• Humans to Titan

    Titan, Saturn's largest moon, is the most welcoming place for Humans beyond Earth in our Solar System,

    let's settle it !

  • 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.

    How would organic materials from the atmosphere makes its way to it ?

  • Latest articles

  • This website is dedicated to furthering the exploration and settlement of Titan by both public and private means.

    First, some cool facts about Titan!

    • 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 is the largest moon of Saturn with a diameter of 5151 km. By comparison, here is the diameter of :
      • Moon : 3474 km
      • Mercury : 4879 km (yep, Titan is bigger than one of our planets !)
      • Ganymede : 5268 km (it's a moon of Jupiter and the largest moon in the Solar System, Titan is second)
      • Mars : 6779 km (so, not much smaller than Mars!!)
      • Earth : 12742 km
    • It is the only moon in the Solar System known to have a dense atmosphere, 4.5 denser than the Earth atmosphere
    • Its atmospheric pressure is the 2nd highest for a body with a surface in the Solar System (excluding the 4 gas giants), after Venus and before Earth. Next in line is Mars with an atmospheric pressure of a mere 0.6% of Earth one ! (compared to 145% for Titan and 9200% for Venus)
      • On Titan, you'd feel the same pressure on your skin as when at the bottom of a pool on Earth, below 5 meters of water
      • Warning : one should not confuse density of the air (calculated in kg of matter per cubic meter of air) and atmospheric pressure (calculated in Newton per square meter, as the weight of a column of air exerted on a given surface, at sea level for instance)
        • Basically Titan air has much more matter per unit of volume than Earth (4.5 times roughly). 
        • As for the atmospheric pressure, that is, the weight of a column of air on a surface, while Titan's air is denser, gravity is also weaker, 14% of that on Earth, so overall atmospheric pressure at ground level is "only" 1.15 times that of Earth at sea level
    • It is the only object in space other than Earth where clear evidence of stable bodies of surface liquid has been found.
    • 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

    • Titan's gravity is 14% of Earth gravity (Moon is 16.5% and Mars 37.6%), meaning someone weighing 100 kg will feel on Titan what someone hypothetically weighing 14kg would feel on Earth.
    • Titan has seasons due to its "obliquity" of 26.7°
      • Planets and moons of the Saturn system orbit the Sun on the same plane because during the Solar System's formation, the planets formed out of a disk of dust which surrounded the Sun. Because that disk of dust was a disk, all in a plane, all of the planets formed in a plane as well.
      • The obliquity (or axial tilt) is the angle between an object's rotational axis and an imaginary axis that is perpendicular to the plane mentionned above.
      • The more tilted a celestial body is, the more variations there will be in the amount of sunlight received at its surface between different areas : at certain times some areas will receive more light than others (what we call summer!)
    • Thanks to its atmosphere, Titan has weather with a methane cycle of evaporation and condensation, leading to clouds, rains, rivers and seas ! Titan has long droughts and big storms !
    • Surface features :
      • At the equator, gigantic dunes sit atop the ice. Instead of being made of sand, the dunes are likely piles of complex organic compounds called hydrocarbons, more viscous than sand. 
      • In the northern polar regions, there are 3 seas of methane-ethane (exact split not well known) :
        • Kraken Mare, 1,170 km long, with depths estimated at 300 m (named after The Kraken, Norse sea monster)
        • Ligeia Mare, 500 km long, 160 m deep (named afterLigeia, one of the Sirens, Greek monsters)
        • Punga Mare, 380 km long (named after Punga, Māori ancestor of sharks and lizards)
      • Hundreds of lakes
      • Rivers
      • Mountains
        • A mountain range measuring 150 kilometers (93 mi) long, 30 kilometers (19 mi) wide and 1.5 kilometers (0.93 mi) high was also discovered by Cassini in 2006. This range lies in the southern hemisphere and is thought to be composed of icy material and covered in methane snow
        • Most of Titan's highest peaks occur near its equator in so-called "ridge belts". In 2016, the Cassini team announced what they believe to be the tallest mountain on Titan : located in the Mithrim Montes range, it is 3,337 m tall. 
        • Though "because Titan's icy mantle is less viscous than Earth's magma mantle, and because its icy bedrock is softer than Earth's granite bedrock, mountains are unlikely to reach heights as great as those on Earth" says Wikipedia
        • According to JPL, "By convention, mountains on Titan are named for mountains from Middle-earth, the fictional setting in fantasy novels by J.R.R. Tolkien." Colles (collections of hills) are named for characters from the same Tolkien works.
      • Maybe cryvolcanoes (wikipedia)
        • Though no volcanic features had been unambiguously identified on Titan so far.
        • If volcanism on Titan really exists, the hypothesis is that it is driven by energy released from the decay of radioactive elements within the mantle, as it is on Earth. Magma on Earth is made of liquid rock, which is less dense than the solid rocky crust through which it erupts. Because ice is less dense than water, Titan's watery magma would be denser than its solid icy crust. This means that cryovolcanism on Titan would require a large amount of additional energy to operate, possibly via tidal flexing from nearby Saturn.
        • The low-pressure ice, overlaying a liquid layer of ammonium sulfate, ascends buoyantly, and the unstable system can produce dramatic plume events. Titan is resurfaced through the process by grain-sized ice and ammonium sulfate ash, which helps produce a wind-shaped landscape and sand dune features.
        • In March 2009, structures resembling lava flows were announced in a region of Titan called Hotei Arcus, which appears to fluctuate in brightness over several months. Though many phenomena were suggested to explain this fluctuation, the lava flows were found to rise 200 meters (660 ft) above Titan's surface, consistent with it having been erupted from beneath the surface
        • Make sure to watch a few minutes of that video stopped at the right time to see what cryolava believed to be made of ammonia and water could look like
        • Cryovolcanism on Titan could cause planetary protection issues if the lava were made of liquid water (mixed with other elements to keep it liquid), but at a probable -150°C, "it's well below the minimum temperature for Earth life. So it should be okay for forward contamination. There is some evidence that life can reproduce very slowly below -20 C. There is no sharp cut off, the colder it gets the longer the generation time until eventually it's millenia for the lifetime of a single microbe.. But at -150 C, no way." says Robert Walker
        • Read as well these articles from 2010 :
    • Titan is even believed to have a global subsurface liquid water ocean
      • The hidden ocean may be 60 to 120 miles (100 to 200 km) thick to be found below the surface ice crust estimated to be 30 to 90 miles (50 to 150 km) thick, Lorenz said. Beneath that may be a few hundred miles of a heavier form of ice "that you get at higher pressures," he explained, on top of a rocky core roughly 1,800 to 2,100 miles (3,000 km to 3,400 km) wide. says Ralph Lorenz

