Composition of Titan's surface from Cassini VIMS

T. B. McCord, G. B. Hansen, B. J. Buratti, R. N. Clark, D. P. Cruikshank, E. D'Aversa, Caitlin Griffith, E. K H Baines, Robert H. Brown, C. M. Dalle Ore, G. Filacchione, V. Formisano, C. A. Hibbitts, R. Jaumann, J. I. Lunine, R. M. Nelson, C. Sotin

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the atmosphere. Thus, the composition of the surface is a major piece of evidence needed to determine Titan's history. However, studies of the surface are hindered by the thick, absorbing, hazy and in some places cloudy atmosphere. Ground-based telescope investigations of the integral disk of Titan attempted to observe the surface albedo in spectral windows between methane absorptions by calculating and removing the haze effects. Their results were reported to be consistent with water ice on the surface that is contaminated with a small amount of dark material, perhaps organic material like tholin. We analyze here the recent Cassini Mission's visual and infrared mapping spectrometer (VIMS) observations that resolve regions on Titan. VIMS is able to see surface features and shows that there are spectral and therefore likely compositional units. By several methods, spectral albedo estimates within methane absorption windows between 0.75 and 5 μm were obtained for different surface units using VIMS image cubes from the Cassini-Huygens Titan Ta encounter. Of the spots studied, there appears to be two compositional classes present that are associated with the lower albedo and the higher albedo materials, with some variety among the brighter regions. These were compared with spectra of several different candidate materials. Our results show that the spectrum of water ice contaminated with a darker material matches the reflectance of the lower albedo Titan regions if the spectral slope from 2.71 to 2.79 μm in the poorly understood 2.8-μm methane window is ignored. The spectra for brighter regions are not matched by the spectrum of water ice or unoxidized tholin, in pure form or in mixtures with sufficient ice or tholin present to allow the water ice or tholin spectral features to be discerned. We find that the 2.8-μm methane absorption window is complex and seems to consist of two weak subwindows at 2.7 and 2.8 μm that have unknown opacities. A ratio image at these two wavelengths reveals an anomalous region on Titan that has a reflectance unlike any material so far identified, but it is unclear how much the reflectances in these two subwindows pertain to the surface.

Original languageEnglish (US)
Pages (from-to)1524-1539
Number of pages16
JournalPlanetary and Space Science
Volume54
Issue number15
DOIs
StatePublished - Dec 2006

Fingerprint

Titan
spectrometer
spectrometers
albedo
ice
methane
reflectance
water
atmospheres
atmosphere
Cassini mission
haze
spectral methods
photochemistry
organic materials
opacity
organic compounds
solid surfaces
encounters
solar system

Keywords

  • Cassini
  • Composition
  • Satellites
  • Spectroscopy
  • Surface
  • Titan

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

McCord, T. B., Hansen, G. B., Buratti, B. J., Clark, R. N., Cruikshank, D. P., D'Aversa, E., ... Sotin, C. (2006). Composition of Titan's surface from Cassini VIMS. Planetary and Space Science, 54(15), 1524-1539. https://doi.org/10.1016/j.pss.2006.06.007

Composition of Titan's surface from Cassini VIMS. / McCord, T. B.; Hansen, G. B.; Buratti, B. J.; Clark, R. N.; Cruikshank, D. P.; D'Aversa, E.; Griffith, Caitlin; Baines, E. K H; Brown, Robert H.; Dalle Ore, C. M.; Filacchione, G.; Formisano, V.; Hibbitts, C. A.; Jaumann, R.; Lunine, J. I.; Nelson, R. M.; Sotin, C.

In: Planetary and Space Science, Vol. 54, No. 15, 12.2006, p. 1524-1539.

