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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Poster Presentation: Optical Test of NGST Developmental Mirrors

An Optical Testing System (OTS) has been developed to measure the figure and radius of curvature of NGST developmental mirrors in the vacuum, cryogenic environment of the X-Ray Calibration Facility (XRCF) at Marshall Space Flight Center (MSFC). The OTS consists of a WaveScope Shack-Hartmann sensor from Adaptive Optics Associates as the main instrument, a Point Diffraction Interferometer (PDI), a Point Spread Function (PSF) imager, an alignment system, a Leica Disto Pro distance measurement instrument, and a laser source palette (632.8 nm wavelength) that is fiber-coupled to the sensor instruments. All of the instruments except the laser source palette are located on a single breadboard known as the Wavefront Sensor Pallet (WSP). The WSP is located on top of a 5-DOF motion system located at the center of curvature of the test mirror. Two PC's are used to control the OTS. The error in the figure measurement is dominated by the WaveScope's measurement error. An analysis using the absolute wavefront gradient error of 1/50 wave P-V (at 0.6328 microns) provided by the manufacturer leads to a total surface figure measurement error of approximately 1/100 wave rms. This easily meets the requirement of 1/10 wave P-V. The error in radius of curvature is dominated by the Leica's absolute measurement error of VI.5 mm and the focus setting error of Vi.4 mm, giving an overall error of V2 mm. The OTS is currently being used to test the NGST Mirror System Demonstrators (NMSD's) and the Subscale Beryllium Mirror Demonstrator (SBNM).

Hadaway, James B.↗
NASA NTRS1994

Theoretical Study of Electron Scattering By Small Clusters and Adsorbates

Current interest in clusters stems from their role as novel materials as well as a possible extension of cluster results to bulk systems. Experimental investigations on clusters have been carried out using laser spectroscopy, microwave spectroscopy, heavy-particle collisions, as well as electron collisions with earlier experimental work on electron attachment and ionization having been reviewed previously. Recently, Mark and coworkers studied the decay channels of cluster ions following electron impact ionization. Rauth et al. reported the formation of the superhalogen ion SF7(-) and other nonstoichiometric cluster ions in their study of electron attachment to SF6 clusters. Kresin et al. measured the absolute electron-impact depletion cross section of metal clusters Na8, Na(20), and Na(40). They found that the inelastic scattering cross section increased with cluster size and was considerably greater than the hard sphere collision cross sections. They hypothesized that electron attachment and collision-induced fragmentation were the dominant physical processes responsible for this effect. For the two smaller clusters, they also found a sharp increase in the cross section near threshold. Most theoretical studies of clusters have been devoted to their electronic structures, vibrational relaxation, and predissociation while investigations of electron scattering from clusters has been lacking. In view of this, we recently undertook an ab initio study of electron scattering from small Be clusters and BeCO. Beryllium was chosen because it is readily amenable to ab t'nitio calculations. Moreover, the electronic structure of Be clusters has been studied extensively, showing that the Be-Be bond is relatively weak in comparison with a normal chemical bond. Our investigation focuses on how the cross sections change with cluster size and geometry. The range of energy studied, 0.05 - 5.0 eV, is chosen because of the ubiquitous resonance in the low-energy scattering of Be. Hence it can be determined if it is possible, as a consequence of the weaker bonds in the Be clusters, to identify the atomic origin of the cluster resonance.

Huo, Winifred M.↗
NASA NTRS2001

Ball Semi-Rigid Advanced Mirror System Demonstrator (AMSD)

The AMSD Program is to design, fabricate, and test a 1.4-m point-to-point hexagon mirror system. The Ball semi-rigid approach will be described and its current status presented, The mirror system includes a lightweighted beryllium mirror that is attached through flexures and actuators to a composite reaction structure enabling optical performance at ambient and cryogenic temperatures and allowing changes of curvature to be imposed via actuation. This program is administered through NASA MSFC and is jointly funded by NASA, the USAF, and the NRO.

