42 results on '"Cruikshank, Dale P."'
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2. Organic Molecules in the Icy Bodies of Planetary Systems – Accepted Notions and New Ideas
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Simonia Irakli and Cruikshank Dale P.
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comets ,planets ,ice ,organic matter ,prebiotic evolution ,Astronomy ,QB1-991 - Abstract
Cometary bodies are acknowledged to contain some of the most pristine matter in the Solar System, including ices and minerals. Certain number of previously unidentified spectral emission features detected in comets can be explained as emission by hydrocarbon molecules enclosed in a Shpolskii matrix and forming frozen hydrocarbon particles. UV-induced photoluminescence spectra of several self-organized molecules exhibit emission lines coincident with unidentified cometary lines, and open the possibility of the presence of this complex organic as components of the pristine organic inventory of comets. Complex organic was detected also in three satellites of Saturn. We describe in this paper results of our investigation of complex organic of the small bodies and present new approaches and hypotheses.
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- 2018
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- View/download PDF
3. Discovering Pluto : Exploration at the Edge of the Solar System
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CRUIKSHANK, DALE P., SHEEHAN, WILLIAM, CRUIKSHANK, DALE P., and SHEEHAN, WILLIAM
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- 2018
4. Eclipse reappearances of Io: Time-resolved spectroscopy (1.9-4.2[mu]m)
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Cruikshank, Dale P., Emery, Joshua P., Kornei, Katherine A., Bellucci, Giancarlo, and D'Aversa, Emiliano
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Astronomy ,Spectrum analysis ,Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.05.035 Byline: Dale P. Cruikshank (a), Joshua P. Emery (b), Katherine A. Kornei (c), Giancarlo Bellucci (d), Emiliano d'Aversa (d) Keywords: Io; Ices; IR spectroscopy; Satellites; Surfaces Abstract: We obtained time-resolved, near-infrared spectra of Io during the 60-90min following its reappearance from eclipse by Jupiter on five occasions in 2004. The purpose was to search for spectral changes, particularly in the well-known SO.sub.2 frost absorption bands, that would indicate surface-atmosphere exchange of gaseous SO.sub.2 induced by temperature changes during eclipse. These observations were a follow-on to eclipse spectroscopy observations in which Bellucci et al. [Bellucci et al., 2004. Icarus 172, 141-148] reported significant changes in the strengths of two strong SO.sub.2 bands in data acquired with the VIMS instrument aboard the Cassini spacecraft. One of the bands (4.07[mu]m [[nu].sub.1 + [nu].sub.3]) observed by Bellucci et al. is visible from ground-based observatories and is included in our data. We detected no changes in Io's spectrum at any of the five observed events during the approximately 60-90min during which spectra were obtained following Io's emergence from Jupiter's shadow. The areas of the three strongest SO.sub.2 bands in the region 3.5-4.15[mu]m were measured for each spectrum; the variation of the band areas with time does not exceed that which can be explained by the Io's few degrees of axial rotation during the intervals of observation, and in no case does the change in band strength approach that seen in the Cassini VIMS data. Our data are of sufficient quality and resolution to show the weak 2.198[mu]m (4549.6cm.sup.-1) 4[nu].sub.1 band of SO.sub.2 frost on Io for what we believe is the first time. At one of the events (June 22, 2004), we began the acquisition of spectra [approximately equal to]6min before Io reappeared from Jupiter's shadow, during which time it was detected through its own thermal emission. No SO.sub.2 bands were superimposed on the purely thermal spectrum on this occasion, suggesting that the upper limit to condensed SO.sub.2 in the vertical column above Io's surface was [approximately equal to]4x10.sup.-5 gcm.sup.-2. Author Affiliation: (a) NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA (b) Dept. of Earth and Planetary Sciences, University of Tennessee, 1412 Circle Dr., Knoxville, TN 37996, USA (c) Dept. of Physics and Astronomy, University of California Los Angeles, Box 951547, Los Angeles, CA 90095, USA (d) INAF-IFSI, Istituto di Fisica dello Spazio Interplanetario, Area Ricerca Tor Vergata, Via Fosso del, Cavaliere 100, I-00133 Roma, Italy Article History: Received 25 September 2006; Revised 28 April 2009; Accepted 1 May 2009
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- 2010
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5. Origins of the Lunar and Planetary Laboratory, University of Arizona
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Cruikshank, Dale P and Hartmann, W. K
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Astronomy - Abstract
The roots of the Lunar and Planetary Laboratory (LPL) extend deep into the rich fabric of G. P. Kuiper's view of the Earth as a planet and planetary systems as expected companions to most stars, as well as the post-war emergent technology of infrared detectors suitable for astronomy. These concepts and events began with Kuiper's theoretical work at Yerkes Observatory on the origin of the Solar System, his discovery of two planetary satellites and observational work with his near-infrared spectrometer on the then-new McDonald 82-inch telescope in the mid- to late-1940s. A grant for the production of a photographic atlas of the Moon in the mid-1950s enabled him to assemble the best existing images of the Moon and acquire new photographs. This brought E. A. Whitaker and D. W. G. Arthur to Yerkes. Others who joined in the lunar work were geologist Carl S. Huzzen and grad student E. P. Moore, as well as undergrad summer students A. B. Binder and D. P. Cruikshank (both in 1958). The Atlas was published in 1959, and work began on an orthographic lunar atlas. Kuiper's view of planetary science as an interdisciplinary enterprise encompassing astronomy, geology, and atmospheric physics inspired his vision of a research institution and an academic curriculum tuned to the combination of all the scientific disciplines embraced in a comprehensive study of the planets. Arrangements were made with the University of Arizona (UA) to establish LPL in affiliation with the widely recognized Inst. of Atmospheric Physics. Kuiper moved to the UA in late 1960, taking the lunar experts, graduate student T. C. Owen (planetary atmospheres), and associate B. M. Middlehurst along. G. van Biesbroeck also joined the migration to Tucson; Binder and Cruikshank followed along as new grad students. Astronomy grad student W. K. Hartmann came into the academic program at UA and the research group at LPL in 1961. Senior faculty affiliating with LPL in the earliest years were T. Gehrels, A. B. Meinel, H. L. Johnson, and F. J. Low, each with their own grad students and associates. Work began on IR spectroscopy and a rectified lunar atlas. Kuiper and Johnson started the search for future observatory sites in N. America and Hawaii.
