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NASA NTRS1986

Advanced infrared astronomy

The CO2 laser heterodyne spectrometer was used at the 3-m IRTF on Mauna Kea to make measurements of Mars during the 1984 opposition. Analysis of the observations of the mesospheric non-thermal emission demonstrated the existence of a warming of the Mars polar mesosphere, similar to the seasonal effects which are well known to occur at the Earth's mesopause. A search for CO2 and NH3 on Comet Halley was done with the new Kitt Peak system as well as with the IRTF heterodyne system. A Lamb-dip absorption cell was designed and constructed. Its use will allow extreme frequency stabilization of the laser local oscillator, which will greatly facilitate measurements of winds and dynamical phenomena. The Lamb-dip cell was used at Kitt Peak to study zonal and meridional winds in the atmosphere of Venus. Water vapor was detected in Comet Halley using Fourier transform spectrometer. The 2.65 micrometer upsilon sub 3 band was seen in emission, confirming non-thermal-equilibrium excitation models for comets. A study was made of the variability of Jovian ethane emission. The average volume mixing ratio of ethane in the Jovian stratosphere was found to be 3x10 to the -6 power, with the greatest variability seen in the auroral regions.

Mumma, M. J.↗
NASA NTRS1986

Theoretical and observational planetary physics

This program supports NASA's deep space exploration missions, particularly those to the outer Solar System, and also NASA's Earth-orbital astronomy missions, using ground-based observations, primarily with the NASA IRTF at Mauna Kea, Hawaii, and also with such instruments as the Kitt Peak 4 meter Mayall telescope and the NRAO VLA facility in Socorro, New Mexico. An important component of the program is the physical interpretation of the observations. There were two major scientific discoveries resulting from 8 micrometer observations of Jupiter. The first is that at that wavelength there are two spots, one near each magnetic pole, which are typically the brightest and therefore warmest places on the planet. The effect is clearly due to precipitating high energy magnetospheric particles. A second ground-based discovery is that in 1985, Jupiter exhibited low latitude (+ or - 18 deg.) stratospheric wave structure.

Caldwell, J.↗
NASA NTRS1986

Planetary submillimeter spectroscopy

A comprehensive observational strategy was developed for the detection and measurement of molecular lines in the millimeter and submillimeter spectra of planetary atmospheres and comets. A sound observational strategy and the associated analytical capability to begin observations from the Caltech Submm Observatory (CSO) on Mauna Kea in FY 87-88. Comet Halley was observed from the NASA-KAO with the dual-frequency (0.8 and 1.6 mm) receiver and conducted a search for NH3 with the DSN 64 m antenna.

Klein, M. J.↗
NASA NTRS1986

Planet-crossing asteroids: Interrelationships within the solar system

Near-infrared reflectance spectra 0.6 to 2.5 micrometer were acquired of asteroids 1627 Ivar (Amor), 43 Ariadne, 335 Roberta, 386 Siegena and 695 Bella (3:1 Kirkwood Gap) with the IRTF, Mauna Kea. CCD spectra 0.5-1.0 micrometer were acquired of 1866 Sisyphus (Apollo), 17 Thetis, 695 Bella, 797 Montana, and 877 Walkure (3:1 Kirkwood Gap) using facilities at Cerro Tololo Inter-American Observatory. An upper limit on the production rate of CN in asteroid 3200 Phaeton of < 4 x 10 to the 23rd power sec was determined based on photometric measurements at 3871A using facilities at Lowell Observatory. This value is in the range of the lowest production rate measured for a comet, however, it does not constitute a positive detection of CN in this asteroid. A first attempt of look for companion objects or evidence of dust debris associated with this asteroid was made with a CCD camera. Whereas the search extended to 19th magnitude (corresponding to 150m and 330m for albedos of 0.15 and 0.03 respectively), a look close enough to the asteroid was not attained to definitively eliminate the presence of coorbiting dust debris.

Mcfadden, L. A.↗
NASA NTRS1987

The 1986 DA and 1986 EB: M-class asteroids in near-Earth orbits

The Earth-approaching asteroid population is composed of asteroids in orbits with short lifetimes compared with the age of the solar system. These objects which are comprised of Aten, Apollo, and Amor asteroids must be replenished from either cometary or mainbelt asteroid sources since lifetimes against collision with or ejection by a planet are on the order of 10 to 100 million years. The physical study of Earth-approaching asteroids is constrained by the generally long period between favorable apparitions and poorly known orbits. Broadband spectrophotometry on the Johnson UBVR system and the Eight-Color Asteroid Survey system were obtained at Kitt Peak National Observatory and on the Johnson JHK system and at 10 and 20 microns at the NASA Infrared Telescope Facility at Mauna Kea Observatory. These observations were used to determine the absolute visual magnitudes and to derive the visual geometric albedos and diameters on the IRAS system. The spectral reflectance properties and geometric albedos of the M-class asteroids are consistent compositions analogous to the iron nickel meteorites or the enstatite-metal assemblages of the enstatite chondrites. The issue of the source(s) of the near-Earth asteroids population was examined by comparing the classifications on the scheme employed by Gradie and Tedesco of 38 such asteroids. Most of the near-Earth objects is indeed the asteroid belt as the observations suggest, then a method for removing extinct nuclei of short period comets must be found since the rate of production of short period comets from the long period comets is relatively large.

