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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Elastohydrodynamic lubrication of elliptical contacts

The determination of the minimum film thickness within contact is considered for both fully flooded and starved conditions. A fully flooded conjunction is one in which the film thickness is not significantly changed when the amount of lubricant is increased. The fully flooded results presented show the influence of contact geometry on minimum film thickness as expressed by the ellipticity parameter and the dimensionless speed, load, and materials parameters. These results are applied to materials of high elastic modulus (hard EHL), such as metal, and to materials of low elastic modulus(soft EHL), such as rubber. In addition to the film thickness equations that are developed, contour plots of pressure and film thickness are given which show the essential features of elastohydrodynamically lubricated conjunctions. The crescent shaped region of minimum film thickness, with its side lobes in which the separation between the solids is a minimum, clearly emerges in the numerical solutions. In addition to the 3 presented for the fully flooded results, 15 more cases are used for hard EHL contacts and 18 cases are used for soft EHL contacts in a theoretical study of the influence of lubricant starvation on film thickness and pressure. From the starved results for both hard and soft EHL contacts, a simple and important dimensionless inlet boundary distance is specified. This inlet boundary distance defines whether a fully flooded or a starved condition exists in the contact. Contour plots of pressure and film thickness in and around the contact are shown for conditions.

Hamrock, B. J.↗
NASA NTRS1989

Low earth orbital atomic oxygen simulation for materials durability evaluation

The erosion yields of numerous materials have been evaluated in low earth orbital space tests. There appears to be three classes of materials: materials of high erosion yield which include most of the hydrocarbon organic materials; materials which either do not react with atomic oxygen or form self-protecting oxides which allow the underlying material to appear durable to atomic oxygen, and materials with low but nonnegligeable erosion yields, such as fluoropolymers. A NASA atomic oxygen effects test program has been established to utilize collective data from a multitude of simulation facilities to promote an understanding of mechanism and erosion yield dependencies. Atomic oxygen protective coatings for Kapton polymide solar array blankets, fiberglass-epoxy composite mast structures, and solar dynamic power system concentrator surfaces have been identified and evaluated under atomic oxygen exposure in RF plasma asher laboratory tests. The control of defect density in protective coatings appears to be the key to the assurance of long-term protection of oxidizable materials in low earth orbit.

Banks, Bruce A.↗
NASA NTRS1999

Evaluation of Spacecraft Shielding Effectiveness for Radiation Protection

The potential for serious health risks from solar particle events (SPE) and galactic cosmic rays (GCR) is a critical issue in the NASA strategic plan for the Human Exploration and Development of Space (HEDS). The excess cost to protect against the GCR and SPE due to current uncertainties in radiation transmission properties and cancer biology could be exceedingly large based on the excess launch costs to shield against uncertainties. The development of advanced shielding concepts is an important risk mitigation area with the potential to significantly reduce risk below conventional mission designs. A key issue in spacecraft material selection is the understanding of nuclear reactions on the transmission properties of materials. High-energy nuclear particles undergo nuclear reactions in passing through materials and tissue altering their composition and producing new radiation types. Spacecraft and planetary habitat designers can utilize radiation transport codes to identify optimal materials for lowering exposures and to optimize spacecraft design to reduce astronaut exposures. To reach these objectives will require providing design engineers with accurate data bases and computationally efficient software for describing the transmission properties of space radiation in materials. Our program will reduce the uncertainty in the transmission properties of space radiation by improving the theoretical description of nuclear reactions and radiation transport, and provide accurate physical descriptions of the track structure of microscopic energy deposition.

