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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Light-element abundances in Population II dwarfs

This paper reviews the abundances of the light elements lithium, beryllium, and boron in main-sequence and subgiant, Population II stars. Li is important to cosmology because it is synthesized in the Big Bang, but is also used to study stellar structure. Beryllium is useful for studying galactic chemical evolution because its formation in the interstellar medium involves different physics to stellar nucleosynthesis, and it thus provides independent data on the evolution of the halo. Some (though not all) inhomogeneous Big Bang nucleosynthesis codes predict a significant primordial component to this element, so its observed abundance may constrain such models. Boron, observations of which became feasible with the operation of the Hubble Space Telescope, provides complementary data to Be, helping check the element ratios predicted by calculations of spallation reactions in the interstellar medium, and will indicate whether the observed Be abundance has an excess over the expected spallation component, indicating a possible primordial component.

Ryan, Sean G.↗
NASA NTRS1991

Graphite Fiber/Copper Matrix Composites for Space Power Heat Pipe Fin Applications

High specific thermal conductivity (thermal conductivity divided by density) is a major design criterion for minimizing system mass for space power systems. For nuclear source power systems, graphite fiber reinforced copper matrix (Gr/Cu) composites offer good potential as a radiator fin material operating at service temperatures above 500 K. Specific thermal conductivity in the longitudinal direction is better than beryllium and almost twice that of copper. The high specific thermal conductivity of Gr/Cu offers the potential of reducing radiator mass by as much as 30 percent. Gr/Cu composites also offer the designer a range of available properties for various missions and applications. The properties of Gr/Cu are highly anisotropic. Longitudinal elastic modulus is comparable to beryllium and about three times that of copper. Thermal expansion in the longitudinal direction is near zero, while it exceeds that of copper in the transverse direction.

McDanels, David L.↗
NASA NTRS1991

Uniformity and transmission of proportional counter window materials for use with AXAF

The X-ray detection system used to calibrate the Advanced X-ray Astrophysics Facility (AXAF) mirrors will include gas flow and sealed proportional counters. To meet the ultimate 1 percent goal of the calibration project, the transmission and uniformity of the windows must be well known for the soft X-ray wavelengths involved. Various window materials for use with proportional counters are examined for transmission at X-ray wavelengths in the range of 0.1 to 5.9 keV. These include the usual window materials (polypropylene and beryllium), as well as materials only recently employed for detector applications (polyimide and diamond). The transmission uniformity of beryllium at 1.49 keV is examined with a microchannel plate detector, producing a 'shadowgraph' of the window material illuminated with soft X-rays. This technique allows us to investigate nonuniformities on a spatial scale of about .2 mm.

Flanagan, K.↗
NASA NTRS1952

Investigation of Wear and Friction Properties Under Sliding Conditions of Some Materials Suitable for Cages of Rolling-Contact Bearings

An investigation of wear and friction properties of a number of materials sliding against SAE 52100 steel was conducted. These materials included brass, bronze, beryllium copper, monel, nichrome v, 24s-t aluminum, nodular iron, and gray cast iron. The metals investigated may be useful as possible cage (separator or retainer) materials for rolling-contact bearings of high-speed turbine engines. The ability of materials to form surface films that prevent welding is a most important factor in both dry friction and boundary lubrication. On the basis of wear and resistance to welding only, the cast irons were the most promising materials investigated; they showed the least wear and the least tendency to surface failure when run dry, and when boundary lubricated they showed the highest load capacity. On the basis of mechanical properties, nodular iron is superior to gray cast iron. Bronze had the lowest friction coefficient under dry sliding conditions. The results with brass, beryllium copper, and aluminum were poor and these materials do not appear, with regard to friction and wear, to be suitable for cages.

