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At least 505 records · Page 28

The Physics of Solar Sails

The concept of using photon pressure for propulsion has been considered since Tsiolkovsky in 1921. In fact, Tsiolkovsky and Tsander wrote of 'using tremendous mirrors of very thin sheets' and 'using the pressure of sunlight to attain cosmic velocities' in 1924. The term 'solar sailing' was coined in the late 1950s and was popularized by Arthur C. Clarke in the short story Sunjammer (The Wind From the Sun) in May 1964. The National Aeronautics and Space Administration (NASA) used sailing techniques to extend the operational life of the Mariner 10 spacecraft in 1974-1975. A problem in the control system was causing Mariner 10 to go off course. By controlling the attitude of Mariner 10 and the angle of the solar power panels relative to the Sun, ground controllers were able to correct the problem without using precious fuel. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this method would need to deploy a thin sail that could be as large as many kilometers in extent. Candidate sail materials should be: 1) strong, 2) ultra-lightweight (density of a few g/sq m), 3) able to be folded or crushed until deployed, 4) subject to minimal sagging or stretching, and 5) resistant to ionizing radiation, such as galactic and solar particles (electrons and protons), x-rays, ultraviolet light, and magnetically trapped charged particles. Solar sails must be resistant to each of these types of radiation.

Hollerman, William Andrew↗

Novel Vibration Damping of Ceramic Matrix Composite Turbine Blades Developed for RLV Applications

The Reusable Launch Vehicle (RLV) represents the next generation of space transportation for the U.S. space program. The goal for this vehicle is to lower launch costs by an order of magnitude from $10,000/lb to $1,000/lb. Such a large cost reduction will require a highly efficient operation, which naturally will require highly efficient engines. The RS-2200 Linear Aerospike Engine is being considered as the main powerplant for the RLV. Strong, lightweight, temperature-resistant ceramic matrix composite (CMC) materials such as C/SiC are critical to the development of the RS-2200. Preliminary engine designs subject turbopump components to extremely high frequency dynamic excitation, and ceramic matrix composite materials are typically lightly damped, making them vulnerable to high-cycle fatigue. The combination of low damping and high-frequency excitation creates the need for enhanced damping. Thus, the goal of this project has been to develop well-damped C/SiC turbine components for use in the RLV. Foster-Miller and Boeing Rocketdyne have been using an innovative, low-cost process to develop light, strong, highly damped turbopump components for the RS-2200 under NASA s Small Business Innovation Research (SBIR) program. The NASA Glenn Research Center at Lewis Field is managing this work. The process combines three-dimensionally braided fiber reinforcement with a pre-ceramic polymer. The three-dimensional reinforcement significantly improves the structure over conventional two-dimensional laminates, including high through-the-thickness strength and stiffness. Phase I of the project successfully applied the Foster-Miller pre-ceramic polymer infiltration and pyrolysis (PIP) process to the manufacture of dynamic specimens representative of engine components. An important aspect of the program has been the development of the manufacturing process. Results show that the three-dimensionally braided carbon-fiber reinforcement provides good processability and good mechanical stiffness and strength in comparison to materials produced with competing processes as shown in the graphs.

Min, James B.↗

2006 Status of the Momentum eXchange Electrodynamic Re-Boost (MXER) Tether Development

The MXER Tether technology development is a high-payoff/high-risk investment area within the NASA In-Space Propulsion Technology (ISPT) Program. The ISPT program is managed by the NASA Headquarters Science Mission Directorate and implemented by the Marshall Space Flight Center in Huntsville, Alabama. The MXER concept was identified and competitively ranked within NASA's comprehensive Integrated In-Space Transportation Plan (IISTP); an agency-wide technology assessment activity. The objective of the MXER tether project within ISPT is to advance the technological maturation level for the MXER system, and its subsystems, as well as other space and terrestrial tether applications. Recent hardware efforts have focused on the manufacturability of space-survivable high-strength tether material and coatings, high-current electrodynamic tether, lightweight catch mechanism, high-accuracy propagator/predictor code, and efficient electron collection/current generation. Significant technical progress has been achieved with modest ISPT funding to the extent that MXER has evolved to a well-characterized system with greater capability as the design has been matured. Synergistic efforts in high-current electrodynamic tethers and efficient electron collection/current generation have been made possible through SBIR and STTR support. The entire development endeavor was orchestrated as a collaborative team effort across multiple individual contracts and has established a solid technology resource base, which permits a wide variety of future space cable/tether applications to be realized.