Cucinotta, Francis A.↗
NASA NTRS2005

Thin Films and Inflatable Applications in Exploration Habitat Structures

NASA's vision to return to the Moon and then extend human exploration to Mars will benefit from human habitat technology development using new and creative applications of polymer materials and concepts. Thin Film and Inflatable (TFVI) materials are particularly interesting for exploration applications due to their light weight and low volume. Whereas TF/I materials can be launched and carried from Earth to multiple and distant exploration sites without the constraints of upmass limitations, eventually, with recycling and reclamation efforts, these materials may be developed using in-situ resources. These materials can be useful for fabricating, patching and repairing vehicles, replacement parts and even habitat structures, as well as for developing stand-alone habitat structure technologies and for nested and integrated applications. TF/Is can also be ideal environmental containment vessels within lunar or Martian regolith walls or as liners inside caves or raw regolith exterior structures for the provisions of atmosphere containment, debris protection and cleanliness. Further, TFOs can be specialized and matured for various and diverse applications. The desired range of applications will require materials specification for such properties as transparency, elasticity, thermal conductivity, mechanical strength, heat capacity, chemical resistance, and permeability. This paper will discuss Marshall Space Flight Center's plans to analyze and prioritize TF/I materials properties and classifications and to develop applications for these highly desirable materials in human habitat construction projects on the Moon and Mars.

Frazier, Donald O.↗
NASA NTRS2006

Dust Spectroscopy and the Nature of Grains

Ground-based, air-borne and space-based, infrared spectra of a wide variety of objects have revealed prominent absorption and emission features due to large molecules and small dust grains. Analysis of this data reveals a highly diverse interstellar and circumstellar grain inventory, including both amorphous materials and highly crystalline compounds (silicates and carbon). This diversity points towards a wide range of physical and chemical birthsites as well as a complex processing of these grains in the interstellar medium. In this talk, I will review the dust inventory contrasting and comparing both the interstellar and circumstellar reservoirs. The focus will be on the processes that play a role in the lifecycle of dust in the interstellar medium.

Tielens, A. G. G. M.↗
NASA NTRS2010

Miniature Lightweight Ion Pump

This design offers a larger surface area for pumping of active gases and reduces the mass of the pump by eliminating the additional vacuum enclosure. There are three main components to this ion pump: the cathode and anode pumping elements assembly, the vacuum enclosure (made completely of titanium and used as the cathode and maintained at ground potential) containing the assembly, and the external magnet. These components are generally put in a noble diode (or differential) configuration of the ion pump technology. In the present state of the art, there are two cathodes, one made of titanium and the other of tantalum. The anodes are made up of an array of stainless steel cylinders positioned between the two cathodes. All the elements of the pump are in a vacuum enclosure. After the reduction of pressure in this enclosure to a few microns, a voltage is applied between the cathode and the anode elements. Electrons generated by the ionization are accelerated toward the anodes that are confined in the anode space by the axial magnetic field. For the generation of the axial field along the anode elements, the magnet is designed in a C-configuration and is fabricated from rare earth magnetic materials (Nd-B-Fe or Sm-Co) possessing high energy product values, and the yoke is fabricated from the high permeability material (Hiperco-50A composed of Fe-Co-V). The electrons in this region collide with the gas molecules and generate their positive ions. These ions are accelerated into the cathode and eject cathode material (Ti). The neutral atoms deposit on the anode surfaces. Because of the chemical activity of Ti, the atoms combine with chemically active gas molecules (e.g. N2, O2, etc.) and remove them. New layers of Ti are continually deposited, and the pumping of active gases is thus accomplished. Pumping of the inert gases is accomplished by their burial several atomic layers deep into the cathode. However, they tend to re-emit if the entrapping lattice atoms are sputtered away. For stable pumping of inert gases, one side of the cathode is made of Ta. Impaction on Ta produces energetic, neutral atoms that pump the inert gases on the anode structure at the peripheral areas of the cathodes (between anode rings). For inert gases stability, a post design has been implemented. Here, posts of cathode material (Ti) are mounted on the cathode. These protrude into the initial part of the anode elements. Materials sputtered from the posts condense on the anode assembly and on the cathode plane at higher rates than in the normal diodes due to enhanced sputtering at glancing angles from geometrical considerations. This increases pumping by burial. This post design has enhanced pumping rates for both active and inert gases, compared with conventional designs.