Johnson, Robert L↗
NASA NTRS1989

Moon base reactor system

The objective of our reactor design is to supply a lunar-based research facility with 20 MW(e). The fundamental layout of this lunar-based system includes the reactor, power conversion devices, and a radiator. The additional aim of this reactor is a longevity of 12 to 15 years. The reactor is a liquid metal fast breeder that has a breeding ratio very close to 1.0. The geometry of the core is cylindrical. The metallic fuel rods are of beryllium oxide enriched with varying degrees of uranium, with a beryllium core reflector. The liquid metal coolant chosen was natural lithium. After the liquid metal coolant leaves the reactor, it goes directly into the power conversion devices. The power conversion devices are Stirling engines. The heated coolant acts as a hot reservoir to the device. It then enters the radiator to be cooled and reenters the Stirling engine acting as a cold reservoir. The engines' operating fluid is helium, a highly conductive gas. These Stirling engines are hermetically sealed. Although natural lithium produces a lower breeding ratio, it does have a larger temperature range than sodium. It is also corrosive to steel. This is why the container material must be carefully chosen. One option is to use an expensive alloy of cerbium and zirconium. The radiator must be made of a highly conductive material whose melting point temperature is not exceeded in the reactor and whose structural strength can withstand meteor showers.

Chavez, H.↗
NASA NTRS1997

Cosmic Ray Induced Degradation in X-Ray Detectors On Board the Near Earth Asteroid Rendezvous Spacecraft

The Near-Earth Asteroid Rendezvous (NEAR) mission is the first in NASA's new Discovery Program to explore the solar system. Launched in February 1996, the NEAR spacecraft will take a long cruise flight arriving at the asteroid 433 Eros in January 1999 for a one year orbiting survey operation. This long exposure to the space environment has already proven to be an additional complication for the x-ray spectrometer. The asteroid pointing detectors for the x-ray spectrometer are three gas-filled proportional counters with resolving power in the range of 1 keV. Therefore, to resolve the important but closely spaced magnesium, aluminum and silicon k alpha lines( 1.255, 1.487, 1.739 keV respectively), magnesium and aluminum balanced filters are used on two of the detectors. The x-ray florescence from the surface of Eros is stimulated by solar x-rays. A proportional counter and a silicon PIN detector are used to monitor the solar incident x-ray flux. The proportional counters are single wire gas filled beryllium lined steel tubes operating at about 1100 volt. The 25 cm(exp 2) optical window is one mil. thick beryllium. To define the detector's active region, two boron nitride disks were incorporated in the tube just outside window area. It appears from the space flight data that the space environment is creating a charge on these boron nitride disks which ultimately distorts the tube gain and resolution. This broadening of the photo peak makes it more difficult to identify weak peaks and so degrades the statistical accuracy for some very important elements such as sulfur, calcium and iron (2.307, 3.690, 6.403 keV respectively). If the broadening is severe enough in the low energy region, counts will be lost as the photo peak spreads below the lower level discriminator (0.7 keV).

Floyd, S. R.↗
NASA NTRS1998

Cryogenic Optical Performance of the Cassini Composite InfraRed Spectrometer (CIRS) Flight Telescope

The CIRS half-meter diameter beryllium flight telescope's optical performance was tested at the instrument operating temperature of 170 Kelvin. The telescope components were designed at Goddard Space Flight Center (GSFC) but fabricated out of house and then assembled, aligned and tested upon receipt at GSFC. A 24 inch aperture cryogenic test facility utilizing a 1024 x 1024 CCD array was developed at GSFC specifically for this test. The telescope,s image quality (measured as encircled energy), boresight stability and focus stability were measured. The gold coated beryllium design exceeded the cold image performance requirement of 80% encircled energy within a 460 micron diameter circle.

