2010 Annual Science Report
NASA Jet Propulsion Laboratory - Titan Reporting | SEP 2009 – AUG 2010
Task 3.5 Titan Genetics
This project addresses the question of how complex molecules might be formed in liquid hydrocarbons, rather than liquid water.
With preliminary funding, Co-Investigator Steven Benner has considered what types of polymeric structures might serve as genetic molecules to support Darwinian evolution in hydrocarbon oceans at low temperatures, such as those found on Titan. This activity discovered that polyether structures of the type shown in Figure 1 (left) are soluble (160 -170 mM) in liquid pentane at 176 K. Because the backbone of these molecules presents to the outside only the negative ends of the repeating dipole, the repeating backbone oxygen might play in hydrocarbon cryosolvents the same role as the repeating backbone charge plays for terrestrial genetic molecules operating in water. This work directs us to polymers of aldehydes (Figure 1, right) as potential genetic molecules on Titan.
These molecules may avoid the “biosignature origins paradox”, which arises under this logic:
(a) To be useful, chemical biosignatures cannot arise via abiological processes.
(b) But if these chemicals cannot arise via abiological processes, then life based on them cannot have originated.
(c) Therefore, the useful chemical biosignatures can detect only those kinds of life that could not have originated.
Here, stereoregularity of side chains in the building blocks would be a biosignature that evades this paradox.
He hopes to learn more about the reactivity of these molecules, asking whether any polar chemistry occurs in low temperature hydrocarbon solvents to form the constituent aldehydes from the reaction of an alkyne with a carboxylic acid, and to convert those aldehydes to polymers. The long-term goal is to produce results that those who are familiar with Astrobiology, but are not within the Titan community, will agree are potentially relevant to biology on Titan.
PROJECT INVESTIGATORS:Steven Benner
RELATED OBJECTIVES:Objective 1.1
Formation and evolution of habitable planets.
Sources of prebiotic materials and catalysts
Origins and evolution of functional biomolecules
Origins of energy transduction