Organic complexes of transition metals for optical maser materials semiannual research report, 1 apr. - 30 sep. 1964
Synthesis and spectroscopy of transition-metal organic complexes
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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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Lunar Science Conference, 4th, Houston, Tex., March 5-8, 1973, Proceedings. Volume 1 - Mineralogy and petrology. Volume 2 - Chemical and isotope analyses. Organic chemistry. Volume 3 - Physical properties
The mineralogy, petrology, chemistry, isotopic composition, and physical properties of lunar materials are described in papers detailing methods, results, and implications of research on samples returned from eight lunar landing sites: Apollo 11, 12, 14, 15, 16, 17, and Luna 16 and 20. The results of experiments conducted or set up on the lunar surface by the astronauts are also described along with observations taken from Command Modules and subsatellites. Major topics include general geology, soil and breccia studies, petrologic studies, mineralogic analyses, elemental compositions, radiometric age determinations, rare gas chemistry, radionuclides, organogenic compounds, particle track records, thermal properties, seismic studies, resonance studies, orbital mapping, lunar atmosphere, magnetic studies, electrical studies, optical properties, and microcratering. Individual items are announced in this issue.
Gose, W. A.↗
A new multifunction acousto-optic signal processor
An acousto-optic architecture for simultaneously obtaining time integration correlation and high-speed power spectrum analysis was constructed using commercially available TeO2 modulators and photodiode detector-arrays. The correlator section of the processor uses coherent interferometry to attain maximum bandwidth and dynamic range while achieving a time-bandwidth product of 1 million. Two correllator outputs are achieved in this system configuration. One is optically filtered and magnified 2 : 1 to decrease the spatial frequency to a level where a 25-MHz bandwidth may be sampled by a 62-mm array with elements on 25-micro centers. The other output is magnified by a factor of 10 such that the center 4 microseconds of information is available for estimation of time-difference-of-arrival to within 10 ns. The Bragg cell spectrum-analyzer section, which also has two outputs, resolves a 25-MHz instantaneous bandwidth to 25 kHz and can determine discrete-frequency reception time to within 15 microseconds. A microprocessor combines spectrum analysis information with that obtained from the correlator.
Berg, N. J.↗
Optimization of thermal systems with sensitive optics, electronics, and structures
A strategy was investigated by which thermal designers for spacecraft could devise an optimal thermal control system to maintain the required temperatures, temperature differences, changes in temperature, and changes in temperature differences for specified equipment and elements of the spacecraft's structure. Thermal control is to be maintained by the coating pattern chosen for the external surfaces and heaters chosen to supplement the coatings. The approach is to minimize the thermal control power, thereby minimizing the weight of the thermal control system. Because there are so many complex computations involved in determining the optimal coating design a computerized approach was contemplated. An optimization strategy including all the elements considered by the thermal designer for use in the early stages of design, where impact on the mission is greatest, and a plan for implementing the strategy were successfully developed. How the optimization process may be used to optimize the design of the Space Telescope as a test case is demonstrated.
Bettini, R. G.↗
An infrared alignment telescope
For problems involving the determination of the relative positions of optical components in a complex assembly, rather precise measurements can be routinely obtained when the visible portion of the spectrum is involved. Problems arise, however, when the lens elements to be aligned are made of infrared transmitting materials such as germanium, which is opaque to visible radiation. The alignment of a multichannel infrared measurement satellite called Haloe, which is currently being developed by NASA, represents an example of a particularly difficult task. The present paper is concerned with an infrared alignment telescope (IAT) which satisfies the need for a precision alignment tool capable of operating anywhere in the 2.4 to 12 micron wavelength range. When coupled to a commercial infrared scanner and display device, the IAT will provide a real-time picture of the relative positions of components and images over distances in the range from 20 inches to infinity.
Dilworth, D. C.↗
High-resolution 18 cm spectra of OH/IR stars
High-velocity-resolution, high-signal-to-noise spectra have been obtained for the 18 cm maser emission lines from a number of optically visible OH/IR stars. The spectra have been interpreted in terms of a recent model by Alcock and Ross (1986), in which OH/IR stars lose mass in discrete elements rather than by a continuous wind. Comparison of the observed spectra with synthetic spectra shows that the lines are the composite emission from thousands or tens of thousands of individual elements.
Fix, John D.↗
Component and prototype panel testing of the mini-dome Fresnel lens photovoltaic concentrator array
The mini-dome Fresnel lens concentrator array, a high-efficiency, lightweight space photovoltaic array concept, is described. The three critical elements of the array concept are the Fresnel lens concentrator, the prismatic cell power cover, and the photovoltaic cell. Prototype concentrator lenses have been fabricated and tested, with optical efficiencies reaching 90 percent. Work is progressing on the design and fabrication of the panel structure. The impact of recent advances in 30 percent-efficient multijunction photovoltaic cells on array performance is also discussed. Near-term performance goals of 300 w/sq m and 100 w/kg are now feasible.