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- 2014
6. Carbon dioxide on planetary bodies: Theoretical and experimental studies of molecular complexes
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Chaban, Galina M., Bernstein, Max, and Cruikshank, Dale P.
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Submarine boats ,Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.10.010 Byline: Galina M. Chaban, Max Bernstein, Dale P. Cruikshank Keywords: Ices; Infrared observations; Spectroscopy; Jupiter; satellites; Saturn; satellites; Satellites; surfaces Abstract: An absorption band at [approximately equal to]4.26[mu]m wavelength attributed to the asymmetric stretching mode of CO in CO.sub.2 has been found on two satellites of Jupiter and several satellites of Saturn. The wavelength of pure CO.sub.2 ice determined in the laboratory is 4.2675 [mu]m, indicating that the CO.sub.2 on the satellites occurs either trapped in a host material, or in a chemical or physical complex with other materials, resulting in a blue shift of the wavelength of the band. In frequency units, the shifts in the satellite spectra range from 3.7 to 11.3 cm.sup.-1. We have performed ab initio quantum chemical calculations of CO.sub.2 molecules chemically complexed with one, two, and more H.sub.2O molecules and molecules of CH.sub.3OH to explore the possibility that the blue shift of the band is caused by chemical complexing of CO.sub.2 with other volatile materials. Our computations of the harmonic and anharmonic vibrational frequencies using high levels of theory show a frequency shift to the blue by 5 cm.sup.-1 from pure CO.sub.2 to CO-H.sub.2O, and an additional 5 cm.sup.-1 from CO.sub.2-H.sub.2O to CO.sub.2-2H.sub.2O. Complexing with more than two H.sub.2O molecules does not increase the blue shift. Complexes of CO.sub.2 with one molecule of CH.sub.3OH and with one CH.sub.3OH plus one H.sub.2O molecule produce smaller shifts than the CO.sub.2-2H.sub.2O complex. Laboratory studies of CO.sub.2:H.sub.2O in a solid N.sub.2 matrix also show a blue shift of the asymmetric stretching mode. Author Affiliation: NASA Ames Research Center, Mail Stop T27B-1, Moffett Field, CA 94035-1000, USA Article History: Received 15 August 2006; Revised 10 October 2006
- Published
- 2007
7. Near-infrared spectra of laboratory H.sub.2O-CH.sub.4 ice mixtures
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Bernstein, Max P., Cruikshank, Dale P., and Sandford, Scott A.
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Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.10.021 Byline: Max P. Bernstein, Dale P. Cruikshank, Scott A. Sandford Keywords: Ices; Infrared observations; Spectroscopy; Surfaces; planets; Surfaces; satellites Abstract: We present 1.25-19 [mu]m infrared spectra of pure solid CH.sub.4 and H.sub.2O/CH.sub.4=87, 20, and 3 solid mixtures at temperatures from 15 to 150 K. We compare and contrast the absorptions of CH.sub.4 in solid H.sub.2O with those of pure CH.sub.4. Changes in selected peak positions, profiles, and relative strength with temperature are presented, and absolute strengths for absorptions of CH.sub.4 in solid H.sub.2O are estimated. Using the two largest ([nu].sub.3+[nu].sub.4) and ([nu].sub.1+[nu].sub.4) near-IR absorptions of CH.sub.4 at 2.324 and 2.377 [mu]m (4303 and 4207 cm.sup.-1), respectively, as examples, we show that peaks of CH.sub.4 in solid H.sub.2O are at slightly shorter wavelength (higher frequency) and broader than those of pure solid CH.sub.4. With increasing temperature, these peaks shift to higher frequency and become increasingly broad, but this trend is reversible on re-cooling, even though the phase transitions of H.sub.2O are irreversible. It is to be hoped that these observations of changes in the positions, profiles, and relative intensities of CH.sub.4 absorptions with concentration and temperature will be of use in understanding spectra of icy outer Solar System bodies. Author Affiliation: NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA Article History: Received 13 July 2005; Revised 17 October 2005
- Published
- 2006
8. Near-infrared laboratory spectra of solid H.sub.2O/CO.sub.2 and CH.sub.3OH/CO.sub.2 ice mixtures
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Bernstein, Max P., Cruikshank, Dale P., and Sandford, Scott A.
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Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.07.009 Byline: Max P. Bernstein, Dale P. Cruikshank, Scott A. Sandford Keywords: Ices; infrared observations; Spectroscopy; Surfaces; planets; satellites Abstract: We present near-IR spectra of solid CO.sub.2 in H.sub.2O and CH.sub.3OH, and find they are significantly different from that of pure solid CO.sub.2. Peaks not present in either pure H.sub.2O or pure CO.sub.2 spectra become evident when the two are mixed. First, the putative theoretically forbidden CO.sub.2 (2[nu].sub.3) overtone near 2.134 [mu]m (4685 cm.sup.-1), that is absent from our spectrum of pure solid CO.sub.2, is prominent in the spectra of H.sub.2O/CO.sub.2=5 and 25 mixtures. Second, a 2.74-[mu]m (3650 cm.sup.-1) dangling OH feature of H.sub.2O (and a potentially related peak at 1.89 [mu]m) appear in the spectra of CO.sub.2-H.sub.2O ice mixtures, but are probably not diagnostic of the presence of CO.sub.2. Other CO.sub.2 peaks display shifts in position and increased width because of intermolecular interactions with H.sub.2O. Warming causes some peak positions and profiles in the spectrum of a H.sub.2O/CO.sub.2=5 mixture to take on the appearance of pure CO.sub.2. Absolute strengths for absorptions of CO.sub.2 in solid H.sub.2O are estimated. Similar results are observed for CO.sub.2 in solid CH.sub.3OH. Since the CO.sub.2 (2[nu].sub.3) overtone near 2.134 [mu]m (4685 cm.sup.-1) is not present in pure CO.sub.2 but prominent in mixtures, it may be a good observational (spectral) indicator of whether solid CO.sub.2 is a pure material or intimately mixed with other molecules. These observations may be applicable to Mars polar caps as well as outer Solar System bodies. Author Affiliation: NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA Article History: Received 4 February 2005; Revised 6 June 2005
- Published
- 2005
9. A spectroscopic study of the surfaces of Saturn's large satellites: [H.sub.2]O ice, tholins, and minor constituents
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Cruikshank, Dale P., Owen, Tobias C., Ore, Cristina Dalle, Geballe, Thomas R., Roush, Ted L., de Bergh, Catherine, Sandford, Scott A., Poulet, Francois, Benedix, Gretchen K., and Emery, Joshua P.
