On the discovery of CO nighttime emissions on Titan by Cassini/VIMS: Derived stratospheric abundances and geological implications

Kevin H. Baines, Pierre Drossart, Miguel A. Lopez-Valverde, Sushil K. Atreya, Christophe Sotin, Thomas W. Momary, Robert H. Brown, Bonnie J. Buratti, Roger N. Clark, Philip D. Nicholson

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

We present a quantitative analysis of CO thermal emissions discovered on the nightside of Titan by Baines et al. [2005. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/VIMS. Earth, Moon, and Planets, 96, 119-147]. in Cassini/VIMS spectral imagery. We identify these emission features as the P and R branches of the 1-0 vibrational band of carbon monoxide (CO) near 4.65 μm. For CH3D, the prominent Q branch of the ν2 fundamental band of CH3D near 4.55 μm is apparent. CO2 emissions from the strong v3 vibrational band are virtually absent, indicating a CO2 abundance several orders of magnitude less than CO, in agreement with previous investigations. Analysis of CO emission spectra obtained over a variety of altitudes on Titan's nightside limb indicates that the stratospheric abundance of CO is 32±15 ppm, and together with other recent determinations, suggests a vertical distribution of CO nearly constant at this value from the surface throughout the troposphere to at least the stratopause near 300 km altitude. The corresponding total atmospheric content of CO in Titan is ∼2.9±1.5×1014 kg. Given the long lifetime of CO in the oxygen-poor Titan atmosphere (∼0.5-1.0 Gyr), we find a mean CO atmospheric production rate of 6±3×105 kg yr-1. Given the lack of primordial heavy noble gases observed by Huygens [Niemann et al., 2005. The abundances of constituents of Titan's atmosphere from the GCMS on the Huygens probe. Nature, 438, 779-784], the primary source of atmospheric CO is likely surface emissions. The implied CO/CH4 mixing ratio of near-surface material is 1.8±0.9×10-4, based on an average methane surface emission rate over the past 0.5 Gyr of 1.3×10-13 gm cm-2 s-1 as required to balance hydrocarbon haze production via methane photolysis [Wilson and Atreya, 2004. Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere. J. Geophys. Res. 109, E06002 Doi:10.1029/2003JE002181]. This low CO/CH4 ratio is much lower than expected for the sub-nebular formation region of Titan and supports the hypothesis [e.g., Atreya et al., 2005. Methane on Titan: photochemical-meteorological-hydrogeochemical cycle. Bull. Am. Astron. Soc. 37, 735] that the conversion of primordial CO and other carbon-bearing materials into CH4-enriched clathrate-hydrates occurs within the deep interior of Titan via the release of hydrogen through the serpentinization process followed by Fischer-Tropsch catalysis. The time-averaged predicted emission rate of methane-rich surface materials is ∼0.02 km3 yr-1, a value significantly lower than the rate of silicate lava production for the Earth and Venus, but nonetheless indicative of significant active geological processes reshaping the surface of Titan.

Original languageEnglish (US)
Pages (from-to)1552-1562
Number of pages11
JournalPlanetary and Space Science
Volume54
Issue number15
DOIs
StatePublished - Dec 2006

Fingerprint

Titan
carbon monoxide
methane
Titan atmosphere
atmosphere
stratopause
Huygens probe
clathrate
atmospheres
serpentinization
vertical distribution
haze
noble gas
clathrates
Venus (planet)
photochemistry
Saturn
catalysis
thermal emission
lava

Keywords

  • Cassini
  • CO
  • Titan
  • VIMS
  • Volcanism

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Baines, K. H., Drossart, P., Lopez-Valverde, M. A., Atreya, S. K., Sotin, C., Momary, T. W., ... Nicholson, P. D. (2006). On the discovery of CO nighttime emissions on Titan by Cassini/VIMS: Derived stratospheric abundances and geological implications. Planetary and Space Science, 54(15), 1552-1562. https://doi.org/10.1016/j.pss.2006.06.020

On the discovery of CO nighttime emissions on Titan by Cassini/VIMS : Derived stratospheric abundances and geological implications. / Baines, Kevin H.; Drossart, Pierre; Lopez-Valverde, Miguel A.; Atreya, Sushil K.; Sotin, Christophe; Momary, Thomas W.; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.

In: Planetary and Space Science, Vol. 54, No. 15, 12.2006, p. 1552-1562.

