Saturn's moon Titan is remarkably similar to Earth. What plans does humanity have for it?

How far from Earth is Titan?

Titan is the sixth moon of the planet Saturn, the sixth planet from the Sun.

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Saturn's great moon, Titan, is an icy world,the surface of which is completely hidden by the misty atmosphere of a golden hue. Titan is the second largest moon in our solar system. Only the satellite of Jupiter - Ganymede - is larger, and then, only by only 2%. Titan is larger than Earth's Moon, and even larger than the planet Mercury.

This giant moon is the only moon inA solar system with a dense atmosphere. In addition, this is the only world besides the Earth, on the surface of which there are rivers, lakes and seas. Like Earth, Titan's atmosphere is composed primarily of nitrogen and small amounts of methane. This is the only place in the solar system, besides the Earth, where, as you know, there is a familiar cycle of fluids. From the clouds they fall on the surface of the moon and fill the lakes and seas, and then evaporate and evaporate back into the sky. It is also believed that Titan has an under-ice ocean that is similar in salinity to the Dead Sea.

Size and distance

The radius of Titan is about 2,575 kilometers,it is almost 50% wider than the moon. Titan is located about 1.2 million kilometers from Saturn, which in itself is about 1.4 billion kilometers from the Sun, or about 9.5 AU. (astronomical units). One au Is the distance from the Earth to the Sun. Light from the Sun reaches Titan in about 80 minutes; Because of the great distance, sunlight on Saturn and Titan is about 100 times weaker than on Earth.

Titan takes 15 days and 22 hours tocomplete a revolution around Saturn. Like Earth's Moon, Titan always shows the planet the same "face" as it orbits. It takes Saturn about 29 Earth years to orbit the sun, and the gas giant's axis of rotation is tilted like Earth, which means the seasons change. True, each such season lasts more than seven Earth years. Each of them on Titan is on the same schedule as Saturn - seasons last more than seven Earth years, a full cycle takes 29 Earth years.

Formation

Scientists are unsure about the origins of Titan.However, its atmosphere provides a clue. Several NASA and ESA Cassini-Huygens instruments have measured nitrogen-14 and nitrogen-15 isotopes in Titan's atmosphere. The instruments found that the nitrogen isotope ratios on Titan are most similar to the nitrogen isotope ratios in comets from the Oort Cloud, a sphere of hundreds of billions of ice bodies believed to orbit the Sun between 5,000 and 100,000 AU. - about 150 million km. The nitrogen ratio in Titan's atmosphere suggests that the building blocks of this moon formed early in the history of the solar system in the same cold disk of gas and dust that formed the sun (called the protosolar nebula).

Surface

By the way, the surface of Titan is one of the mostsimilar to the Earth places in the solar system, although the temperatures there are much lower, and the "coating" itself has a different chemical composition. It is so cold here (-179 ° C) that the ice from the water looks more like rocks. On Titan, as on Earth, volcanic activity is possible, but with liquid water "lava" instead of molten rock. Titan's surface is formed by streams of methane and ethane that cut riverbeds and fill large lakes with liquefied natural gas. No other world in the solar system other than Earth has such liquid activity on its surface.

Atmosphere

Our solar system is home to morethan 150 moons, but Titan is unique in that it is the only moon with a dense atmosphere. On the surface of Titan, atmospheric pressure is about 60% higher than on Earth - about the same as a person would feel if swimming about 15 meters below the surface in the ocean on Earth. Since Titan is less massive than Earth, its gravity does not hold its gas shell as much, so the atmosphere extends to an altitude 10 times the Earth's - almost 600 km into space.

Titan's atmosphere is mostly nitrogen(about 95%) and methane (about 5%) with a small amount of other carbon-rich compounds. High in Titan's atmosphere, methane and nitrogen molecules are separated by ultraviolet light from the Sun and high-energy particles accelerated in Saturn's magnetic field. Portions of these molecules recombine to form various organic chemicals (substances containing carbon and hydrogen) and often include nitrogen, oxygen, and other elements essential to life on Earth. Some of the compounds formed from this breakdown and recycling of methane and nitrogen create a kind of smog - a thick orange haze that makes the lunar surface difficult to see from space. (However, spacecraft and telescopes can see through haze at certain wavelengths of light beyond the human eye.)

How was Titan studied and what missions await it?

