camera instrument suite for 360-degree imaging of the ACS3 solar sail during and after deployment is also housed within the bus module. The ACS3 80-m2 solar sail design is a sub-scale version of an intermediate-size 500-m2 solar sail using NASA deployable composite boom technology. The sail consists of four metallized 2-m thick polyethylene naphthalate (PEN) 20-m2 triangular quadrants supported by four 7-m long lenticular cross-section composite booms. Booms are flattened and co-coiled for stowage within a tape-spool driven deployer mechanism. Total mass of the ACS3 space vehicle including solar sail is 16 kg. An overview of the ACS3 mission and mission systems will be provided in this presentation. This overview will include descriptions of the solar sail structures and materials technology used with ACS3, and discussion of the scalability and extensibility of the ACS3 solar sail to future larger-scale solar sailing mission requirements. An update on progress towards the launch of ACS3 in July 2023 will also be provided. References [1] https://www.nasa.gov/directorates/spacetech/small_spacecraft/ACS3 [2] https://www.nasa.gov/directorates/spacetech/game_changing_development/projects/dcb

Solar sail↗

TriTruss: A New and Novel Structural Concept Enabling Modular Space Telescopes and Space Platforms

Modular structures that can be assembled on-orbit will be the backbone for all future persistent missions, including in-space assembled telescopes and platforms for science and communications. The TriTruss is a new and innovative structural module that has been conceived by researchers at the NASA Langley Research Center for platform and telescope applications. Some of the innovative features of the TriTruss include: very compact packaging for launch, the possibility of staged packaging, simple robotic deployment, ease of embedding payload components, an innovative structural connector that has linear structural performance, ease of module-to-module robotic assembly, design versatility, and ease of customizing its design for specific applications. This paper will introduce the TriTruss concept and describe how it can serve as the foundation for many different mission applications, in particular, a 20-meter diameter large space telescope and a beam-type platform that can host a variety of payloads and instruments. The geometry of the TriTruss will be described and the various truss design variables (such as truss depth, member diameter, material modulus, etc.) and each of their impacts on the truss performance will be illustrated. The TriTruss can be mapped to a variety of structural forms, such as beams, two-dimensional platforms and filled curved apertures (for antennas and telescopes), and examples will be illustrated. The TriTruss lends itself to a large variety of packaging schemes; the structural concepts associated with packaging and deployment will be described, as well as the means for robotically deploying TriTruss modules and locking them into their final configuration. TriTruss module-to-TriTruss module robotic assembly operations will also be described. Equations will be presented to structurally size TriTruss modules, such that when assembled into the final persistent platform, the platform achieves a desired level of global structural performance. A status of the TriTruss development will also be presented. This material will cover design and fabrication of TriTruss hardware for platform and telescope applications as well as structural testing of that hardware (the struts, connectors and platforms). Robotic assembly of TriTruss modules is also being performed, and the results of those tests will be summarized.

Doggett, William↗

Concepts and analysis for precision segmented reflector and feed support structures

Several issues surrounding the design of a large (20-meter diameter) Precision Segmented Reflector are investigated. The concerns include development of a reflector support truss geometry that will permit deployment into the required doubly-curved shape without significant member strains. For deployable and erectable reflector support trusses, the reduction of structural redundancy was analyzed to achieve reduced weight and complexity for the designs. The stiffness and accuracy of such reduced member trusses, however, were found to be affected to a degree that is unexpected. The Precision Segmented Reflector designs were developed with performance requirements that represent the Reflector application. A novel deployable sunshade concept was developed, and a detailed parametric study of various feed support structural concepts was performed. The results of the detailed study reveal what may be the most desirable feed support structure geometry for Precision Segmented Reflector/Large Deployable Reflector applications.

Miller, Richard K.↗

Full-scale Skylab Apollo telescope mount deployment tests

During the initial stages of the NASA Skylab orbit, the Apollo telescope mount (ATM) is deployed by the deployment assembly (DA) which clears the multiple docking adapter axial docking port. This is an essential prerequisite to docking the command service module with the orbital workshop and subsequent occupancy of the workshop by the Apollo three-man crew. The objectives of the full-scale NASA Skylab ATM deployment test program were (1) to evaluate the design concept of the DA and deployment mechanisms while functioning in a zero-g environment with simulated ATM mass properties and (2) to evaluate the effects of handling, transporting, and deployment with respect to the structural geometry and stability of the DA.