Research output: Contribution to journalArticle

McCord, TB, Hansen, GB, Buratti, BJ, Clark, RN, Cruikshank, DP, D'Aversa, E, Griffith, C, Baines, EKH, Brown, RH, Dalle Ore, CM, Filacchione, G, Formisano, V, Hibbitts, CA, Jaumann, R, Lunine, JI, Nelson, RM & Sotin, C 2006, 'Composition of Titan's surface from Cassini VIMS', Planetary and Space Science, vol. 54, no. 15, pp. 1524-1539. https://doi.org/10.1016/j.pss.2006.06.007
McCord TB, Hansen GB, Buratti BJ, Clark RN, Cruikshank DP, D'Aversa E et al. Composition of Titan's surface from Cassini VIMS. Planetary and Space Science. 2006 Dec;54(15):1524-1539. https://doi.org/10.1016/j.pss.2006.06.007
McCord, T. B. ; Hansen, G. B. ; Buratti, B. J. ; Clark, R. N. ; Cruikshank, D. P. ; D'Aversa, E. ; Griffith, Caitlin ; Baines, E. K H ; Brown, Robert H. ; Dalle Ore, C. M. ; Filacchione, G. ; Formisano, V. ; Hibbitts, C. A. ; Jaumann, R. ; Lunine, J. I. ; Nelson, R. M. ; Sotin, C. / Composition of Titan's surface from Cassini VIMS. In: Planetary and Space Science. 2006 ; Vol. 54, No. 15. pp. 1524-1539.
@article{1c19076fe4d4464c8044eb45ee6f5b14,
title = "Composition of Titan's surface from Cassini VIMS",
abstract = "Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the atmosphere. Thus, the composition of the surface is a major piece of evidence needed to determine Titan's history. However, studies of the surface are hindered by the thick, absorbing, hazy and in some places cloudy atmosphere. Ground-based telescope investigations of the integral disk of Titan attempted to observe the surface albedo in spectral windows between methane absorptions by calculating and removing the haze effects. Their results were reported to be consistent with water ice on the surface that is contaminated with a small amount of dark material, perhaps organic material like tholin. We analyze here the recent Cassini Mission's visual and infrared mapping spectrometer (VIMS) observations that resolve regions on Titan. VIMS is able to see surface features and shows that there are spectral and therefore likely compositional units. By several methods, spectral albedo estimates within methane absorption windows between 0.75 and 5 μm were obtained for different surface units using VIMS image cubes from the Cassini-Huygens Titan Ta encounter. Of the spots studied, there appears to be two compositional classes present that are associated with the lower albedo and the higher albedo materials, with some variety among the brighter regions. These were compared with spectra of several different candidate materials. Our results show that the spectrum of water ice contaminated with a darker material matches the reflectance of the lower albedo Titan regions if the spectral slope from 2.71 to 2.79 μm in the poorly understood 2.8-μm methane window is ignored. The spectra for brighter regions are not matched by the spectrum of water ice or unoxidized tholin, in pure form or in mixtures with sufficient ice or tholin present to allow the water ice or tholin spectral features to be discerned. We find that the 2.8-μm methane absorption window is complex and seems to consist of two weak subwindows at 2.7 and 2.8 μm that have unknown opacities. A ratio image at these two wavelengths reveals an anomalous region on Titan that has a reflectance unlike any material so far identified, but it is unclear how much the reflectances in these two subwindows pertain to the surface.",
keywords = "Cassini, Composition, Satellites, Spectroscopy, Surface, Titan",
author = "McCord, {T. B.} and Hansen, {G. B.} and Buratti, {B. J.} and Clark, {R. N.} and Cruikshank, {D. P.} and E. D'Aversa and Caitlin Griffith and Baines, {E. K H} and Brown, {Robert H.} and {Dalle Ore}, {C. M.} and G. Filacchione and V. Formisano and Hibbitts, {C. A.} and R. Jaumann and Lunine, {J. I.} and Nelson, {R. M.} and C. Sotin",
year = "2006",
month = "12",
doi = "10.1016/j.pss.2006.06.007",
language = "English (US)",
volume = "54",
pages = "1524--1539",
journal = "Planetary and Space Science",
issn = "0032-0633",
publisher = "Elsevier Limited",
number = "15",

}

TY - JOUR

T1 - Composition of Titan's surface from Cassini VIMS

AU - McCord, T. B.

AU - Hansen, G. B.

AU - Buratti, B. J.

AU - Clark, R. N.

AU - Cruikshank, D. P.

AU - D'Aversa, E.

AU - Griffith, Caitlin

AU - Baines, E. K H

AU - Brown, Robert H.

AU - Dalle Ore, C. M.

AU - Filacchione, G.

AU - Formisano, V.

AU - Hibbitts, C. A.

