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Earth, our Moon and Titan juxtaposed, at scale. Titan is seen with its thick orange atmosphere of nitrogen and methane. Among all the bodies with a surface in the Solar System, only Venus has a denser atmosphere !
Titan's water subsurface liquid ocean is considered to be the most likely habitable environment. This hidden ocean may be 60 to 120 miles (100 to 200 km) thick, below the surface ice crust 30 to 90 miles (50 to 150 km) thick.
But how would organic materials from the atmosphere make their way to the surface ?
Where to Look for Life on Titan : Would fresh impact craters or cryovolcanoes make better targets for astrobiologists? (June 2018, Airspacemag.com, by Dirk Schulze-Makuch)
See Titan's surface area laid out in the top right hand corner : it's the fifth largest terrestrial body of the Solar System after the Earth, Venus, Mars and Ganymede (moon of Jupiter), and before Mercury!
Titan was discovered in 1655 by the Dutch astronomer Christiaan Huygens. It was the 6th moon to be discovered, after Earth's Moon and the Galilean moons of Jupiter.
Huygens named his discovery Saturni Luna (or Luna Saturni, Latin for "Saturn's moon").
The name Titan, and the names of all 7 satellites of Saturn then known (62 known moons now), came from John Herschel in 1847. He suggested the names of the mythological Titans, brothers and sisters of Cronus, the Greek Saturn. In Greek mythology, the Titans were a race of powerful deities, descendants of Gaia and Uranus, that ruled during the legendary Golden Age.
Titan orbits at 1.2 million km from Saturn, Saturn orbiting itself at 1,5 billion km from the Sun. By comparison Earth and Mars orbits respectively at 150 million km and 225 million km from the Sun
Saturn (and Titan) takes 30 years to orbit the Sun. So a year on Titan lasts 30 Earth years
A Titan day lasts 16 Earth days
Average temperature at the surface : −179.5 °C (yes it's cold, but it's not a show-stopper, see further below)
Atmospheric composition (troposphere ) : 95% N2 (Nitrogen), 4.9% CH4 (Methane) and traces of H2 (Di-Hydrogen)
On Earth : 78% nitrogen (N2), 20.95% oxygen (O2), 0.930% argon, 0.0402% carbon dioxide (CO2), and ~ 1% water vapor (climate-variable)
“If you press forward in time, and if the methane doesn't kept replenished, all of it will be transformed by photolysis and Titan will have a blue sky and a nitrogen atmosphere with sand dunes of hydrocarbons,” said Jeffrey Moore from NASA’s Ames Research Center
These molecules are associated with the creation of organic compounds in interstellar dust clouds and with the amino acids and other biological building blocks that have been detected on meteorites and comets.
The fact that similar chemistry occurs in Titan's clouds suggests that the creation of life's building blocks could be a “universal process,” Desai said, “with universal drivers behind it.”
Desai, a physicist at University College London, emphasized that you'd need several steps to get from carbon chain anions to actual living beings. In an absolute best-case scenario, these molecules would trigger the reaction of bigger organic compounds, which are then combined into amino acids, which build proteins, which are an essential ingredient for cells. Scientists don't yet have proof that all those steps are happening on Saturn's moon. But they do know that Titan's atmosphere contains a wealth of large organic compounds — rings and chains of hydrogen, carbon and nitrogen, some of them hundreds of atoms long, that emerge as you drift down toward the surface. And Hörst has performed experiments in her lab here on Earth showing that amino acids and nucleotides (the basic units of DNA) can be concocted from the chemical broth of the moon's haze.
"We would build large enclosed habitats - and there are no strong winds on the surface at all, only a light breeze, the winds are higher up, and stable geologically - so in the low gravity and with equal pressure inside and out you could paraterraform areas of Titan more easily than anywhere else in the solar system and with all that wind power you have plenty of power for the lighting and to keep it warm. It would be easier to enclose large areas than it is to do that on Earth." says Robert Walker
Titan, the best place where to fly in our Solar System
Here below is what happens when an aircraft is launched above the surface of the 32 largest Solar System bodies !
