At Titan, the same instrument detected extremely large negative hydrocarbon ions with masses up to 13,800 times that of hydrogen. A paper in Planetary and Space Science by Coates and colleagues in December 2009. They found showed that, at Titan, the largest hydrocarbon or nitrile ions are seen at the lowest altitudes of the atmosphere that Cassini flew (950 kilometers, or 590 miles). They suggest these large ions are the source of the smog-like haze that blocks most of Titan’s surface from view. They may be representative of the organic mix called “tholins” by Carl Sagan when he produced the reddish brew of prebiotic chemicals in the lab from gases that were known to be present in Titan’s atmosphere. Tholins that may be produced in Titan’s atmosphere could fall to the moon’s surface and may even make up the sand grains of the dunes that dominate part of Titan’s equatorial region.

The findings add to our growing knowledge about the detailed chemistry of Enceladus’ plume and Titan’s atmosphere, giving new understanding of environments beyond Earth where pre-biotic or life-sustaining environments might exist.

This Cassini Science League entry is an overview of a science paper authored, or co-authored, by at least one Cassini scientist. The information above was derived from the following publications:

1) “Negative ions in the Enceladus plume,” A.J.Coates, (Mullard Space Science Lab. University College of London); G.H. Jones, G.R. Lewis, A. Wellbrock (Mullard Space Science Lab and Centre for Planetary Sciences at University College of London); D.T. Young, F.J. Crary (Southwest Research Institute, San Antonio Texas); R.E. Johnson, T.A. Cassidy (University of Virginia, Charlottesville); T.W. Hill (Rice University, Houston, Texas), Icarus, in press, online July 17, 2009
2) “Heavy negative ions in Titan’s ionosphere: Altitude and latitude dependence,” A.J.Coates, A.Wellbrock, G.R. Lewis, G.H. Jones (Mullard Space Science Lab and Centre for Planetary Sciences at University College of London), D.T. Young, F.J. Crary, J.H. Waite Jr. (Southwest Research Institute, San Antonio, Texas), Planetary and Space Science, Volume 57, Issues 14-15, December 2009, Pages 1866-1871

Titan Through the Haze
The Cassini spacecraft peers through the hazy atmosphere of Titan for a close view of light and dark terrain on Saturn's largest moon.

3) “Heavy ion formation in Titan's ionosphere: Magnetospheric introduction of free oxygen and a source of Titan's aerosols?” E.C. Sittler Jr., (NASA Goddard Space Flight Center (GSFC), Maryland); A. Ali (NASA GSFC and University of Maryland, College Park, Maryland); J.F. Cooper, R.E. Hartle (NASA GSFC); R.E. Johnson (University of Virginia, Charlottesville), A.J. Coates (Mullard Space Science Lab. University College of London) and D.T. Young (Southwest Research Institute, San Antonio, Texas), Planetary and Space Science, Volume. 57, Issue 13, November 2009, Pages 1547-1557.

4) “On the amount of heavy molecular ions in Titan's ionosphere,” J.-E. Wahlund (Swedish Institute of Space Physics, Uppsala); M. Galand, I. Müller-Wodarg, J. Cui (Imperial College of London); R.V. Yelle (University of Arizona); F.J. Crary, K. Mandt, B. Magee, J.H. Waite Jr., D.T. Young (Southwest Research Institute, San Antonio, Texas); A.J. Coates (Mullard Space Science Laboratory, University College of London); P. Garnier (Swedish Institute of Space Physics, Uppsala, University of Toulouse, France, and CNRS, Toulouse); K. Ågren, M. André, A.I. Eriksson (Swedish Institute of Space Physics, Uppsala); T.E. Cravens (University of Kansas); V. Vuitton (Laboratory of Planetology of Grenoble, France); D.A. Gurnett and W.S. Kurth (University of Iowa), Planetary and Space Science, Volume 57, Issues 14-15, December 2009, Pages 1857-1865

5) “Negative ion chemistry in Titan's upper atmosphere,” V. Vuitton (Laboratory of Planetology of Grenoble, France and University of Arizona, Tuscon); P. Lavvas, R.V. Yelle (University of Arizona, Tuscon); M. Galand (Imperial College, London), A. Wellbrock, G.R. Lewis, A.J. Coates (Mullard Space Science Laboratory and Centre for Planetary Sciences, University College of London) and J.-E. Wahlund (Swedish Institute of Space Physics, Uppsala, Sweden) Laboratory of Planetology of Grenoble, France) aboratoire de Planétologie de Grenoble, CNRS, Grenoble, France, Planetary and Space Science, Volume 57, Issues 14-15, December 2009, Pages 1857-1865

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