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NASA NTRS1987

Holographic interferometry at Wright Aeronautical Laboratories

The optical diagnostics requirements and plans for the Aero Propulsion Lab. are described. This laboratory is performing work in combustion as related to aero propulsion systems. They would like to use holography and other types of optical instrumentation for combustion diagnostics and flow visualization. A movie of a laser light sheet flow visualization of a combustor in operation was shown. This movie showed extremely clear examples of vortical and unsteady flow, and it would be of interest to use image analysis to quantify such data.

Roquemore, Mel↗

NASA NTRS1987

A survey of simulation and diagnostic techniques for hypersonic nonequilibrium flows

The possible means of simulating nonequilibrium reacting flows in hypersonic environments, and the required diagnostic techniques, are surveyed in two categories: bulk flow behavior and determination of chemical rate parameters. Flow visualization of shock shapes for validation of computational-fluid dynamic calculations is proposed. The facilities and the operating conditions necessary to produce the required nonequilibrium conditions, the suitable optical techniques, and their sensitivity requirements, are surveyed. Shock-tubes, shock-tunnels, and ballistic ranges in a wide range of sizes and strengths are found to be useful for this purpose, but severe sensitivity requirements are indicated for the optical instruments, which can be met only by using highly-collimated laser sources. Likewise, for the determination of chemical parameters, this paper summarizes the quantities that need to be determined, required facilities and their operating conditions, and the suitable diagnostic techniques and their performance requirements. Shock tubes of various strengths are found to be useful for this purpose. Vacuum ultraviolet absorption and fluorescence spectroscopy and coherent anti-Stokes Raman spectroscopy are found to be the techniques best suited for the measurements of the chemical data.

Sharma, Surendra P.↗

NASA NTRS1987

A method of atmospheric density measurements during Shuttle entry using UV laser Rayleigh scattering

A detailed study is described of the performance capabilities and the hardware requirements for a method in which ambient density is measured along the Space Shuttle flight path using on-board optical instrumentation. The technique relies on Rayleigh scattering of light from a pulsed, ultraviolet, ArF excimer laser operating at a wavelength of 193 nm. The method is shown to be capable of providing direct measurements of ambient density with an uncertainty of less than 1 percent and with a spatial resolution of 1 km, over an altitude range from 50 to 90 km. In addition, extensions of this concept are discussed that allow measurements of the shock wave location and the density profile within the shock layer. Two approaches are identified that appear to be feasible, in which the same laser system is used for the extended measurements as that required for the ambient density measurements.

Mckenzie, Robert L.↗

NASA NTRS1987

Atmospheric electricity

In the last three years the focus was on the information contained in the lightning measurement, which is independent of other meteorological measurements that can be made from space. The characteristics of lightning activity in mesoscale convective systems were quantified. A strong relationship was found between lightning activity and surface rainfall. It is shown that lightning provides a precursor signature for wet microbursts (the strong downdrafts that produce windshears hazardous to aircraft) and that the lightning signature is a direct consequence of storm evolution. The Universities Space Research Association (USRA) collaborated with NASA scientists in the preliminary analysis and scientific justification for the design and deployment of an optical instrument which can detect lightning from geostationary orbit. Science proposals for the NASA mesoscale science program and for the Tethered Satellite System were reviewed. The weather forecasting research and unmanned space vehicles. Software was written to ingest and analyze the lightning ground strike data on the MSFC McIDAS system. The capabilities which were developed have a wide application to a number of problems associated with the operational impacts of electrical discharge within the atmosphere.

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NASA NTRS1988

The role of fiberoptics in remote temperature measurement

The use of optical fibers in conjunction with infrared detectors and signal processing electronics represents the latest advance in the field of non-contact temperature measurement and control. The operating principles and design of fiber-optic radiometric systems are discussed and the advantages and disadvantages of using optical fibers are addressed. Signal processing requirements and various infrared detector types are also described. Several areas in which infrared fiber-optic instrumentation is used for temperature monitoring and control are discussed.

