Dragonfly Proposed to NASA as Daring New Frontiers Mission to Titan

In late 1970s and early 80s, scientists got their first detailed look at Saturn’s largest moon Titan. Thanks to the Pioneer 11 probe, which was then followed by the Voyager 1 and 2 missions, the people of Earth were treated to images and readings of this mysterious moon. What these revealed was a cold satellite that nevertheless had a dense, nitrogen-rich atmosphere.

Thanks to the Cassini-Huygens mission, which reached Titan in July of 2004 and will be ending its mission on September 15th, the mysteries of this moon have only deepened. Hence why NASA hopes to send more missions there in the near future, like the Dragonfly concept. This craft is the work of the John Hopkins University Applied Physics Laboratory (JHUAPL), which they just submitted an official proposal for.

Essentially, Dragonfly would be a New Frontiers-class mission that would use a dual-quadcopter setup to get around. This would enable vertical-takeoff and landing (VTOL), ensuring that the vehicle would be capable of exploring Titan’s atmosphere and conducting science on the surface. And of course, it would also investigate Titan’s methane lakes to see what kind of chemistry is taking place within them.

Image of Titan’s atmosphere, snapped by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute

The goal of all this would be to shed light on Titan’s mysterious environment, which not only has a methane cycle similar to Earth’s own water cycle, but is rich in prebiotic and organic chemistry. In short, Titan is an “ocean world” of our Solar System – along with Jupiter’s moons Europa and Ganymede, and Saturn’s moon of Enceladus – that could contain all the ingredients necessary for life.

What’s more, previous studies have shown that the moon is covered in rich deposits of organic material that are undergoing chemical processes, ones that might be similar to those that took place on Earth billions of years ago. Because of this, scientists have come to view Titan as a sort of planetary laboratory, where the chemical reactions that may have led to life on Earth could be studied.

As Elizabeth Turtle, a planetary scientist at JHUAPL and the principal investigator for the Dragonfly mission, told Universe Today via email:

“Titan offers abundant complex organics on the surface of a water-ice-dominated ocean world, making it an ideal destination to study prebiotic chemistry and to document the habitability of an extraterrestrial environment. Because Titan’s atmosphere obscures the surface at many wavelengths, we have limited information about the materials that make up the surface and how they’re processed.  By making detailed surface composition measurements in multiple locations, Dragonfly would reveal what the surface is made of and how far prebiotic chemistry has progressed in environments that provide known key ingredients for life, identifying the chemical building blocks available and processes at work to produce biologically relevant compounds.”

In addition, Dragonfly would also use remote-sensing observations to characterize the geology of landing sites. In addition to providing context for the samples, it would also allow for seismic studies to determine the structure of the Titan and the presence of subsurface activity. Last, but not least, Dragonfly would use meteorology sensors and remote-sensing instruments to gather information on the planet’s atmospheric and surface conditions.

The Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR) is another concept for an aerial explorer for Titan. Credit: Mike Malaska

While multiple proposals have been made for a robotic explorer mission of Titan, most of these have taken the form of either an aerial platforms or a combination balloon and a lander. The Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR), a proposal made in the past by Jason Barnes and a team of researchers from the University of Idaho, is an example of the former.

In the latter category, you have concepts like the Titan Saturn System Mission (TSSM), a concept that was being jointly-developed by the European Space Agency (ESA) and NASA. An Outer Planets Flagship Mission concept, the design of the TSSM consisted of three elements – a NASA orbiter, an ESA-designed lander to explore Titan’s lakes, and an ESA-designed Montgolfiere balloon to explore its atmosphere.

What separates Dragonfly from these and other concepts is its ability to conduct aerial and ground-based studies with a single platform. As Dr. Turtle explained:

“Dragonfly would be an in situ mission to perform detailed measurements of Titan’s surface composition and conditions to understand the habitability of this unique organic-rich ocean world.  We proposed a rotorcraft to take advantage of Titan’s dense, calm atmosphere and low gravity (which make flight easier on Titan than it is on Earth) to convey a capable suite of instruments from place to place — 10s to 100s of kilometers apart — to make measurements in different geologic settings.  Unlike other aerial concepts that have been considered for Titan exploration (of which there have been several), Dragonfly would spend most of its time on the surface performing measurements, before flying to another site.”