Piszczor, Michael F.↗
Intricacies of Using Kevlar Cord and Thermal Knives in a Deployable Release System: Issues and Solutions
The utilization of Kevlar cord and thermal knives in a deployable release system produces a number of issues that must be addressed in the design of the system. This paper proposes design considerations that minimize the major issues, thermal knife failure, Kevlar cord relaxation, and the measurement of the cord tension. Design practices can minimize the potential for thermal knife laminate and element damage that result in failure of the knife. A process for in-situ inspection of the knife with resistance, rather than continuity, checks and 10x zoom optical imaging can detect damaged knives. Tests allow the characterization of the behavior of the particular Kevlar cord in use and the development of specific prestretching techniques and initial tension values needed to meet requirements. A new method can accurately measure the tension of the Kevlar cord using a guitar tuner, because more conventional methods do not apply to arimid cords such as Kevlar.
Stewart, Alphonso↗
Intricacies of Using Kevlar and Thermal Knives in a Deployable Release System: Issues and Solutions
The utilization of Kevlar cord and thermal knives in a deployable release system produces a number of issues that must be addressed in the design of the system. This paper proposes design considerations that minimize the major issues, thermal knife failure, Kevlar cord relaxation, and the measurement of the cord tension. Design practices can minimize the potential for thermal knife laminate and element damage that result in failure of the knife. A process for in-situ inspection of the knife with resistance, rather than continuity, checks and 10x zoom optical imaging can detect damaged knives. Tests allow the characterization of the behavior of the particular Kevlar cord in use and the development of specific pre-stretching techniques and initial tension values needed to meet requirements. A new method can accurately measure the tension of the Kevlar cord using a guitar tuner, because more conventional methods do not apply to arimid cords such as Kevlar.
Stewart, Alphonso C.↗
The NASA GSFC MEMS Colloidal Thruster
A number of upcoming missions require different thrust levels on the same spacecraft. A highly scaleable and efficient propulsion system would allow substantial mass savings. One type of thruster that can throttle from high to low thrust while maintaining a high specific impulse is a Micro-Electro-Mechanical System (MEMS) colloidal thruster. The NASA GSFC MEMS colloidal thruster has solved the problem of electrical breakdown to permit the integration of the electrode on top of the emitter by a novel MEMS fabrication technique. Devices have been successfully fabricated and the insulation properties have been tested to show they can support the required electric field. A computational finite element model was created and used to verify the voltage required to successfully operate the thruster. An experimental setup has been prepared to test the devices with both optical and Time-Of-Flight diagnostics.
Cardiff, Eric H.↗
Modeling of Biological Fluid Systems
This study presents a detailed methodology for modeling and validating three- dimensional fluid flow in realistic reconstructed vasculature geometry. Optical scanned data from a sectioned stenotic lumen having -65% area constriction within an arterial vessel of 9 mm diameter is processed and converted into a finite-element mesh. Mass and momentum transfer equations within the reconstructed stenotic vessel with a-flow rate of 200 ml/rnin is solved using the Galarkin Finite Element formulation. The calculated velocities at several axial locations along the length of the vessel are compared with the Particle Image Velocimetry (PIV) measurements. The computation results are in agreement with the initial steady state PIV measurements. In addition, initial results from pulsatile flow computations at different time points of a pulse cycle will be presented.
Banerjee, Rupak↗
Wide Angle Liquid Crystal Optical Phased Array
Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.
Wang, Xing-Hua↗
The Realuminizing of the 7-Meter Diameter Solar Simulator Collimating Mirror
This paper describes the modification of a three-electron-beam (EB) gun system for vacuum depositing a highly reflective aluminum coating on a 7.01-m (23-ft) -diam nickel-plated aluminum collimating mirror. The mirror is part of the JPL 7.62-m space simulator that was recently modernized with a new high vacuum pumping system, solar lamp power supplies, solar optic lens system, and refurbished collimating mirror. The mirror is the primary reflector for the solar simulation system and the aluminized reflective surface is its most critical performance element. The uniformity of thickness and high reflectivity of the coating is visible and near-ultraviolet (UV) light governs the accuracy of the beam for solar testing. The uniformity of the thin-film thickness also controls the durability of the mirror over time.
solar↗
THE DESIGN, CONSTRUCTION AND OPERATION OF GOUND-BASED TRACKING EQUIPMENT FOR EXPERIMENTS UTILIZING OPTICAL TRACE MATERIALS TO STUDY ATMOSPHERIC PARAMETERS.
