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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Absolute calibration of Apollo lunar orbital mass spectrometer.

Recent experiments were conducted in Langley Research Center's molecular beam system to perform an absolute calibration of the lunar orbital mass spectrometer which was flown on the Apollo 15 and 16 missions. Tests were performed with several models of the instrument using two test gases, argon and neon, in the 1 ntorr to .1 picotorr range. Sensitivity to argon at spacecraft orbital velocity was .00028 A/torr enabling partial pressures in the .01-picotorr range to be measured at the spacecraft altitude. Neon sensitivity was nearly a factor of 5 less. Test data support the feasibility of using the lunar orbital mass spectrometer as a tool to gather information about the lunar atmosphere.

Yeager, P. R.↗
NASA NTRS1974

Spectrometer

Ultraviolet spectrometer measures pure monochromatic wavelengths in predetermined narrow wave bands. Two stages are incorporated: stationary dispersed beam is intercepted by array of slits cut into plate at discrete wavelength locations; second stage is inverted spectrometer which recombines dispersed spectrum at single exit slit.

Menzel, D. H.↗
NASA NTRS1973

LLL electron and proton spectrometer on NASA's Orbiting Geophysical Observatory 5

The LLL energetic electron and proton spectrometer on NASA's Orbiting Geophysical Observatory 5 (OGO-5) operated successfully from launch - March 4, 1968 - until retirement in August 1971. Data recovery during this time was about 95% of the orbit except for the last few months. The electron spectrometer used a magnetic field for electron momentum selection which served also as an electron broom for a proton range - energy telescope. The energy range was approximately 60 to 2950 keV for electrons (seven channels) and 0.10 to approximately 94 MeV for protons (seven channels). The experiment was scanned relative to the stabilized OGO-5 for obtaining directional information. Excellent data were taken throughout the magnetosphere and in the interplanetary region. Studies were carried out in the areas of equatorial pitch-angle distributions, substorm dynamics and field topology, particle spectra (time history), particle spatial distributions, and solar particle events.

West, H. I., Jr.↗
NASA NTRS1973

Preliminary results from the first satellite of a high-resolution germanium gamma-ray spectrometer: Backgrounds from electron bremsstrahlung and from electron-positron annihilation

Detailed data are presented on the bremsstrahlung backgrounds measured by a satellite-borne high resolution Ge(Li) gamma ray spectrometer. Two bremsstrahlung classes were discussed: (1) those arising from radiation belt electrons stopping in the vicinity of the spectrometer, and (2) bremsstrahlung produced by electrons precipitating into the earth's atmosphere.

Imhof, W. L.↗
NASA NTRS1974

X-ray evaluation of crystals for stellar spectrometers

The report consists of three parts. The first part is an analysis of the principles involved in X-ray crystal evaluation and how they are applied to a number of crystals. The principles of crystal evaluation analysis as they apply to the special problems of X-ray astronomy are presented. A number of crystals were evaluated, and the energy dependence of the diffraction properties of (002) PET, (111) Ge, (101) ADP, (001) KAP, and (001) RAP are reported. The second part is a compilation of the diffraction properties of a number of crystals as reported by other authors. In the third part some technical details of a triple crystal spectrometer built by the author at Polytechnic Institute of Brooklyn are given. This spectrometer seems to be a most appropriate instrument for evaluation of crystal properties. (Modified author abstract)

Alexandropolos, N. G.↗
NASA NTRS1974

Study to evaluate the integration of a mass spectrometer with a wet chemistry instrument

The charactertistics and performance capability of the current Viking '75 Gas Chromatograph/Mass Spectrometer Instrument are reviewed and documented for the purpose of possible integration with a wet chemistry instrument. Interface, high mass discrimination, and vacuum requirements were determined in a simulated flight investigation. Suggestions for future investigations, tradeoff studies, and design modifications are presented, along with the results of column bleed measurements. A preliminary design of an integrated Wet Chemistry/Mass Spectrometer instrument for amino acid analysis is shown, including estimates of additional weight, volume, and power requirements.

