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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Flutter tests (IS4) of the 0.0125-scale shuttle reflection plane model 30-OTS in the Langley Research Center 26-inch transonic blowdown tunnel test no. 547

A series of slab wing flutter models with rigid orbiter fuselage, external tank, and SRB models of the space shuttle were tested, in a reflection plane arrangement, in the NASA Langley Research Center's 26-inch Transonic Blowdown Tunnel. Model flutter boundaries were obtained for both a wing-alone configuration and a wing-with-orbiter, tank and SRB configuration. Additional test points were taken of the wing-with-orbiter configuration, as a correlation with the wing-alone condition. A description of the wind tunnel models and test procedures utilized in the experiment are provided.

Kotch, M. A.↗
NASA NTRS1974

Mean isotopic composition of cosmic rays with 12 less than Z less than or equal to 26 at 2.7 to 3.0 GV

Results are presented from a high-altitude balloon flight in September 1972 near 3-GV geomagnetic cutoff. The detector is a combination of ionization chambers and a Lucite Cerenkov counter with a charge resolution of 0.34 charge units. Following the technique described by Lund et al. (1971), use is made of the geomagnetic rigidity cutoff and measured momentum-per-nucleon spectra of individual elements to determine values of A/Z for even Z elements of 16 less than or equal to Z less than or equal to 26 relative to A/Z of silicon.

Maehl, R. C.↗
NASA NTRS1975

Performance of DSS 13 26-m antenna at X-band

The X-band low-noise antenna (XLA) measurement feedcone was operated on the DSS 13 26-m antenna at Goldstone, California, during June 1975 to evaluate, primarily, the overall system efficiency. Radio sources were selected, commonly accepted values of flux density established, and measurements completed, and some conclusions were drawn. The antenna system presently suffers from poor pointing stability. On the other hand, the previously welded and rebolted main reflector has remained quite stable over a period of approximately 5 years.

Freiley, A. J.↗
NASA NTRS1976

The isotopic composition of cosmic rays with Z between 5 and 26

Results are reported for a high-altitude balloon flight which measured the isotopic composition of cosmic rays by using a Cerenkov-range technique to determine the masses of arriving cosmic rays with charges between 5 and 26 for kinetic energies around 450 MeV/amu. Event-selection criteria are discussed, and the mass-determination technique is outlined. Some of the mass histograms resulting from the analysis are presented along with the mean masses calculated from the data, and the derived isotopic compositions. It is found that: (1) C, N, and O are consistent with pure C-12, N-14, and O-16 sources; (2) Mg seems to require some neutron-rich component at the source; (3) Ne appears to require a source isotopic composition that is even more neutron-rich than the universal abundances; and (4) the source may be somewhat enriched in Fe-54. It is suggested that the fundamental nuclear physics which governed the synthesis of solar-system material may also be responsible for cosmic rays, implying that the solar system is probably an average sample of galactic matter.

Fisher, A. J.↗
NASA NTRS1976

Global characteristics of 0.2 to 26 keV charged particles at F region altitudes

Measurements have been made by the low energy electron experiment (LEE) on the Atmosphere Explorer-C satellite (AE-C) of electrons and protons in the energy range 0.2 to 26 keV. Data taken in the altitude range 250 to 300 km during the period 15 December 1973 to 25 May 1975 are analyzed. Measurements were made over a range of magnetic latitudes extending from the equator to 80 deg. The average electron flux at midlatitudes at night is found to be about (1-5) x 10 to the -4 ergs/sq cm/s, and increases by about an order of magnitude during the day. The upper limit for the nighttime and daytime proton energy flux is about 1 x 10 to the -4th ergs/sq cm/s. The total nighttime energy flux will result in a production rate of .3 to 10 ions/cu cm/s at the base of the F region and in the D region, respectively, and should constitute an important source of ionization in the nocturnal ionosphere.

Torr, D. G.↗
NASA NTRS1977

Dual-frequency feed system for 26-meter antenna conversion

New cassegrain feed cone assemblies were designed as part of the upgrade of three 26-meter diameter antennas to 34-meter diameter with improved performance. The new dual-frequency feed cone (SXD) will provide both S- and X-band feed systems and traveling wave masers, with a reflex reflector system to permit simultaneous operation analogous to the 64-meter antennas. Tasks involved in adding the X-band receiving capability and improving the S-band feed performance in support of Voyager and later missions described in.

