July 6, 2019 : Researchers From SMU In Dallas Will Try To Recreate The Environment Of Titan In The Laboratory In The Prospect Of The Dragonfly Mission

The Cassini-Huygens mission in the Saturn System came to an end in September 2017 with the targeted crash of the Cassini orbiter into the Gas Giant Saturn. A huge amount of scientific data regarding Saturn, its rings and its numerous moons has been collected by the scientists of the mission. Thus, they are in a position to better understand the chemistry, the climate, the meteorology or the internal activity of worlds like Saturn, Titan or Enceladus. Due to its remarkable dynamics and due to its complex chemistry involving hydrocarbons or organics, Titan draws our whole attention. That's why a new mission to Saturn's largest moon has been planned. In late June, NASA announced that we will fly back to Titan in less than two decades. The new mission known as Dragonfly will involve a drone or a rotorcraft that will explore a land of dunes and a major crater from the year 2034. We want to study the chemistry and the dynamics of the soil and the atmosphere. The probe or drone will do much more than the Huygens probe did since it will explore dozens of promising places. The long journey is expected to start in 2026.

Recently, the Southern Methodist University (SMU), located in Dallas, was awarded a grant of 195,000 dollars for a mission to simulate the environment of the Opaque Moon in the laboratory. One of the goals is to better understand the complex chemistry of Titan and in particular the chemistry of organics and hydrocarbons which may represent a pre-biotic chemistry or a chemistry that can lead to life. The project or the mission which is financed by the Houston-based Welch Foundation will be led by Tom Runcevski who is an assistant professor of chemistry in SMU's Dedman College of Humanities and Sciences and will involve Christina McConville who is a graduate student from SMU and who was awarded a fellowship, as well, by the Texas Space Grant Consortium. Christina McConville will bring her skills to make the mission advance. The work of the planetologists regarding the potential chemistry of Titan's environment is likely to help the scientists and the engineers of the Dragonfly mission prepare the future campaign of the drone or rotorcraft.

We have time to prepare the ground for the mission of the drone in the exotic environment of the giant moon since the probe or rotorcraft is expected to enter Titan's atmosphere in 2034. The researchers from SMU will have to simulate the environment of the Opaque Moon on the basis of our scientific knowledge regarding the Titanian soil, the Titanian atmosphere or the Titanian haze which appears particularly complex. The chemists will resort to multiple glass cylinders whose size is comparable to that of a needle top. Therefore, they will be in a position to determine the type of chemical structures that are likely to take shape on Titan's surface. Can the soil of Titan allow the development of any lifeform based on hydrocarbons or organics ? Are there signs of ancient life on Titan ? Is there an exotic lifeform on Titan today ? Can the relatively complex chemistry of Saturn's largest moon lead to the emergence or the development of any simple lifeform in that harsh environment ? We can learn a lot regarding the chemistry of organics or regarding the origin or the mechanisms that can lead to the emergence or the development of life on any world.

Scientists often regard Titan as a pre-biotic natural laboratory since the Titanian atmosphere looks like the atmosphere of the Early Earth. The environmental temperature of the Opaque Moon is extremely low due to the fact that the giant moon is much farther from the Sun than the Earth but the composition of Titan's atmosphere is relatively close to the composition of our atmosphere today. Titan's atmosphere is dominated by molecular nitrogen like the atmosphere of the Earth. However, oxygen is absent or almost absent in the Titanian atmosphere. The second most abundant gas in Titan's atmosphere appears to be methane. There are no clouds of water ice on Titan but there are clouds of methane or ethane on that enigmatic moon. A parallel can be drawn between the water cycle of the Earth and the methane cycle of Titan. Lakes, seas and rivers of methane or ethane can be found in the high latitudes of Saturn's largest moon. Those humid areas can experience rainfall events from time to time. The level or the size of the pools of liquid can change due to seasonal factors. Planetologists suspect the presence of a subsurface ocean of liquid water beneath the external crust of Titan.