Ground based tracking for experiments utilizing optical trace materials to study atmospheric parameters
TRACKING↗
Models of polarized infrared emission from bipolar nebulae
Many stars with circumstellar dust shells show a high degree of linear polarization (Sato et al. 1985). We are developing a model which assumes that the polarization arises from scattering by circumstellar dust. Our model assumes a geometry in which the star is surrounded by an optically thin spherical dust shell and embedded within an optically thick disk. This geometry is consistent with that proposed for objects with bipolar molecular outflow. This is important because many bipolar flow objects have also been observed to be highly polarized. The high degree of linear polarization is produced because the disk differentially attenuates the light from the star. The light incident from the point source is attenuated by a factor of exp(-tau/cos theta) where theta is the angle between a ray from the point source to the scatterer and a ray normal to the disk; tau is the optical depth at the wavelength of interest. Hence, the light scattered from the regions directly above and below the disk give the largest contribution to the total flux. The scattering angle for light from these regions is near 90 deg., so the light is strongly polarized and, in the Rayleigh scattering regime, is polarized parallel to the disk. The Stokes parameters for the scattered light from each particle in the shell are calculated by using the scattering matrix elements generated by a Mie scattering program. After the Stokes parameters for each particle are computed they are summed to give the Stokes parameters for the entire shell. Two graphs are presented which show the intensity and polarization spectrum generated by our model using the optical constants for astronomical silicates as defined by Draine and Lee (1984).
Burns, M. S.↗
Infrared-Bolometer Arrays with Reflective Backshorts
Integrated circuits that incorporate square arrays of superconducting-transition- edge bolometers with optically reflective backshorts are being developed for use in image sensors in the spectral range from far infrared to millimeter wavelengths. To maximize the optical efficiency (and, thus, sensitivity) of such a sensor at a specific wavelength, resonant optical structures are created by placing the backshorts at a quarter wavelength behind the bolometer plane. The bolometer and backshort arrays are fabricated separately, then integrated to form a single unit denoted a backshort-under-grid (BUG) bolometer array. In a subsequent fabrication step, the BUG bolometer array is connected, by use of single-sided indium bump bonding, to a readout device that comprises mostly a superconducting quantum interference device (SQUID) multiplexer circuit. The resulting sensor unit comprising the BUG bolometer array and the readout device is operated at a temperature below 1 K. The concept of increasing optical efficiency by use of backshorts at a quarter wavelength behind the bolometers is not new. Instead, the novelty of the present development lies mainly in several features of the design of the BUG bolometer array and the fabrication sequence used to implement the design. Prior to joining with the backshort array, the bolometer array comprises, more specifically, a square grid of free-standing molybdenum/gold superconducting-transition-edge bolometer elements on a 1.4- m-thick top layer of silicon that is part of a silicon support frame made from a silicon-on-insulator wafer. The backshort array is fabricated separately as a frame structure that includes support beams and contains a correspond - ing grid of optically reflective patches on a single-crystal silicon substrate. The process used to fabricate the bolometer array includes standard patterning and etching steps that result in the formation of deep notches in the silicon support frame. These notches are designed to interlock with the support beams on the backshort-array structure to provide structural support and precise relative positioning. The backshort-array structure is inserted in the silicon support frame behind the bolometer array, and the notches in the frame serve to receive the support beams of the backshort-array structure and thus determine the distance between the backshort and bolometer planes. The depth of the notches and, thus, the distance between the backshort and bolometer planes, can be tailored to a value between 25 to 300 m adjusting only a few process steps. The backshort array is designed so as not to interfere with the placement of indium bumps for subsequent indium bump-bonding to the multiplexing readout circuitry
Miller, Timothy M.↗
PROCSIMA: Diffractionless Beamed Propulsion for Breakthrough Interstellar Missions
The following report describes a new propulsion concept based on self-guiding of combined light and particle beam and explores the physics, technology and design principles needed to implement such a system for an interstellar fly-by mission to Proxima b. While the relevant self-focusing mechanism has been considered in an optical context, this is the first application to space propulsion known to the authors.The purpose of the present study is to provide a broad overview of the pertinent physics and design principles, credibly assess propulsion capabilities, and lay a comprehensive foundation for further, more targeted investigations of critical system elements and processes. Starting from basic principles, this report describes the equations of motion and physical phenomena needed to establish the feasibility of self-guiding and furthermore analyze the production and sustainment of the self-guided beam. Compared with laser or particle beam propulsion alone, the self-guided beam concept introduces a plethora of light-matter interactions and additional complexities, imposing certain constraints on the geometric and physical characteristics of the beam sources. In particular, we have the identified the particle beam as a crucial element of the proposed concept. System constraints are quantitatively analyzed and then explored by developing and applying a mission design process to a Proxima b flyby mission as well as a nearer-term mission to the solar gravitational lens point.
Mechanism↗
Electron gun test report
Shock and vibration tests were performed to determine the electron optical properties of the electron gun. The test procedure included complete mechanical inspection including a dimensional check of all critical parts. Electrical inspection involved tests for dielectric strengths and element to element leakage resistance. All test circuits and equipment for each test are specified in the test plan.
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