    The 12 reasons to colonize Titan

    • 1. Titan surface is protected from harmful solar radiation and galactic cosmic rays thanks to its thick atmosphere (unlike Mars, meaning we can live on the surface, not buried underground, and can go out and walk on the surface much more often and for much longer than on Mars, which should help at the psychological level)
    • 2. Titan thick atmosphere (in the sense of more atoms of gas per cubic meter) also helps protect from micrometeorites, even against large meteorites up to several meters across similarly to Earth's atmosphere (unlike on Mars where micrometeorites reach the ground and can damage habitats)
    • 3. Surface atmospheric pressure is 1.45 of Earth's, meaning we won't need to pressurise space suits nor habitats (making building habitats and walking on the surface much more affordable and simple than on Mars)
    • 4. There is plenty of water available (as land is actually made of water ice, not even counting the subsurface water ocean)
    • 5. There are many ways to get energy : wind, hydropower, solar, chemical (see Energy Options for Future Humans on Titan, june 2017, more details in next section)
    • 6. Oxygen can be made using water and energy
    • 7. The water ice surface is covered with organic dust that can be used with energy to create plastic and build plenty of habitats. Low gravity is of further help here!
    • 8. It's ideal for flight, including human powered flight (due to low gravity and thick atmosphere)
      • That will make exploration of Titan way easier than on other bodies
      • "Because of Titan's low gravity (it's about 14 percent of Earth normal) and dense atmosphere, you could jump off a high spot and use your coat to glide down. "Hang gliding would take on a whole new meaning," astrobiologist Chris McKay said
    • 9. Nearby resources (thanks to the many Saturnian moons)
    • 10. Abundant Fertilizers (there’s so much nitrogen in Titan’s atmosphere that we could use it for fertilizer just as we do here on Earth.)
    • 11. Possibility to study potential Titan life (without risk of harming it as it would be very different from Earth life, unlike with Mars)
      • It has been suggested that life could exist in the lakes of liquid methane on Titan, just as organisms on Earth live in water. Such organisms would inhale H2 in place of O2, metabolize it with acetylene (C2H2) instead of glucose (C6H12O6), and exhale methane (CH4) instead of carbon dioxide (CO2). A process called called hydrogenation.
        • Acetylene (C2H2) is a hydrocarbon, colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution Pure acetylene is odorless.
      • In 2005, astrobiologist Chris McKay argued that if methanogenic life did exist on the surface of Titan, it would likely have a measurable effect on the mixing ratio in the Titan troposphere: levels of hydrogen and acetylene would be measurably lower than otherwise expected
      • In 2010, Darrell Strobel, from Johns Hopkins University, identified a greater abundance of molecular hydrogen in the upper atmospheric layers of Titan compared to the lower layers, arguing for a downward flow at a rate of roughly 1028 molecules per second and disappearance of hydrogen near Titan's surface; as Strobel noted, his findings were in line with the effects McKay had predicted if methanogenic life-forms were present. The same year, another study showed low levels of acetylene on Titan's surface, which were interpreted by McKay as consistent with the hypothesis of organisms consuming hydrocarbons.
      • NASA researchers have confirmed the existence in Titan’s atmosphere of vinyl cyanide, also known as acrylonitrile. It's is an organic compound with the formula CH2CHCN that could potentially provide the cellular membranes for microbial life to form in Titan’s vast methane oceans. If true, it could prove to us that life can flourish without the ubiquitous H2O.
      • Another key ingredient for life confirmed on Titan : long chains of carbon atoms that may be “universal drivers” for the chemistry that precedes life called a carbon chain anion. It appears to be a catalyst for complicated chemical reactions. (from This weird moon of Saturn has some essential ingredients for life, Aug 2017, Washington Post)
        • Much the way lemon juice reacts with baking soda to make a cake rise, this anion, or negatively charged molecule, may trigger reactions that produce bigger organic molecules.
        • 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.