Sinha, Mahadeva P.↗
NASA NTRS2013

Conformal Ablative Thermal Protection System for Planetary and Human Exploration Missions:An Overview of the Technology Maturation Effort

The Office of Chief Technologist, NASA identified the need for research and technology development in part from NASAs Strategic Goal 3.3 of the NASA Strategic Plan to develop and demonstrate the critical technologies that will make NASAs exploration, science, and discovery missions more affordable and more capable. Furthermore, the Game Changing Development Program is a primary avenue to achieve the Agencys 2011 strategic goal to Create the innovative new space technologies for our exploration, science, and economic future. The National Research Council (NRC) Space Technology Roadmaps and Priorities report highlights six challenges and they are: Mass to Surface, Surface Access, Precision Landing, Surface Hazard Detection and Avoidance, Safety and Mission Assurance, and Affordability. In order for NASA to meet these challenges, the report recommends immediate focus on Rigid and Flexible Thermal Protection Systems. Rigid TPS systems such as Avcoat or SLA are honeycomb based and PICA is in the form of tiles. The honeycomb systems are manufactured using techniques that require filling of each (38 cell) by hand, and in a limited amount of time all of the cells must be filled and the heatshield must be cured. The tile systems such as PICA pose a different challenge as the low strain-to-failure and manufacturing size limitations require large number of small tiles with gap-fillers between the tiles. Recent investments in flexible ablative systems have given rise to the potential for conformal ablative TPS. A conformal TPS over a rigid aeroshell has the potential to solve a number of challenges faced by traditional rigid TPS materials. The high strain-to-failure nature of the conformal ablative materials will allow integration of the TPS with the underlying aeroshell structure much easier and enable monolithic-like configuration and larger segments (or parts) to be used. By reducing the overall part count, the cost of installation (based on cost comparisons between blanket and tile materials on shuttle) should be significantly reduced. The conformal ablator design will include a simplified design of seams between gore panels, which should eliminate the need for gap filler design, and should accommodate a wider range of allowable carrier structure imperfections when compared to a rigid material such as PICA.The Conformal TPS development project leverages the past investments made by earlier projects with a goal to develop and deliver a TRL 5 conformal TPS capable of 250 Wcm2 for missions such as MSL or COTS missions. The capabilities goal for the conformal TPS is similar to an MSL design reference mission (250 Wcm2) with matching pressures and shear environments. Both conformal and flexible carbon-felt based materials were successfully tested in stagnation aerothermal environments above 500 Wcm2 under earlier programs. Results on a myriad of materials developed during FY11 were used to determine which materials to start with in FY12. In FY12, the conformal TPS element focused on establishing materials requirements based on MSL-type and COTS Low Earth orbit (LEO) conditions (q 250 Wcm2) to develop and deliver a Conformal Ablative TPS. In FY13, development and refining metrics for mission utilization of conformal ablator technology along with assessment for potential mission stakeholders will be carried out.

Thermal protection materials↗
NASA NTRS2004

Analysis of Stainless Steel Sandwich Panels with a Metal Foam Core for Lightweight Fan Blade Design

The quest for cheap, low density and high performance materials in the design of aircraft and rotorcraft engine fan and propeller blades poses immense challenges to the materials and structural design engineers. The present study investigates the use of a sandwich foam fan blade mae up of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. The resulting structures possesses a high stiffness while being lighter than a similar solid construction. The material properties of 17-4 PH metal foam are reviewed briefly to describe the characteristics of sandwich structure for a fan blade application. A vibration analysis for natural frequencies and a detailed stress analysis on the 17-4 PH sandwich foam blade design for different combinations of kin thickness and core volume are presented with a comparison to a solid titanium blade.

Min, James B.↗
NASA NTRS1978

Sail film materials and supporting structure for a solar sail, a preliminary design, volume 4

Solar sailing technology was examined in relation to a mission to rendezvous with Halley's Comet. Development of an ultra-light, highly reflecting material system capable of operating at high solar intensity for long periods of time was emphasized. Data resulting from the sail materials study are reported. Topics covered include: basic film; coatings and thermal control; joining and handling; system performance; and supporting structures assessment for the heliogyro.

