A work presented virtually on March 16th during the 52nd Lunar and Planetary Science Conference 2021, the largest Planetary Sciences conference promoted by Lunar and Planetary Institute and the Johnson Space Center da NASA, brought important information about one of the most researched topics by scientists in the field: the possibility of finding life outside planet Earth. O study “Exploring the habitability conditions in Titan's impact record: the formation of the Menrva crater” is the result of the project that professor Alvaro Penteado Crósta, from the Geosciences Institute at Unicamp, began developing between 2018 and 2019 during the period in which he was as a visiting scientist at the Jet Propulsion Laboratory (JPL), research center of California Institute of Technology (Caltech) and NASA, which develops advanced research in space exploration.
Titan is Saturn's largest moon and its diameter is 50% larger than that of Earth's moon. It is the only one in the Solar System that has a significant atmosphere and its surface is formed by icy hydrocarbons, with large lakes and seas of liquid methane and ethane – providing some of the so-called prebiotic conditions, similar to those on Earth in primordial times. It is assumed that about 100 km below the icy layer there is liquid water. The interaction of hydrocarbons and water in the presence of thermal energy generated by impacts can promote conditions for the generation of rudimentary forms of life (microorganisms). Crósta conducted numerical simulations of the formation process of Menrva, the largest crater on Titan with around 425 km in diameter. The model obtained suggests that the crater was the result of the impact of a space rock measuring 34 km in diameter that hit Titan's surface at 7 km/s.
Analyzed from the perspective of geobiological processes, the impact can considerably influence planetary habitability. The findings of Crósta and scientists from JPL and North American, Canadian and French universities revealed in the study show significant exchange of organic materials and ice with the ocean water on Menrva. The combination of processes added to the transfer of thermal energy from the impact to Titan's crust may have resulted in a near-optimal habitable ecosystem, albeit temporary. The discovery caught the attention of the magazine Science, who recently published an article about the study.
The data used in the Menrva crater research were obtained through the Cassini-Huygens mission, which departed from Cape Canaveral in the United States in 1997, on a journey that lasted 7 years. Cassini entered Saturn's orbit and the Huygens probe landed on Titan in January 2005. The orbiter disintegrated in 2017 after sending a large amount of data, which should be studied for many years to come. “Huygens operated for just 1h10, which was the projected lifetime of the batteries, but the information collected in this short space of time was of fundamental importance in deciphering the icy world of Titan, eternally shrouded in dense clouds formed by hydrocarbons in its atmosphere. ”, says Crósta. The study was developed by the Unicamp professor within the macro project “Habitability of worlds with hydrocarbons: Titan and beyond”, coordinated by Brazilian Rosaly Lopes, who is part of the NASA Astrobiological Institutes Program (NAI).
A new mission, the Dragonfly, is scheduled to be sent to Titan in 2026 and targets the Selk crater. “The choice of Selk as the target for the Dragonfly Mission was made while we were developing the study of Menrva. On the other hand, the choice of Menrva to develop our project was due to the fact that it is the largest crater on Titan and very little is known about it, such as its age and the way it evolved morphologically. What we learn about Menrva will certainly be very useful in guiding the exploration of Selk. The Dragonfly mission will include the possibility of visiting other craters using a drone helicopter to land in various locations”, says Crósta.
“Titan, despite being a moon of Saturn, is undoubtedly one of the most fascinating planetary bodies in the Solar System. It is an extremely active body from an atmospheric/geological/geomorphological point of view, with processes very similar to those on Earth, such as a complete hydrological cycle, but with liquid methane and ethane instead of water, processes of erosion, transport and sedimentation, among others”, analyzes the Unicamp geologist. “Having the opportunity to work with the formation process of a crater of enormous proportions that has not yet been studied, in a body basically composed of a thick ice crust covering an ocean of salt water, was very challenging and, at the same time, a privilege”, is proud.
Alvaro says that there are very good opportunities to develop research or work with planetary sciences and that there are several institutions always interested in recruiting talented young people, whatever their nationality. “NASA, for example, welcomes young scientists from all over the world, including Brazil. At JPL, where I worked, I met more than 40 Brazilian scientists and engineers. An example is Rosaly Lopes herself, who has worked at NASA for more than 3 decades. This shows that this type of opportunity is concrete and viable and I highlight this in order to encourage those who are interested in planetary sciences”, she concludes.