      • The chance to discover a form of life with a different chemical basis than life on Earth has led some researchers to consider Titan the most important world on which to search for extraterrestrial life. In a paper in the journal Astrobiology, Robert Shapiro, a professor of chemistry at New York University, and Dirk Shulze-Makuch of Washington State University rated Titan a higher-priority target for investigation than even Mars.
      • A National Academy of Sciences study panel concluded that “the environment of Titan meets the absolute requirements for life, which include thermodynamic disequilibrium, abundant carbon-containing molecules and heteroatoms (atoms other than carbon and hydrogen), and a fluid environment…” The panel report further stated that “this makes inescapable the conclusion that if life is an intrinsic property of chemical reactivity, life should exist on Titan.”
      • Here is NASA's 5-year plan to study Habitability of Hydrocarbon Worlds: Titan and Beyond 05/2018 - 04/202 (Make sure to click to see the great illustration of Titan's different crust layers)
    • 12. It's arguably the cheapest place beyond Earth where to go and build a settlement (once you include cost of building habitats, as this will be cheaper than anywhere else thanks to the thick atmosphere and not having to pressurise habitats, same for suits to wear to go outside)
      • "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

    • 13. As a bonus, for the view of Saturn in Titan sky, which will look on average approximately 10 times bigger than the Moon for us from Earth
      • Please note that Titan is tidally locked to Saturn, so it always shows the same face to Saturn. So Saturn won't be seen from all over Titan, and from the places where it can be seen, it will always apear in the same place in the sky.
      • A full Saturn, seen at night from Titan equator, is estimated to be 3 times less bright than a full Moon seen from the Earth
        • The calculation : Saturn gets 1/100 of the light the Moon gets from the Sun (because it's 10 times further from the Sun (and light received decrease with square of distance), but Saturn has an apparent radius in the sky from Titan that is 10 times larger than for the Moon from Earth, meaning the apparent surface is 100 times bigger in the sky. Saturn reflects the light 3 times better than the Moon (based on what is called the Bond albedo), and after that Titan lets only through 1/10 of the light it gets compared to the Earth. So we have for a full Saturn in Titan's sky: 1/100 *100*3*1/10 = 0.3 times the brightness of a full Moon in the Earth sky, roughly.

    Why Titan and not Mars ?

    • We believe that we shouldn't send Humans to Mars as :

      • It would increase dramatically the risk of forward contamination of the Mars surface with our earthly microbes, which would ruin our unique chance to study a pristine Mars
      • All the reasons advanced to vindicate the act of Humans traveling to Mars are either wrong or can be addressed in a way that spares Mars.
    • The above claims sound controversial, but we've detailed them with many sources to back them up in that op-ed published on the space news site of reference in Asia-Pacific, SpaceTechAsia.com : Why we shouldn’t send humans to Mars

    The 8 Main objections to choosing Titan as our second home and their answers

    • It's far, it took 7 years for Cassini-Huygens to reach Titan
      • Yes, but with faster propulsion, in particular Nuclear Electric Propulsion, it should be possible to shorten the trip to 2 years, maybe even 1 year
        • Also the thick atmosphere helps again here, as it allows the spacecraft to perform an aerocapture of Titan, which requires only one pass through the atmosphere to reduce its velocity and enter orbit (a process that last hours to days). 
          • As Mars atmosphere is too thin, such a manoeuver isn't possible, meaning only aerobraking is possible there, which takes on the order of 100 to 400 passes, taking weeks to months, to achieve the desired velocity reduction using only that technique (of course with chemical retropropulsion it can be fastened, but requires more fuel).
    • It's dark
      • Yes, but not too dark, like a few minutes after sunset on Earth. And  it's possible to concentrate sunlight using thin film mirrors, which are low mass so can be transported out there. Anyway, better to be able to live and walk on the surface of Titan with such levels of light, protected from the radiations by the thick atmosphere, rather than living underground or mostly indoor on Mars which has a very thin atmosphere letting the Galactic Cosmic Rays and solar energetic particles reach the surface.
      • Anyone living on Titan would probably need to live in conditions of permanent artificial lighting, would be like living in Alaska in winter all year round. 
      • Interestingly, there's enough light that reaches Saturn’s moon Titan to make Earth-type photosynthesis possible in theory says astrobiologist Dirk Schulze-Makuch
    • Gravity is too low
      • Yes, but as it's similar to our Moon's gravity, by studying its effect on the Moon we'll learn how to best cope with low gravity. And in any case, we can think of building habitats or sleeping quarters in large enough centrifuge machines so as to recreate Earth gravity.
    • Energy is scarce
      • Not really, we could use for instance :
        • the equivalent of hydropower, leveraging the elevated bodies of liquid methane
          • "Dams or waterwheels could generate power from hydrocarbons made liquid by Titan’s extremely low temperatures, but it could be difficult to get the liquid flowing as the largest lakes and seas are lower than surrounding terrain. The topography doesn’t make it impossible, it just makes it a very big engineering project to carve out a river that flows downhill out of the sea." says Dr Hendrix
        • tidal power
          • A better option than traditional hydropower could be to put turbines in the seas because Saturn creates strong tides on Titan. Its largest sea, Kraken Mare, experiences up to a metre of tidal change each day. Those tides all flow through a narrow constriction separating the northern and southern parts of the sea, Seldon Fretum, or as it is nicknamed, the Throat of the Kraken.
        • chemical energy (hydrogen and acetylene can be extracted from Titan's atmosphere and react together to produce energy)
          • According to Cassini data from 2008, Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth. These hydrocarbons rain from the sky and collect in vast deposits that form lakes and dunes. Though, as there isn't easily accessible oxygen to combust these hydrocarbons, they can't be used to produce energy. Oxygen could be extracted from water ice Titan crust is made of, but it wouldn't make economic sense as that process itself would require energy !
        • solar power (it's been estimated that supporting 300 million people would require a solar farm covering 10 percent of Titan)
        • wind power (as surface winds are slow we could use tethered blimp or balloon mounted windmills at a height of 3 km where the speed is 2 meters per second (4.4 miles per hour) or even better at 40 km where the wind speeds are 20 meters per second (44 miles per hour). These could generate hundreds of terrawatts). Wind turbines suspended in the atmosphere would be far easier on Titan than on Earth in the low gravity !
      • See Energy Options for Future Humans on Titan, june 2017
     
