2012 Annual Science Report

NASA Jet Propulsion Laboratory - Titan Reporting  |  SEP 2011 – AUG 2012

Executive Summary

A series of coupled model simulations and novel laboratory experiments comprise the core research program of the NAI Titan team. The objective of this coordinated research is to understand the extent to which processes that could be active currently in Titan could lead to the formation of significant prebiotic molecular compounds, to be defined hereinafter as being composed of atoms of hydrogen, carbon, nitrogen, and oxygen. These processes might have been important in the early Earth environment and be on the path to the formation of life.

The NAI Titan research program is organized along the lines of three research themes—“Titan’s geology—places where organic chemistry can operate”, “The complexity of atmospheric organic chemistry”, and “The evolved chemical state of the Titan surface”. Note that the last half of reporting period covers the first half of the fourth project year for the NAI ... Continue reading.

Field Sites
17 Institutions
21 Project Reports
11 Publications
0 Field Sites

Project Reports

  • Task 3.1.1.2 Reactions of Organic Ices With Electrons (Part 2)

    Secondary electrons can stimulate the polymerization of HCN. These electrons are present at low altitudes and in the near surface regions of Titan and not only lead to polymerization, but also negative charging of the haze particles.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 2.1.1.2 Titan Aerosol Chemistry

    The observed vertical profiles of Titan organic aerosols have been analyzed and the possible chemistry forming these aerosols studied. The elementary reaction of the ethynyl radical with diacetylene represents an efficient pathway to produce triacetylene in Titan’s atmosphere in those regions where density profiles of photolytically-generated ethynyl radicals and diacetylene overlap. The model of Titan’s atmosphere indicates that successive reactions of the triacetylene molecule can yield even more complex polyynes. These polyynes are thought to be the basis out of which the organic aerosols are formed.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 1.1.2.2 Models of the Reaction Between Hydrocarbons and Water Ice (Part 2)

    In the clathrate phase, there can be an exchange between primordial methane clathrates, which are believed to make at least part of Titan’s upper crust, and ethane, which is the primary product of Titan’s atmospheric chemistry and is one of the major constituents of the lakes. Including these exchanges in a geophysical model of Titan allows explaining Titan’s shape as measured by the Cassini mission. These exchanges also may have an influence on Titan’s hydrocarbon cycle.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.3.1 Solubility of Gases and Organics in Liquid Methane and Ethane

    A goal is to measure the solubilities of Titan surface and atmospheric species in cryogenic liquid hydrocarbons, in order to constrain the composition of the hydrocarbon lakes, and provide an understanding into the nature of erosion and sedimentation on Titan.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.5.1 Titan Genetics

    This project seeks to determine what chemical structures might support the genetic component of Darwinian evolution in Titan environments.

    ROADMAP OBJECTIVES: 2.2 3.2 4.2 6.2
  • Task 3.5.2 Energetics of Titan Life

    Infall to the Titan system of both interplanetary and circum-Saturnian dust and ice particles can provide exogenic fluxes of several elements, such as germanium and oxygen, which may be important in facilitating potential Titan metabolisms.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.4.1 Tholin Chemical Analysis Using Nuclear Magnetic Resonance

    One effort is to develop techniques for analyzing the structural features of Titan organic aerosol analogues (tholins) and HCN polymers.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.3.2 Precipitation of Organics in Titan Lakes

    Laboratory experiments simulating processes on the beaches of Titan lakes have been pursued. Work to date suggests that, at 94 K and 1 bar pressure, the precipitation of dissolved acetylene and benzene results in the formation of both solids on the beaches.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.1.1.3 Reactions of Organics With Ices and Mineral Grains

    One focus is on understanding reactions occurring on Titan’s surface with an emphasis on determining whether mineral deposits from meteoritic infall can catalyze the formation of more complex molecules of prebiotic relevance such as amines, polyamines or simple amino acids.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 2.2.1 Characterization of Aerosol Nucleation and Growth