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Saturn (Planet) -- Discovery and exploration ,Astronomy ,Earth sciences - Abstract
We present spectra of Saturn's icy satellites Mimas, Enceladus, Tethys, Dione, Rhea, and Hyperion, 1.0-2.5 [micro]m, with data extending to shorter (Mimas and Enceladus) and longer (Rhea and Dione) wavelengths for certain objects. The spectral resolution (R = [lambda]/[DELTA][lambda]) of the data shown here is in the range 800-1000, depending on the specific instrument and configuration used; this is higher than the resolution (R = 225 at 3 [micro]m) afforded by the Visual-Infrared Mapping Spectrometer on the Cassini spacecraft. All of the spectra are dominated by water ice absorption bands and no other features are clearly identified. Spectra of all of these satellites show the characteristic signature of hexagonal [H.sub.2]O ice at 1.65 [micro]m. We model the leading hemisphere of Rhea in the wavelength range 0.3-3.6 [micro]m with the Hapke and the Shkuratov radiative transfer codes and discuss the relative merits of the two approaches to fitting the spectrum. In calculations with both codes, the only components used are [H.sub.2]O ice, which is the dominant constituent, and a small amount of tholin (Ice Tholin II). Tholin in small quantities (few percent, depending on the mixing mechanism) appears to be an essential component to give the basic red color of the satellite in the region 0.3-1.0 [micro]m. The quantity and mode of mixing of tholin that can produce the intense coloration of Rhea and other icy satellites has bearing on its likely presence in many other icy bodies of the outer Solar System, both of high and low geometric albedos. Using the modeling codes, we also establish detection limits for the ices of C[O.sub.2] (a few weight percent, depending on particle size and mixing), C[H.sub.4] (same), and N[H.sub.4]OH (0.5 weight percent) in our globally averaged spectra of Rhea's leading hemisphere. New laboratory spectral data for N[H.sub.4]OH are presented for the purpose of detection on icy bodies. These limits for C[O.sub.2], C[H.sub.4], and N[H.sub.4]OH on Rhea are also applicable to the other icy satellites for which spectra are presented here. The reflectance spectrum of Hyperion shows evidence for a broad, unidentified absorption band centered at 1.75 [micro]m. Keywords: Ices: Infrared observations: Satellites of Saturn: Spectroscopy: Surfaces, satellite: Organic chemistry
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- 2005
10. Neptune and Triton
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Cruikshank, Dale P., Editor, Matthews, M. S., Schumann, A. M., Cruikshank, Dale P., Matthews, M. S., and Schumann, A. M.
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- 2016
11. Laboratory experiments of Titan tholin formed in cold plasma at various pressures: implications for nitrogen-containing polycyclic aromatic compounds in Titan haze
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Imanaka, Hiroshi, Khare, Bishun N., Elsila, Jamie E., Bakes, Emma L.O., McKay, Christopher P., Cruikshank, Dale P., Sugita, Seiji, Matsui, Takafumi, and Zare, Richard N.
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Titan (Satellite) -- Research ,Titan (Satellite) -- Natural history ,Astronomy ,Earth sciences - Abstract
Titan, the largest satellite of Saturn, has a thick nitrogen/methane atmosphere with a thick global organic haze. A laboratory analogue of Titan's haze, called tholin, was formed in an inductively coupled plasma from nitrogen/methane = 90/10 gas mixture at various pressures ranging from 13 to 2300 Pa. Chemical and optical properties of the resulting tholin depend on the deposition pressure in cold plasma. Structural analyses by IR and UV/VIS spectroscopy, microprobe laser desorption/ionization mass spectrometry, and Raman spectroscopy suggest that larger amounts of aromatic ring structures with larger cluster size are formed at lower pressures (13 and 26 Pa) than at higher pressures (160 and 2300 Pa). Nitrogen is more likely to incorporate into carbon networks in tholins formed at lower pressures, while nitrogen is bonded as terminal groups at higher pressures. Elemental analysis reveals that the carbon/nitrogen ratio in tholins increases from 1.5-2 at lower pressures to 3 at 2300 Pa. The increase in the aromatic compounds and the decrease in C/N ratio in tholin formed at low pressures indicate the presence of the nitrogen-containing polycyclic aromatic compounds in tholin formed at low pressures. Tholin formed at high pressure (2300 Pa) consists of a polymer-like branched chain structure terminated with -C[H.sub.3], -N[H.sub.2], and -C[equivalent to]N with few aromatic compounds. Reddish-brown tholin films formed at low pressures (13-26 Pa) shows stronger absorptions (almost 10 times larger k-value) in the UV/VIS range than the yellowish tholin films formed at high pressures (160 and 2300 Pa). The tholins formed at low pressures may be better representations of Titan's haze than those formed at high pressures, because the optical properties of tholin formed at low pressures agree well with that of Khare et al. (1984a, Icarus 60, 127-137), which have been shown to account for Titan's observed geometric albedo. Thus, the nitrogen-containing polycyclic aromatic compounds we find in tholin formed at low pressure may be present in Titan's haze. These aromatic compounds may have a significant influence on the thermal structure and complex organic chemistry in Titan's atmosphere, because they are efficient absorbers of UV radiation and efficient charge exchange intermediaries. Our results also indicate that the haze layers at various altitudes might have different chemical and optical properties. Keywords: Titan; Haze; Tholin; Spectroscopy; Organic chemistry; Nitrogen-containing polycyclic aromatic compounds
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- 2004
12. Analysis of the time-dependent chemical evolution of Titan haze tholin
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Khare, Bishun N., Bakes, E.L.O., Imanaka, Hiroshi, McKay, Christopher P., Cruikshank, Dale P., and Arakawa, Edward T.