"When it comes to flying, Titan might be better than Earth. Its atmosphere is thick but its gravity is light, giving it a surface pressure only 50% higher than Earth’s with air four times as dense. Its gravity—lower than that of the Moon—means that flying is easy. Our Cessna could get into the air under pedal power.
In fact, humans on Titan could fly by muscle power. A human in a hang glider could comfortably take off and cruise around powered by oversized swim-flipper boots—or even take off by flapping artificial wings. The power requirements are minimal—it would probably take no more effort than walking."
We believe that we shouldn't send Humans to Mars as :
It's not an issue in Antarctica. Or indeed if anyone has been camping in winter. Or Eskimoes in igloos. And titan is far colder. Canada also has many buildings built over permafrost.
"Fairly little of the surface will be disturbed to begin with. The gas expansion which occurs in a vacuum optimized rocket nozzle cools the exhaust substantially; while temperatures may exceed 3000 K in the chamber, the exhaust may be well below 1000K at the nozzle exit plane. The exhaust gas will be relatively tenuous for the same reason, and it will disperse rapidly in vacuum, so it will only transfer a small amount of heat to the surface in the few seconds of landing." says Russell Borogove
"At Titan the surface temperature is ~95 K (-180 C), and at the tropopause is ~77 K—really cold! And the surface atmospheric pressure is nearly 1.5 bars, for a mass density ~4 times that of Earth's. The gravitational acceleration is only ~1/7 of Earth's. I doubt that they would try to land on Titan with a BFR spaceship as currently envisioned. The cold, dense atmosphere makes for a tremendous convective cooling rate, so without prodigious heating many spacecraft parts would go below their allowable minimum temperatures, especially any exposed electronics and parts with lubricants. Handling the environment at Titan would require an extensive redesign. Titan's low gravity leads to a very large atmospheric scale height, the vertical distance over which the pressure changes by a factor of e. Couple that to the high surface pressure and you get an atmosphere that produces measurable aerodynamic drag nearly 1000 km above the surface (!), as Cassini and Huygens verified. When the hypersonic/supersonic deceleration phase is finished, there's still a long way to go to the surface, and that takes time. The Huygens probe took 2-1/2 hours to get down after opening its parachute, even with a change to a smaller 'chute on the way down. During that time the craft is exposed to even more intense convective cooling." says Tom Spilker
That said, Titan's atmosphere and low gravity make aeronautics easy. It lets you glide most of the way down rather than having to burn precious propellants. As mentioned above, the duration of the part of the landing burn with the plumes impinging on the surface would be short enough that the amount of melting would be small.
If the landing legs did indeed stick to the mostly-ice surface material, a quick blast of electrical or chemical heating on the pads would release them.
There are all kinds of other options and issues to consider, such as: use of parachutes or a parafoil on the way down; use of a (really large!) balloon for the initial departure ascent so aerodynamic drag doesn't cost so much in ∆v; and use of rocket propulsion, or aerodynamics to land." says Tom Spilker
Planetary scientist Dr. Ralph Lorenz of the Applied Physics Lab at Johns Hopkins University, on the issue of thermal transfer on Titan between the Huygens lander and the thick and cold atmosphere: "Same problem Huygens confronted. At these low temperatures, radiation basically doesn't transfer any heat at all. The atmosphere is sufficiently thick and cold that all of the outer surfaces of Huygens were quenched at about 94°K, or maybe 96°K, relatively quickly. Huygens had a 5 cm thick layer of foam insulation that basically limits the heat transfer. the interior was benign, room temperature freezing point, something like that, and outside was 94°K. So it was loosing 350W of heat to maintain that differential. Any long term system at Titan has to buffer that loss, and that's why the radio isotope systems are so important because they have that waste heat available. The engineering solution is that you insulate." (from that conference on Youtube, set at the exact time)
"The mission’s star instrument, however, would be its mass spectrometer. This instrument, derived from similar instruments for the Mars Curiosity and the European ExoMars rovers, would be able to detect the presence of different ices and hydrocarbons at minute levels. By measuring the precise chemistry of ices from different locations, scientists can understand the processes that created them. This instrument’s sensitivity would make Dragonfly an exciting astrobiology mission."