    One goal has been to elucidate the mechanisms and develop a quantitative understanding of particle formation and growth in the Titan atmosphere. Work has focused on elucidating the role of molecular interactions in growth of Titan aerosol particles using numerical simulations.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 2.1.2.1 Atmospheric State and Dynamics

    To support the master atmospheric model, realistic Titan atmospheric profiles [winds, temperatures and densities] from the surface to ~1200km, for a variety of seasons and solar cycles, is needed.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 2.1.2.2 Atmospheric Observations

    Airglow emission from the atmosphere was discovered while Titan was deep in Saturn’s shadow. This suggests an important role for charged particles in producing this airglow.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 2.1.1.1 Master Atmospheric Chemistry Simulation

    A new approach to the condensation of molecules onto grains and sublimation back to the gas has been implemented to account for these processes in an approach that is numerically stable and relies on the extensive database of laboratory data on the saturation vapor pressures of molecules. This, combined with the new description of grain size distribution (implemented last year), will provide a great improvement in the description of the organic chemistry in Titan’s atmosphere.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 1.2 Interaction of Methane/ethane With Water Ice

    A Titan lake simulation system is under construction to provide a testbed for testing small instruments and components at Titan lake conditions in preparation for future in-situ missions.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 1.1.2.1 Models of the Reaction Between Hydrocarbons and Water Ice (Part 1)

    Studying the morphology and composition of Titan’s northern lakes and seas allow refining the values of the carbon contained in different reservoirs (atmosphere, lakes, dune fields). From this a carbon cycle can be constructed that takes into account the interactions between the interior, surface, and atmosphere.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.2 Cosmic-Ray Induced Surface Ice Chemistry

    Oxygenation chemistry involving the condensed Titan’s organic aerosols with water-ice on Titan’s surface may be induced by high energy photons simulating the cosmic ray induced chemistry on Titan’s surface.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.4.2 Tholin Analysis Based on Selective Detection of Functional Groups

    The goal of this project has been to develop methods to identify and determine the structure of complex organic compounds formed in the Titan environment. These methods also may be useful for in situ chemical analyses in future robotic explorations of Titan’s complex atmospheric and surface chemical environment.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 1.1.1 Models of the Internal Dynamics: Formation of Liquids in the Subsurface and Relationships With Cryovolcanism

    The effort focused on establishing the geologically-determined conditions for organic evolution in the surface and interior. Using the standard prescription for modeling of satellite interiors, novel equations of state and thermal parameters were included that more realistically simulate Titan’s interior. The new value of the tidal love number for Titan was considered, along with inclusion of crustal clathrate. The likelihood of direct contact between an interior ocean and rock, as well as the cycling of hot water from rock to ocean, was demonstrated. The result raises the interest of Titan as an astrobiologically significant object in the solar system.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 2.2.2 Ultraviolet/infrared Spectroscopy and Photoprocessing of Ice Films

    Investigations of the condensed phase chemistry of Titan’s atmospheric aerosols has continued. The focus this year has been on the photochemistry of acetylene imbedded in C4N2 ice—to simulate atmospheric aerosol photochemistry involving most abundant unsaturated molecule (acetylene) in Titan’s atmosphere.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.1.1.1 Reactions of Organic Ices With Electrons (Part 1)

    Ices exposed to low-energy electrons can be the cradle to further chemical reactions.

    ROADMAP OBJECTIVES: 2.2 3.1
  • Task 3.1.2 Chemistry Active in Titan Dunes

    The goal of this project is to demonstrate that chemical reactions can occur between atmospheric organics and water ice, even at the low temperature (ca. 100 K) of Titan’s surface, leading to the incorporation of oxygen to form molecules of astrobiological significance. Studies using a low temperature fluidized bed reactor demonstrate that amino acids, glycine specifically, are produced by tribochemical reactions driven by Aeolian processes in Titan’s dunes.

    ROADMAP OBJECTIVES: 2.2 3.1