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Titan (Satellite) ,Stratospheric circulation -- Observations ,Astronomy ,Earth sciences - Abstract
Haze particles exert a significant influence over the thermodynamics and radiation absorption properties of the Titan haze, as well as its complex organic chemistry. Characterization of both the molecular and the submicrometer components of the haze is therefore vital for understanding the global properties of Titan. We have carried out a Titan tholin synthesis experiment and measured the time variation of the infrared spectrum of the product as a thin film developed. Also, to examine the possibility of oxygen contamination, we compared the infrared spectrum of the tholin film with that of a tholin film exposed to dry air and laboratory air. The objective of this study is to understand the chemical processes related to how simple organic molecules are processed into more complex haze particles. The progressive development of features characteristic of amines, aromatic and aliphatic hydrocarbons, and nitriles in the experimental mixture is clear. Of particular interest is the formation of aromatic rings after only a few seconds of glow discharge, indicating that these compounds appear to be intermediates between simple haze molecules and microphysical aerosols. The early dominance of aromatic ring structures is accompanied during the later stages of the experiment by the appearance of nitrile and amine compounds. This time-dependent succession of chemical structures provides vital clues to the possible chemical formation pathways of Titan haze aerosols. Key Words: Titan; tholins; stratospheric chemistry; aromatics; amines; alkanes; hydrocarbons; aerosols.
- Published
- 2002
13. Search for the 3.4-[micro]m C-H spectral bands on low-albedo asteroids
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Cruikshank, Dale P., Geballe, Thomas R., Owen, Tobias C., Dalle Ore, Cristina M., Roush, Ted L., Brown, Robert H., and Lewis, John H.
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Asteroids -- Analysis ,Astronomical research -- Evaluation ,Astronomical spectroscopy -- Usage ,Infrared spectroscopy -- Usage ,Chemistry, Organic -- Usage ,Hydrocarbons -- Observations ,Astronomy ,Earth sciences - Abstract
A report of the detection of the C-H hydrocarbon band complex at 3.4/[micro]m in an asteroid spectrum, by D. P. Cruikshank and R. H. Brown (1987, Science 238, 183-184) is not confirmed by recent data of higher quality. Spectra of the same asteroid and six other low-albedo asteroids do not show this feature, which if present would indicate the presence of hydrocarbons and might link these asteroids with certain classes of carbonaceous meteorites. Key Words: asteroid composition; infrared observations; organic chemistry; spectroscopy; asteroid surfaces.
- Published
- 2002
14. Constraints on the composition of Trojan asteroid 624 Hektor
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Cruikshank, Dale P., Dalle Ore, Cristina M., Roush, Ted L., Geballe, Thomas R., Owen, Tobias C., de Bergh, Catherine, Cash, Michele D., and Hartmann, William K.
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Asteroids -- Models ,Astrogeology -- Research ,Astronomy ,Earth sciences - Abstract
We present a composite spectrum of Trojan asteroid 624 Hektor, 0.3-3.6 [micro]m, and models computed for the full wavelength range with the Hapke scattering theory. The data show that there is no discernible 3-[micro]m absorption band. Such a band would indicate the presence of OH- or [H.sub.2]O-bearing silicate minerals, or macromolecular carbon-rich organic material of the kind seen on the low-albedo hemisphere of Saturn's satellite Iapetus. The absence of spectral structure is itself indicative of the absence of the nitrogen-rich tholins (which show a distinctive absorption band attributed to N-H). The successful models in this study all incorporate magnesium-rich pyroxene (Mg, Fe Si[O.sub.3]), which satisfactorily matches the red color of Hektor. Pyroxene is a mafic mineral common in terrestrial and lunar lavas, and is also identified in Main Belt asteroid spectra. An upper limit to the amount of crystalline [H.sub.2]O ice (30-[micro]m grains) in the surface layer of Hektor accessible to near-infrared remote sensing observations is 3 wt%. The upper limit for serpentine, as a representative of hydrous silicates, is much less stringent, at 40%, based on the shape of the spectral region around 3 [micro]m. Thus, the spectrum at 3 [micro]m does not preclude the presence of a few weight percent of volatile material in the uppermost surface layer of Hektor. Below this 'optical' surface that our observations probe, any amount of [H.sub.2]O ice and other volatile-rich materials might exist. All of the models we calculated require a very low-albedo, neutral color material to achieve the low geometric albedo that matches Hektor; we use elemental carbon. If elemental carbon is present on Hektor, it could be of organic or inorganic origin. By analogy, other D-type asteroids could achieve their red color, low albedo, and apparent absence of phyllosilicates from compositions similar to the models
- Published
- 2001
15. The detection of water ice in comet Hale-Bopp
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Davies, John K., Roush, Ted L., Cruikshank, Dale P., Bartholomew, Mary Jane, Geballe, Thomas R., Owen, Tobias, and Bergh, Catherine de
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Hale-Bopp (Comet) -- Observations ,Comets -- Spectra ,Astronomy ,Earth sciences - Abstract
We present spectra of Comet Hale-Bopp (C/1995 O1) covering the range 1.4-2.5 [[micro]meter] that were recorded when the comet was 7 AU from the Sun. These spectra show broad absorption features at 1.5 and 2.05 [[micro]meter]. While we recognize that much of the light from the comet is scattered from the coma, we show that some, but not all, of the absorption features can be matched by an intimate mixture of water ice and a low-albedo material such as carbon on the nucleus. Furthermore, the absence of the 1.65-[[micro]meter] absorption feature of crystalline ice suggests that the cometary ice was probably in an amorphous state at the time of these observations. An unidentified additional component may be required to account for the downward slope at the long-wavelength end of the spectrum.
- Published
- 1997
16. Near-infrared spectral geometric albedos of Charon and Pluto: constraints on Charon's surface composition
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Roush, Ted L., Cruikshank, Dale P., Pollack, James B., Young, Eliot F., and Bartholomew, Mary J.
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Charon (Satellite) -- Research ,Pluto (Planet) -- Atmosphere ,Satellites -- Pluto ,Albedo -- Research ,Astronomy ,Earth sciences - Published
- 1996
17. Tholins as Coloring Agents on Outer Solar System Bodies
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Cruikshank, Dale P, Imanaka, Hiroshi, and DalleOre, Cristina M
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Astronomy - Abstract
The red colors of many solid bodies in outer Solar System may be caused by tholins, which are refractory organic complexes, incorporated in their surface materials. Tholins synthesized in the laboratory are shown to match the colors of these bodies when their optical properties are used in rigorous scattering models. We review recent successes in modeling the spectra of icy outer Solar System bodies with tholins as the coloring agents. New work on the systematic laboratory synthesis and analysis of tholins made by cold plasma discharge in mixtures of gaseous CH4/N2 shows that the composition of the tholin depends strongly on the pressure in the reaction chamber, and only weakly on the mixing fraction of CH4 relative to N2. In tholins made at high pressure (e.g., 23 hPa) the abundance of aliphatic hydrocarbons is greater and the abundance of aromatic hydrocarbons is less than in tholins made at low pressure (e.g., 0.13 hPa). Tholins made at low deposition pressures show a greater abundance of N-H bonds.