One advantage over chemical rockets is the virtually unlimited energy density it offers compared to chemical rocket fuel. This would cut the total amount of propellant needed, thus cutting launch weight and the cost of individual missions. A more powerful nuclear engine would mean reduced trip times. Already, NASA has estimated that an NTP system could make the voyage to Mars to four months instead of six, which would reduce the amount of radiation the astronauts would be exposed to in the course of their journey.
Researchers at NASA's Marshall Space Flight Center are once again looking to develop nuclear rockets. As part of NASA's Game Changing Development Program, the Nuclear Thermal Propulsion (NTP) project would see the creation of high-efficiency spacecraft that would be capable of using less fuel to deliver heavy payloads to distant planets, and in a relatively short amount of time.
As Sonny Mitchell, the project of the NTP project at NASA's Marshall Space Flight Center, said in a recent NASA press statement:
"As we push out into the solar system, nuclear propulsion may offer the only truly viable technology option to extend human reach to the surface of Mars and to worlds beyond. We're excited to be working on technologies that could open up deep space for human exploration."
To see this through, NASA has entered into a partnership with BWX Technologies (BWXT), a Virginia-based energy and technology company that is a leading supplier of nuclear components and fuel to the U.S. government. To assist NASA in developing the necessary reactors that would support possible future crewed missions to Mars, the company's subsidiary (BWXT Nuclear Energy, Inc.) was awarded a three-year contract worth $18.8 million.
During this three years in which they will be working with NASA, BWXT will provide the technical and programmatic data needed to implement NTP technology. This will consist of them manufacturing and testing prototype fuel elements. BWXT will also aid NASA planners in addressing the issues of feasibility and affordably with their NTP program.
The concept of using nuclear rockets to explore the Universe is not new. In fact, NASA has explored the possibility of nuclear propulsion extensively under the Space Nuclear Propulsion Office (SNPO ), which between 1959 and 1972 conducted 23 reactor tests
In 1963, the SNPO also created the Nuclear Engine for Rocket Vehicle Applications (NERVA) program to develop nuclear-thermal propulsion for long-range crewed mission to the moon and interplanetary space. This led to the creation of the NRX/XE, a nuclear-thermal engine which the SNPO certified as having met the requirements for a crewed mission to Mars.
Here is a 1968 22-min NASA video that describes the NERVA program of nuclear powered rockets that NASA planned to use for its manned missions to Mars it had planned to send in 1978. Although it met its program goals, its massive expense caused it to be canceled in favor of the space shuttle in 1972.
HI-SEAS (Hawaii Space Exploration Analog and Simulation) is an analog habitat for human spaceflight to Mars. HI-SEAS is located in an isolated position on the slopes of the Mauna Loa volcano on the island of Hawaii. The area has Mars-like features and an elevation of approximately 8,200 feet (2,500 m) above sea level. The first HI-SEAS study was in 2013 and NASA's Human Research Program continues to fund and sponsor follow-up studies. The missions are of extended duration from four months to a year.
One thing under study by NASA is trying to understand crew dynamics such as morale, stress management, and how they solve problems as group.
The purpose of the detailed research studies is to determine what is required to keep a space flight crew happy and healthy during an extended mission to Mars and while living on Mars.
Research into food, crew dynamics, behaviors, roles and performance, and other aspects of space flight and a mission on Mars itself is the primary focus.
The HI-SEAS researchers also carry out studies on a variety of other topics as part of their daily activities.