The haze of the Orange Moon is likely to engender snowfall events. The dunes found in the dark areas of the low or mid-latitudes of Titan may be closely related to the haze of the giant moon. There are complex interactions between the atoms, ions or molecules found in the upper atmosphere under the influence of UV light from the Sun in particular. Tom Runcevski pointed out :  Titan is a hostile place, with lakes and seas of liquid methane, and rains and storms of methane. The storms carry organic molecules produced in the atmosphere to the surface, and at the surface conditions, only methane, ethane and propane are liquids. All other organic molecules are in their solid form or, as we would call them on Earth, minerals.  For instance, water can only appear in its solid form on Titan's surface simply because the environmental temperature at  sea level  is extremely low, around minus 180 degrees Celsius, minus 292 degrees Fahrenheit or 93 Kelvin. However, beneath the presumed icy crust, one can imagine an ocean or pockets of liquid water if there are strong energy sources in the interior of the giant moon. The gravitational influence of Saturn and the other moons is likely to play a key role in the process of tidal heating.

Titan's surface may be very different, in terms of composition, from the surface of worlds like the Earth, the Moon or Mars because the mean density of the Opaque Moon is much lower than that of those worlds. Tom Runcevski argued :  We are interested in the chemical composition and crystal structure of these organic minerals, because it is believed that minerals played a key role in the origins of life on Earth.  He added :  Hence, our research may help assess these possibilities for strange 'methanogenic' Titanean life.  The Huygens probe had detected the release of methane during the landing phase on January 14, 2005. As a result, we know that Titan's surface is rich in hydrocarbons or organics but its exact composition is unknown today. Are there complex molecules like sugars, amino acids or even proteins on the Titanian soil ? We don't know yet ! Tom Runcevski explained that the experiments that the team will lead are likely to bring key information regarding the properties of Titan's surface or the structure of the external crust of the giant moon. The simulations will probably be very useful for the ambitious Dragonfly mission proposed by NASA.

Thanks to the Cassini-Huygens mission, we know, now, that Titan is far from being a uniform world since it unveils various types of terrain. The humid areas tend to be found in the polar regions or in the high latitudes of each hemisphere. The dark areas or the low-albedo areas of the low or mid-latitudes tend to be dominated by linear and parallel dunes extending over long distances. The radar data as well as the infrared or near-infrared data obtained from the Cassini orbiter during its long mission in the Saturn System from 2004 to 2017 will be very useful for the Dragonfly mission. We already know that the drone will explore an area of dunes. The simulations performed by the researchers from SMU and mobilizing jars or cylinders composed of glass will be strongly influenced by what we have gathered during the fruitful Cassini-Huygens mission. Tom Runcevski pointed out :  We can recreate this world step by step in a cylinder made of glass.  He explained :  First, we will introduce water, which freezes into ice. Second, we will top that layer of ice with ethane that liquidizes as a 'lake'. Then we will fill the remaining cylinder with nitrogen. 

The simulations will reproduce the presumed soil, the potential seas, lakes or rivers as well as the potential air or atmosphere. Once the main ingredients of the system have been introduced, the researchers will be in a position to simulate various mechanisms or phenomena such as rainfall events. What happens in the simulated environment with a determined concentration of methane or ethane in the system for instance ? Lastly, the researchers intend to 'dry' the simulated lakes by slightly increasing the environmental temperature. What are the interactions between the lakes or seas and the soil ? Is the soil porous for instance ? The cylinder reproducing the potential environment of Titan is specifically designed so that several state-of-the-art simulations or experiments can be carried out in the prospect of better understanding the chemistry and the dynamics of Titan's complex environment. Significant parts of these experiments or simulations will be carried out at research facilities that are equipped with modern synchrotron and neutron radiation, such as Argonne National Laboratory located in Illinois and the National Institute of Standards and Technology located in Maryland. The environment of Titan is likely to help us significantly improve our understanding of nature and the chemistry of organics in particular.

The image above reveals a portion of a radar swath obtained from the Radar Mapper of the Cassini orbiter during the T3 Flyby of February 15, 2005. Each side of the view represents 100 km. One can notice topographic features which appear to be dunes. Those dunes appear relatively linear and parallel. The rotorcraft of the Dragonfly mission may explore that type of terrain in the area of Shangri-La from the start of the mission on Titan in 2034. Credit for the original radar view: NASA/JPL/Cassini RADAR team/Jason Perry. Credit for the image adjustments: Marc Lafferre, 2019.

- To get further information on that news, go to: https://blog.smu.edu/research/2019/07/03/smus-titans-in-a-jar-could-answer-key-questions-ahead-of-nasas-space-exploration.



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