Program contestant for its mission #13 is Journey to Enceladus and Titan (JET), an astrobiology Saturn orbiter that would assess the habitability potential of Enceladus and Titan. In 2015, the NASA Innovative Advanced Concepts program (NIAC) awarded a Phase II grant to a design study of a Titan Submarine to explore the seas of Titan.Lorenz, R. D.; Oleson, S.; Woytach, J.; Jones, R.; Colozza, A.; Schmitz, P.; Landis, G.; Paul, M.; and Walsh, J. (March 16–20, 2015). "Titan Submarine: Vehicle Design and Operations Concept for the Exploration of the Hydrocarbon Seas of Saturn's Giant Moon", 46th Lunar and Planetary Science Conference, The Woodlands, Texas. LPI Contribution No. 1832, p.1259 Prebiotic conditions and life Titan is thought to be a prebiotic environment rich in complex organic compounds, but its surface is in a deep freeze at so life as we know it cannot exist on the moon's frigid surface. However, Titan seems to contain a global ocean beneath its ice shell, and within this ocean, conditions are potentially suitable for microbial life. The Cassini–Huygens mission was not equipped to provide evidence for biosignatures or complex organic compounds; it showed an environment on Titan that is similar, in some ways, to ones hypothesized for the primordial Earth. Scientists surmise that the atmosphere of early Earth was similar in composition to the current atmosphere on Titan, with the important exception of a lack of water vapor on Titan. Formation of complex molecules The Miller–Urey experiment and several following experiments have shown that with an atmosphere similar to that of Titan and the addition of UV radiation, complex molecules and polymer substances like tholins can be generated. The reaction starts with dissociation of nitrogen and methane, forming hydrogen cyanide and acetylene. Further reactions have been studied extensively. It has been reported that when energy was applied to a combination of gases like those in Titan's atmosphere, five nucleotide bases, the building blocks of DNA and RNA, were among the many compounds produced. In addition, amino acids, the building blocks of protein were found. It was the first time nucleotide bases and amino acids had been found in such an experiment without liquid water being present. On April 3, 2013, NASA reported that complex organic chemicals could arise on Titan based on studies simulating the atmosphere of Titan. On June 6, 2013, scientists at the IAA-CSIC reported the detection of polycyclic aromatic hydrocarbons (PAH) in