    • It's cold, at -180°C (-291°F) on average at the surface
      • Yes, but a thick enough suit would be enough to protect ourselves from the cold. Such a suit could be donned in minutes as opposed to hours for a spacesuit on Mars, because on Titan there wouldn't be any need to pressurise the suit, contrary to Mars. Such a suit would also be much cheaper to use and would last much longer (existing spacesuits cost around 2 million USD each, and were predicted to be used for up to 25 spacewalks or EVA, Extra Vehicular Activity)
      • "Titan’s surface temperature is 179°C, so it will be essential to keep both Titannauts and equipment warm
        inside a cocoon of insulation. Nevertheless, the temperature difference between the skin and the environment
        is only about twice that seen in the coldest terrestrial environments and, on what is currently known and inferred,there is little wind on Titan. Furthermore, gas conductivity falls sharply with temperature, so that simple trapped-gas insulation will work better than on Earth. With a surface area of 2 m2 and insulation 7.5 cm thick, heat loss should be about 150 W, which can be generated by light activity. Batteries to heat a visor and gloves would weigh little on Titan." (source Titan: A Distant But Enticing Destination for Human Visitors, by Julian Nott, University of California, Santa Barbara)
    • It lacks metals for construction and manufacturing
      • "It would have iron in its core of course but not accessible for settlers. So indeed, it might have less accessible metals than most places. But to start with, there is much less need for metals there, because we don't need to build pressure vessels for the habitats. We can do a lot with plastic. " says Robert Walker. So it's certainly not a show-stopper, whatever little metals are needed can be imported from the Asteroid Belt thanks to ion thrusters (they move slowly but expends little propellant, so are much cheaper to operate)
    • The water ice crust will make it impossible to build habitats : since they would be heated, they would make the surface crust melt
      • 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.

    • It will be hard for a rocket using retropropulsion to land on a body whose crust is made of water ice
      • Issue: If Titan's surface is made of water ice and hydrocarbon dust, were a big rocket to land using retropropulsion, wouldn't the ice melt due to the heat of the exhaust gases and make it really tricky for the rocket to stabilise on the surface ? And let's assume the rocket does land. Then the water that would have melted would solidify again as ice around the rockets legs and imprison them ? That would make it way harder for the rocket to take off again, wouldn't it ?
      • "Ice does have a pretty high heat capacity. And it is a very low temperature on Titan so you have to raise it a lot more than on Earth" says Robert Walker
      • I asked the question on space.stackexchange.com and here are the responses, it's an issue, but not a total show stopper
      • "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 hte exact time)

      • What about landing elsewhere than on ice ? "So far we've seen no evidence for anything other than water and organics on Titan's surface. When it formed, the silicates and metals (heavy stuff) sank to form the core, and it looks like no strong convection (cryovolcanism) has brought any of that up onto the ice crust. The organics are the result of sun-driven photochemistry of the methane (and a few other very minor species) in the upper atmosphere raining down onto the surface, "tholins" as Carl Sagan called them. At warmer temperatures most would be gas, liquid, or something akin to grease, not any better than ice to land on." says Tom Spilker
      • "Finding the equivalent of a car parking lot to set down on. Titan would probably be the least risky in that regard, but you can't just set down anywhere. There are rugged mountain ranges, lakes and seas, river channels, etc. The only location where we know we could find a suitable landing spot is near the Huygens landing site."  says Tom Spilker

    How you can help

    • Share this website with friends and invite them to follow these steps !
     
    • Subscribe to this site's newsletter to keep up with Titan news, click here !
       