Vanzetti, Riccardo↗

NASA NTRS1988

Optical environment of the Spacelab 1 mission

The passing of large orbital vehicles through the space environment often generates such emissions as glows on or near the vehicle surface and halos surrounding the vehicle. These induced emissions may affect observations made with the optical instrumentation carried by the vehicles. The glows' causative mechanisms appear to be a complex function of altitude, time in orbit, materials, insolation, and vehicular size and orientation. Attention is presently given to contamination environment data obtained for the instrument suite carried by the Spacelab 1 Space Shuttle mission.

Torr, Marsha R.↗

NASA NTRS1989

Spectrograph Measures Contamination Of Optical Elements

Scanning-monochromator spectrograph designed to measure contamination on surfaces of optical elements as function of time. Repeatedly exposes samples to environment, then measures their transmittances or reflectances over range of wavelengths. Intended for use at vacuum-ultraviolet wavelengths to evaluate effects of outgassing, heating, and cooling on optical instruments. Principle of operation also applicable to spectral monitoring of time-dependent contamination at other wavelengths and in laboratory, industrial, or other settings.

Flint, Bruce K.↗

NASA NTRS1988

Space Station-based deep-space optical communication experiments

A series of three experiments proposed for advanced optical deep-space communications is described. These proposed experiments would be carried out aboard the Space Station to test and evaluate the capability of optical instruments to conduct data communication and spacecraft navigation for deep-space missions. Techniques for effective data communication, precision spacecraft ranging, and accurate angular measurements will be developed and evaluated in a spaceborne environment.

Chen, Chien-Chung↗

NASA NTRS1990

KD2PO4 Polarization Modulator With Large Field Of View

Improved potassium dideuterium phosphate (KD2PO4) electro-optical linear-polarization modulator suitable for use with optical instruments having large (wide-angle) fields of view. Errors previously caused by convergence of light eliminated.

West, Edward A.↗

NASA NTRS1989

Research and test facilities for development of technologies and experiments with commercial applications

One of NASA'S agency-wide goals is the commercial development of space. To further this goal NASA is implementing a policy whereby U.S. firms are encouraged to utilize NASA facilities to develop and test concepts having commercial potential. Goddard, in keeping with this policy, will make the facilities and capabilities described in this document available to private entities at a reduced cost and on a noninterference basis with internal NASA programs. Some of these facilities include: (1) the Vibration Test Facility; (2) the Battery Test Facility; (3) the Large Area Pulsed Solar Simulator Facility; (4) the High Voltage Testing Facility; (5) the Magnetic Field Component Test Facility; (6) the Spacecraft Magnetic Test Facility; (7) the High Capacity Centrifuge Facility; (8) the Acoustic Test Facility; (9) the Electromagnetic Interference Test Facility; (10) the Space Simulation Test Facility; (11) the Static/Dynamic Balance Facility; (12) the High Speed Centrifuge Facility; (13) the Optical Thin Film Deposition Facility; (14) the Gold Plating Facility; (15) the Paint Formulation and Application Laboratory; (16) the Propulsion Research Laboratory; (17) the Wallops Range Facility; (18) the Optical Instrument Assembly and Test Facility; (19) the Massively Parallel Processor Facility; (20) the X-Ray Diffraction and Scanning Auger Microscopy/Spectroscopy Laboratory; (21) the Parts Analysis Laboratory; (22) the Radiation Test Facility; (23) the Ainsworth Vacuum Balance Facility; (24) the Metallography Laboratory; (25) the Scanning Electron Microscope Laboratory; (26) the Organic Analysis Laboratory; (27) the Outgassing Test Facility; and (28) the Fatigue, Fracture Mechanics and Mechanical Testing Laboratory.

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NASA NTRS1991

Preventing Aim At An Undesired Target

Electronic system controls changes in orientation of optical instrument. Slew-control system includes avoidance-control logic, which overrides slew-control error generator when line of sight of instrument comes within cone of avoidance around line of sight to Sun. Normal slewing trajectory interrupted by avoidance-control logic, which computes actuator torques taking line of sight around cone of avoidance. Used to protect delicate photodetectors in servocontrolled infrared spectrometer or imaging instrument against damage occurring if instrument aimed at Sun or another excessively bright object.