Fricker, G. F.↗

Multi-hundred kW solar arrays for space

A system-level approach has been applied in designing a cost-effective 300-1000 kW solar array for Low Earth Orbit (LEO) application with a mission time frame of mid-1980's. Technology investigations and performance and cost prognoses in the area of solar cells and reflector material form a key influence on array design and performance. Major tradeoffs were conducted between planar and concentrator concepts and between silicon and GaAs solar cells. Three baseline design concepts emerged: planar, low-CR concentrator (CR = 5), and high-CR concentrator (CR = 125). Combinations of these concepts with silicon and GaAs solar cells were analyzed in terms of electrical performance, thermal behavior, structural configuration, weight, stowed and deployed volume, and installation/deployment method. To identify the most cost-effective designs, a cost analysis of the candidate arrays was performed. The low-CR/GaAs array and the planar/silicon array demonstrate the greatest cost-effectiveness of the candidate arrays in terms of dollars/watt and energy life-cycle cost. Due to the high uncertainty of GaAs cell-cost prognoses, the sensitivity of the results to the GaAs cell cost is discussed.

Woodcock, W. G., III↗

On the danger of redundancies in some aerospace mechanisms

An attempt is made to show that redundancies in some aerospace mechanisms do not generally improve the odds for success. Some of these redundancies may even be the very cause for failure of the system. To illustrate this fallacy, two designs based on the Control of Flexible Structures I (COFS I) Mast deployer and retractor assembly (DRA) are presented together with novel designs to circumvent such design inadequacies, while improving system reliability.

Chew, M.↗

Member vibration effects on LSS behavior

This paper evaluates the sensitivity of modal characteristics of large deployable lattice-type space structures to joint boundary conditions. The evaluation of joint rotational boundary conditions is accomplished by a review of modal strain energy among elements of the analytic dynamic model. This review shows that space structure designs having no bending energy in lattice members in the low frequency range are insensitive to joint rotational boundary conditions in that frequency range. Evaluation of joint translation boundary conditions is accomplished by the 'modal freeplay method' which is described in this paper. The modal freeplay method relates modal frequency to joint translational freeplay and to amplitude of applied forces.

White, Charles W.↗

Sunlight Diffusing Tent for Lunar Worksite

The purpose is to provide a solution to problems astronauts encounter with sunlight on the lunar surface. Due to the absence of an atmosphere the Moon is subjected to intense sunlight creating problems with color and contrast. This problem can be overcome by providing a way to reduce intensity and diffuse the light in a working environment. The solution to the problem utilizes an umbrella, tent-like structure covered with a diffusing material. The design takes into account structural materials, stresses, fabrics, and deployment.

Burleson, Blair↗

Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

Surface errors on parabolic reflector antennas degrade the overall performance of the antenna. Space antenna structures are difficult to build, deploy and control. They must maintain a nearly perfect parabolic shape in a harsh environment and must be lightweight. Electromagnetic compensation for surface errors in large space reflector antennas can be used to supplement mechanical compensation. Electromagnetic compensation for surface errors in large space reflector antennas has been the topic of several research studies. Most of these studies try to correct the focal plane fields of the reflector near the focal point and, hence, compensate for the distortions over the whole radiation pattern. An alternative approach to electromagnetic compensation is presented. The proposed technique uses pattern synthesis to compensate for the surface errors. The pattern synthesis approach uses a localized algorithm in which pattern corrections are directed specifically towards portions of the pattern requiring improvement. The pattern synthesis technique does not require knowledge of the reflector surface. It uses radiation pattern data to perform the compensation.

