March 12, 2012

In lab Titan's chemical evolution

Titan, the Saturn's biggest moon, is the subject of many studies because it is an active world, both geologically and chemically. The chemistry in the atmosphere and on the surface of Titan seems to be particularly complex and it may inform us on the carbon molecules' evolution process, some of which could be a basis for life as we know it on Earth. This chemistry, triggered in the Titan's upper atmosphere, gave birth to a set of chemical reactions which have been producing increasingly complex carbon molecules (hydrocarbons, nitriles, etc.), even solid particles, aerosols, which form the orange fog and give its distinctive colour to Titan.
Update: 03/13/2012

Some in lab experiments, performed on Earth, try to understand what happen to those aerosols when touching the Titan's icy surface. Using experimental devices which simulate the atmosphere chemistry, it is possible to synthesize Titan's aerosol analogues.

Such experiment was carried out at LISA (CNRS, Paris-Est University and Paris Diderot University) and at the LGPM (École Centrale of Paris) with the supports of CNES and INSU. It allowed scientists to produce aerosols' analogues and study their evolutions in simulated Titan's surface and underground conditions.

At the surface of Titan the temperature is around -180ºC and the ground is composed of as hard as rock water ice. However, some studies showed that liquid water reservoirs could exist under the surface and flows of water mixed with ammonia, spread on the surface through volcanic craters, seemed to appear on Cassini-Huygens probe's observations.

The LISA's team studied the evolution of Titan's aerosols in those conditions (liquid water with and without ammonia).

After a preliminary work in 2010 and thanks to the implementation of an optimised analyse protocol, a new study allowed scientists to precise the production output of urea and amino-acids when those aerosols touch the water or ammonia reservoirs.

After 10 weeks of evolution, the results showed that the measured output in water and ammonia is between 6 and 12% for urea and range from 0.001 to 0.4% for amino-acids: glycine, alanine, aspartic acid and uracil, a nitrogenous base. Those results indicates that on Titan, such reservoirs may give rise to the molecules production of prebiotic interest such as the amino-acids which are the basis of the life on Earth. They invite questioning about a later eventual sophistication of the organic matter on Titan or in a potential underground ocean.

Article references

O. Poch1, P. Coll1, A. Buch2, S.I. Ramírez3, F. Raulin1, Production yields of organics of astrobiological interest from H2ONH3 hydrolysis of Titan’s tholins Planetary and Space Science 61 (1), 114-123, 2012

1 Laboratoire Inter-universitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot, Institut Pierre Simon Laplace, C.M.C., 61 avenue du Général de Gaulle, 94010 Créteil Cédex, France
2 Laboratoire de Génie des Procédés et Matériaux (LGPM), Ecole Centrale Paris, Grande voie des vignes, 92295 Chatenay-Malabry, France
3 Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001. Col. Chamilpa, Cuernavaca, Morelos, C.P. 62209, Mexico

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