Rowe, W. M.↗
NASA NTRS1984

Forecasting of high voltage insulation performance: Testing of recommended potting materials and of capacitors

Nondestructive high voltage test techniques (mostly electrical methods) are studied to prevent total or catastrophic breakdown of insulation systems under applied high voltage in space. Emphasis is on the phenomenon of partial breakdown or partial discharge (P.D.) as a symptom of insulation quality, notably partial discharge testing under D.C. applied voltage. Many of the electronic parts and high voltage instruments in space experience D.C. applied stress in service, and application of A.C. voltage to any portion thereof would be prohibited. Suggestions include: investigation of the ramp test method for D.C. partial discharge measurements; testing of actual flight-type insulation specimen; perfect plotting resin samples with controlled defects for test; several types of plotting resins and recommendations of the better ones from the electrical characteristics; thermal and elastic properties are also considered; testing of commercial capaciters; and approximate acceptance/rejection/rerating criteria for sample test elements for space use, based on D.C. partial discharge.

Bever, R. S.↗
NASA NTRS1982

Growth of diamondlike films for power applications

Diamond has a high thermal conductivity (approximately 5 times that of copper) and is an ideal heat sink material for high power semiconductor devices as well as being of interest as a semiconductor material. Numerous vacuum deposition processes are being evaluated by NASA-LeRC which have demonstrated the capability to deposit carbon films having some of the properties of diamond. Current activities include Investigation of high deposition rate vacuum processes suitable for synthesis of diamondlike carbon films. The results of recent film characterization tests are reported.

Banks, B. A.↗
NASA NTRS1983

Damping mechanisms in fiber reinforced laminates

Low strain damping in fiber reinforced composite materials is due to material loss factors in both fibers and matrix materials. The high modulus of the fibers makes up for the low damping factor. Strains high enough to cause transverse layer cracking in laminates with organic matrix materials causes a large permanent increase in the damping factor. This increase is not due to the transverse cracks but rather to short microcracks in the high shear strain regions. Other damping mechanisms at high strains are also discussed.

Plunkett, R.↗
NASA NTRS2017

Near Earth Asteroid Scout: NASA's Solar Sail Mission to a NEA

NASA is developing a solar sail propulsion system for use on the Near Earth Asteroid (NEA) Scout reconnaissance mission and laying the groundwork for their use in future deep space science and exploration missions. Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellantless thrust, allowing for very high Delta V maneuvers on long-duration, deep space exploration. Since reflected light produces thrust, solar sails require no onboard propellant. The Near Earth Asteroid (NEA) Scout mission, funded by NASA's Advanced Exploration Systems Program and managed by NASA MSFC, will use the sail as primary propulsion allowing it to survey and image Asteroid 1991VG and, potentially, other NEA's of interest for possible future human exploration. NEA Scout uses a 6U cubesat (to be provided by NASA's Jet Propulsion Laboratory), an 86 m(exp. 2) solar sail and will weigh less than 12 kilograms. NEA Scout will be launched on the first flight of the Space Launch System in 2018. The solar sail for NEA Scout will be based on the technology developed and flown by the NASA NanoSail-D and The Planetary Society's Lightsail-A. Four approximately 7 m stainless steel booms wrapped on two spools (two overlapping booms per spool) will be motor deployed and pull the sail from its stowed volume. The sail material is an aluminized polyimide approximately 2.5 microns thick. As the technology matures, solar sails will increasingly be used to enable science and exploration missions that are currently impossible or prohibitively expensive using traditional chemical and electric propulsion systems. This paper will summarize the status of the NEA Scout mission and solar sail technology in general.

Johnson, Les↗
NASA NTRS1998

Space Manufacturing: The Next Great Challenge

Space manufacturing encompasses the research, development and manufacture necessary for the production of any product to be used in near zero gravity, and the production of spacecraft required for transporting research or production devices to space. Manufacturing for space, and manufacturing in space will require significant breakthroughs in materials and manufacturing technology, as well as in equipment designs. This report reviews some of the current initiatives in achieving space manufacturing. The first initiative deals with materials processing in space, e.g., processing non-terrestrial and terrestrial materials, especially metals. Some of the ramifications of the United States Microgravity Payloads fourth (USMP-4) mission are discussed. Some problems in non-terrestrial materials processing are mentioned. The second initiative is structures processing in space. In order to accomplish this, the International Space Welding Experiment was designed to demonstrate welding technology in near-zero gravity. The third initiative is advancements in earth-based manufacturing technologies necessary to achieve low cost access to space. The advancements discussed include development of lightweight material having high specific strength, and automated fabrication and manufacturing methods for these materials.