Stutzman, W. L.↗

A variational approach to dynamics of flexible multibody systems

This paper presents a variational formulation of constrained dynamics of flexible multibody systems, using a vector-variational calculus approach. Body reference frames are used to define global position and orientation of individual bodies in the system, located and oriented by position of its origin and Euler parameters, respectively. Small strain linear elastic deformation of individual components, relative to their body references frames, is defined by linear combinations of deformation modes that are induced by constraint reaction forces and normal modes of vibration. A library of kinematic couplings between flexible and/or rigid bodies is defined and analyzed. Variational equations of motion for multibody systems are obtained and reduced to mixed differential-algebraic equations of motion. A space structure that must deform during deployment is analyzed, to illustrate use of the methods developed.

Wu, Shih-Chin↗

Computational methods and software systems for dynamics and control of large space structures

Two key areas of crucial importance to the computer-based simulation of large space structures are discussed. The first area involves multibody dynamics (MBD) of flexible space structures, with applications directed to deployment, construction, and maneuvering. The second area deals with advanced software systems, with emphasis on parallel processing. The latest research thrust in the second area involves massively parallel computers.

Park, K. C.↗

Modeling and initialization of a segmented telescope

The closely integrated design effort entailed by such prospective NASA-JPL project hardware as the Large Deployable Reflector, encompassing controls, dynamics, structures, optics, and thermal considerations, has prompted the development of the Figure Control Simulation, or 'FCSim' simulation program. This code is presently demonstrated for the case of a 7-segment, 3.65-m diameter primary mirror designed for 100-800 micron wavelengths. The optical component of the analysis can handle multispectral images, extended sources, image smear due to structural jitter, and mirror segment surface irregularities.

Sirlin, Samuel W.↗

Computational methods and software systems for dynamics and control of large space structures

This final report on computational methods and software systems for dynamics and control of large space structures covers progress to date, projected developments in the final months of the grant, and conclusions. Pertinent reports and papers that have not appeared in scientific journals (or have not yet appeared in final form) are enclosed. The grant has supported research in two key areas of crucial importance to the computer-based simulation of large space structure. The first area involves multibody dynamics (MBD) of flexible space structures, with applications directed to deployment, construction, and maneuvering. The second area deals with advanced software systems, with emphasis on parallel processing. The latest research thrust in the second area, as reported here, involves massively parallel computers.

Park, K. C.↗

Surface Habitat Systems

The Surface Habitat Systems (SHS) Focused Investment Group (FIG) is part of the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) effort to provide a focused direction and funding to the various projects that are working on human surface habitat designs and technologies for the planetary exploration missions. The overall SHS-FIG effort focuses on directing and guiding those projects that: 1) develop and demonstrate new surface habitat system concepts, innovations, and technologies to support human exploration missions, 2) improve environmental systems that interact with human habitats, 3) handle and emplace human surface habitats, and 4) focus on supporting humans living and working in habitats on planetary surfaces. The activity areas of the SHS FIG described herein are focused on the surface habitat project near-term objectives as described in this document. The SHS-FIG effort focuses on mitigating surface habitat risks (as identified by the Lunar Surface Systems Project Office (LSSPO) Surface Habitat Element Team; and concentrates on developing surface habitat technologies as identified in the FY08 gap analysis. The surface habitat gap assessment will be updated annually as the surface architecture and surface habitat definition continues to mature. These technologies are mapped to the SHS-FIG Strategic Development Roadmap. The Roadmap will bring to light the areas where additional innovative efforts are needed to support the development of habitat concepts and designs and the development of new technologies to support of the LSSPO Habitation Element development plan. Three specific areas of development that address Lunar Architecture Team (LAT)-2 and Constellation Architecture Team (CxAT) Lunar habitat design issues or risks will be focused on by the SHS-FIG. The SHS-FIG will establish four areas of development that will help the projects prepare in their planning for surface habitat systems development. Those development areas are the 1) surface habitat concept definition, 2) inflatable surface habitat development, and 3) autonomous habitat operations, and 4) cross-cutting / systems engineering. In subsequent years, the SHS-FIG will solicit a call for innovations and technologies that will support the development of these four development areas. The other development areas will be assessed yearly and identified on the SHS-FIG s Strategic Development Roadmap. Initial investment projects that are funded by the Constellation Program Office (CxPO), LSSPO, or the Exploration Technology Development Projects (ETDP) will also be included on the Roadmap. For example, in one or two years from now, the autonomous habitat operations and testbed would collaborations with the Integrated Systems Health Management (ISHM) and Automation for Operations ETDP projects, which will give the surface habitat projects an integrated habitat autonomy testbed to test software and systems. The SHS-FIG scope is to provide focused direction for multiple innovations, technologies and subsystems that are needed to support humans at a remote planetary surface habitat during the concept development, design definition, and integration phases of that project. Subsystems include: habitability, lightweight structures, power management, communications, autonomy, deployment, outfitting, life support, wireless connectivity, lighting, thermal and more.