Gradie, Jonathan↗
NASA NTRS1987

Non-equilibrium freezing of water-ice in sandy basaltic regoliths and implications for fluidized debris flows on Mars

Many geomorphic features on Mars were attributed to Earth-analogous, cold-climate processes involving movement of water or ice lubricated debris. Clearly, knowledge of the behavior of water in regolith materials under Martian conditions is essential to understanding the postulated geomorphic processes. Experiments were performed with sand-sized samples of natural basaltic regoliths in order to further elucidate how water/regolith interactions depend upon grain size and mineralogy. The data reveal important contrasts with data for clay-mineral substrates and suggest that the microphysics of water/mineral interactions might affect Martian geomorphic processes in ways that are not fully appreciated. Sand and silt sized fractions of two soils from the summit of Mauna Kea were used as Mars-analogous regolith materials. Temperatures were measured for water/ice phase transitions as wet slurries of individual soil fractions which were cooled or heated at controlled rates under a carbon dioxide atmosphere. Freezing and melting of ice was studied as a function of water/soil mass ratio, soil particle size, and thermal-cycle rate. Comparison tests were done under the same conditions with U.S. Geological Survey standard rock powders.

Gooding, J. L.↗
NASA NTRS1986

The variability of Halley's Comet during the Vega, Planet-A, and Giotto encounters

Narrowband photometry of Halley obtained at Cerro Tololo Inter-American Observatory (CTIO), Mauna Kea Observatory (MKO), and Perth Observatory was combined to determine the relative level of activity during the interval spanning the spacecraft encounters. Measurements of the flux from the comet in emission bands of OH, NH, CN, C3, and C2, as well as at 2 continuum points, were obtained at CTIO on each night between 5 March and 17 March 1986. Observations were made on many of these same dates at MKO and Perth using comparable interference filters. The date clearly show variation of a factor of 2.5 in the production of all observed species with a characteristic time scale of a few days.

Schleicher, D. G.↗
NASA NTRS1986

Submillimeter and millimeter observations of Uranus and Neptune

Neptune and Uranus were studied at submillimeter and millimeter wavelengths for 2 yr using the UK IR telescope and the NASA IR telescope at Mauna Kea and the 12 dish at Kitt Peak, AZ. The brightness temperatures of both planets are provided at various wavelengths over the 0.35-3.3 mm interval scanned in the study. The present data, in combination with data from the 17 microns-3 mm interval scanned in the study. The present data, in combination with data from the 17 microns-3 mm interval taken during previous campaigns, are employed to model the temperature structures in the atmospheres of the two planets over the vertical range 100 mbar-8 bar. The data support the presence of active convection processes at the 1 bar level and deeper in both atmospheres. A static equilibrium however, exists between para-H2 and ortho-H2, along with a constant CH4 fraction of 2 percent. Deficiencies in the current database are detailed.

Orton, G. S.↗
NASA NTRS1987

Infrared radiometry of Uranus and Neptune at 21 and 32 microns

Mauna Kea's NASA IRTF has been used to obtain 21- and 32-cm radiometric measurements of Uranus and Neptune; brightness temperatures of 54.1 + or - 0.3 K for Uranus and 58.1 + or 0.3 K for Neptune were obtained by calibrating the 21-cm data against Alpha Boo. A calibration of the 32-cm data against Callisto and Ganymede yielded respective temperatures of 51.8 + or - 1.5 K and 55.6 + or - 1.2 K. The general decrease of brightness temperatures with wavelength from 20 to 30 microns is confirmed. The two planets are noted to appear as bodies sufficiently different to depart from the hypothesis of smooth planetary bulk property variation as a function of heliocentric distance.

Orton, Glenn S.↗
NASA NTRS1987

The distribution of gas and galaxies around the distant quasar PKS 1614 + 051

The results of narrow-band and broad-band filter observations of the region surrounding the z = 3.21 quasars, PKS 1614 + 051, made under subarcsec seeing conditions with the 3.6 m CFHT telescope at Mauna Kea are reported. The nuclear region of the Lyman-alpha companion to the quasar is resolved with a FWHM of about 0.9 arcsec A magnitude fainter. Limits on detectable continuum flux from this object suggest that it is a gas cloud interacting with the quasar, and its emission is consistent with simple photoionization by the quasar. However, the presence of several galaxies around the periphery of the quasar is noted. A search of 11 additional quasars at z greater than 3 has failed to show any other such systems. It is argued that this is consistent with the statistics of extended emission line systems in low-z quasars.

