Engineering Papers⌕ Search

Engineering topics

Hanel, R. A.

Publications and source records attributed to Hanel, R. A..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The helium abundance of Jupiter from Voyager

Full disk measurements recorded 31 days before the Voyager 1 encounter with Jupiter by the radiometer of the infrared instrument, IRIS, indicate a geometric albedo of 0.274 + or - 0.013. Combining this measurement with the Pioneer derived phase integral of 1.25 and our error estimate of 0.1 yields a Jovian Bond albedo of 0.343 + or - 0.032. Infrared spectra recorded at the same time by the Michelson interferometer, along with a model extrapolation to low wave numbers not covered by the instrument, yield a thermal emission of (1.359 + or - 0.014) .001 W cm to the (-2) power. As in the case of the albedo measurement, the quoted errors in the emission measurement reflect estimates of systematic effects and are uncertain while the random component is negligible. From these measurements the internal heat flux of Jupiter is estimated to be (5.444 + or - 0.425) .0001 W cm to the (-2) power, and the energy balance defined as the ratio of emitted thermal to absorbed solar energy is 1.668 + or - 0.085.

Gautier, D.↗
NASA NTRS1978

What the Voyager infrared investigators hope to learn about the Saturn system

The Voyager infrared investigation uses a Michelson interferometer (IRIS) covering the spectral range from 200 to 3000 cm/1 (3.3 to 50 micrometers) and a bore sighted radiometer covering the range from 5000 to 25000 cm/1 (0.4 to 2 micrometers). The spectral resolution of the interferometer is 4.3 cm/1 and the field of view is 0.25 deg. Scientific results anticipated from the investigation of the Saturnian system are discussed.

Hanel, R. A.↗
NASA NTRS1977

High spectral resolution ground-based observations of Venus in the 450- to 1250 kayser region

Ground-based observations of Venus were made with a 5-cm drive Michelson interferometer during December 1970 and December 1973. The thermal emission spectrum of the central portion of the apparent disk was recorded from 450-1250 kaysers with an apodized spectral resolution of 0.25 kaysers. All statistically significant sharp line-absorption features in the spectrum have been identified with gaseous CO2. Comparison between the observed spectrum and a synthetic spectrum computed from a model atmosphere, assuming gaseous CO2 and a sulfuric acid haze as opacity sources, indicates good agreement. A broad diffuse absorption feature associated with the sulfuric acid haze is evident in the 870- to 930 kayser region. With the exception of the rotational lines of the 927 kayser CO2 band, the above feature appears as a continuum down to 0.25 kayser resolution. In the 750- to 1250 kayser range, the spectrum exhibits moderate thermal contrast with maximum brightness temperatures of 234-238 K occurring near 825 kaysers. These temperatures are in general agreement with previous measurements.

Kunde, V. G.↗
NASA NTRS1976

High spectral resolution ground-based observations of Venus in the 450-1250 cm sup-1 region

The thermal emission of Venus was recorded during the winter of 1970-1971, and in 1973 using the 2.7m telescope at McDonald Observatory. The double beam Michelson interferometer installed at the Coude focus was used. The spectrum was recorded between 400/cm and 1,400/cm. For the 1970 observations, the spectral resolution was 0.25/cm and the linear spatial resolution was 3/4 of the disk of Venus. In 1973 the spectral resolution was 0.20/cm with a spatial resolution 1/3 of the planetary disk. In addition to Venus, the moon, the sky adjacent to each object, and the zenith sky were recorded to help eliminate the absorption and emission effects of the earth's atmosphere.

Kunde, V. G.↗
NASA NTRS1976

Exploration of the giant planets by infrared spectroscopy

The infrared spectrometer and radiometer for the Mariner-Jupiter-Saturn mission is described. Results of Nimbus and Mariner 9 IR spectroscopy of earth and Mars are used as examples to demonstrate the power and diversity of the technique. Determinations of planetary surface compositions, surface temperatures, vertical temperature profiles, surface pressures, and atmospheric constituents are summarized. Applications to Jupiter and Saturn are briefly mentioned.

Hanel, R. A.↗
NASA NTRS1975

Fourier spectroscopy in planetary research

The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, The Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered. The prospects and limitations of FTS for planetary research in the forthcoming years are discussed.

Hanel, R. A.↗
NASA NTRS1975

Venus cloud properties - Infrared opacity and mass mixing ratio

By using the Mariner 5 temperature profile and a homogeneous cloud model, and assuming that CO2 and cloud particles are the only opacity sources, the wavelength dependence of the Venus cloud opacity is inferred from the infrared spectrum of the planet between 450 and 1250 per cm. Volume extinction coefficients varying from 0.000005 to 0.000015 per cm, depending on the wavelength, are determined at the tropopause level of 6110 km. By using all available data, a cloud mass mixing ratio of approximately 0.000005 and a particle concentration of about 900 particles per cu cm at this level are also inferred. The derived cloud opacity compares favorably with that expected for a haze of droplets of a 75% aqueous solution of sulfuric acid.