Research output: Contribution to journalArticle

Baines, KH, Drossart, P, Lopez-Valverde, MA, Atreya, SK, Sotin, C, Momary, TW, Brown, RH, Buratti, BJ, Clark, RN & Nicholson, PD 2006, 'On the discovery of CO nighttime emissions on Titan by Cassini/VIMS: Derived stratospheric abundances and geological implications', Planetary and Space Science, vol. 54, no. 15, pp. 1552-1562. https://doi.org/10.1016/j.pss.2006.06.020
Baines, Kevin H. ; Drossart, Pierre ; Lopez-Valverde, Miguel A. ; Atreya, Sushil K. ; Sotin, Christophe ; Momary, Thomas W. ; Brown, Robert H. ; Buratti, Bonnie J. ; Clark, Roger N. ; Nicholson, Philip D. / On the discovery of CO nighttime emissions on Titan by Cassini/VIMS : Derived stratospheric abundances and geological implications. In: Planetary and Space Science. 2006 ; Vol. 54, No. 15. pp. 1552-1562.
@article{118ae8c0a8334fc68a76dd9abcf7b0b8,
title = "On the discovery of CO nighttime emissions on Titan by Cassini/VIMS: Derived stratospheric abundances and geological implications",
abstract = "We present a quantitative analysis of CO thermal emissions discovered on the nightside of Titan by Baines et al. [2005. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/VIMS. Earth, Moon, and Planets, 96, 119-147]. in Cassini/VIMS spectral imagery. We identify these emission features as the P and R branches of the 1-0 vibrational band of carbon monoxide (CO) near 4.65 μm. For CH3D, the prominent Q branch of the ν2 fundamental band of CH3D near 4.55 μm is apparent. CO2 emissions from the strong v3 vibrational band are virtually absent, indicating a CO2 abundance several orders of magnitude less than CO, in agreement with previous investigations. Analysis of CO emission spectra obtained over a variety of altitudes on Titan's nightside limb indicates that the stratospheric abundance of CO is 32±15 ppm, and together with other recent determinations, suggests a vertical distribution of CO nearly constant at this value from the surface throughout the troposphere to at least the stratopause near 300 km altitude. The corresponding total atmospheric content of CO in Titan is ∼2.9±1.5×1014 kg. Given the long lifetime of CO in the oxygen-poor Titan atmosphere (∼0.5-1.0 Gyr), we find a mean CO atmospheric production rate of 6±3×105 kg yr-1. Given the lack of primordial heavy noble gases observed by Huygens [Niemann et al., 2005. The abundances of constituents of Titan's atmosphere from the GCMS on the Huygens probe. Nature, 438, 779-784], the primary source of atmospheric CO is likely surface emissions. The implied CO/CH4 mixing ratio of near-surface material is 1.8±0.9×10-4, based on an average methane surface emission rate over the past 0.5 Gyr of 1.3×10-13 gm cm-2 s-1 as required to balance hydrocarbon haze production via methane photolysis [Wilson and Atreya, 2004. Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere. J. Geophys. Res. 109, E06002 Doi:10.1029/2003JE002181]. This low CO/CH4 ratio is much lower than expected for the sub-nebular formation region of Titan and supports the hypothesis [e.g., Atreya et al., 2005. Methane on Titan: photochemical-meteorological-hydrogeochemical cycle. Bull. Am. Astron. Soc. 37, 735] that the conversion of primordial CO and other carbon-bearing materials into CH4-enriched clathrate-hydrates occurs within the deep interior of Titan via the release of hydrogen through the serpentinization process followed by Fischer-Tropsch catalysis. The time-averaged predicted emission rate of methane-rich surface materials is ∼0.02 km3 yr-1, a value significantly lower than the rate of silicate lava production for the Earth and Venus, but nonetheless indicative of significant active geological processes reshaping the surface of Titan.",
keywords = "Cassini, CO, Titan, VIMS, Volcanism",
author = "Baines, {Kevin H.} and Pierre Drossart and Lopez-Valverde, {Miguel A.} and Atreya, {Sushil K.} and Christophe Sotin and Momary, {Thomas W.} and Brown, {Robert H.} and Buratti, {Bonnie J.} and Clark, {Roger N.} and Nicholson, {Philip D.}",
year = "2006",
month = "12",
doi = "10.1016/j.pss.2006.06.020",
language = "English (US)",
volume = "54",
pages = "1552--1562",
journal = "Planetary and Space Science",
issn = "0032-0633",
publisher = "Elsevier Limited",
number = "15",

}

TY - JOUR

T1 - On the discovery of CO nighttime emissions on Titan by Cassini/VIMS

T2 - Derived stratospheric abundances and geological implications

AU - Baines, Kevin H.

AU - Drossart, Pierre

AU - Lopez-Valverde, Miguel A.

AU - Atreya, Sushil K.

AU - Sotin, Christophe

AU - Momary, Thomas W.

AU - Brown, Robert H.

AU - Buratti, Bonnie J.

AU - Clark, Roger N.

AU - Nicholson, Philip D.