       
      • Support Nuclear Electric Rockets that are required for any sustainable manned exploration of the Outer Solar System. It means having high eletric power in space AND fast propulsion. The best combination seems to be Nuclear Electric power AND Plasma propulsion
        • About plasma propulsion : in particular the VASIMR engine by the Ad Astra Rocket company, the most advanced form of plasma propulsion nearing completion, you can follow their Twitter account and Facebook account as a sign of support ! I highly recommend :
          • watching this cool 20-min intro video by Ad Astra, the company behind VASIMR engine on their endeavour to create the engine that will open the Outer Solar System to Humans
          • reading that great article about the man behind VASIMR, Dr Chang Diaz, 7-time space shuttle astronaut, who's been working on that technology for 40 years  
          • Interestingly, Dr Chang Diaz chose to incorporate its company Ad Astra on the very day Huygens landed on Titan ! Coincidence ? Maybe he's got some nice lans in mind ! :)
          • Dr Chang Diaz designed a conceptual nuclear-electric human interplanetary transport ship with VASIMR engines as primary propulsion :
            • "The liquid hydrogen propellant is stored in a toroidal cluster of tanks to provide radiation shielding to a cylindrical crew module located on the axis.
            • A high magnetic field superconducting radiation shield, nested inside the propellant tank cluster, provides additional shielding against galactic cosmic radiation (GCR) and secondary particles. 
            • The 4 nuclear reactors with magneto-hydrodynamic power conversion provide primary power to the engines and the rest of the ship and are located on radial booms. 
            • The reactor cores sit on top of “dish-like” high-density gamma shields and are surrounded by thermal radiating surfaces to dissipate the excess heat. 
            • High power nuclear-electric engines such as those on this ship will be fully tested at Ad Astra’s future lunar test facility on the surface of the Moon."
          • In 2013, the VASIMR ® team published a short study for fast and operationally robust human missions to Mars, based on high power NEP. The system considered an advanced, high temperature, gas cooled, nuclear magneto hydrodynamic (MHD) power plant, as proposed by Litchford and Harada in 2011, combined with high power VASIMR plasma propulsion. The general architecture of such a system featured a multi-megawatt closed cycle MHD nuclear plant, using non-equilibrium He/Xe frozen inert plasma (FIP) working fluid. The fission reactor mass estimate was based on the NERVA design for a 350 MW nuclear reactor with a mass of 1785 kg, increased to 3000 kg to account for containment and shielding margin.
        • About nuclear electric power in space as a power source to feed the propulsion system
          • the most recent project that needs support is the Kilopower project, read in particular "Kilopower Project: NASA Pushes Nuclear Power for Deep-Space Missions" (Space.com, jan 2018)
            • "A successful Kilopower test will be a great leap forward for space nuclear power. However, there is much more work to do to engineer and qualify a real flight system." said Steve Jurczyk, associate administrator of NASA's Space Technology Mission Directorate
            • "The pioneering Kilopower reactor represents a small and simple approach for long-duration, sun-independent electric power for space or extraterrestrial surfaces."
            • "This new technology could provide kilowatts and can eventually be evolved to provide hundreds of kilowatts, or even megawatts of power." (the VASIMR engine's designers say that they would need a power source of 200MW for a ship able to take Humans fast enough to Mars and beyond)
            • Read about it on the NASA website and watch the 3-min intro youtube video
            • And here is the scientific paper : NASA’s Kilopower Reactor Development and the Path to Higher Power Missions (Mar 2017)
            • Watch this 4 min video that explains clearly a concept of Small Reactor for Deep Space Exploration being investigated by the Los Alamos National Lab (2012)
              • "This is the first demonstration of a space nuclear reactor system to produce electricity in the United States since 1965, and an experiment demonstrated the first use of a heat pipe to cool a small nuclear reactor and then harvest the heat to power a Stirling engine at the Nevada National Security Site's Device Assembly Facility confirms basic nuclear reactor physics and heat transfer for a simple, reliable space power system."
          • Is it dangerous to send fissile material in space ?
            • Fissile material is wgat is used in a Nuclear Fission Reactor
            • "It presents absolutely no radiation risk. The fuel is not more radioactive than rocks until you start to burn it, and since it is only for use in space, you simply don't turn the engines on until you are safely away from Earth. If this was commonly understood half a century ago, we'd be living in a completely different world." says Kim Holder from Moonwards
            • "You don't really need to worry about unused fission fuel. The usual ceramic form of the fuel could be used for a dinner plate. The "unused" is important. Once you start up a fission reactor, the fission products are highly radioactive. So don't ever start up a space fission reactor until it's well out in space and not coming back." (source)
        • A recent proposal for an efficient nuclear space power plant by Litchford and Harada in 2011 (extracts)
          • Magnetohydrodynamic (MHD) electrical power generators are devices in which, according to the magnetohydrodynamics laws, a conversion of the energy of working fluid into electrical energy takes place. The principle of operation of MHD generators as well as conventional electrical generators is based on Faraday's induction law. In an electrically conducting fluid, moving at velocity  in a magnetic field  , an electromotive force is induced
          • "For larger missions over 1 MWe, gas-cooled NFR and vapor core reactors with CCMHD energy conversion have also been considered and studied"
          • "For many science-based robotic missions and surface power applications, power plant outputs of 100-120 kWe are considered readily achievable with currently available nuclear technologies, and various Advanced Radioisotope (AR) or Nuclear Fission Reactor (NFR) electric power generation systems could be engineered and developed with minimal R&D needs. For missions with larger electric power requirements, however, innovative low specific mass Nuclear Fission Reactor (NFR) systems with efficient electric power conversion are clearly needed. Here, we propose consideration of nuclear closed-cycle MHD (CCMHD)"
          • "In contrast to turbo-generator systems, MHD generators extract energy at temperatures beyond solid material limits and provide high-temperature heat rejection. This advantage translates into weight savings via reduction in space radiator size and weight. If these potential specific power gains can be realized, it would open up entirely new vistas for rapid deep-space transport."
          • "The principle technical obstacle to deep-space utilization of high-power nuclear electric propulsion (NEP) is the need for end-to-end system specific mass approaching 1 kg/kW. One of the few potentially feasible approaches for achieving the requisite power-to-weight performance are closed-cycle nuclear space power plants utilizing a High Temperature Gas Reactor (HTGR) coupled with a magnetohydrodynamic (MHD) generator, a concept readily scalable for application to multi-MW-class NEP systems."
       