Source record↗
NASA NTRS1973

Conical focusing crystal spectrometers for cosmic X-ray astronomy

A crystal spectrometer for rocket and satellite experiments is described. Parallel X rays from a stellar object are reflected at constant angle by Bragg crystals arranged around the sector of a cone so that a single wavelength is brought to a focus onto the axis of the cone. The aberrations produced when this array is tilted to change the wavelength are considered. It is shown that these are minimized by moving cone and detector in a nearly theta to two-theta motion and by using a small-angle sector. In a specific design for a satellite instrument using LiF crystal to observe a spectral region including the iron lines at 1.9 A, a spectral resolution of 3 mA over a spectral range of 1.6-2.1 A can be obtained, with the cosmic-ray background rate, and hence the time to detect a weak line decreased by a factor 80 compared to a flat crystal spectrometer. Examples of performance for a low energy rocket experiment are also given.

Woodgate, B. E.↗
NASA NTRS1973

Some correlations between measurements by the Apollo gamma-ray spectrometer and other lunar observations

Observations by the Apollo 15 and 16 gamma-ray spectrometers are compared with those of a number of other experiments, both compositional and noncompositional. A general correspondence with topography is seen. The Van de Graaff area is a unique farside region with respect to observations by the laser altimeter, the subsatellite magnetometer, and the gamma-ray spectrometer. X-ray and alpha particle orbital measurements show a broad general agreement with gamma-ray data, although results from additional elements in the gamma-ray spectrum are needed to extend the comparison with X-ray data. A comparison of Th concentrations with those found at various landing sites shows generally good agreement, with the orbital values tending to be somewhat higher.

Trombka, J. I.↗
NASA NTRS1974

Extreme ultraviolet spectrometer for space research

A normal incidence spectrometer for use in the wavelength region from 200 to 1270 A has been developed. The design and calibration of the instrument are described in detail. The spectrometer can be employed to detect extreme UV radiation at a minimum flux level of 1 rayleigh with a spectral resolution of 40 A and a spatial resolution of 6 deg. Data on the extreme UV night sky spectrum between 780 and 1270 A obtained with this instrument on a recent rocket flight are presented.

Kumar, S.↗
NASA NTRS1974

The Apollo X-ray fluorescence spectrometer

The Apollo X-ray fluorescence spectrometer was a part of a geochemical package flown on the Apollo 15 and 16 missions. The device was to map the concentrations of aluminum, magnesium, and silicon in the lunar regolith along the spacecraft ground track. A functional description of the spectrometer is given and the telemetry data format is discussed together with the pulse height analyzer, the pulse shape discriminator, questions of in-flight calibration, and the flight results.

Jagoda, N.↗
NASA NTRS1974

Comparison of atomic oxygen measurements by incoherent scatter and satellite-borne mass spectrometer techniques

Atomic oxygen densities determined by the incoherent scatter technique are compared to densities deduced from satellite-borne mass spectrometer measurements and are found to agree within experimental error. The diurnal variations inferred from the incoherent scatter measurements do show, however, some departure from diurnal variations found by modeling the mass spectrometer results. Some implications of these departures are briefly discussed.

Hedin, A. E.↗
NASA NTRS1974

A new mass spectrometer system for investigating laser-induced vaporization phenomena

A laser has been combined with a mass spectrometer in a new configuration developed for studies of high-temperature materials. A vacuum-lock, solid-sample inlet is mounted at one end of a cylindrical, high-vacuum chamber one meter in length with a nude ion-source, time-of-flight mass spectrometer at the opposite end. The samples are positioned along the axis of the chamber at distances up to one meter from the ion source, and their surfaces are vaporized by a pulsed laser beam entering via windows on one side of the chamber. The instrumentation along with its capabilities is described, and results from laser-induced vaporization of several graphites are presented.

Lincoln, K. A.↗
NASA NTRS1974

Mariner 9 ultraviolet spectrometer experiment - Pressure-altitude measurements on Mars

Ultraviolet spectrometer measurements of the reflectance at 3050 A are modeled to give pressure-altitudes for Mars assuming a quiescent atmosphere. Ultraviolet light that is Rayleigh-scattered by the Mars molecular atmosphere, with allowance for uniform turbidity, is proportional to surface pressure independent of atmospheric temperature structure. All model constants except the over-all scaling factors are found by requiring ultraviolet spectrometer pressures of 47 locations on the planet to be the same when measured at different geometries. The overall scaling factor is found by intercomparison with Mariner 9 occultation pressures. Comparison with other Mars pressure-altitude measurements show deviations from the assumption of uniform turbidity to occur over the Hesperia plateau for ultraviolet measurements obtained during the 13-26 February 1972 time period.