Dragonfly‘s suite of instruments would include mass spectrometers to study the composition of the surface and atmosphere; gamma-ray spectrometers, which would measure the composition of the subsurface (i.e. looking for evidence of an interior ocean); meteorology and geophysics sensors, which would measure wind, atmospheric pressure, temperature and seismic activity; and a camera suite to snap pictures of the surface.

Artist’s concept of the Titan Aerial Daughter quadcopter and its “Mothership” balloon. Credit: NASA/STMD

Given Titan’s dense atmosphere, solar cells would not be an effective option for a robotic mission. As such, the Dragonfly would rely on a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) for power, similar to what the Curiosity rover uses. While robotic missions that rely on nuclear power sources are not exactly cheap, they do enable missions that can last for years at a time and conduct invaluable research (as Curiosity has shown).

As Peter Bedini – the Program Manager at the JHUAPL Space Department and Dragonfly’s project manager – explained, this would allow for a long-term mission with significant returns:

“We could take a lander, put it on Titan, take these four measurements at one place, and significantly increase our understanding of Titan and similar moons. However, we can multiply the value of the mission if we add aerial mobility, which would enable us to access a variety of geologic settings, maximizing the science return and lowering mission risk by going over or around obstacles.”

In the end, a mission like Dragonfly would be able to investigate how far prebiotic chemistry has progressed on Titan. These types of experiments, where organic building blocks are combined and exposed to energy to see if life emerges, cannot be performed in a laboratory (mainly because of the timescales involved). As such, scientists hope to see how far things have progressed on Titan’s surface, where prebiotic conditions have existed for eons.

Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural-color view from the Cassini spacecraft. Cassini captured this image in 2012. Image Credit: NASA/JPL-Caltech/Space Science Institute
Titan’s thick, nitrogen and hydrocarbon-rich atmosphere lends the planet a cloudy, yellowsh-brown appearance. Credit: NASA/JPL-Caltech/Space Science Institute

In addition, scientists will also be looking for chemical signatures that indicate the presence of water and/or hydrocarbon-based life. In the past, it has been speculated that life could exist within Titan’s interior, and that exotic methanogenic lifeforms could even exist on its surface. Finding evidence of such life would challenge our notions of where life can emerge, and greatly enhance the search for life within the Solar System and beyond.

As Dr. Turtle indicated, mission selection will be coming soon, and whether or not the Dragonfly mission will be sent to Titan should be decided in just a few years time:

“Later this fall, NASA will select a few of the proposed New Frontiers missions for further work in Phase A Concept Studies” she said. “Those studies would run for most of 2018, followed by another round of review.  And the final selection of a flight mission would be in mid-2019… Missions proposed to this round of the New Frontiers Program would be scheduled to launch before the end of 2025.”

And be sure to check out this video of a possible Dragonfly mission, courtesy of the JHUAPL:

Further Reading: JHU Hub

Life On Titan Possible Without Water

Saturn’s largest moon Titan is a truly fascinating place. Aside from Earth, it is the only place in the Solar System where rainfall occurs and there are active exchanges between liquids on the surface and fog in the atmosphere – albeit with methane instead of water. It’s atmospheric pressure is also comparable to Earth’s, and it is the only other body in the Solar System that has a dense atmosphere that is nitrogen-rich.

For some time, astronomers and planetary scientists have speculated that Titan might also have the prebiotic conditions necessary for life. Others, meanwhile, have argued that the absence of water on the surface rules out the possibility of life existing there. But according to a recent study  produced by a research team from Cornell University, the conditions on Titan’s surface might support the formation of life without the need for water.

When it comes to searching for life beyond Earth, scientists focus on targets that possess the necessary ingredients for life as we know it – i.e. heat, a viable atmosphere, and water. This is essentially the “low-hanging fruit” approach, where we search for conditions resembling those here on Earth. Titan – which is very cold, quite distant from our Sun, and has a thick, hazy atmosphere – does not seem like a viable candidate, given these criteria.

Diagram of the internal structure of Titan according to the fully differentiated dense-ocean model. Credit: Wikipedia Commons/Kelvinsong
Diagram of the internal structure of Titan according to the fully differentiated dense-ocean model. Credit: Wikipedia Commons/Kelvinsong

However, according to the Cornell research team – which is led by Dr. Martin Rahm – Titan presents an opportunity to see how life could emerge under different conditions, one which are much colder than Earth and don’t involve water.