        • Molten Salt Reactors (MSRs) are particularly promising
          • We invite you to read : 
          • Since former NASA engineer Kirk Sorensen revived forgotten MSR technology in the 2000s, interest in MSR technology has been growing quickly. Since 2011, four separate companies in North America have announced plans for MSRs: 
          • MSRs are meant to be much more compact, cheaper to build and operate and much safer.
            • A molten salt reactor (MSR) is a type of nuclear reactor that uses liquid fuel instead of the solid fuel rods used in conventional nuclear reactors. Using liquid fuel provides many advantages in safety and simplicity of design.
            • MSRs where first developed in the U.S. in the 1950s for use in a nuclear-powered aircraft bomber (the idea being that the bomber could remain in the air indefinitely). Though a small experimental reactor ran successfully, the program was canceled when it became clear that in-air refueling of bombers was viable.
              • The NB-36 bomber plane completed 47 test flights and 215 hours of flight time (during 89 of which the reactor was operated). The crew worked from a lead-shielded cockpit. The 3MW air-cooled reactor in the NB-36H did not power any of the aircraft's systems, nor did it provide propulsion, but was placed on the NB-36H to measure the effectiveness of the shielding.
       
      • Nuclear Thermal Rockets (NTR) are also of interest
        • Below, the best part of that article : NASA Reignites Program for Nuclear Thermal Rockets (aug 2017)
          • In an NTP rocket, uranium or deuterium reactions are used to heat liquid hydrogen inside a reactor, turning it into ionized hydrogen gas (plasma), which is then channeled through a rocket nozzle to generate thrust.
          • 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.

        • See as well :
          • Nuclear thermal propulsion, which was studied in the Cold War for space travel, could make a comeback to fly humans to Mars.(feb 2018, PopularMechanics.com)
            • "To begin work on a new NTP rocket engine, NASA awarded an $18.8 million contract to BWXT Nuclear Energy in August 2017. BWXT, which has a long history of making nuclear fuel for the U.S. Navy, will design a nuclear reactor that uses low-enriched uranium nuclear fuel in the form of "Cermet" (ceramic metallic) rods. NASA has also partnered with Aerojet Rocketdyne to design an engine that could be mated to the reactor to produce thrust, and NASA will study cryogenic storage options for carrying liquid hydrogen propellant. Finally, NASA and BWXT will work to develop an exhaust capture system that would be used for future ground testing of the NTP engine."
            • "Building an NTP engine is just part of the equation. You'd also need to estimate just how hard (and costly) it would be to build an interplanetary spacecraft powered by nuclear thermal propulsion. Sheehy figures the cost at a few billions of dollars, though the full cost analysis will not be available for another year or so."
          • NASA's Nuclear Thermal Propulsion (NTP) Project (pdf, Nasa.gov, 2017)
            • NTP is initial step towards advanced space nuclear power and propulsion, which could eventually help enable exploration and development of the solar system
       
      • Support a base on the Moon as it will let us study the effects of low gravity and will be a source of "affordable" water ice that may be needed to shield manned spaceships from harmful radiations
        • Read in particular this article "Op-ed | Moon Direct: How to build a moonbase in four years" by Robert Zubrin (march 2018) :
          • Would need only 3 $100-million Falcon Heavy and 1 $60-million Falcon 9
          • "Assuming that cost of the mission hardware will roughly equal the cost to launch it, we should be able to create and sustain a permanently occupied lunar base at an ongoing yearly cost of less than $700 million. This is less than 4% of NASA’s current budget" (NASA budget itself was of $18.4 billion in 2011, that's 0.5% of the US federal budget)

      Main challenges to overcome to get to Titan

      • Better knowledge of Titan (for this, let's support the Dragonfly project, see above)
      • Faster propulsion (high power electric propulsion and VASIMR is the most likely solution)
      • Nuclear electric power in space (to power the electric engine)
      • Artificial gravity (needed to recreated gravity in the spaceship, could be obtained by rotating the ship)
      • A base on the Moon so as to :
        • study the effect of low gravity on the human body (Titan and our Moon have similar gravity levels)
        • mine water ice that will be eventually cheaper to send to space than from Earth, as it will be needed for protect space travelers from radiation
      • Protection against solar storms and Galactic Cosmic Rays during the trip
        • 2 meter-thick of water ice around the ship would do
        • unless we opt for a "Spacecraft Scale Magnetospheric Protection", one of the 25 NASA's Innovative Advanced Concepts disclosed in March 2018
        • As Erik Seedhouse and Dr Chang Diaz (the astronaut and engineer working on VASIMR) are writing in their book To Mars and Beyond, Fast!: How Plasma Propulsion Will Revolutionize Space Exploration : "Radiation exposure can be mitigated during flight by utilizing material shielding rich in hydrogen (such as water and a number of plastics). It has been calculated that about 100 centimeters of water or polyethylene shielding might be sufficient to stop most of these radiations. In the VASIMR ship, the bulk of the proton radiation from the Sun could be effectively shielded by the liquid hydrogen making up the propellant. This propellant could be strategically located in cryogenic storage tanks surrounding the crew module. In addition, the liquid hydrogen could enable the installation of a nested toroidal superconducting magnetic shield, which will further increase the radiation protection.
          • just FYI, water ice density is 0.92 g/cm3 while polyethylene density is 0.97 g/cm3, so won't be lighter to use polyethylene for shielding
      • These 3 life-support closed-system technologies for long duration manned space trip : food generation, air recycling and water recycling
        • As Robert Walker says "We already have that with BIOS-3 - not tested in space but tested for several growing cycles (growing cycle of a month) in Russia."
      • The Human factor : can a team of people cooperate in confined habitats for extended periods of time ?
        • This is being investigated, see in patricular :
          • MARS-500 : 
            • The Mars-500 mission was a psychosocial isolation experiment conducted between 2007 and 2011 by Russia, the European Space Agency and China, in preparation for an unspecified future manned spaceflight to the planet Mars
            • 3 different crews of volunteers lived and worked in a mock-up spacecraft at IBMP. The final stage of the experiment, which was intended to simulate a 520-day manned mission, was conducted by an all-male crew consisting of 6 people. The mock-up facility simulated an Earth-Mars shuttle spacecraft, an ascent-descent craft, and the Martian surface. The volunteers who participated in the three stages included professionals with experience in engineering, medicine, biology, and human spaceflight. The experiment yielded important data on the physiological, social and psychological effects of long-term close-quarters isolation
          • HI-SEAS
            • 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
            • 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.[3] It was designed to explore the web of interactions within life systems in a structure with different areas based on various biological biomes.