Bonometti, Joseph A.↗

Advanced Optical Technologies for Space Exploration

NASA Langley Research Center is involved in the development of photonic devices and systems for space exploration missions. Photonic technologies of particular interest are those that can be utilized for in-space communication, remote sensing, guidance navigation and control, lunar descent and landing, and rendezvous and docking. NASA Langley has recently established a class-100 clean-room which serves as a Photonics Fabrication Facility for development of prototype optoelectronic devices for aerospace applications. In this paper we discuss our design, fabrication, and testing of novel active pixels, deformable mirrors, and liquid crystal spatial light modulators. Successful implementation of these intelligent optical devices and systems in space, requires careful consideration of temperature and space radiation effects in inorganic and electronic materials. Applications including high bandwidth inertial reference units, lightweight, high precision star trackers for guidance, navigation, and control, deformable mirrors, wavefront sensing, and beam steering technologies are discussed. In addition, experimental results are presented which characterize their performance in space exploration systems.

Clark, Natalie↗

NASA Tech Briefs, September 2005

Topivs include: Diamond-Coated Carbon Nanotubes for Efficient Field Emission; Improved Anode Coatings for Direct Methanol Fuel Cells; Advanced Ablative Insulators and Methods of Making Them; PETIs as High-Temperature Resin-Transfer-Molding Materials; Stable Polyimides for Terrestrial and Space Uses; Low-Density, Aerogel-Filled Thermal-Insulation Tiles; High-Performance Polymers Having Low Melt Viscosities; Nonflammable, Hydrophobic Aerogel Composites for Insulation; Front-Side Microstrip Line Feeding a Raised Antenna Patch; Medium-Frequency Pseudonoise Georadar; Facilitating Navigation Through Large Archives; Program for Weibull Analysis of Fatigue Data; Comprehensive Micromechanics-Analysis Code - Version 4.0; Component-Based Visualization System; Software for Engineering Simulations of a Spacecraft; LabVIEW Interface for PCI-SpaceWire Interface Card; Path Following with Slip Compensation for a Mars Rover; International Space Station Electric Power System Performance Code-SPACE; Software for Automation of Real-Time Agents, Version 2; Software for Optimizing Plans Involving Interdependent Goals; Computing Gravitational Fields of Finite-Sized Bodies; Custom Sky-Image Mosaics from NASA's Information Power Grid; ANTLR Tree Grammar Generator and Extensions; Generic Kalman Filter Software; Alignment Stage for a Cryogenic Dilatometer; Rugged Iris Mechanism; Treatments To Produce Stabilized Aluminum Mirrors for Cryogenic Uses; Making AlNx Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam; Making Wide-IF SIS Mixers with Suspended Metal-Beam Leads; Sol-Gel Glass Holographic Light-Shaping Diffusers; Automated Counting of Particles To Quantify Cleanliness; Phase Correction for GPS Antenna with Nonunique Phase Center; Compact Infrasonic Windscreen; Broadband External-Cavity Diode Laser; High-Efficiency Solar Cells Using Photonic-Bandgap Materials; Generating Solid Models from Topographical Data; Computationally Lightweight Air-Traffic-Control Simulation; Spool Valve for Switching Air Flows Between Two Beds; Partial Model of Insulator/ Insulator Contact Charging; Asymmetric Electrostatic Radiation Shielding for Spacecraft; and Reusable Hybrid Propellant Modules for Outer-Space Transport.

Source record↗

Research Activities in High Voltage (HV) Materials for Aerospace Systems

This presentation gives an overview of recent materials research activities carried out at NASA Glenn Research Center. The background and motivation for the development of thermally conductive electrical insulation for a high voltage (HV) turboelectric aircraft concept is briefly discussed. A summary of the challenges and technology gap associated with HV aerospace electrical systems is also covered as well as the development of electrical insulation and engineered ceramic fillers and HV test capabilities. The research has expanded to include the development of a lightweight copper/ carbon nanotube composite conductor. Applications for these materials include hybrid electric aircraft, all electric aircraft, spacecraft, electric propulsion systems, and future power transmission systems for Lunar and Martian destinations.