Kendrick, Stephen↗
NASA NTRS2001

The Vitrification and Determination of the Crystallization Time Scales of a Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 Bulk Metallic Glass Forming Liquid

Zr58.5Nb2.8Cul5.6Nil2.8All0.3 is the first bulk glass forming liquid that does not contain beryllium to be vitrified by purely radiative cooling in the containerless electrostatic levitation process. The measured critical cooling rate is 1.75 K/s. The sluggish crystallization kinetics enable the determination of the time-temperature-transformation (TTT) diagram between the liquidus and the glass transition temperatures. At the nose of the TTT diagram, the shortest time to reach crystallization in an isothermal experiment is 32 seconds. In contrast to other bulk metallic glasses the scatter in the crystallization onset times are small at both high and low temperatures.

Hays, C. C.↗
NASA NTRS2001

Overview of SBMD, NMSD and AMSD

For the past several years, NASA has conducted a coordinated mirror technology development program via SBIR's and contracts. This presentation provides a programmatic overview of three specific projects: SBMD (Subscale Beryllium Mirror Demonstrator), NMSD (NGST Mirror System Demonstrator) and AMSD (Advanced Mirror System Demonstrator). Specific emphasis will be given to technical constraints and objectives.

Stahl, H. Philip↗
NASA NTRS1995

Theoretical Study of Low-Energy Electron-Molecule Collisions

Polarized studies of electron collisions with carbon tetrafluoride and beryllium carbonyl are reported. In the e-CF4 study, the resonance structure between 8-9 eV is shown to be a superposition of the T2- and A1-symmetry shape resonances. The unequivocal assignment of this feature as a double-resonance structure clarifies certain discrepancies in previous attempts to ascribe the 8-9 eV feature to a shape resonance in one or another partial channel and explains the sensitivities found in the fragment ion production in the resonance region. The Be-CO system is chosen as a prototypical example of an absorbate-substrate interaction. To understand how bonding with the substrate affects the CO resonance, electron collision with two states of BeCO are studied, one with a very weak van der Waals bond and the other, with a normal chemical bond. It is shown that the nature of the Be-CO bond has strong effects on the cross section feature.

Huo, Winfred M.↗
NASA NTRS2002

Materials Properties Research at MSFC

MSFC is currently planning, organizing and directing test coupon fabrication and subsequent CTE testing for two mirror materials of specific interest to the AMSD and NGST programs, Beryllium 0-30H (Be 0-30H) and Ultra Low Expansion glass (ULE). The ULE test coupons are being fabricated at MSFC from AMSD core residuals provided by Kodak, The Be 0-30H test coupons are being fabricated at Brush Wellman using residuals from the SBMD. Both sets of test coupons will be sent to a test vendor selected through the NASA competitive proposal process with the test results being provided by written report to MSFC by the end of the fiscal year. The test results will become model input data for the AMSD analysts, both MSFC and contractor, providing an enhancement to the historical CTE data currently available.

Presson, Joan B.↗
NASA NTRS2002

Status of NASA Mirror Technology Development for Large Space Telescopes

This paper presents the current status of several NASA technology development activities, including: Sub-scale Beryllium Mirror Demonstrator (SBMD), NGST (Next Generation Space Telescope) Mirror System Demonstrator (NMSD), Advanced Mirror System Demonstrator (AMSD), etc.. It also describes how these activities map into future NASA mission requirements, including: Next Generation Space Telescope (NGST), Single Aperture Far Infrared Observatory (SAFIR), Space Ultraviolet/Optical Observatory (SUVO), etc..

Stahl, H. Philip↗
NASA NTRS2002

Ball Aerospace AMSD Progress Update

The current status of the Advanced Mirror System Demonstrator program being performed by Ball Aerospace is presented. The hexagonal low-areal density Beryllium mirror blank has been fabricated and undergoing polishing at the time of this presentation.

Blair, Mark↗
NASA NTRS2002

Ball Aerospace SBMD Coating Test Results

The Sub-scale Beryllium Mirror Demonstrator that was successfully tested to demonstrate cryogenic figuring of a bare mirror has been coated with a protected gold reflective surface and retested at cryogenic temperatures. Results showing less than 9 nm rms surface distortion attributable to the added coating are presented.