- Published
- 2005
18. Temperature of nitrogen ice on Pluto and its implications for flux measurements
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Tryka, Kimberly A., Brown, Robert H., Cruikshank, Dale P., Owen, Tobias C., Geballe, Thomas R., and DeBergh, Catherine
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Pluto (Planet) -- Research ,Astronomy ,Earth sciences - Abstract
Spectroscopic observations of Pluto reveal that the nitrogen ice on Pluto has a temperature of 40 Kelvin. This is higher than the temperature of nitrogen on the satellite Triton. The study indicates that the nitrogen on the planet is concentrated at the polar caps of the planet and absent in the equatorial region.
- Published
- 1994
19. Spectroscopy of Mars from 2.04 to 2.44 micrometer during the 1993 opposition: absolute calibration and atmospheric vs mineralogic origin of narrow absorption features
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Bell, James F., III, Pollack, James B., Geballe, Thomas R., Cruikshank, Dale P., and Freedman, Richard
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Mars (Planet) -- Spectra ,Carbon dioxide -- Research ,Solar radiation -- Research ,Astronomy ,Earth sciences - Abstract
Seven narrow absorption bands are found in the moderate-resolution reflectance spectra of Mars. The reflectance spectra are obtained using the UKIRT 3.8 meter telescope in the 2.04 to 2.44 micrometer region of the seven bands, five of which are produced by the CO2 and CO present in the atmosphere of Mars. The other two bands may be caused by nonatmospheric absorptions and may be due to the reflection of sun's light.
- Published
- 1994
20. Infrared spectroscopy of Triton and Pluto ice analogs: the case for saturated hydrocarbons
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Bohn, Robert B., Sandford, Scott A., Allamandola, Louis J., and Cruikshank, Dale P.
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Pluto (Planet) -- Atmosphere ,Hydrocarbon research -- Observations ,Astronomy ,Earth sciences - Abstract
Excess absorption features in the infrared transmission spectra of the surface of Pluto and Triton are due to the alkanes and other similar molecules frozen in the nitrogen. This indicates that Triton and Pluto have several types of organic compounds embedded in the N2 ices found on the surface. The absorption features caused by these organic compounds occur in the region lower then 4, 450 per centimeter of the spectra.
- Published
- 1994
21. Near-infrared photometry and spectroscopy of the unusual minor planet 5145 Pholus (1992AD)
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Davies, John K., Sykes, Mark V., and Cruikshank, Dale P.
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Asteroids -- Observations ,Astronomical photometry -- Usage ,Astronomy ,Earth sciences - Abstract
The near-infrared spectrum of the minor planet 5145 Pholus was investigated using near-infrared photometry. The results showed that 5145 Pholus possessed unusual red visual to infrared colors. The near-infrared spectrum featured a structure in the range of 1.8 to 2.4 micrometers. This possibly indicated that surface ices mixed with yet-unknown complex organic compounds existed on Pholus' surface.
- Published
- 1993
22. Comet Observations with SIRTF
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Cruikshank, Dale P
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Astronomy - Abstract
Comet observations are included in the programs of the Guaranteed Time Observers (GTO) on the Space Infrared Telescope Facility (SIRTF), scheduled to be in space and operational for five years beginning in late 2003. SIRTF is a cryogenic telescope with three basic instruments for imaging, photometry and spectroscopy from 3.6 m to 160 m. All of these capabilities will be used in studies of comets. The intent is to study the infrared radiation (emission) from comets (and dust tails, where relevant) in all stages of evolution, starting with Kuiper Belt objects and Centaurs (thermal emission at 24,70, and 160 m to derive dimensions and albedos). Active comets will be observed spectroscopically and in deep thermal images. Several known or suspected extinct comets will be observed spectroscopically (5-37 m) for information on their surface compositions. There are opportunities for Guest Observers (GO) to propose additional comet work. .
- Published
- 2003
23. Extraordinary colors of asteroidal object (5145) 1992 AD
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Mueller, Beatrice E.A., Tholen, David J., Hartmann, William K., and Cruikshank, Dale P.
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Asteroids -- Research ,Space biology -- Research ,Infrared spectroscopy -- Research ,Astronomy ,Earth sciences - Abstract
Asteroid 1992 AD or 5145 has been posited to harbor organic materials due to spectroscopic analysis. A history of the asteroid and the reasons for research into its make-up is presented. When compared to other asteroids, it is only the organic material which explains the unique red color. Tholins and irradiated methane ice are posited to be the organic materials in question. Additional research is recommended.
- Published
- 1992
24. Physical Properties of Centaur Objects
- Author
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Cruikshank, Dale P and DeVincenzi, Donald L
- Subjects
Astronomy - Abstract
Centaurs are objects in unstable orbits that cross the orbits of the giant planets. They are presumed to be recent additions to the planetary zone of the Solar System, having been dynamically perturbed from the Kulper Disk by the gravitational action of Neptune. Telescopic observations of Centaurs are important because they give us a view of the composition (and in some cases cometary activity) of large bodies that are normally to far from the Sun to be studied in detail. This paper reports on physical observations, primarily through spectroscopy, of the compositions of a small number of Centaurs that have been studied to date. In particular, the composition of 5145 Pholus is reviewed, following the published work of Crulkshank et al., in which compositional models that fit the spectrum well included H2O ice, the organic solid Titan tholin, a light hydrocarbon ice (e.g., CH3OH), the silicate mineral olivine, and amorphous carbon. The Centaur 1997 CU(26) shows evidence for H2O ice, but nothing else is yet identified.