Kennedy, Kriss J.↗

NASA Tech Briefs, November 2003

Topics covered include: Computer Program Recognizes Patterns in Time-Series Data; Program for User-Friendly Management of Input and Output Data Sets; Noncoherent Tracking of a Source of a Data-Modulated Signal; Software for Acquiring Image Data for PIV; Detecting Edges in Images by Use of Fuzzy Reasoning; A Timer for Synchronous Digital Systems; Prototype Parts of a Digital Beam-Forming Wide-Band Receiver; High-Voltage Droplet Dispenser; Network Extender for MIL-STD-1553 Bus; MMIC HEMT Power Amplifier for 140 to 170 GHz; Piezoelectric Diffraction-Based Optical Switches; Numerical Modeling of Nanoelectronic Devices; Organizing Diverse, Distributed Project Information; Eigensolver for a Sparse, Large Hermitian Matrix; Modified Polar-Format Software for Processing SAR Data; e-Stars Template Builder; Software for Acoustic Rendering; Functionally Graded Nanophase Beryllium/Carbon Composites; Thin Thermal-Insulation Blankets for Very High Temperatures; Prolonging Microgravity on Parabolic Airplane Flights; Device for Locking a Control Knob; Cable-Dispensing Cart; Foam Sensor Structures Would be Self-Deployable and Survive Hard Landings; Real-Gas Effects on Binary Mixing Layers; Earth-Space Link Attenuation Estimation via Ground Radar Kdp; Wedge Heat-Flux Indicators for Flash Thermography; Measuring Diffusion of Liquids by Common-Path Interferometry; Zero-Shear, Low-Disturbance Optical Delay Line; Whispering-Gallery Mode-Locked Lasers; Spatial Light Modulators as Optical Crossbar Switches; Update on EMD and Hilbert-Spectra Analysis of Time Series; Quad-Tree Visual-Calculus Analysis of Satellite Coverage; Dyakonov-Perel Effect on Spin Dephasing in n-Type GaAs; Update on Area Production in Mixing of Supercritical Fluids; and Quasi-Sun-Pointing of Spacecraft Using Radiation Pressure.

Source record↗

Multifunctional Deployment Hinges Rigidified by Ultraviolet

Multifunctional hinges have been developed for deploying and electrically connecting panels comprising planar arrays of thin-film solar photovoltaic cells. In the original intended application of these hinges, the panels would be facets of a 32-sided (and approximately spherical) polyhedral microsatellite (see figure), denoted a PowerSphere, that would be delivered to orbit in a compact folded configuration, then deployed by expansion of gas in inflation bladders. Once deployment was complete, the hinges would be rigidified to provide structural connections that would hold the panels in their assigned relative positions without backlash. Such hinges could also be used on Earth for electrically connecting and structurally supporting solar panels that are similarly shipped in compact form and deployed at their destinations. As shown in section A-A in the figure, a hinge of this type is partly integrated with an inflation bladder and partly integrated with the frame of a solar panel. During assembly of the hinge, strip extensions from a flexible circuit harness on the bladder are connected to corresponding thin-film conductors on the solar panel by use of laser welding and wrap-around contacts. The main structural component of the hinge is a layer of glass fiber impregnated with an ultraviolet-curable resin. After deployment, exposure to ultraviolet light from the Sun cures the resin, thereby rigidifying the hinge.

Kerslake, Thomas W.↗