Their study – titled “Polymorphism and electronic structure of polyimine and its potential significance for prebiotic chemistry on Titan” – appeared recently in the Proceedings of the National Academy of Sciences (PNAS). In it, Rahm and his colleagues examined the role that hydrogen cyanide, which is believed to be central to the origin of life question, may play in Titan’s atmosphere.

Previous experiments have shown that hydrogen cyanide (HCN) molecules can link together to form polyimine, a polymer that can serve as a precursor to amino acids and nucleic acids (the basis for protein cells and DNA). Previous surveys have also shown that hydrogen cyanide is the most abundant hydrogen-containing molecule in Titan’s atmosphere.

As Professor Lunine – the David C. Duncan Professor in the Physical Sciences and Director of the Cornell Center for Astrophysics and Planetary Science and co-author of the study – told Universe Today via email: “Organic molecules, liquid lakes and seas (but of methane, not water) and some amount of solar energy reaches the surface. So this suggests the possibility of an environment that might host an exotic form of life.”

What other surprises may be found beneath Titan's thick haze and clouds? (NASA/JPL/SSI/J. Major)
Titan’s thick, hazy atmosphere may conceal clues as to the possibility of life-giving conditions on its surface. Credit: NASA/JPL/SSI/J. Major

Using quantum mechanical calculations, the Cornell team showed that polyimine has electronic and structural properties that could facilitate prebiotic chemistry under very cold conditions. These involve the ability to absorb a wide spectrum of light, which is predicted to occur in a window of relative transparency in Titan’s atmosphere.

Another is the fact that polyimine has a flexible backbone, and can therefore take on many different structures (aka. polymorphs). These range from flat sheets to complex coiled structures, which are relatively close in energy. Some of these structures, according to the team, could work to accelerate prebiotic chemical reactions, or even form structures that could act as hosts for them.

“Polyimine can form sheets,” said Lunine, “which like clays might serve as a catalytic surface for prebiotic reactions. We also find the polyimine absorbs sunlight where Titan’s atmosphere is quite transparent, which might help to energize reactions.”

In short, the presence of polyimine could mean that Titan’s surface gets the energy its needs to drive photochemical reactions necessary for the creation of organic life, and that it could even assist in the development of that life. But of course, no evidence has been found that polyimine has been produced on the surface of Titan, which means that these research findings are still academic at this point.

On the left is TALISE (Titan Lake In-situ Sampling Propelled Explorer), the ESA proposal. This would have it's own propulsion, in the form of paddlewheels. Credit: bisbos.com
Proposed missions to Titan have included (from left to right) the TALISE (Titan Lake In-situ Sampling Propelled Explorer) and NASA’s Titan Mare Explorer. Credit: bisbos.com

However, Lunine and his team indicate that hydrogen cyanide may very well have lead to the creation of polyimine on Titan, and that it might have simply escaped detection because of Titan’s murky atmosphere. They also added that future missions to Titan might be able to look for signs of the polymer, as part of ongoing research into the possibility of exotic life emerging in other parts of the Solar System.

“We would need an advanced payload on the surface to sample and search for polyimines,” answered Lunine, “or possibly by a next generation spectrometer from orbit. Both of these are “beyond Cassini”, that is, the next generation of missions.”

Perhaps when Juno is finished surveying Jupiter’s atmosphere in two years time, NASA might consider retasking it for a flyby of Titan? After all, Juno was specifically designed to peer beneath a veil of thick clouds. They don’t come much thicker than on Titan!

Further Reading: PNAS

How Do We Terraform Saturn’s Moons?

Continuing with our “Definitive Guide to Terraforming“, Universe Today is happy to present our guide to terraforming Saturn’s Moons. Beyond the inner Solar System and the Jovian Moons, Saturn has numerous satellites that could be transformed. But should they be?

Around the distant gas giant Saturn lies a system of rings and moons that is unrivaled in terms of beauty. Within this system, there is also enough resources that if humanity were to harness them – i.e. if the issues of transport and infrastructure could be addressed – we would be living in an age a post-scarcity. But on top of that, many of these moons might even be suited to terraforming, where they would be transformed to accommodate human settlers.

As with the case for terraforming Jupiter’s moons, or the terrestrial planets of Mars and Venus, doing so presents many advantages and challenges. At the same time, it presents many moral and ethical dilemmas. And between all of that, terraforming Saturn’s moons would require a massive commitment in time, energy and resources, not to mention reliance on some advanced technologies (some of which haven’t been invented yet).

Continue reading “How Do We Terraform Saturn’s Moons?”