Whitaker, Ann F.↗
NASA NTRS2015

Solar Sail Propulsion for Interplanetary Cubesats

NASA is developing two small satellite missions as part of the Advanced Exploration Systems (AES) Program, both of which will use a solar sail to enable their scientific objectives. Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror‐like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellantless thrust, allowing for very high (Delta)V maneuvers on long‐duration, deep space exploration. Since reflected light produces thrust, solar sails require no onboard propellant. Solar sail technology is rapidly maturing for space propulsion applications within NASA and around the world.

Johnson, Les↗
NASA NTRS2015

Status of Solar Sail Propulsion Within NASA - Moving Toward Interstellar Travel

NASA is developing solar sail propulsion for two near-term missions and laying the groundwork for their future use in deep space and interstellar precursor missions. Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellantless thrust, allowing for very high (Delta)V maneuvers on long-duration, deep space exploration. Since reflected light produces thrust, solar sails require no onboard propellant. The Near Earth Asteroid (NEA) Scout mission, managed by MSFC, will use the sail as primary propulsion allowing it to survey and image one or more NEA's of interest for possible future human exploration. Lunar Flashlight, managed by JPL, will search for and map volatiles in permanently shadowed Lunar craters using a solar sail as a gigantic mirror to steer sunlight into the shaded craters. The Lunar Flashlight spacecraft will also use the propulsive solar sail to maneuver into a lunar polar orbit. Both missions use a 6U cubesat architecture, a common an 85 sq m solar sail, and will weigh less than 12 kilograms. Both missions will be launched on the first flight of the Space Launch System in 2018. NEA Scout and Lunar Flashlight will serve as important milestones in the development of solar sail propulsion technology for future, more ambitious missions including the Interstellar Probe - a mission long desired by the space science community which would send a robotic probe beyond the edge of the solar system to a distance of 250 Astronomical Units or more. This paper will summarize the development status of NEA Scout and Lunar Flashlight and describe the next steps required to enable an interstellar solar sail capability.

Johnson, Les↗
NASA NTRS2017

Deployable Propulsion and Power Systems for Solar System Exploration

NASA is developing thin-film based, deployable propulsion, power and communication systems for small spacecraft that could provide a revolutionary new capability allowing small spacecraft exploration of the solar system. The Near Earth Asteroid (NEA) Scout reconnaissance mission will demonstrate solar sail propulsion on a 6U CubeSat interplanetary spacecraft and lay the groundwork for their future use in deep space science and exploration missions. Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellantless thrust, allowing for very high delta V maneuvers on long-duration, deep space exploration. Since reflected light produces thrust, solar sails require no onboard propellant. The Lightweight Integrated Solar Array and Transceiver (LISA-T) is a launch stowed, orbit deployed array on which thin-film photovoltaic and antenna elements are embedded. Inherently, small satellites are limited in surface area, volume, and mass allocation; driving competition between power, communications, and GN&C (guidance navigation and control) subsystems. This restricts payload capability and limits the value of these low-cost satellites. LISA-T is addressing this issue, deploying large-area arrays from a reduced volume and mass envelope - greatly enhancing power generation and communications capabilities of small spacecraft. The NEA Scout mission, funded by NASA's Advanced Exploration Systems Program and managed by NASA MSFC, will use the solar sail as its primary propulsion system, allowing it to survey and image one or more NEA's of interest for possible future human exploration. NEA Scout uses a 6U cubesat (to be provided by NASA's Jet Propulsion Laboratory), an 86 sq m solar sail and will weigh less than 12 kilograms. NEA Scout will be launched on the first flight of the Space Launch System in 2018. Similar in concept to the NEA Scout solar sail, the LISA-T array is designed to fit into a very small volume and provide abundant power and omnidirectional communications in just about any deployment configuration. The technology is being proposed for flight validation as early as 2019 in a low earth orbit demonstration using a 3U cubesat, of which less than 1U will be devoted to the LISA-T power and propulsion system. By leveraging recent advancements in thin films, photovoltaics and miniaturized electronics, new mission-level capabilities will be enabled aboard lower-cost small spacecraft instead of their more expensive, traditional counterparts, enabling a new generation of frequent, inexpensive deep space missions.

Johnson, Les↗