PY - 2006/12

Y1 - 2006/12

N2 - We present a quantitative analysis of CO thermal emissions discovered on the nightside of Titan by Baines et al. [2005. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/VIMS. Earth, Moon, and Planets, 96, 119-147]. in Cassini/VIMS spectral imagery. We identify these emission features as the P and R branches of the 1-0 vibrational band of carbon monoxide (CO) near 4.65 μm. For CH3D, the prominent Q branch of the ν2 fundamental band of CH3D near 4.55 μm is apparent. CO2 emissions from the strong v3 vibrational band are virtually absent, indicating a CO2 abundance several orders of magnitude less than CO, in agreement with previous investigations. Analysis of CO emission spectra obtained over a variety of altitudes on Titan's nightside limb indicates that the stratospheric abundance of CO is 32±15 ppm, and together with other recent determinations, suggests a vertical distribution of CO nearly constant at this value from the surface throughout the troposphere to at least the stratopause near 300 km altitude. The corresponding total atmospheric content of CO in Titan is ∼2.9±1.5×1014 kg. Given the long lifetime of CO in the oxygen-poor Titan atmosphere (∼0.5-1.0 Gyr), we find a mean CO atmospheric production rate of 6±3×105 kg yr-1. Given the lack of primordial heavy noble gases observed by Huygens [Niemann et al., 2005. The abundances of constituents of Titan's atmosphere from the GCMS on the Huygens probe. Nature, 438, 779-784], the primary source of atmospheric CO is likely surface emissions. The implied CO/CH4 mixing ratio of near-surface material is 1.8±0.9×10-4, based on an average methane surface emission rate over the past 0.5 Gyr of 1.3×10-13 gm cm-2 s-1 as required to balance hydrocarbon haze production via methane photolysis [Wilson and Atreya, 2004. Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere. J. Geophys. Res. 109, E06002 Doi:10.1029/2003JE002181]. This low CO/CH4 ratio is much lower than expected for the sub-nebular formation region of Titan and supports the hypothesis [e.g., Atreya et al., 2005. Methane on Titan: photochemical-meteorological-hydrogeochemical cycle. Bull. Am. Astron. Soc. 37, 735] that the conversion of primordial CO and other carbon-bearing materials into CH4-enriched clathrate-hydrates occurs within the deep interior of Titan via the release of hydrogen through the serpentinization process followed by Fischer-Tropsch catalysis. The time-averaged predicted emission rate of methane-rich surface materials is ∼0.02 km3 yr-1, a value significantly lower than the rate of silicate lava production for the Earth and Venus, but nonetheless indicative of significant active geological processes reshaping the surface of Titan.

AB - We present a quantitative analysis of CO thermal emissions discovered on the nightside of Titan by Baines et al. [2005. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/VIMS. Earth, Moon, and Planets, 96, 119-147]. in Cassini/VIMS spectral imagery. We identify these emission features as the P and R branches of the 1-0 vibrational band of carbon monoxide (CO) near 4.65 μm. For CH3D, the prominent Q branch of the ν2 fundamental band of CH3D near 4.55 μm is apparent. CO2 emissions from the strong v3 vibrational band are virtually absent, indicating a CO2 abundance several orders of magnitude less than CO, in agreement with previous investigations. Analysis of CO emission spectra obtained over a variety of altitudes on Titan's nightside limb indicates that the stratospheric abundance of CO is 32±15 ppm, and together with other recent determinations, suggests a vertical distribution of CO nearly constant at this value from the surface throughout the troposphere to at least the stratopause near 300 km altitude. The corresponding total atmospheric content of CO in Titan is ∼2.9±1.5×1014 kg. Given the long lifetime of CO in the oxygen-poor Titan atmosphere (∼0.5-1.0 Gyr), we find a mean CO atmospheric production rate of 6±3×105 kg yr-1. Given the lack of primordial heavy noble gases observed by Huygens [Niemann et al., 2005. The abundances of constituents of Titan's atmosphere from the GCMS on the Huygens probe. Nature, 438, 779-784], the primary source of atmospheric CO is likely surface emissions. The implied CO/CH4 mixing ratio of near-surface material is 1.8±0.9×10-4, based on an average methane surface emission rate over the past 0.5 Gyr of 1.3×10-13 gm cm-2 s-1 as required to balance hydrocarbon haze production via methane photolysis [Wilson and Atreya, 2004. Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere. J. Geophys. Res. 109, E06002 Doi:10.1029/2003JE002181]. This low CO/CH4 ratio is much lower than expected for the sub-nebular formation region of Titan and supports the hypothesis [e.g., Atreya et al., 2005. Methane on Titan: photochemical-meteorological-hydrogeochemical cycle. Bull. Am. Astron. Soc. 37, 735] that the conversion of primordial CO and other carbon-bearing materials into CH4-enriched clathrate-hydrates occurs within the deep interior of Titan via the release of hydrogen through the serpentinization process followed by Fischer-Tropsch catalysis. The time-averaged predicted emission rate of methane-rich surface materials is ∼0.02 km3 yr-1, a value significantly lower than the rate of silicate lava production for the Earth and Venus, but nonetheless indicative of significant active geological processes reshaping the surface of Titan.

KW - Cassini

KW - CO

KW - Titan

KW - VIMS

KW - Volcanism

UR - http://www.scopus.com/inward/record.url?scp=33749234429&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33749234429&partnerID=8YFLogxK

U2 - 10.1016/j.pss.2006.06.020

DO - 10.1016/j.pss.2006.06.020

M3 - Article

AN - SCOPUS:33749234429

VL - 54

SP - 1552

EP - 1562

JO - Planetary and Space Science

JF - Planetary and Space Science

SN - 0032-0633

IS - 15

ER -