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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Feasibility study for the use of a YF-12 aircraft as a scientific instrument platform for observing the 1970 solar eclipse

The scientific and engineering findings are presented of the feasibility study for the use of a YF-12 aircraft as a scientific instrument platform for observing the 1970 solar eclipse. Included in the report is the computer program documentation of the solar eclipse determination; summary data on SR-71A type aircraft capabilities and limitations as an observing platform for solar eclipses; and the recordings of an informal conference on observations of solar eclipses using SR-71A type aircraft.

Mercer, R. D.↗
NASA NTRS1973

Thermal surveillance of volcanoes of the Cascade Range utilizing ERTS DCP systems and imagery

The author has identified the following significant results. Successful installation of DCP sets at Mt. Baker volcano and at Mt. St. Helens volcano, Washington, completed the installation phase of experiment SR 251. Aerial IR scanner missions over the Cascade volcanoes were completed with a mission April 29th which provided thermographic IR images of Glacier Peak, Mt. Baker, Mt. St. Helens, Mt. Rainier, and Mt. Adams. Earlier repetitive coverage had obtained IR images depicting thermal anomalies of Lassen Volcanic National Park, Shasta, Crater Lake, and the northern Cascades. The April 29th mission and subsequent ground reconnaissance yielded new information on 48 heretofore unreported pinpoint radiation anomalies, of possible fumarolic origin, on the flanks of Mt. Rainier and several new thermal points on Mt. Baker. Cartographic plots of these anomalies, in conjunction with surface temperature and other data obtained as a result of experiment SR 251 will permit estimation of radiation heat loss during the repose periods of the host volcanoes.

Friedman, J. D.↗
NASA NTRS1973

Solar cosmic ray micro-events

To study small discrete solar particle events, it has proven useful to define a special class such that the proton flux at energies greater than 20 MeV exceed 0.0001 protons/sq cm-sec-sr-MeV. These increases are termed microevents. An arbitrary upper limit is placed at 2 X 0.02 protons/sq cm-sec-sr-MeV. By demanding a measurable flux above 20 MeV, a better separation from corotating events is achieved and onset times can in general be determined more precisely. Over an observing period extending from May 1967 through December 1971, approximately 105 events were observed. There are several different sources of these small events. Some are produced by moderate to large solar flares near the east limb or by solar flares on the nonvisible disk of the sun. Others are produced by generally minor solar activity: typically in 1N flare, a group of type 3 radio bursts and a well defined X-ray burst. A significant number of this latter type are accompanied by type 2 radio emission. A small sample of the micro-events can be classified as scatter-free events. For these the distance traveled by the particles before their initial detection at earth is on the order of 1.5 AU and observed rise and decay times are much less than normal. Examples of these general types of micro-events and their solar association are discussed.

Mcdonald, F. B.↗
NASA NTRS1974

Measurements of sonic booms generated by an airplane flying at Mach 3.5 and 4.8

Sonic booms generated by the X-15 airplane flying at Mach numbers of 3.5 and 4.8 were measured. The experimental results agreed within 12 percent with results obtained from theoretical methods. No unusual phenomena related to overpressure were encountered. Scaled data from the X-15 airplane for Mach 4.8 agreed with data for an SR-71 airplane operating at lower Mach numbers and similar altitudes. The simple technique used to scale the data on the basis of airplane lift was satisfactory for comparing X-15 and SR-71 sonic boom signatures.

Green, K. S.↗
NASA NTRS1975

Study of bone mineral metabolism

The use of Sr-85 as an indicator of the skeletal location and relative amount of bone demineralization which occurs during immobilization of the body or body parts, bed-rest or space flight was studied. The bone mineral replacement which occurs after immobilization was measured rather than the bone loss which occurs during immobilization. In a study with two adult beagle dogs, the Sr-85 uptake in a leg which had been immobilized for two months was 400 percent higher than the uptake in the legs in regular use. This increased uptake probably resulted from only a few percent loss in bone mineral and indicates that losses less than one percent can be easily detected and located. The sensitivity, simplicity, and low radiation dose associated with the use of this method indicates that it should receive consideration for use on humans in bed-rest and space flight studies. Methods for measuring changes in total body nitrogen and in assisting the Johnson Space Center in calibrating a whole body counter for total body potassium measurements were also investigated.

Palmer, H. E.↗
NASA NTRS1975

Cosmic ray positron and negatron spectra between 20 and 800 MeV measured in 1974

A balloon-borne spark chamber magnetic spectrometer was used to measure separate spectra of positrons and negatrons in two flights during summer, 1974. The total electron flux is about 0.3 m(-2) s(-1) sr(-1) MeV(-1) between 70 and 800 MeV, and increases toward lower energies. The positron spectrum decreases sharply toward lower energies from a value of about 0.08 m(-2) s(-1) sr(-1) MeV(-1) at 650 MeV, and only upper limits are obtained for positrons below 200 MeV. At energies above 180 MeV, the spherically symmetric Fokker-Planck equation provides reasonable fits to both the positron and total electron data. At energies below 180 MeV the data are consistent with a continuation of the same diffusion coefficient and local source of negatrons, or a change in the diffusion coefficient to a constant value.