- Published
- 2001
25. Solar System Studies with the Space Infrared Telescope Facility (SIRTF)
- Author
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Cruikshank, Dale P and DeVincenzi, Donald L
- Subjects
Astronomy - Abstract
SIRTF (Space Infrared Telescope Facility) is the final element in NASA's 'Great Observatories' program. It consists of an 85-cm cryogenically-cooled observatory for infrared astronomy from space. SIRTF is scheduled for launch in late 2001 or early 2002 on a Delta rocket into a heliocentric orbit trailing the Earth. Data from SIRTF will be processed and disseminated to the community through the SIRTF Science Center (SSC) located at the Infrared Processing and Analysis Center (IPAC) at Caltech. Some 80/% of the total observing time (estimated at a minimum of 7500 hours of integration time per year for the mission lifetime of about 4 years) will be available to the scientific community at large through a system of refereed proposals. Three basic instruments are located in the SIRTF focal plane. The Multiband Imaging Photometer (MIPS), the Infrared Array Camera (IRAC), and the Infrared Spectrometer (IRS), taken together, provide imaging and spectroscopy from 3.5 to 160 microns. Among the solar system studies suited to SIRTF are the following: 1) spectroscopy and radiometry of small bodies from the asteroid main belt, through the Trojan clouds, to the Kuiper Disk; 2) dust distribution in the zodiacal cloud and the Earth's heliocentric dust ring; 3) spectroscopy and radiometry of comets; and 4) spectroscopy and radiometry of planets and their satellites. Searches for, and studies of dust disks around other stars, brown dwarfs, and superplanets will also be conducted with SIRTF. The SORTIE web site (http://ssc.ipac.caltech.edu/sirtf) contains important details and documentation on the project, the spacecraft, the telescope, instruments, and observing procedures. A community-wide workshop for solar system studies with SIRTF is in the planning stages by the author and Martha S. Hanner for the summer of 1999.
- Published
- 1998
26. Spectroscopy of Kuiper Belt Objects and Centaurs
- Author
-
Cruikshank, Dale P, Brown, Robert H, Pendleton, Y. J, and Veeder, Glenn J
- Subjects
Astronomy - Abstract
Recent near-infrared spectroscopy of Kuiper Belt objects and Centaurs indicates considerable spectral diversity among them. Some have entirely bland spectra with no discernible spectral features (e.g., Chiron), while 5145 Pholus has a very active spectrum with absorption bands of H2O, CH3OH, and probably the mineral olivine present. In addition, the strong red color of Pholus indicates the presence of organic solids. Among the KBOs, 1993 SC has an active spectrum with the probably presence of hydrocarbons and possibly the ices of H2O and N2. The diversity among these spectra and the implications that such diversity has for models of the formation of the formation of the planets will be discussed.
- Published
- 1998
27. Note: the 1.95-2.50 [micro]m spectrum of J6 Himalia
- Author
-
Geballe, Thomas R., Ore, C.M. Dalle, Cruikshank, Dale P., and Owen, T.C.
- Subjects
Astronomical spectroscopy ,Satellites -- Jupiter ,Astronomy ,Earth sciences - Abstract
The reflectance spectrum of Jupiter's sixth satellite, Himalia, is featureless in the wavelength region 1.95-2.50 [micro]m as seen at a spectral resolution of 0.005 [micro]m, with no absorptions deeper than a few percent. From model calculations we establish an upper limit of 10% by weight of [H.sub.2]O (30-[micro]m grains) mixed intimately in the soil of Himalia, or alternatively 0.3% of the surface covered by exposures of [H.sub.2]O ice spatially segregated from the darker soil. For C[H.sub.4] and C[O.sub.2] ices the upper limits in spatially segregated models, are both 0.3%. Key Words: ices; satellites of Jupiter; spectroscopy; surfaces, satellite.
- Published
- 2002
28. Ice from the beginning of time
- Author
-
Cruikshank, Dale P.
- Subjects
Comets -- Composition ,Ice -- Observations ,Hale-Bopp (Comet) -- Observations ,Astronomy - Abstract
It has long been thought that much of a comet's nucleus is composed of ice. The detection of frozen water in the nucleus of Comet Hale-Bopp in September 1995 is the first direct observation of ice on a comet and this supports the aforementioned theory.
- Published
- 1995
29. Life from the stars?
- Author
-
Pendleton, Yvonne J. and Cruikshank, Dale P.
- Subjects
Life -- Origin ,Interstellar matter -- Research ,Astronomy ,Origin ,Research - Abstract
Billions of years ago comets and asteroids delivered enormous quantities of organic matter to Earth just about the time life arose here. Coincidence -- or cause and effect? EACH YEAR [...]
- Published
- 1994
30. Search for Outer Satellites of Saturn to V=22.5
- Author
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Cruikshank, Dale P and Witteborn, Fred C
- Subjects
Astronomy - Abstract
A wide-field, prime-focus photographic search of most of the dynamically permitted satellite space of Saturn and Uranus to limiting magnitude 22.5 revealed no new outer satellites. This search is approximately 2.5 mag deeper than previous surveys. For bodies of geometric albedo 0.04, the search would have revealed outer satellites of Saturn with diameter 20 km and greater, and outer satellites of Uranus with diameter 70 km and greater. This work was carried out with the Canada-France-Hawaii 3.6-m telescope on Mauna Kea.
- Published
- 1994
31. Detection of solid C(triple bond)N bearing materials on solar system bodies
- Author
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Cruikshank, Dale P, Hartmann, W. K, Tholen, David J, Allamandola, L. J, Brown, R. H, Matthews, C. N, and Bell, J. F
- Subjects
Astronomy - Abstract
We found observational evidence for the presence of C(triple bond)N-bearing solid materials on four classes of Solar System bodies: comets, asteroids, the rings of Uranus, and Saturn's satellite Iapetus. Gaseous CN was known in comet spectra, and the IR spectra of Comet P/Halley show emission of the CN fundamental at 4.5 microns interpreted as solids containing CN- group in the grains of the inner coma. The presented data offer the first evidence for chemically related material on the other objects.
- Published
- 1991
32. Galileo support observations of Asteroid 951 Gaspra
- Author
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Goldader, Jeffrey D, Tholen, David J, Cruikshank, Dale P, and Hartmann, William K
- Subjects
Astronomy - Abstract
Observations of 951 Gaspra in support of the Galileo spacecraft encounter are reported. Photometric observations of the asteroid yield a synodic rotational period of 7.042 46 and a slope parameter G of 0.285 + or - 0.005. It is inferred from data obtained on May 18, 1990, that the subearth latitude was higher at that time than it was earlier in the opposition. This places a limit on the possible pole orientation of the asteroid. A slope parameter of 0.25 is proposed on the basis of a comparison of the present result for the slope parameter with that of Barucci et al. (1990). A low-quality 0.8-2.5-micron spectrum of 951 Gaspra suggests a high olivine/pyroxene ratio, which is indicative of a source region in the lower mantle of a differentiated asteroid, and similarities to 8 Flora and particularly 15 Eunomia.