Samuelson, R. E.↗
NASA NTRS1974

Fourier spectroscopy and planetary research

The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, the Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered and the prospects and limitations of FTS for planetary research in the forthcoming years are discussed.

Hanel, R. A.↗
NASA NTRS1974

Venus cloud properties: Infrared opacity and mass mixing ratio

By using the Mariner 5 temperature profile and a homogeneous cloud model, and assuming that CO2 and cloud particles are the only opacity sources, the wavelength dependence of the Venus cloud opacity is inferred from the infrared spectrum of the planet between 450 and 1250/cm. Justification for applying the homogeneous cloud model is found in the fact that numerous polarization and infrared data are mutually consistent within the framework of such a model; on the other hand, dense cloud models are not satisfactory. Volume extinction coefficients varying from 0.000005 to 0.000015/cm depending on the wavelength, are determined at the tropopause level of 6110 km. By using all available data, a cloud mass mixing ratio of approximately 0.000005 and a particle concentration of about 900 particles per cu cm at this level are also inferred. The derived cloud opacity compares favorably with that expected for a haze of droplets of a 75% aqueous solution of sulfuric acid.

Samuelson, R. E.↗
NASA NTRS1974

Nimbus 4 IRIS spectra in the 750-1250 wavelengths/cm atmospheric window region

Present operational schemes for infrared remote sounding measurements of surface temperature use the 899 wavelengths/cm atmospheric window region. Spectra from the Nimbus 4 IRIS in the 750 to 1250 wavelengths/cm region are analyzed. Comparison of the actual surface temperature and the observed brightness temperature at 10 wavelengths/cm resolution shows that the clearest windows were at 936 and 960 wavelengths/cm. Although there is a small amount of CO2 absorption in these regions, this is compensated for by a decrease in water vapor continuum absorption. Atmospheric absorption was 0.5 K less than experienced by the 899 wavelengths/cm window.

Kunde, V. G.↗
NASA NTRS1974

The Nimbus 4 infrared spectroscopy experiment. II - Comparison of observed and theoretical radiances from 425-1450 wavelengths/cm

The Nimbus 4 infrared interferometer spectrometer (IRIS) measured the thermal emission of the earth's atmosphere and surface from 400-1600 wavelengths/cm with an apodized spectral resolution of 2.8 wavelengths/cm. A comparison of theoretical radiances, computed from in situ measurements and using a direct integration slant path atmospheric transmittance model, with the observed IRIS radiances has been made to verify the radiometric and spectral performance of the instrument and to assess the accuracy of the atmospheric transmittances. The radiance comparison has indicated a relatively constant difference of less than 5% in the water vapor continuum in the 425 to 550 wavelengths/cm and 750 to 1200 wavelengths/cm atmospheric 'window' regions, whereas in the 667 wavelengths/cm CO2 band the difference was 5-10%.

Kunde, V. G.↗
NASA NTRS1973

Mars - Mariner 9 spectroscopic evidence for H2O ice clouds

Spectral features observed with the Mariner 9 interferometer spectrometer are identified as those of H2O ice. The measured spectra are compared with theoretical calculations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate H2O ice clouds composed of particles with a mean radius of 2.0 microns and an integrated cloud mass of .00005 g/sq cm.

Curran, R. J.↗
NASA NTRS1973

Mars: Mariner 9 spectroscopic evidence for H2O ice clouds

Spectral features observed with the Mariner 9 Interferometer Spectrometer are identified as those of water ice. Measured spectra are compared with theoretical calulations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate water ice clouds composed of particles with mean radius 2.0 microns and integrated cloud mass 0.00005 g/sq cm.

Curran, R. J.↗
NASA NTRS1973

The Nimbus 4 infrared spectroscopy experiment. 2: Comparison of observed and theoretical radiance from 425-1450 cm(minus 1)

The Nimbus 4 infrared interferometer spectrometer (IRIS) measured the thermal emission of the earth's atmosphere and surface from 400-1600/cm with an apodized spectral resolution of 2.8/cm. A comparison of theoretical radiances, computed from in-situ measurements and using a direct integration slant path atmospheric transmittance model, with the observed IRIS radiances has been made to verify the radiometeric and spectral performance of the instrument and to assess the accuracy of the atmospheric transmittances. The radiance comparison has indicated a relatively constant difference of less than 5% in the water vapor continuum in the 425-550/cm and 750-1200/cm atmospheric window regions while in the 667/cm CO2 band the difference was 5-10%. The absolute accuracy was found to be approximately 5-10% for each of the parameters; measured radiances, in-situ measurements, and the atmospheric transmittances, thus it is not possible to uniquely specify the degree of error arising from each parameter in the total resultant difference.

Kunde, V. G.↗
NASA NTRS1973

Nimbus 4 IRIS spectra in the 750-1250/cm atmospheric window region

Several Nimbus 4 IRIS spectra are presented for the 700-1300/cm region as examples of free atmosphere spectra to illustrate problems encountered in interpreting window measurements. Several atmospheric windows near 936 and 960/cm appear significantly more transparent than the 899/cm window presently used in operational remote sensing systems.

Kunde, V. G.↗