Brown, Robert↗
NASA NTRS1997

Gold Coating

Epner Technology Inc. responded to a need from Goddard Space Flight Center for the ultimate in electroplated reflectivity needed for the Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA). Made of beryllium, the MOLA mirror was coated by Epner Technology Laser Gold process, specially improved for the project. Improved Laser Gold- coated reflectors have found use in an epitaxial reactor built for a large semiconductor manufacturer as well as the waveguide in Braun-Thermoscan tympanic thermometer and lasing cavities in various surgical instruments.

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NASA NTRS1994

Disk Drives

A new material known as AlBeMet, developed by Brush Wellman for research applications in the National Aero-Space Plane (NASP) program, is now used for high performance disk drives. AlBeMet is a compression of aluminum, beryllium metal matrix composite. It reduces system weight and its high thermal conductivity can effectively remove heat and increase an electrical system's lifetime. The lighter, stiffer AlBeMet (AlBeMet 160) used in the disk drive means heads can be moved faster, improving disk performance.

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NASA NTRS2002

Compositionally-Graded Shape Memory Film for Self-Deployment of Membrane Reflectors and Optics

The next generation of space systems will require large apertures in order to image faint targets or cover large areas of Earth. These large apertures must be able to fit inside a launch vehicle fairing, be light enough for launch into orbit, and deploy on orbit with repeatability and reliability. The current state-of-the-art in flight optics is represented by the 4 meter LAMP telescope, with an areal density of 10 km sq m. Development of a Beryllium mirror demonstration article for NGST (Next Generation Space Telescope) at the University of Arizona indicate areal densities of 0.5 kg sq m with flight hardware in the 12 meter range. With progressive improvements in existing deployment, packaging, and structural technologies, the size of optics and reflectors will continue to increase, while mass is reduced. However, without a breakthrough in materials, packaging and/or deployment technologies, the goal for Gossamer structures of 0.1 kg sq m is unachievable for the near and mid-term NASA missions. Membrane technology provides the best hope of achieving such low areal densities. In combination with advances in membrane materials and structures, development of revolutionary techniques for deployment systems can provide significant improvements in large aperture technology. In this paper, the results of a six-month Phase I research effort to demonstrate the application of thin film NiTi to aerospace-qualified membrane and mesh materials are presented. Deposition of shape memory thin film was achieved Astromesh (trademark) metal mesh and CP-1, and optical-quality polymer membrane. Not only was full-coating deposition demonstrated, but also small segment deposition which holds potential for local surface control. Deployment of these materials was also demonstrated, setting the stage for the development of a larger test article.

Hill, Lisa↗
NASA NTRS2003

Solar System Observing with the Space Infrared Telescope Facility (SIRTF)

SIRTF is NASA's Space Infrared Telescope Facility. Currently planned for launch on 15 Apr 2003, it is the final element in NASA's Great Observatories Program. SIRTF has an 85 cm diameter f/12 lightweight beryllium telescope, cooled to lekss than 5.5K. It is diffraction-limited at 6.5 microns, and has wavelengthcoverage from 3-180 microns. Its estimated lifetime (limited by cryogen) is 2.5 years at minimum, with a goal of 5+ years. SIRTF has three instruments, IRAC, IRS, and MIPS. IRAC (InfraRed Array Camera) provides simultaneous images at wavelengths of 3.6, 4.5, 5.8, and 8.0 microns. IRS (InfraRed Spectrograph) has 4 modules providing low-resolution (R=60-120) spectra from 5.3 to 40 microns, high-resolution (R=600) spectra from 10 to 37 microns, and an autonomous target acquisition system (PeakUp) which includes small-field imaging at 15 microns. MIPS (Multiband Imaging Photometer for SIRTF)} does imaging photometry at 24, 70, and 160 m and low-resolution (R=15-25) spectroscopy (SED) between 55 and 96 microns. The SIRTF Guaranteed Time Observers (GTOs) are planning to observe Outer Solar System satellites and planets, extinct comets and low-albedo asteroids, Centaurs and Kuiper Belt Objects, cometary dust trails, and a few active short-period comets. The GTO programs are listed in detail in the SIRTF Reserved Observations Catalog (ROC). We would like to emphasize that there remain many interesting subjects for the General Observers (GO). Proposal success for the planetary observer community in the first SIRTF GO proposal cycle (GO-1) determines expectations for future GO calls and Solar System use of SIRTF, so we would like promote a strong set of planetary GO-1 proposals. Towards that end, we present this poster, and we will convene a Solar System GO workshop 3.5 months after launch.