Hartop, R. W.↗
NASA NTRS1977

Energy spectra of cosmic ray nuclei - Z of 4 to 26 and E of 0.3 to 2 GeV/amu

The differential kinetic-energy spectra of cosmic-ray nuclei in the charge range from 4 to 28 are determined using data obtained from a high-altitude balloonborne detector. The data are derived from the response of an acrylic plastic Cerenkov counter and cover the kinetic-energy range from 400 to 2100 MeV/amu. A Cerenkov pulse-height histogram is obtained for each charge, and the kinetic-energy spectra are derived by means of a formal mathematical deconvolution of these histograms. Results of the deconvolution calculation extrapolated to the top of the atmosphere are presented for the most abundant nuclei; it is found that the spectra are not amenable to representation by spectral indices, so the relative spectra of the different elements are compared by evaluating the charge ratios as a function of energy. The results show that secondary/primary ratios decrease with increasing energy, while primary/primary ratios are constant for Z of 6 to 10 and 14 to 26 but vary for Z of 10 to 14. It is concluded that the data seem to indicate more than one cosmic-ray source region.

Maehl, R. C.↗
NASA NTRS1980

Utilization of the Venus Station (DSS 13) 26 meter antenna during CY 1979

The various activities for which the Venus Station's 26 m antenna was used are described and the number of manned tracking hours devoted to each activity are given. A brief description of the goal of each activity supported is provided, and, where appropriate, the observing technique is summarized. Projects involving spacecraft tracking, advanced systems development, and radio astronomy are included.

Jackson, E. B.↗
NASA NTRS1980

Measurements of NO, O3, and temperature at 19.8 km during the total solar eclipse of 26 February 1979

Local measurements of stratospheric NO and O3 mixing ratios and air temperature were made during the total solar eclipse of 26 February 1979. The instrumentation was carried aboard a U-2 aircraft flown at an altitude of 19.8 km in the region near 47 deg N, 112 deg W. Eclipse maximum occurred approximately in the middle of the 2-3/4-hr measurement period. The NO mixing ratio was reduced at least a factor of 25 at the maximum of the eclipse. The decrease and recovery of NO during the passage of the Moon's shadow over the measurement region follows approximately the predictions of two independent models. No change was observed in either the O3 mixing ratio or the air temperature that could be attributed to the eclipse.

Starr, W. L.↗
NASA NTRS1980

Transport functions of nitrogen up to 26,000 K

The current field strength characteristic, E(1), and a large number of radial temperature distributions, T(r,I), measured in a 5 mm N2 cascade arc at normal pressure are used to evaluate the transport properties of nitrogen up to 26,000 K. The electrical conductivity sigma (T) and the Coulomb cross section are determined directly from the E(I) and several T(r,I) curves. Between 10,000 and 15,000 K the radiative energy flux for different arc current, the thermal conductivity, and from this the charge exchange cross section are determined in a good approximation utilizing the large number of measured temperature distributions. It turns out, that at the highest measured arc current, i.e., 570 A, in the axial region of the arc about 95% of the supplied energy is carried off by radiation.

Hermann, W.↗
NASA NTRS1981

On the outburst of flare activity of 26 November, 1973

The possible source of a strong 30 hour-long outburst of homologous flare activity, and an unusual growth and brightening of coronal loops in the active region McMath 12628, on the eastern solar hemisphere, on Nov. 1973, as seen from Skylab are analyzed. Prior to that date, not many flares and subflares in the region were associated with radio bursts. However, almost all flares after that date were accompanied by microwaves and type III bursts until the last flare of this kind appeared at 03:52 on the 27th. All the type III bursts were accompanied by type U-bursts, giving evidence for strong closed fields rooted in the site of the radio bursts. It is recorded that U-bursts stopped after 07:18 on Nov. 26, and a change noted is attributed to the occurrence of two two-ribbon flares at the site of the recurrent activity which could have destroyed the U-type favorable situation. A two-ribbon flare, according to Kopp and Pneuman (1976), opens the magnetic field-configuration, and it is therefore suggested that a newly emerging magnetic flux was the source of the complex solar situation. It is suggested that this kind of activity should be studied during the FBS-ALERT periods in 1980-81.

Howard, R.↗
NASA NTRS1981

Cosmic-ray abundances of elements with atomic number 26 less than or equal to 40 measured on HEAO 3

Individual elements in the cosmic radiation of even atomic number (Z) in the interval 26-40 have been resolved and their relative abundances measured. The results are inconsistent with a cosmic-ray source whose composition in this charge interval is dominated by r-process nucleosynthesis. The ratios of cosmic-ray source abundances to solar system abundances in this interval follow the same general correlation with first ionization potential as for the lighter elements, although there are deviations in detail.

Binns, W. R.↗
NASA NTRS1981

A dedicated 26-m SETI sky survey instrument facility: A feasibility study

The feasibility of converting a deactivated GSTDN 26 m facility into a dedicated SETI Instrument Facility is examined. Additional benefits that would accrue from the proposed utilization of these facilities are the capability for remote and control the Deep Space Communications Complex (DSCC) Signal Processing Center, combined with a reduction in ground-induced radio frequency interference due to the physical distance to the other DSCC front end areas and the Signal Processing Center.

Berman, A. L.↗