Composite conductors↗

Isogrid Membranes for Precise, Singly Curved Reflectors

A new type of composite material has been proposed for membranes that would constitute the reflective surfaces of planned lightweight, single-curvature (e.g., parabolic cylindrical) reflectors for some radar and radio-communication systems. The proposed composite materials would consist of polyimide membranes containing embedded grids of highstrength (e.g., carbon) fibers. The purpose of the fiber reinforcements, as explained in more detail below, is to prevent wrinkling or rippling of the membrane.

Fang, Houfei↗

Launch vehicle flight control augmentation using smart materials and advanced composites (CDDF Project 93-05)

The Marshall Space Flight Center has a rich heritage of launch vehicles that have used aerodynamic surfaces for flight stability such as the Saturn vehicles and flight control such as on the Redstone. Recently, due to aft center-of-gravity locations on launch vehicles currently being studied, the need has arisen for the vehicle control augmentation that is provided by these flight controls. Aerodynamic flight control can also reduce engine gimbaling requirements, provide actuator failure protection, enhance crew safety, and increase vehicle reliability, and payload capability. In the Saturn era, NASA went to the Moon with 300 sq ft of aerodynamic surfaces on the Saturn V. Since those days, the wealth of smart materials and advanced composites that have been developed allow for the design of very lightweight, strong, and innovative launch vehicle flight control surfaces. This paper presents an overview of the advanced composites and smart materials that are directly applicable to launch vehicle control surfaces.

Barret, C.↗

Lightweight Exoskeletons with Controllable Actuators

A proposed class of lightweight exoskeletal electromechanical systems would include electrically controllable actuators that would generate torques and forces that, depending on specific applications, would resist and/or assist wearers movements. The proposed systems would be successors to relatively heavy, bulky, and less capable human-strength-amplifying exoskeletal electromechanical systems that have been subjects of research during the past four decades. The proposed systems could be useful in diverse applications in which there are needs for systems that could be donned or doffed easily, that would exert little effect when idle, and that could be activated on demand: examples of such applications include (1) providing controlled movement and/or resistance to movement for physical exercise and (2) augmenting wearers strengths in the performance of military, law-enforcement, and industrial tasks. An exoskeleton according to the proposal would include adjustable lightweight graphite/epoxy struts and would be attached to the wearer's body by belts made of hook-and-pile material. At selected rotary and linear joints, the exoskeleton would be fitted, variously, with lightweight, low-power-consumption rotary and linear brakes, clutches, and motors. The exoskeleton would also be equipped with electronic circuitry for monitoring, control, and possibly communication with external electronic circuits that would perform additional monitoring and control functions.

Bar-Cohen, Yoseph↗

Superior Ballistic Impact Resistance Achieved by the Co-Base Alloy Haynes 25

The fan case in a jet engine is required to contain a fan blade in the rare event of a blade loss during operation. Because of its function, the fan case is the largest structural component in high-bypass-ratio turbofan engines used in commercial aircraft. Therefore, the use of lighter and stronger materials would be advantageous in most engines and is practically a necessity in the latest generation of high-bypass engines. Small panels, 7 in. wide by 7 in. long, of a number of metallic alloys were impact tested at room temperature with a 0.50-caliber blunt-nose titanium alloy projectile at the NASA Glenn Research Center (ref. 1). These metallic systems included several high-strength aluminum (Al) alloys, Al-based laminates, aluminum metal matrix composites (Al-MMCs), nickel-base superalloys (Inconel 718 and 625), several titanium (Ti) alloys in different heat treated conditions, 304L stainless steel, a stainless-steel-based laminate, and a high strength steel (Nitronic 60). It was determined that a simple Co-base alloy (Haynes 25) had the best impact resistance on an areal weight basis. Haynes 25 was at least 10 percent better than IMI 550, the best titanium alloy tested to date, and it was far superior to other metals, especially at higher impact velocities (greater than 1100 ft/sec). Because this material could be ideal for fan containment applications in supersonic aircraft as a replacement for titanium, impact tests were also conducted at 371 oC and compared with results from alloys tested at elevated temperature under previous programs (i.e., Inconel 718, Ti-6242, M-152, Timetal 21S, and Aeromet 100). Although cobalt-base alloys are used in some high-temperature engine applications, to our knowledge they are not used in any containment systems. Advantages of cobalt over titanium include lower cost, easier processing, better high-temperature strength, and no fire hazard if tip rub occurs. Future plans include testing of lightweight sandwich panels with Haynes 25 as a core material in the form of a foam or lattice block structure and scaling up the current tests by using blade-simulating projectiles impacting large plates and half rings.