Hu, Esther M.↗
NASA NTRS1987

Mars: Near-infrared comparative spectroscopy during the 1986 opposition

Near-infrared spectral observations of Mars during the 1986 opposition were performed at the Mauna Kea Observatory utilizing the University of Hawaii's 88 inch telescope. Spectra were obtained of several Martian locations using a continuously variable filter (CVF) spectrometer with a resolution of 1.25 percent. Spot-to-spot ratios were produced between spectra taken in different geological regions.

Bell, James F., III↗
NASA NTRS1987

Recent comet impacts on the moon - The evidence from remote-sensing studies

Multispectral images and near-infrared reflectance spectra were obtained for the Reiner Gamma Formation, a swirllike albedo and magnetic anomaly in the western portion of the lunar near side, as well as for nearby geologic units in Oceanus Procellarum, using the University of Hawaii 2.24-m telescope at the Mauna Kea Observatory. The spectra of the high albedo swirl material are closely matched by models incorporating 90-95 percent fresh mare basalt with 5-10 percent highlands debris.

Bell, Jeffrey F.↗
NASA NTRS1987

The impact of infrared arrays on 1-5 microns spectroscopy

The use of two-dimensional infrared arrays for astronomical imaging and spectroscopy is now occurring and immensely changing the field. In view of this 'revolution' in infrared astronomy, some of the implications for future infrared spectroscopy are discussed in this paper. A method is presented for comparing the infrared background to future spectrometers at 1-5 microns. Some of the current developments in infrared spectroscopy at Mauna Kea are discussed.

Tokunaga, Alan↗
NASA NTRS1987

Undercooled water in basaltic regoliths and implications for fluidized debris flows on Mars

Pursuant to the past attribution of many geomorphic features on Mars to the movements of water- or ice-lubricated debris, experiments have been conducted for water freezing in wet, sand-like basaltic substrates. It is found that substantial undercooling can be achieved under Martian conditions, independently of freezing-point depressions due to soluble salts. Attention is given to results for a clay-poor soil with negligible salinity from Mauna Kea, Hawaii, which demonstrate that the degree of undercooling is essentially independent of both soil particle size and water/soil mass ratio, albeit with cooling rate variations.

Gooding, James L.↗
NASA NTRS1987

Nitrous oxide in the tropical middle atmosphere, observed by ground-based mm-wave spectrometry

Measurements of stratospheric N2O were made from Mauna Kea in Hawaii in June 1983, and in May and June 1986, by observing thermal emission of the molecule in a rotational transition at about 1 mm wavelength. Analyses of the data yield altitude profiles in the middle and upper stratosphere. Useful measurements of N2O may be made in one to two hours. The N2O profiles agree reasonably well with model predictions and with published satellite data, though significantly more N2O is reported near the stratopause than shown by the satellite measurement, and significantly more N2O in the middle stratosphere than in one of the models. The discrepancy between these data and the satellite measurement may be due in part to variations induced by the solar cycle.

Connor, Brian J.↗
NASA NTRS1988

mm-wave observations of stratospheric HCN at tropical latitudes

Middle and upper stratospheric HCN has been measured using ground-based mm-wave emission spectroscopy during a series of observations made in Mauna Kea, HI, in June 1986. A volume mixing ratio of 190 + or - 40 pptv at about 40 km, and a decrease of concentration with altitude that is considerably slower than that predicted by current models are found. This could be an indication of an atmospheric source of HCN as yet unidentified.

Jaramillo, M.↗
NASA NTRS1988

V482 Cygni - An R Coronae Borealis star in a quadruple system

Observations of the R CrB variable star V482 Cyg, obtained with the University of Rochester 32 x 32 InSb array camera at the NASA IR Telescope Facility on Mauna Kea on August 20, 1984, are reported. The data-reduction and analysis procedures are described in detail, and the results are presented in tables and maps. V482 Cyg is shown to be a member of a quadruple system or perhaps a small obscured cluster. Parameters determined include distance 1.7 kpc, circumstellar-shell temperature 800 K, and absolute magnitude M(V) = -2.8.

Gaustad, John E.↗
NASA NTRS1988

Infrared polar brightenings on Jupiter. IV - Spatial properties of methane emission

Different polar 'hot spot' differences are revealed between the northern and southern hemispheres of Jupiter by 7.8-micron observations made with NASA's Mauna Kea IR Telescope Facility. While the northern hot spot is fixed, relative to system III coordinates, at 180 + or - 10 deg longitude and 60 + or - 10 deg latitude, the southern hot spot is fixed with respect to neither the system III longitude and latitude, nor the subpolar point, or even Io's position. Voyager I IRIS data show the north polar hot spot to be more extended in longitude than latitude.

Caldwell, John↗