2009 Annual Science Report
NASA Jet Propulsion Laboratory - Titan Reporting | JUL 2008 – AUG 2009
Task 2.2.1 Characterization of Aerosol Nucleation and Growth
Aerosol nucleation in the Titan atmosphere may form the orange material seen in visible images.
Co-Investigator Richard Flagan and his group reviewed approaches for quantitative measurements of the rate of homogeneous nucleation. They have built a nucleation-pulse expansion cloud chamber, illustrated in Figure 1, for this study. In this system, supersaturation sufficient to induce nucleation is produced by adiabatic expansion. This system uses adiabatic expansion to produce supersaturation in a vapor mixture, maintains that supersaturation for a fixed time interval to allow nuclei to form, and then recompresses the gas to reduce the supersaturation so the nuclei grow without additional new particle formation. Mie scattering patterns in light scattering at fixed angle are used to determine the number concentration of grown particles from which the nucleation rate is calculated. Operational testing of the apparatus is now underway. For the initial experiments, the conditions and vapors used in previous nucleation studies to enable apparatus validation before moving on to low temperature studies of tholin-related vapors.
PROJECT INVESTIGATORS:Richard Flagan
RELATED OBJECTIVES:Objective 1.1
Formation and evolution of habitable planets.
Outer Solar System exploration
Sources of prebiotic materials and catalysts
Origins and evolution of functional biomolecules
Origins of energy transduction