Goodzeit, Neil E.↗

NASA NTRS1991

Mechanical strain isolator mount

Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

James, Gordon E.↗

NASA NTRS1990

Search for lightning-induced electron precipitation with rocket-borne photometers

Photometers at 3914 A and 5577 A and an optical imager were part of an experimental package launched on a sounding rocket in the 1987 Wave Induced Particle Precipitation campaign at Wallops Island, Virginia. The objective was to measure lightning-induced electron precipitation (LEP) by means of its optical signature. This was the first attempt to measure LEP using rocket-borne optical instrumentation. Launch criteria included nearby thunderstorm activity and ground-based observations of Trimpi events. Lightning flashes are clearly discernible in the data. The photometer data was also characterized by large spin and precession modulations in the photon count rate, consistent with elevated steady particle fluxes in the northern portion of the instrument field of view. No evidence of LEP was observed by the photometers or onboard particle detectors (Arnoldy and Kintner, 1989). Analysis of the data has made it possible to place an upper limit of 0.0008 ergs/sq cm per sec on any burst precipitation energy flux that may have occurred during the rocket flight in the regions explored by the photometers.

Massey, R. D.↗

NASA NTRS1990

Remote sensing of the biosphere; Proceedings of the Meeting, Orlando, FL, Apr. 19, 20, 1990

The global context and monitoring of the biological aspects relevant to the EOS program are addressed, the large-scale regional field experiments required to understand ecosystem functioning in more detail and to calibrate the application of remote-sensing techniques for extracting flux and state information are covered, and sensors of the proposed EOS platform are discussed. Attention is given to terrestrial productivity, both tropical-forest and semiarid environments, coastal environments, and global oceanic productivity. Focus is placed on the First International Field Experiment (FIFE) in Kansas, the HAPEX field experiment in France, the ABLE-2 experiment in the Amazon, and the Forest Ecosystem Study in Maine. The proposed electro-optical instruments for EOS including both MODIS-N and MODIS-T, the AIRS and MISR instruments, the ITIR, and ERBE calibration issues are considered.

Smith, James A.↗

NASA NTRS1991

The structure and composition of metal particles in two type 6 ordinary chondrites

The microstructure and composition of taenite particles were examined in two type-6 ordinary chondrites, Kernouve (H6) and Saint Severin (LL6), using reflected light microscopy and a combination of electron optical instruments. It was found that, in both meteorites, the taenite particles consisted of a narrow rim of high-Ni taenite and a central region of cloudy zone similar to those present in iron meteorites. The microstructure of the cloudy zone in Saint Severin was coarser than that in Kernouve , due to the higher Ni content and slower cooling rate of the former. Three microstructural zones were observed in the outer taenite rim of both meteorites, the origin of which is considered likely to be due to the presence of ordered domain boundaries or to the presence of two phases FeNi and FeNi3 in the high-Ni region of the outer taenite rim.

Holland-Duffield, C. E.↗

NASA NTRS1991

Polarimetry of extreme ultraviolet lines in solar astronomy

Ways are suggested in which recent advancements in the fabrication of ultrasmooth, low scatter flow-polished mirror substrates and high-quality multilayer and interference film coatings can be used to create novel optical instruments for observing linear-polarization effects in the outer solar atmosphere. Attention is given to the observational parameters of all-reflective FUV/EUV imaging polarimeters; such a coronagraph/polarimeter, operating at Ly-alpha, could yield the first measurements of coronal vector magnetic fields.

Fineschi, Silvano↗

NASA NTRS1990

A non-optical real-time particle fallout monitor

The paper describes a size-selective fallout monitor that can be employed to assess the degradation of sensitive optical surfaces as well as facilitate the analysis of particle types. The device combines a vertical elutriator and a quartz crystal microbalance, and only particles greater than a specific size can pass through an upward laminar flow generated in the device. The larger particles cause a frequency shift in the crystal oscillator, thereby permitting the measurement of the fallout associated with the contamination of optical instruments.

Chuan, Raymond L.↗

NASA NTRS1992

Dimensionally Stable Graphite-Fiber/Glass Composites

Method of making composites of glass matrices reinforced by graphite fibers provides for control of proportions, orientations, and distributions of fibers in matrices and for fused bonds between fibers and matrices. Enables fabrication of composites of high specific strength and dimensional stability. Method particularly suitable for making low-thermal-expansion platforms for optical instruments.

Harris, Robert↗