Hord, C. W.↗
NASA NTRS1974

Balloon-borne ultraviolet stellar spectrometer: Acquisition, tracking and command systems

The NASA Balloon-borne Ultraviolet Stellar Spectrometer (BUSS) which is carried to an altitude of 40 km by a 15 million cubic foot balloon for night-time observations of ultraviolet stellar spectra is discussed. The BUSS optical system, comprising an 0.40 m aperture Cassegrain telescope and an Ebert-Fastie spectrometer, points at various selected stars and focuses a portion of their spectra on the photocathode of an image dissector tube. The spectral region between 2,775 Angstroms and 2,825 Angstroms is sampled by the detector at 0.25 Angstroms increments using photon counting techniques. The pointing system for the payload uses a pair of orthogonal magnetometers which sense the earth's magnetic field for an aximuth reference, and a platform potentiometer for an elevation reference. This pointing system places the target star within the 3x1 degree field of view of an outer optical star tracker. The outer star tracker is then used to point the entire instrument to within one arc minute of the target star.

Gibson, W. C.↗
NASA NTRS1975

Investigation of Facsimile Camera-spectrometer Capability in the 1.0 to 2.7 Micron Spectral Range

The capability of the facsimile camera augmented with a filter-spectrometer to provide scientifically valuable information in the 1.0 to 2.7 microns spectral range was investigated for a future planetary lander mission to Mars. A computer model was used to evaluate tradeoffs between signal-to-noise ratio, spatial and spectral resolution, and the number of spectral channels. Spectral absorption features resulting from water and chemical variations found in pyroxenes were used to represent scientific information of interest to biologists and geologists. Expected output data from a filter-spectrometer is illustrated which indicates that important information pertaining to water content and chemical composition can be obtained using six to eight spectral channels with 0.3 degree spatial resolution.

Kelly, W. L., IV↗
NASA NTRS1975

Sensitivity limits of an infrared heterodyne spectrometer for astrophysical applications

A discussion and an evaluation of the degradation in sensitivity is given for a heterodyne spectrometer employing a HgCdTe photodiode mixer and tunable diode lasers. The minimum detectable source brightness is considered as a function of the mixer parameters, transmission coefficient of the beam splitter, and local oscillator emission powers. The degradation in the minimum detectable line source brightness which results from the bandwidth being a function of the line width is evaluated and plotted as a function of the wavelength and bandwidth for various temperature to mass ratios. It is shown that the minimum achievable degradation in the sensitivity of a practical astronomical heterodyne spectrometer is approximately 30. Estimates of signal-to-noise ratios with which infrared line emission from astronomical sources of interest may be detected are given.

Abbas, M. M.↗
NASA NTRS1976

Data analysis for Skylab proton spectrometer

The data from a proton spectrometer flown aboard Skylab is examined. The instrument is sensitive to protons in the energy range 18 to 400 MeV. A partial failure of the spectrometer restricted spectral analysis to two energy bands, 18 to 27 MeV and 27 to 400 MeV. The directional data showed that a Gaussian angular distribution parameter of at least 70 degrees is required for the low energy band and at least 40 degrees for the high energy band. The data, integrated over angle, indicate that the AP3 model extrapolated down to 18-27 MeV is high by factors of 2 to 5 over most of the B-L space mapped. In the 27 to 400 MeV range, the AP3 model is 20 to 100 percent low at low and high values of L, and is high at medium L values in the B-L space mapped.

Hill, C. W.↗
NASA NTRS1976

Sensitivity limits of an infrared heterodyne spectrometer for astrophysical applications

A discussion and an evaluation of the degradation in sensitivity are given for a heterodyne spectrometer employing a HgCdTe photodiode mixer and tunable diode lasers. The minimum detectable source brightness is considered as a function of the mixer parameters, transmission coefficient of the beam splitter, and local oscillator emission powers. The degradation in the minimum detectable line source brightness that results from the bandwidth being a fraction of the line width is evaluated and plotted as a function of the wavelength and bandwidth for various temperature to mass ratios. It is shown that the minimum achievable degradation in the sensitivity of a practical astronomical heterodyne spectrometer is about 30. Estimates of SNRs with which IR line emission from astronomical sources of interest may be detected are given.

Abbas, M. M.↗