Hebsur, Mohan G.↗

Lightweight magnets for MPD arcs.

Electro- and permanent magnet configurations using different materials analyzed, determining lowest mass magnet system for MPD ARCS

WEIGHT FACTOR↗

Lightweight orthotic braces

Leg brace is constructed of fiber-reinforced polymer material. Composite material is stiffer, stronger, and lighter than most metals.

Baucom, R. M.↗

Lightweight Modular Instrumentation for Planetary Applications

An instrumentation, called Space Active Modular Materials ExperimentS (SAMMES), is developed for monitoring the spacecraft environment and for accurately measuring the degradation of space materials in low earth orbit (LEO). The SAMMES architecture concept can be extended to instrumentation for planetary exploration, both on spacecraft and in situ. The operating environment for planetary application will be substantially different, with temperature extremes and harsh solar wind and cosmic ray flux on lunar surfaces and temperature extremes and high winds on venusian and Martian surfaces. Moreover, instruments for surface deployment, which will be packaged in a small lander/rover (as in MESUR, for example), must be extremely compact with ultralow power and weight. With these requirements in mind, the SAMMES concept was extended to a sensor/instrumentation scheme for the lunar and Martian surface environment.

Joshi, P. B.↗

Selection of burn-resistant materials for oxygen-driven turbopumps

NASA goals for reusable space-based, high-performance orbit transfer vehicle propulsion systems have resulted in a need for oxygen/hydrogen engines which include lightweight, highly reliable, liquid oxygen pumps. The selection of ignition- and burn-resistant materials is a major factor in the design of a compact 75,000-rpm turbopump which can deliver 6 lbM/sec of liquid oxygen at 5,000 psia. The potential operational hazards of rubbing friction and impact of foreign particles at high velocity were investigated experimentally for a wide range of candidate materials, i.e., nickel, copper, monel, 316 Stainless Steel, Hastelloy-X, Invar-36, and silicon carbide. Test parameters included oxygen pressure and temperature up to 5,000 psia and 800 F, respectively. The effect of increasing the O2 pressure from 1000 to 5000 psi is discussed. The applicability of the candidate materials to oxygen pump design was ranked by comparing the experimental results among themselves and with an analytically determined parameter, i.e., the burn factor. Nickel and copper demonstrated superior resistance to ignition and burn in the friction rubbing and particle impact tests relative to monel, stainless steel, and nickel-iron base superalloys.

Schoenman, L.↗

Navigation for the ACS3 Solar Sail Mission

NASA’s Advanced Composite Solar Sail System (ACS3) mission consists of a spacecraft that plans to be launched in early 2024. The spacecraft carries an 80 m2 solar sail that can produce effective thrust to alter the initial 1000 km sun-synchronous orbit. The main objective of the mission is to demonstrate the capabilities of the solar sail to effectively change various orbital parameters such as the semi-major axis and the inclination. Various composite materials were used to produce the sail, together with lightweight booms that will deploy from a 12U CubeSat bus. The astrodynamics team at NASA Ames Research Center has built a Flight Dynamics System (FDS) to provide mission navigation and to produce regular ephemeris once in orbit. The FDS can compute the trajectories that the spacecraft will perform once the sail is deployed. To achieve that, GPS data is obtained from the spacecraft telemetry and then is used with a Kalman filter and a smoother to obtain an orbit determination solution. The outcome of this process reduces the position and velocity uncertainty in a daily cadence. After that, the state vector output is used to feed a propagation model that includes the updated attitude and orbit of the spacecraft at that given moment. The trajectory model considers the updated attitude plan of the spacecraft as well as the environment conditions such as the solar weather to compute the associated drag and solar radiation pressure. This paper explains in detail the implementation of the FDS, as well as the solar sail solar radiation pressure trajectory model. We also present the results of several potential trajectory models under various assumptions of orbit parameters, attitude, environment, and material properties. In addition, we introduce a trajectory model for potential interplanetary use of an equivalent solar sail in the future. The outcome of this process will be critical to achieving the objective of determining effective altitude change produced by the solar sail.