Losch, Patricia↗
NASA NTRS1998

Cryogenic Optical Performance of the Cassini Composite Infrared Spectrometer (CIRS) Flight Telescope

The CIRS half-meter diameter beryllium flight telescope's optical performance was tested at the instrument operating temperature of 170 Kelvin. The telescope components were designed at Goddard Space Flight Center (GSFC) but fabricated out of house and then assembled, aligned and tested upon receipt at GSFC. A 24 inch aperture cryogenic test facility utilizing a 1024 x 1024 CCD array was developed at GSFC specifically for this test. The telescope's image quality (measured as encircled energy), boresight stability and focus stability were measured. The gold coated beryllium design exceeded the image performance requirement of 80% encircled energy within a 432 microns diameter circle.

Losch, Patricia↗
NASA NTRS2001

MSFC Optical Test Pallet

Several mirror technology development programs have been initiated by Marshall Space Flight Center (MSFC) in support of the Next Generation Space Telescope (NGST) program. The goal is to advance the technology for producing 0.5-2.0 m class, ultra light-weight (<15 kg/sq m) mirrors that can be operated at or near 35 K. The NGST Mirror System Demonstrators (NMSDs) consist of a 1.6 m glass-on-composite mirror from Composite Optics Incorporated (COI) and a 2.0 m glass-on-actuators-on-composite mirror from the University of Arizona. The Subscale Beryllium Mirror Demonstrator (SBMD) is a 0.5 m beryllium mirror from Ball Aerospace. These mirrors require cryogenic surface figure and radius of curvature testing in order to verify their performance in the operational environment predicted for the NGST. An optical testing capability has been developed at the X-Ray Calibration Facility (XRCF) at MSFC. This paper will describe the optical test goals, the optical testing system design, the test instrumentation, and the test system performance as used for SBMD & NMSD cryogenic testing.

Hadaway, James B.↗
NASA NTRS2001

MSFC SBMD Cryogenic Test Data Review

The Subscale Beryllium Mirror Demonstrator (SBMD) was developed in support of the Next Generation Space Telescope program. The goal was to produce a 0.5 m class, ultra lightweight (<12 kg/sq m), beryllium mirror that could be operated at 35 K. The mirror, developed by Ball Aerospace, has been cryogenically tested at the Marshall Space Flight Center (MSFC) a total of three times. The first two tests established the cryogenic performance and repeatability of the SBMD. Between the second and third tests, the mirror was cryo-figured. Thus, the third test measured the performance of the mirror with cryo-figuring applied. This paper will describe the test goals, the test instrumentation, and the test results (low & high order figure and radius of curvature) for all three cryogenic tests.

Hadaway, James B.↗
NASA NTRS2003

High Accuracy Thermal Expansion Measurement At Cryogenic Temperatures

A new, interferometer based system for measuring thermal expansion to an absolute accuracy of 20 ppb or better at cryogenic temperatures has been developed. Data from NIST Copper SRM 736 measured from room temperature to 15 K will be presented along with data from many other materials including beryllium, ULE, Zerodur, and composite materials. Particular attention will be given to a study by the Space Optics Manufacturing Technology Center (SOMTC) investigating the variability of ULE and beryllium materials used in the AMSD program. Approximately 20 samples of each material, tested from room temperature to below 30 K are compared as a function of billet location.

Stallcup, Michael↗
NASA NTRS2003

High Accuracy Thermal Expansion Measurement at Cryogenic Temperatures

A new, interferometer-based system for measuring thermal expansion to an absolute accuracy of 20 ppb or better at cryogenic temperatures has been developed. Data from NIST Copper SRM 736 measured from room temperature to 15 K will be presented along with data from many other materials including beryllium, ULE, Zerodur, and composite materials. Particular attention will be given to a study by the Space Optics Manufacturing Technology Center (SOMTC) investigating the variability of ULE and beryllium materials used in the AMSD program Approximately 20 samples of each material, tested from room temperature to below 30 K are compared as a function of billet location.