            • See :

      Other recommended articles

    • Recommended videos and documentaries

      • Destination: Titan (BBC, 2011, 58 min, Youtube link)
        • It's a very interesting BBC documentary centered on the Cassini-Huygens mission and in particular on the British team that worked on the surface instruments of the lander Huygens. First 15 minutes are a recap of the history of humans in space with cool footage of Yuri Gargarin visiting England, following 30 minutes are about the years of work leading to the launch of the rocket, last 15 minutes are about the arrival of Cassini-Huygens at the Saturn system, the successful landing of Huygens on Titan as the furthest landing of a man-made machine in history, and about what we learnt there !
        • It features scientists John Zarnecki and Ralf Lorenz
        • As described on the BBC dedicated page : "It's a voyage of exploration like no other - to Titan, Saturn's largest moon and thought to resemble our own early Earth. For a small team of British scientists this would be the culmination of a lifetime's endeavour - the flight alone, some 2 billion miles, would take a full seven years. This is the story of the space probe they built, the sacrifices they made and their hopes for the landing. Would their ambitions survive the descent into the unknown on Titan's surface?"
       
       
      • Ralph Lorenz | Sailing the Seas of Titan (Youtube, oct 2014, 56 min)
        • Dr. Ralph Lorenz is a planetary scientist on the Principal Professional Staff of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, MD, USA. He is a member of the Cassini Radar team, and helped to develop the Huygens Surface Science Package. He is involved in formulating mission and instrument concepts at Titan, Europa, Venus and Mars, and served as the Project Scientist for the Titan Mare Explorer (TiME) Discovery Phase A study, a proposal to sail a capsule on Titan's seas. He has played a major role in the definition of a range of US and European Titan mission concepts, from airships and hot-air balloons, through airplanes, landers and even a submarine.
        • Oceanography is no longer just an Earth Science. The NASA/ESA Cassini mission - was still making exciting discoveries 10 years after its arrival in the rich Saturnian system - found that 3 seas of liquid hydrocarbons adorn Saturn’s giant, frigid moon Titan. Titan was already exotic, having a thick, organic-rich atmosphere, and a diverse landscape with mountains, craters, river channels and vast fields of sand dunes, but these seas, and hundreds of lakes, present a new environment (low gravity, dense atmosphere, hydrocarbon liquid) in which to explore familiar and important physical processes such as air, sea heat and moisture exchange, wind-driven currents and waves, etc. 
        • Moreover, Titan’s seas (notably the two largest ones, Kraken Mare and Ligiea Mare, about 1000km and 400km across, respectively) offer an appealing and accessible target for future Titan exploration.
        • Thomson--Reuters Sciencewatch in 2011 named Ralph Lorenz as one of the world's top planetary scientists by impact, ranking him #3 by publications and #10 by citations. He holds 5 NASA Group Achievement awards.
       
      • Titan's Chemical Cocktail (Youtube, oct 2013, 3 min) 
        • It has nice animations of chemical reactions on Titan, very clear stuff
        • A video from the Goddard Space Flight Center, narrated by a NASA scientist
       
       
       
      • Titan: The Mystery of the Missing Waves (Youtube, Space Rip channel, jul 2013, 4 min)
        •  Titan is the only natural satellite known to have a dense atmosphere and the only object, other than Earth, for which clear evidence of stable bodies of surface liquid has been found.  However, these bodies of liquid are incredibly still, with no sign of wave activity.  What is causing this incredible phenomenon?
       
       
      • Must watch : Saturn's Moon Titan: A Future Abode for Life (Youtube, 2014, 1 hour)
        • Passionate talk by Carrie Anderson
          • Carrie is the associate chief at the Goddard Planetary Systems Laboratory of NASA's Goddard Space Flight Center in Greenbelt, Md. She has worked extensively on the Cassini spacecraf​t
        • Main learning and question : when our sun warms up, hundreds of millions of years from now, there will be a time window of 100 millions years during which Titan will be in the Habitable Zone (HZ) and hence have liquid water. As it has plenty of organics already, will life arise ?
          • Personal note : one can assume that by then Humans would have visited Titan many times and hence Earth life would have been seeded intently or not, which would make it way harder if not impossible for water-based life to emerge on its own
        • Another detail : the energetic particles received by Titan (and that contributes to the chemical reactions in its atmosphere outputting hydrocarbons) mostly come from Saturn's magnetic field, not the Sun (which provides the UV)
    • Recommended books about Titan