Cleve, J. Van↗
NASA NTRS2004

The X-ray Polarimetry Explorer (XPE)

We present details of a Thomson scattering polarimeter suitable for a small-explorer- class mission. Termed XPE, for X-Ray Polarimetry Explorer, the instrument consists of a beryllium scattering cone surrounded by an annular multiwire proportional counter which registers the energy and position of scattered source photons. The polarimeter is sensitive over an energy range of 7-27 keV and will achieve 3% minimum detectable polarization of Her X-1 in a 1/2-day observation, and cover a 30-target core observation program, at the same sensitivity level, in approximately 8 months.

Ramsey, Brian↗
NASA NTRS2004

James Webb Space Telescope (JWST) Primary Mirror Material Selection

The James Webb Space Telescope (JWST) conducted a phase down select process via the Advanced Mirror System Demonstrator (AMSD) project to assess the Technology Readiness Level of various candidate mirror materials. This process culminated in the selection of Beryllium as the JWST primary mirror material. This paper outlines the mirror evaluation process, defines the selection criteria and summarizes the candidate mirror's performances.

Stahl, H. Philip↗
NASA NTRS2004

Measurement of the Abundance of Radioactive Be-10 and Other Light Isotopes in Cosmic Radiation Up to 2 GeV /Nucleon with the Balloon-Borne Instrument Isomax

The Isotope Magnet Experiment (ISOMAX), a balloon-borne superconducting magnet spectrometer, was designed to measure the isotopic composition of the light isotopes (3 les than or = Z less than or = 8) of cosmic radiation up to 4 GeV/nucleon with a mass resolution of better than 0.25 amu by using the velocity versus rigidity technique. To achieve this stringent mass resolution, ISOMAX was composed of three major detector systems: a magnetic rigidity spectrometer with a precision drift chamber tracker in conjunction with a three-layer time-of-flight system, and two silica-aerogel Cerenkov counters for velocity determination. A special emphasis of the ISOMAX program was the accurate measurement of radioactive Be-10 with respect to its stable neighbor isotope Be-9, which provides important constraints on the age of cosmic rays in the Galaxy. ISOMAX had its first balloon flight on 1998 August 4-5 from Lynn Lake, Manitoba, Canada. Thirteen hours of data were recorded during this flight at a residual atmosphere of less than 5 g/sq cm. The isotopic ratio at the top of the atmosphere for Be-10/Be-9 was measured to be 0.195 +/- 0.036 (statistical) +/- 0.039 (systematic) between 0.26 and 1.03 GeV/nucleon and 0.317 +/- 0.109(statistical) +/- 0.042(systematic) between 1.13 and 2.03 GeV/nucleon. This is the first measurement of its kind above l GeV/nucleon. ISOMAX results tend to be higher than predictions from current propagation models. In addition to the beryllium results, we report the isotopic ratios of neighboring lithium and boron in the energy range of the time-of-flight system (up to approx. 1 GeV/nucleon). The lithium and boron ratios agree well with existing data and model predictions at similar energies.

Hams, T.↗
NASA NTRS2004

B-Roll of AMSD Mirror

This video shows the Advanced Mirror System Demonstrator (AMSD) mirror being inspected and handled at Tinsley. The mirror is a beryllium mirror technology demonstrator that is a critical item demonstrating that the James Webb Space Telescope mirrors can be fabricated and will meet the performance requirements. Because Tinsley is very concerned about sharing proprietary information, the video, shot by them, does not show any key aspects of the polishing process (such as the polishing heads). The video includes workers at Tinsley rotating and inspecting the mirror. Excerpts of this video will be provided as part of a press release on JWST technology.

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