- Published
- 1991
- Full Text
- View/download PDF
33. Planetary astronomy
- Author
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Morrison, David, Hunten, Donald, Ahearn, Michael F, Belton, Michael J. S, Black, David, Brown, Robert A, Brown, Robert Hamilton, Cochran, Anita L, Cruikshank, Dale P, and Depater, Imke
- Subjects
Astronomy - Abstract
The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed.
- Published
- 1991
34. Decoding the Domino: The Dark Side of Iapetus
- Author
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Owen, Tobias C., Cruikshank, Dale P., Ore, C. M. Dalle, Geballe, T. R., Roush, T. L., de Bergh, C., Meier, Roland, Pendleton, Yvonne J., and Khare, Bishun N.
- Subjects
Iapetus (Satellite) -- Research ,Satellites -- Saturn ,Planets -- Spectra ,Atmospheric chemistry -- Research ,Astronomy ,Earth sciences - Abstract
We present new spectra of the leading and trailing hemispheres of Iapetus from 2.4 to 3.8 [micro]m. We have combined the leading hemisphere spectra with previous observations by others to construct a composite spectrum of the dark side (leading) hemisphere from 0.3 to 3.8 [micro]m. We review attempts to deduce the composition of the dark material from previously available spectrophotometry. None of them (numbering more than 20 million!) leads to a synthetic spectrum that matches the new data. An intimate mixture of water ice, amorphous carbon, and a nitrogen-rich organic compound (modeled here as Triton tholin) can fit the entire composite dark side spectrum. Observations in this spectral region have not revealed this mix of material on any other object observed thus far. We propose that this dark material may have originated on Titan, where atmospheric photochemistry has been producing nitrogen-rich organic compounds for 4.5 GY. [C] 2001 Academic Press Key Words: Iapetus; organic chemistry; satellites of Saturn; spectrophotometry.
- Published
- 2001
35. Detection of Sub-Micron Radiation from the Surface of Venus by Cassini/VIMS
- Author
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Baines, Kevin H., Bellucci, Giancarlo, Bibring, Jean-Pierre, Brown, Robert H., Buratti, Bonnie J., Bussoletti, Ezio, Capaccioni, Fabrizio, Cerroni, Priscilla, Clark, Roger N., Coradini, Angioletti, Cruikshank, Dale P., Drossart, Pierre, Formisano, Vittorio, Jaumann, Ralf, Langevin, Yves, Matson, Dennis L., McCord, Thomas B., Mennella, Vito, Nelson, Robert M., Nicholson, Philip D., Sicardy, Bruno, Sotin, Christophe, Hansen, Gary B., Aiello, John J., and Amici, Stefania
- Subjects
Spectrophotometry -- Research ,Venus (Planet) -- Spectra ,Planets -- Surfaces ,Surfaces (Physics) -- Observations ,Astronomy ,Earth sciences - Abstract
We report the first detection and profile characterization of thermal emission from the surface of Venus at 0.85 and 0.90 [micro]m, observed in the first planetary spectrum acquired by the Visual-Infrared Mapping Spectrometer onboard the Cassini spacecraft en route to the Saturn system. The strength and shape of these two newly observed nightside emissions agree with theoretical predictions based on the strength of the strong emission observed at 1.01 [micro]m. These emissions, together with previously-reported surface emission features at 1.01, 1.10, and 1.18 [micro]m, potentially provide a new technique for remotely mapping the mineralogical composition of the venusian surface. [C] 2000 Academic Press Key Words: Venus; spectrophotometry; surfaces, Planets; Venus, surface; minerology.
- Published
- 2000
36. Water Ice on Triton
- Author
-
Cruikshank, Dale P., Schmitt, Bernard, Roush, Ted L., Owen, Tobias C., Quirico, Eric, Geballe, Thomas R., de Bergh, Catherine, Bartholomew, Mary Jane, Dalle Ore, Cristina M., Doute, Sylvain, and Meier, Roland
- Subjects
Triton (Satellite) -- Natural history ,Satellites -- Neptune ,Astronomy ,Earth sciences - Abstract
We discuss the spectroscopic detection of [H.sub.2]O ice on Triton, evidenced by the broad absorption bands in the near infrared at 1.55 and 2.04 [micro]m. The detection of water ice on Triton reconfirms earlier preliminary studies (D. P. Cruikshank et al 1984, Icarus 58, 293-305). Although crystalline [H.sub.2]O ice has a distinctive spectral band at 1.65 [micro]m, and our new models slightly favor the presence of this phase, we cannot unambiguously determine whether Triton's water ice is crystalline or amorphous. Both phases might be present, and special conditions in the surface microstructure may affect the spectroscopic signature of water ice in such a way that crystalline ice is present and its 1.65 [micro]m spectral band is masked. Our spectra (1.87-2.5 [micro]m) taken at an interval of nearly 3.5 years do not show any significant changes that might relate to reports of changes in Triton's spectral reflectance (B. Buratti et al. 1999, Nature 397,219), or in Triton's surface pressure (J. L. Elliot et al. 1998, Nature 393, 765-767). [C] 2000 Academic Press Key Words: Triton; spectroscopy; ices; infrared observations; satellites of Neptune; surfaces, satellite.
- Published
- 2000
37. Composition, physical state, and distribution of ices at the surface of Triton
- Author
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Quirico, Eric, Doute, Sylvain, Schmitt, Bernard, Bergh, Catherine de, Cruikshank, Dale P., Owen, Tobias C., Geballe, Thomas R., and Roush, Ted L.