      • Beyond Earth: Our Path to a New Home in the Planets, by Charles Wohlforth & Amanda R. Hendrix (320 pages, nov 2016)
        • "From a leading planetary scientist and an award-winning science writer, a propulsive account of the developments and initiatives that have transformed the dream of space colonization into something that may well be achievable. In Beyond Earth, Charles Wohlforth and Amanda R.Hendrix offer groundbreaking research and argue persuasively that not Mars, but Titan—a moon of Saturn with a nitrogen atmosphere, a weather cycle, and an inexhaustible supply of cheap energy, where we will even be able to fly like birds in the minimal gravitational field—offers the most realistic and thrill­ing prospect of life without support from Earth.
        • Though, the book has its own limitations, this Amazon review and it comments are a must read
       
      • To Mars and Beyond, Fast!: How Plasma Propulsion Will Revolutionize Space Exploration
        • by Franklin Chang Díaz, Erik Seedhouse, 200 pages, june 2017
        • The VASIMR® engine is the most advanced high-power plasma propulsion system operating in the world today and it may place long, fast interplanetary journeys withinour reach in the near future. 
        • Franklin Chang Díaz is a 7-tim Space Shuttle astronaut, he arrived in America from Costa-Rica in 1968 with $50 dollars in his pocket and speaking no English. He's been working on the VASIMR engine for 40 years almost.
        • As advanced in-space propulsion moves from science fiction to reality, the Variable Specific Impulse Magnetoplasma Rocket, or VASIMR® engine, is a leading contender for making 'Mars in a month' a possibility (as well as making the Outer Solwar System accessible to Humans). A paradigm shift in space transportation, this book is an in-depth and compelling story co-written by its inventor. It traces the riveting history of the development of the VASIMR® engine. This landmark technology is grounded in concepts of advanced plasma physics. It cross-pollinates ideas and disciplines to offer a new, practical, and sustainable solution for in-space transportation beyond low Earth orbit in the decades to come. Invented by the co-holder of the world’s spaceflight record, astronaut Franklin Chang Díaz, the VASIMR®  engine is developed by Ad Astra Rocket Company in its Texas facilities with NASA as part of the NextSTEP VASIMR® partnership. With adequate funding, the first spaceflight of the VASIMR® engine is imminent. Plasma rockets feature exhaust velocities far above those achievable by conventional chemical rockets. 
       
      • Titan Unveiled: Saturn's Mysterious Moon Explored​
        • (haven't read it yet)
        • First published in 2008, republished with a new afterword in 2010, by Ralph Lorenz &‎ Jacqueline Mitton, 275 pages
        • 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."

       
       
      • A novel recommened by Ralph Lorenz : Titan
        • 2013, by Stephen Baxter, 692 pages
        • Amazon blurb
          • 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.

    • Titan

      (seen in infrared)

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    • Other interesting Titan exploration concepts

      • Titan Saturn System Mission (TSSM)
        • The TSSM mission consists of an orbiter and 2 Titan exploration probes
          • a hot air balloon ("Montgolfier" type) that will float in Titan's clouds
          • a lander, the Titan Mare Explorer (or TiME) that will splash down on one of its methane seas.
        • Status : cancelled, as in 2009, a mission to Jupiter and its moons was given priority over Titan Saturn System Mission.
        • Watch this nice 3 min video about the mission, with cool animations
        • About TiME – The Titan Mare Explorer
          • Titan Mare Explorer (TiME) is a proposed design for a lander for Saturn's moon Titan. 
          • TiME is a relatively low-cost, outer-planet mission designed to measure the organic constituents on Titan and would have performed the first nautical exploration of an extraterrestrial sea, analyze its nature and, possibly, observe its shoreline. As a Discovery-class mission it was designed to be cost-capped at US$425 million, not counting launch vehicle funding. It was proposed to NASA in 2009 by Proxemy Research as a scout-like pioneering mission, originally as part of NASA's Discovery Program. The TiME mission design reached the finalist stage during that Discovery mission selection, but was not selected, and despite attempts in the U.S. Senate failed to get earmark funding in 2013
          • Status : cancelled
          • See dedicated page on Wikipedia
          • See the scientific pdf paper introducing the concept
      • AVIATR (Aerial Vehicle for In situ and Airborne Titan Reconnaissance)
        • A proposed airplane mission concept to Titan, a moon of Saturn. The concept was developed in 2011 by a team of scientists led by Jason W. Barnes at the University of Idaho
        • The design called for a 120 kg airplane powered by an advanced Stirling radioisotope generator that would have allowed it to fly uninterrupted for about one year.
        • Status : the National Research Council's "Decadal Survey" did not prioritize the moon Titan for exploration, and the development of the advanced Stirling radioisotope generator was suspended indefinitely.
      • Titan Submarine: Exploring the Depths of Kraken (1 main design and 2 variants)
        • This mission would be a logical follow-on to a Titan surface mission such as TiME (Titan Mare Explorer) 
        • Titan Submarine, or Titan Sub for short, will be a fully autonomous, highly capable science craft that will allow a complete exploration of what exists beneath the waves on another world. 
        • A 90-day, 1,250-mile voyage exploring Kraken Mare, a sea comparable in size to the Great Lakes, is proposed. 
        • “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."

        • See source on NASA website

        • Watch the 1min 40 sec animation on Youtube Titan Submarine: Exploring the Depths of Kraken Mare

        • 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)

    • About the editor

      This website is edited by Thomas Jestin, a Frenchman based out of Singapore passionate about space exploration. Find him on Linkedin, on Twitter and on his own webpage where he lists all his articles about a wide range of topics in English here and in French there.