Hartman, R. C.↗
NASA NTRS1975

76535 - An old lunar rock

Measurements of Rb-Sr systematics, K-Ar gas retention ages, and the isotopic compositions of He, Ne, and Ar have been performed for lunar troctolite 76535. Other investigators have presented evidence that this important rock formed as a cumulate at depth, which would make it an important link in the early chronology of the moon. Rb-Sr data do not define an isochron. Total Ar-40/K ages of whole rock and plagioclase range from 4.40-4.54 b.y. The trapped Ne and Ar in 76535 cannot be uniquely characterized as either 'planetary derived' or solar wind derived, but appear to have characteristics of both. The data suggest that 76535 formed 4.3-4.6 b.y. ago, and the accumulation process and/or subsequent annealing may have incorporated excess noble gases. Separation of radiogenic parents and daughters with incomplete isotopic equilibration may also have occurred during cooling or during a subsequent 'event'.

Bogard, D. D.↗
NASA NTRS1974

Mineralogy, petrology, and chemistry of basalt fragments returned by Luna 16

Mineralogical, petrological, and chemical analyses, along with Rb-Sr age and Ar-40/Ar-39 measurements, were carried out with the B-1 sample returned from the Luna 16 mission. The sample, weighing 62 mg, is a fine-grain basalt of ophitic structure. It differs from the Apollo samples in that the pyroxene and plagioclass contents are almost identical, and the ilmenite content (7%) lies between those of the Apollo-11 and Apollo-12 samples. Chemically, it is characterized by a high Sr content and a high K/U ratio.

Albee, A. L.↗
NASA NTRS1975

Neutral hydrogen flux measured at 100- to 200-km altitude in an electron aurora

Neutral hydrogen fluxes were measured at altitudes of 120-200 km by a rocket payload that also measured electron and proton fluxes and vector magnetic fields. An intense electron arc was crossed, while an upper limit to the flux of 0.5- to 20-keV protons was 1,000,000 per sq cm s sr keV. A neutral flux of 50,000,000 per sq cm s sr was observed, assuming hydrogen with greater than 1-keV energy, with greater north-south extent than the electron flux. Its pitch angle distribution was peaked toward 90 deg, tending toward isotropy in the center. This is fitted to a model describing spreading of an initial proton arc above 500 km.

Iglesias, G. E.↗
NASA NTRS1974

Provenance of KREEP and the exotic component - Elemental and isotopic studies of grain size fractions in lunar soils

Sieve fraction analyses of lunar soils reveal the presence of a fine-grained exotic component enriched in K, Rb, Sr, Ba, and in radiogenic Sr in all soils. The probable source of this exotic component is the areas of high-surficial radioactivity observed by orbital gamma ray spectrometry, such as those at Fra Mauro and Archimedes. If the exotic component is fine-grained KREEP, the origin and distribution of KREEP fragments in the soils are identified. It is suggested that the exotic component represents trace element enriched material located at some depth in the Imbrium area which was surficially deposited during Imbrium excavation.

Evensen, N. M.↗
NASA NTRS1975

Use of dew-point detection for quantitative measurement of sweating rate

A method of measuring sweat rate (SR) based on detection of dew point (DP) is proposed which has advantages that may be attractive to other laboratories concerned with recording SR from selected areas of skin. It is similar to other methods in that dry gas is passed through a capsule which isolates several square centimeters of skin surface. The difference is in the means of determining how much gaseous water is carried off in the effluent moist gas. The DP detector used is free of the drawbacks of previous devices. DP is obtained through the fundamental technique of determining the temperature at which condensate forms on a mirror. Variations in DP are tracked rapidly, and accurately (+ or - 0.8 C nominal, sensitivity + or - 0.05 C) over a wide range ( -40 C to +50 C) without measurable hysteresis. The detector asembly is rugged and readily opened for cleaning and inspection.

Brengelmann, G. L.↗
NASA NTRS1975

Splash albedo protons between 4 and 315 MeV at high and low geomagnetic latitudes

Results are reported for measurements of the differential energy spectrum of splash-albedo protons at high geomagnetic latitude during three periods of the last solar cycle as well as at low latitude during one of those periods. The measurements were made with a balloon-borne solid-state detector telescope. Splash-albedo protons with energies between 4 and 315 MeV were observed in fluxes of approximately 81, 70, and 48 protons/sq m per sec per sr at high latitude and in fluxes of approximately 37 protons/sq m per sec per sr at low latitude. It is shown that the difference between the first and third high-latitude measurements was due to solar modulation of the cosmic-ray parent nuclei. The albedo spectrum is found to have a similar shape for both latitudes, and it is suggested that the difference in intensity can be explained by different local geomagnetic cutoffs.