- Subjects
Triton (Satellite) -- Research ,Lunar geology -- Research ,Spectral energy distribution -- Analysis ,Satellites -- Neptune ,Astronomy ,Earth sciences - Abstract
This paper presents the analysis of near-infrared observations of the icy surface of Triton, recorded on 1995 September 7, with the cooled grating spectrometer CGS4 at the United Kingdom Infrared Telescope (Mauna Kea, HI). This analysis was performed in two steps. The first step consisted of identifying the molecules composing Triton's surface by comparing the observations with laboratory transmission spectra (direct spectral analysis); this also gives information on the physical state of the components. Most of the bands in Triton's spectrum were assigned to specific vibration bands of the [CH.sub.4], [N.sub.2], CO, and C[O.sub.2] molecules previously discovered. A detailed comparison of the frequencies of the [CH.sub.4] bands confidently indicated that this molecule exists in a diluted state in solid [Beta]-[N.sub.2]. Three new bands peaking at 5717, 5943, and 6480 [cm.sup.-1] (1.749, 1.683, and 1.543 [[micro]meter], respectively) were also observed. Laboratory experiments have shown that [C.sub.2][H.sub.6] isolated in solid [N.sub.2] fits well the second band, but this would imply the appearance of unobserved bands and thus rules out this assignment. However, [C.sub.2][H.sub.6] may exist in another physical state, and more experiments are necessary. No plausible candidate was found for these three bands when comparing with the spectra of nine molecules ([C.sub.2][H.sub.2], [C.sub.2][H.sub.4], [C.sub.3][H.sub.8], N[H.sub.3], S[O.sub.2], [HC.sub.3]N, [CH.sub.3]OH, NO, N[O.sub.2]). In view of the results of D. P. Cruikshank et al. (1993, Science 261, 742; in preparation), the work presented here leads to two possible representations of the surface of Triton. First, a two-region surface composed of a [N.sub.2]: [CH.sub.4]: CO terrain, [N.sub.2]: [CH.sub.4] :CO consisting of a solid solution in which [N.sub.2] is the dominant molecule, and of a [H.sub.2]O + C[O.sub.2] terrain, composed of a mixture of pure crystalline [H.sub.2]O and C[O.sub.2] grains. The second representation is a three-region surface composed of a [N.sub.2] : [CH.sub.4]: CO terrain and two geographically separated [H.sub.2]O and C[O.sub.2] terrains. The second step of the analysis consisted of using a bidirectionnal reflectance model (S. Doute and B. Schmitt 1998, J. Geophys. Res. Planets 103, 31367). The modeling first confirms the direct spectral analysis in that [CH.sub.4] is diluted in solid [Beta]-[N.sub.2], giving a high degree of confidence to the conclusion that the [N.sub.2]: [CH.sub.4]: CO terrain is in fact a solid solution. It also provides numerical information on this terrain, namely the size of the grains, the geographical abundance, and the [CH.sub.4] and CO concentrations. The large grain size (around 10 cm) would mean that the texture of this terrain is a compact crystalline solid rather than granular, which is in agreement with calculations from J. Eluszkiewicz (1991, J. Geophys. Res. 96, 19,217). In addition, an accurate modeling of the [N.sub.2] band could suggest that the temperature is greater or equal to 35.6 K. Although undistinguishable in the spectra, a maximum of 10% surface area of pure [CH.sub.4] ice can be present at the surface of Triton, thus explaining the high atmospheric [CH.sub.4] abundance observed by Voyager 2. Finally, the modeling showed that none of the two- or three-region representations was able to fit simultaneously the K and H regions of the spectrum of Triton. The origin of this misfit is not yet elucidated, but an instrumental effect is suspected. Some questions about the physical state of the [H.sub.2]O and C[O.sub.2] molecules are thus raised, but unfortunately observational constraints are missing. New near-infrared observations could partly provide these missing constraints, and would be important for detecting new molecules on Triton's surface. Such new data would be especially useful to identify the three bands at 5717, 5943, and 6480 [cm.sup.-1] (1.749, 1.683, and 1.543 [[micro]meter]). Key Words: Triton; infrared spectroscopy; ices; surfaces; satellites.
- Published
- 1999
38. Research in planetary astronomy and operation of the Mauna Kea Observatory
- Author
-
Cruikshank, Dale P
- Subjects
Astronomy - Abstract
Spectroscopic studies with ground-based telescopes at low resolution can give compositional information of the surfaces and atmospheres of planets, satellites, asteroids, and comets. Solid state absorptions in ices and minerals are measurable by the low-resolution spectrophotometric technique. This program includes spectroscopy of distant comets, asteroids of particular interest in various contexts (planet crossers, outer main belt, trojans, etc.), Pluto and Charon, and planetary satellites of particular interest (Iapetus, Io, Uranian satellites, etc.). In the case of planets, satellites, and comets, emphasis is placed on volatiles (ices and organics), while for asteroids the stress is on mineralogy and the connection with the meteorites. New spectra show that the IR signature of Triton has changed since 1980, in that the methane bands are significantly weaker. Spectral evidence for the presence of molecular nitrogen remains convincing. Also, the brightness of Triton throughout its orbital cycle was measured to higher precision than before and was found to be constant to better than 0.02 mag. Suggestive spectral evidence was found for the presence of the C-H stretching mode band in diffuse reflection on asteroid 130 Elektra.
- Published
- 1988
39. Space infrared telescope facility project
- Author
-
Cruikshank, Dale P
- Subjects
Astronomy - Abstract
The functions undertaken during this reporting period were: to inform the planetary science community of the progress and status of the Space Infrared Telescope Facility (SIRTF) Project; to solicit input from the planetary science community on needs and requirements of planetary science in the use of SIRTF at such time that it becomes an operational facility; and a white paper was prepared on the use of the SIRTF for solar system studies.
- Published
- 1988
40. Trojan and Hilda asteroid lightcurves. I - Anomalously elongated shapes among Trojans (and Hildas?)
- Author
-
Hartmann, William K, Binzel, Richard P, Tholen, David J, Cruikshank, Dale P, and Goguen, Jay
- Subjects
Astronomy - Abstract
A comparison of the available sample of lightcurves for 26 Trojan and Hilda asteroids with belt asteroid lightcurves shows the former to be distinguished by a higher incidence of high amplitudes rgan belt asteroids of comparable size, suggesting more elongated shapes; they currently have, moreover, only a few percent of the main-belt asteroids' collision frequency. A more modest collisional evolution that may have affected the relative degree of fragmentation of these bodies, and thus their shapes, is inferred.
- Published
- 1988
- Full Text
- View/download PDF
41. Research in planetary studies and operation of the Mauna Kea Observatory
- Author
-
Cruikshank, Dale P
- Subjects
Astronomy - Abstract
The research programs are highlighted in the following areas: major planets; planetary satellites and rings; asteroids; comets; dark organic matter; theoretical and analytical structures; extrasolar planetary; and telescopes.
- Published
- 1986
42. Infrared studies of solar system bodies.
- Author
-
Araki, H., Ehlers, J., Hepp, K., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Lawrence, Andrew, and Cruikshank, Dale P.
- Abstract
Recent progress in near-infrared reflectance spectroscopy of several solar system bodies is reviewed. [ABSTRACT FROM AUTHOR]
- Published
- 1988
- Full Text
- View/download PDF
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