Tucker, Jim↗
NASA NTRS2004

Selection of Optical Cavity Surface Coatings for 1micron Laser Based Missions

The particulate surface cleanliness level on several coatings for aluminum and beryllium substrates were examined for use in the optical cavities of high pulse energy Nd:YAG Q-switched, diode-pumped lasers for space flight applications. Because of the high intensity of the lasers, any contaminants in the laser beam path could damage optical coatings and limit the instrument mission objectives at the operating wavelength of 1 micron (micrometer). Our goal was to achieve an EST-STD-CC1246D Level 100 particulate distribution or better to ensure particulate redistribution during launch would not adversely affect the performance objectives. Tapelifts were performed to quantify the amount of particles using in-house developed procedures. The primary candidate coatings included chromate conversion coating aluminum (Al), uncoated Al electroless Nickel (Ni) on Al, Ni-gold (Au) on Al, anodized Al, and gold (Au)/Ni on Beryllium (Be). The results indicate that there were advantages in Ni and Au coating applications for the two major substrates, Al and Be, when considering applications that need to meet launch environments.

Hedgeland, Randy J.↗
NASA NTRS2004

JWST: A New Kind of Space Telescope

Contents include the following: Why are the mirrors segmented? Why lightweight segmented mirrors? Why cold (cryogenic) mirrors? Why a space telescope? How did NASA go about developing the mirror technology to enable this? Why was beryllium selected for JWST s mirrors? How are the Beryllium mirrors made? What happens to the mirrors once they are complete?

Keski-Kuha, Ritva↗
NASA NTRS2006

Cryogenic Fracture Toughness Evaluation of an Investment Cast Al-Be Alloy for Structural Applications

Aluminum-Beryllium metal matrix composite materials are useful due to their desirable performance characteristics for aerospace applications. Desirable characteristics of this material includes light-weight, dimensional stability, stiffness, good vibration damping characteristics, low coefficient of thermal expansion, and workability, This material is 3.5 times stiffer and 22% lighter than conventional aluminum alloys. electro-optical systems, advanced sensor and guidance components for flight and satellite systems, components for light-weight high-performance aircraft engines, and structural components for helicopters. Aluminum-beryllium materials are now available in the form of near net shape investment castings. In this materials properties characterization study, the cryogenic tensile and fracture properties of an investment casting alloy, Beralcast 363, were determined. Tensile testing was performed at 21 C (70 F), -73.3 C (-100 F), -195.5 C (-320 F) and -252.8 C (-423 F), and fracture (K(sub lc) and da/dN) testing was performed at -73.3 C (-100 F), -195.5 C (-320 F) and -252.8 C (-423 F). Their use is attractive for weight critical structural applications such as advanced

Gamwell, W. R.↗
NASA NTRS2011

Metal-Matrix/Hollow-Ceramic-Sphere Composites

A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

Baker, Dean M.↗
NASA NTRS2012

James Webb Space Telescope Optical Telescope Element Mirror Development History and Results

In a little under a decade, the James Webb Space Telescope (JWST) program has designed, manufactured, assembled and tested 21 flight beryllium mirrors for the James Webb Space Telescope Optical Telescope Element. This paper will summarize the mirror development history starting with the selection of beryllium as the mirror material and ending with the final test results. It will provide an overview of the technological roadmap and schedules and the key challenges that were overcome. It will also provide a summary or the key tests that were performed and the results of these tests.

Feinber, Lee D.↗
NASA NTRS2012

Lightweight Metal Matrix Composite Segmented for Manufacturing High-Precision Mirrors

High-precision mirrors for space applications are traditionally manufactured from one piece of material, such as lightweight glass sandwich or beryllium. The purpose of this project was to develop and test the feasibility of a manufacturing process capable of producing mirrors out of welded segments of AlBeMet(Registered Trademark) (AM162H). AlBeMet(Registered Trademark) is a HIP'd (hot isostatic pressed) material containing approximately 62% beryllium and 38% aluminum. As a result, AlBeMet shares many of the benefits of both of those materials for use in high performance mirrors, while minimizing many of their weaknesses.

Vudler, Vladimir↗