Wenzel, K.-P.↗
NASA NTRS1976

Phase B: Final definition and preliminary design study for the initial Atmospheric Cloud Physics Laboratory (ACPL), a spacelab mission payload

A preliminary identification of the Supporting Research and Technology (SR&T) necessary during the planned evolution of atmospheric cloud physics is discussed. All requirements are for subsequent flights over its expected ten year lifetime. Those components identified as requiring some SR&T work prior to inclusion are listed. A data sheet is included for each item, briefly justifying the need, giving general objectives for the proposed development effort and identifying approximate schedule requirements on the program.

Source record↗
NASA NTRS1976

Neutral calcium, strontium and barium - Determination of f values of the principal series by the hook method

The hook method is used to measure the absolute gf values of the following lines: the first 13 members of the principal series, the ground-level transition at 2275.46 A, and the intercombination line at 6572.78 A in Ca I; the first 22 members of the principal series, the ground-level transitions at 2428.1 and 2680.08 A, and the intercombination line at 6892.6 A in Sr I; and the members from principal quantum numbers 12 to 21, inclusive, as well as the ground-level transitions at 2432.5, 2444.6, and 2454.06 A in Ba I. The results are compared with those of previous measurements, and the quantum-defect method is applied to plot the oscillator strengths of the discrete transitions in the principal series of Mg I, Ca I, and Sr I in order to obtain estimates of the photoionization cross sections at the first ionization limit. The resulting cross sections are found to be about twice as large as previous values based on vapor-pressure data.

Parkinson, W. H.↗
NASA NTRS1975

Isotopic composition of cosmic ray nitrogen at 1.5 GeV/amu

For any location, the earth's magnetic field acts as a filter for incoming cosmic rays, allowing only particles above a certain rigidity. The relative isotopic composition of abundant elements can be measured with a detector sensitive to the velocity of particles in the penumbra of the earth's magnetic field. In this paper, the nitrogen velocity spectrum is compared with that of carbon plus oxygen as a reference, since in this case Z-dependent effects are minimal. The form of the energy spectrum of carbon, nitrogen, and oxygen, needed for proper correction, was measured in the same experiment. The results were obtained using a scintillator-Cerenkov counter telescope with a geometric factor of 0.25 sq in sr, flown twice on high-altitude balloons from Palestine, Texas, obtaining an exposure factor of 20 sq m sr hr. Results are presented on the isotopic composition of nitrogen at about 1.5GeV/amu.

Dwyer, R.↗
NASA NTRS1977

Simplified methods for calculating photodissociation rates

Simplified methods for calculating the transmission of solar UV radiation and the dissociation coefficients of various molecules are compared. A significant difference sometimes appears in calculations of the individual band, but the total transmission and the total dissociation coefficients integrated over the entire SR (solar radiation) band region agree well between the methods. The ambiguities in the solar flux data affect the calculated dissociation coefficients more strongly than does the method. A simpler method is developed for the purpose of reducing the computation time and computer memory size necessary for storing coefficients of the equations. The new method can reduce the computation time by a factor of more than 3 and the memory size by a factor of more than 50 compared with the Hudson-Mahle method, and yet the result agrees within 10 percent (in most cases much less) with the original Hudson-Mahle results, except for H2O and CO2. A revised method is necessary for these two molecules, whose absorption cross sections change very rapidly over the SR band spectral range.

Shimazaki, T.↗
NASA NTRS1976

Inferences about magma sources and mantle structure from variations of Nd-143/Nd-144

Continental flood basalts and mid-ocean ridge (MOR) tholeiitic basalts have distinctly different Nd-143/Nd-144 which may permit a priori distinction between continental and oceanic igneous rocks. Initial Nd-143/Nd-144 of continental igneous rocks through time fall on a Sm/Nd evolution curve with chondritic REE abundance ratio. These observations indicate that many continental igneous rocks are derived from a reservoir with chondritic REE pattern which may represent primary material remaining since the formation of the earth. Oceanic igneous rocks are derived from a different ancient reservoir which has Sm/Nd higher than chondritic. Initial Nd-143/Nd-144 and Sr-87/Sr-86 in young basalts from both oceans and continents show a strong correlation suggesting that Sm-Nd and Rb-Sr fractionation events in the mantle may be correlative and caused by the same process. From this correlation Rb/Sr for the earth is inferred to be 0.029.

Depaolo, D. J.↗