Biosphere 2 is an American Earth system science research facility located in Oracle, Arizona. It has been owned by the University of Arizona since 2011. Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the universe. It is a 3.14-acre (1.27-hectare) structure originally built to be an artificial, materially closed ecological system, or vivarium. It remains the largest closed system ever created.
Biosphere 2 was originally meant to demonstrate the viability of closed ecological systems to support and maintain human life in outer space. It was designed to explore the web of interactions within life systems in a structure with different areas based on various biological biomes.
Recommended videos and documentaries
Recommended books about Titan
Amazon blurb :
"Ralph Lorenz and Jacqueline Mitton take readers behind the scenes of the Cassini-Huygens mission. Launched in 1997, Cassini entered orbit around Saturn in summer 2004. Its formidable payload included the Huygens probe, which successfully parachuted down through Titan's atmosphere in early 2005, all the while transmitting images and data--and scientists were startled by what they saw. One of those researchers was Lorenz, who gives an insider's account of the scientific community's first close encounter with an alien landscape of liquid methane seas and turbulent orange skies. Amid the challenges and frayed nerves, new discoveries are made, including methane monsoons, equatorial sand seas, and Titan's polar hood. Lorenz and Mitton describe Titan as a world strikingly like Earth and tell how Titan may hold clues to the origins of life on our own planet and possibly to its presence on others."
"Generously illustrated with many stunning images, Titan Unveiled is essential reading for anyone interested in space exploration, planetary science, or astronomy."
Signs of life have been found on Titan, Saturn’s largest moon.
A group of visionaries led by NASA’s Paula Benacerraf plan a daring one-way mission that will cost them everything. Taking nearly a decade, the billion-mile voyage includes a ‘slingshot’ transit of Venus, a catastrophic solar storm, and a constant struggle to keep the ship and crew functioning.
But it is on the icy surface of Titan itself that the true adventure begins. In the orange methane slush the astronauts will discover the secrets of life’s origins and reach for a human destiny beyond their wildest dreams.
(seen in infrared)
Other interesting Titan exploration concepts
“The mission concept will investigate a full spectrum of oceanographic phenomena: chemical composition of the liquid, surface and subsurface currents, mixing and layering in the “water” column, tides, wind and waves, bathymetry, and bottom features and composition,” explains Oleson. “Measurements of all these aspects of Titan’s hydrocarbon ocean environment can only be made through focused exploration with a well-instrumented craft.”
"Communicating with Earth would not be possible when the vehicle is submerged, so it would need to make regular trips to the surface to transmit science data. Due to the length of time needed to develop the hardware, travel time and the fact that seasons last seven years on Titan, Oleson and his team propose a launch in the 2040s, one of the summer periods."
2 different designs are under study :
One is a narrow robot submarine around 20 feet (6 m) long that would surface to send data directly back to Earth (cheaper than initial design).
The other is the Titan Turtle, a round-shelled, autonomous bot that would communicate with Earth through an orbiting spacecraft. The Turtle and orbiter design would be less risky than initial design, and would have more bandwidth for sending data back to Earth, Hartwig said.
Status (as of Feb 2018): "The project recently moved from the first phase of experimental funding under the NASA Innovative Advanced Concepts (NIAC) program. It's now moving toward the technology-development stage, with initial tests of some systems planned for late 2018 or early 2019, Hartwig said."
"If the mission is approved, the probe could be launched in the mid-2030s and arrive at the Saturn system in the late 2030s or early 2040s, one of the project leaders at NASA's Glenn Research Center, aerospace engineer Jason Hartwig, told Live Science."
Read NASA’s Testing a Space Submarine to Use in Titan’s Seas. (Futurism.com, feb 2018)
Read These seafaring robots will search for life across the solar system (popsci.com, april 2018)
Read Why NASA Wants to Send a Submarine to Titan (nbcnews.com, feb 2017)