AU - Jaumann, R.

AU - Lunine, J. I.

AU - Nelson, R. M.

AU - Sotin, C.

PY - 2006/12

Y1 - 2006/12

N2 - Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the atmosphere. Thus, the composition of the surface is a major piece of evidence needed to determine Titan's history. However, studies of the surface are hindered by the thick, absorbing, hazy and in some places cloudy atmosphere. Ground-based telescope investigations of the integral disk of Titan attempted to observe the surface albedo in spectral windows between methane absorptions by calculating and removing the haze effects. Their results were reported to be consistent with water ice on the surface that is contaminated with a small amount of dark material, perhaps organic material like tholin. We analyze here the recent Cassini Mission's visual and infrared mapping spectrometer (VIMS) observations that resolve regions on Titan. VIMS is able to see surface features and shows that there are spectral and therefore likely compositional units. By several methods, spectral albedo estimates within methane absorption windows between 0.75 and 5 μm were obtained for different surface units using VIMS image cubes from the Cassini-Huygens Titan Ta encounter. Of the spots studied, there appears to be two compositional classes present that are associated with the lower albedo and the higher albedo materials, with some variety among the brighter regions. These were compared with spectra of several different candidate materials. Our results show that the spectrum of water ice contaminated with a darker material matches the reflectance of the lower albedo Titan regions if the spectral slope from 2.71 to 2.79 μm in the poorly understood 2.8-μm methane window is ignored. The spectra for brighter regions are not matched by the spectrum of water ice or unoxidized tholin, in pure form or in mixtures with sufficient ice or tholin present to allow the water ice or tholin spectral features to be discerned. We find that the 2.8-μm methane absorption window is complex and seems to consist of two weak subwindows at 2.7 and 2.8 μm that have unknown opacities. A ratio image at these two wavelengths reveals an anomalous region on Titan that has a reflectance unlike any material so far identified, but it is unclear how much the reflectances in these two subwindows pertain to the surface.

AB - Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the atmosphere. Thus, the composition of the surface is a major piece of evidence needed to determine Titan's history. However, studies of the surface are hindered by the thick, absorbing, hazy and in some places cloudy atmosphere. Ground-based telescope investigations of the integral disk of Titan attempted to observe the surface albedo in spectral windows between methane absorptions by calculating and removing the haze effects. Their results were reported to be consistent with water ice on the surface that is contaminated with a small amount of dark material, perhaps organic material like tholin. We analyze here the recent Cassini Mission's visual and infrared mapping spectrometer (VIMS) observations that resolve regions on Titan. VIMS is able to see surface features and shows that there are spectral and therefore likely compositional units. By several methods, spectral albedo estimates within methane absorption windows between 0.75 and 5 μm were obtained for different surface units using VIMS image cubes from the Cassini-Huygens Titan Ta encounter. Of the spots studied, there appears to be two compositional classes present that are associated with the lower albedo and the higher albedo materials, with some variety among the brighter regions. These were compared with spectra of several different candidate materials. Our results show that the spectrum of water ice contaminated with a darker material matches the reflectance of the lower albedo Titan regions if the spectral slope from 2.71 to 2.79 μm in the poorly understood 2.8-μm methane window is ignored. The spectra for brighter regions are not matched by the spectrum of water ice or unoxidized tholin, in pure form or in mixtures with sufficient ice or tholin present to allow the water ice or tholin spectral features to be discerned. We find that the 2.8-μm methane absorption window is complex and seems to consist of two weak subwindows at 2.7 and 2.8 μm that have unknown opacities. A ratio image at these two wavelengths reveals an anomalous region on Titan that has a reflectance unlike any material so far identified, but it is unclear how much the reflectances in these two subwindows pertain to the surface.

KW - Cassini

KW - Composition

KW - Satellites

KW - Spectroscopy

KW - Surface

KW - Titan

UR - http://www.scopus.com/inward/record.url?scp=33751240805&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33751240805&partnerID=8YFLogxK

U2 - 10.1016/j.pss.2006.06.007

DO - 10.1016/j.pss.2006.06.007

M3 - Article

VL - 54

SP - 1524

EP - 1539

JO - Planetary and Space Science

JF - Planetary and Space Science

SN - 0032-0633

IS - 15

ER -