Andres Dono Perez↗

Navigation for the ACS3 Solar Sail Mission

NASA’s Advanced Composite Solar Sail System (ACS3) mission consists of a spacecraft that plans to be launched no earlier than April 2024. The spacecraft carries an 81 m2 solar sail that can produce effective ΔV to alter the initial 1000 km sun-synchronous orbit. The main objective of the mission is to demonstrate the capabilities of the solar sail to effectively change the semi-major axis of its initial orbit. Various composite materials were used to produce the sail, together with lightweight booms that will deploy from a 12U CubeSat bus. The ACS3 navigation team at NASA Ames Research Center has built a Flight Dynamics System (FDS) to provide mission navigation and to produce regular ephemeris once in orbit. The FDS can compute the orbit transfers that the spacecraft will perform once the sail is deployed. To achieve that, GPS data is obtained from the spacecraft telemetry and then is used with a Kalman filter and a smoother to obtain an orbit determination solution. The outcome of this process reduces the position and velocity uncertainty in a daily cadence. After that, the state vector output is used to feed a propagation model that includes the updated attitude and orbit of the spacecraft at that given moment. The trajectory model considers the updated attitude plan of the spacecraft as well as the environment conditions such as the solar weather to compute the associated drag and solar radiation pressure. This paper explains in detail the implementation of the FDS, as well as the solar sail solar radiation pressure trajectory model. We also present the results of several potential trajectory models under various assumptions of orbit parameters, attitude, environment, and material properties. In addition, we introduce a trajectory model for potential interplanetary use of an equivalent solar sail in the future. The outcome of this process will be critical to achieving the objective of determining effective semi-major axis change produced by the solar sail.

Andres Dono↗

Space plasma high-voltage drainage experiment (A0054)

The objectives of this experiment are to place large numbers of dielectric samples under electric stress in space; to determine their in-space current drainage behavior; to recover, inspect, and further test these samples in laboratory facilities; and finally to specify allowable electric stress levels for these materials as applied to solar-array and thermal control coatings for prolonged exposure in space. These findings, in turn, will pace the design of encapsulated, lightweight, high-voltage solar arrays as well as the development of coating materials for spacecraft operation in energetic charged-particle environments such as that experienced at geosynchronous altitudes during magnetic substorms.

Taylor, W. W. L.↗

Genetic Optimization of a Tensegrity Structure

Marshall Space Flight Center (MSFC) is charged with developing advanced technologies for space telescopes. The next generation of space optics will be very large and lightweight. Tensegrity structures are built of compressive members (bars), and tensile members (strings). For most materials, the tensile strength of a longitudinal member is larger than its buckling strength; therefore a large stiffness to mass ratio can be achieved by increasing the use of tensile members. Tensegrities are the epitome of lightweight structures, since they take advantage of the larger tensile strength of materials. The compressive members of tensegrity structures are disjoint allowing compact storage of the structure. The structure has the potential to eliminate the requirement for assembly by man in space; it can be deployed by adjustments in its cable tension. A tensegrity structure can be more reliably modeled since none of the individual members experience bending moments. (Members that experience deformation in more than one dimension are much harder to model.) Structures that can be more precisely modeled can be more precisely controlled. Furthermore, an astoundingly wide variety of natural systems, including carbon atoms, water molecules, proteins, viruses, cells, tissues and even human and other living creatures are tensegrity structures. Through the process of evolution, nature continually improves the design of living creatures for the environment they live in. Since tensegrities are nature's structure of choice, it is conceivable that they have other benefits we are unaware of. A. Keane and S. Brown designed a satellite boom truss system with an enhanced vibration performance. They started with a standard truss system, then used a genetic algorithm to alter the design, while optimizing the vibration performance. An improvement of over 20,000% in frequency-averaged energy levels was obtained using this approach. In this report an introduction to tensegrity structures is given, along with a description of how to generate the nodal coordinates and connectivity of a multiple stage cylindrical tensegrity structure. A description of how finite elements can be used to develop a stiffness and mass matrix so that the modes of vibration can be determined from the eigenvalue problem is shown. A brief description of a micro genetic algorithm is then presented.

Jaime R. Taylor↗