"Cassini-Huygens"

For over ten years, spaceNASA's Cassini spacecraft shared the wonders of Saturn and its family of icy moons, taking us to amazing worlds. Cassini delivered a passenger to Saturn's moon system - the European probe Huygens - the first man-made object to land on a planet in the distant outer solar system

After 20 years in space, 13 of which exploredSaturn, the ship has run out of fuel. To protect the planet's moons, NASA explained, Cassini was sent on a daring final mission that sealed its fate. On September 15, 2017, at 14:55:06 Moscow time, the spacecraft completed its 20-year mission in the Saturn system and burned up in the atmosphere of the gas giant, having managed to poison the latest data on the gas giant to Earth. NASA broadcast the last minutes of the life of the space probe live.

Cassini-Huygens showed that Titan is one ofthe most Earth-like worlds we have encountered, and shed light on the history of our home planet. The point is that Cassini was in a sense a time machine. He identified the processes that likely shaped the development of our solar system. Cassini's long mission made it possible to observe the weather and seasonal changes on another planet. The mission revealed that the moons of Saturn are unique worlds that can tell their stories.

Cassini-Huygens showed that Titan is one ofthe most Earth-like worlds we have encountered, and shed light on the history of our home planet. The point is that Cassini was in a sense a time machine. He identified the processes that likely shaped the development of our solar system. The long Cassini mission made it possible to observe the weather and seasonal changes on another planet. The mission revealed that the moons of Saturn are unique worlds that can tell their stories. Numerous measurements of the gravity of Titan by the Cassini spacecraft have shown that the Moon hides an underground ocean of liquid water (probably mixed with salts and ammonia).

European Space Agency probeHuygens also measured radio signals during its descent to the surface in 2005, which strongly indicated the presence of an ocean 55-80 km below the icy ground. The discovery of a global ocean of liquid water adds Titan to a handful of worlds in our solar system that could potentially contain habitable environments. In addition, Titan's rivers, lakes and seas of liquid methane and ethane can serve as habitats on the moon's surface, although any life there is likely to be very different from life on Earth. While there is no evidence yet for life on Titan, its complex chemistry and unique environment have made it a place for further research.

Dragonfly

In the summer of 2019, NASA announced that the next targetin the solar system - the unique, richly organic world of Titan. Furthering the search for the building blocks of life, the Dragonfly mission will take multiple sorties to explore and explore the areas around Saturn's icy moon.

Dragonfly was originally scheduled to launch at2026 with and arrival in 2034. However, in September 2020, NASA asked the Dragonfly team for an alternative launch readiness date in 2027. No changes to the mission architecture will be required to accommodate this new date, and launching at a later date will not affect Dragonfly.

The rotorcraft will fly in tenspromising sites on Titan in search of prebiotic chemical processes common to both Titan and Earth. Dragonfly marks NASA's first flight in a multi-rotor science vehicle on another planet; it has eight rotors and flies like a big drone. It will take advantage of Titan's dense atmosphere - four times as dense as Earth - to become the first vehicle ever to deliver all of its scientific payload to new locations for repeatable and targeted access to surface materials.

Titanium is analogous to the very early Earth andcan provide a clue to how life could arise on our planet. During its 2.7-year base mission, Dragonfly will explore a diverse environment from organic dunes to the bottom of an impact crater, where liquid water and complex organic materials key to life once coexisted for perhaps tens of thousands of years. His instruments will study how far prebiotic chemistry has advanced. They will also investigate the properties of the Moon's atmosphere and surface, its subsurface ocean and liquid reservoirs. In addition, the tools will look for chemical evidence of past or present life.

How will Titan still be useful to humanity?

First, let's make it clear that Titan isthe moon, which in many ways is more like a planet. It has a thick atmosphere, which is about 1.5 times the pressure on the surface of the earth's atmosphere. None of the 177 other satellites in the solar system have such an atmosphere. In addition, Titan is the only place in the solar system besides Earth with stable fluids on its surface: Titan's surface has lakes and seas. So, Titan is a wonderful and very Earth-like world.

The dense atmosphere of Titan is useful because itmeans you don't need to wear a bulky spacesuit when you're on Titan. But the main reason I like it is simple: Titan's atmosphere will help us survive. In space, radiation is deadly. Energy particles from the Sun, and especially galactic cosmic rays (GCR), penetrate human tissues, causing cancer and cognitive impairment. To stay within NASA's current cancer risk limits, astronauts can travel beyond Low Earth Orbit (LEO) for as much as 200 days; a trip to Mars will probably take over 600 days. But these destructive particles cannot reach the surface of Titan; they are absorbed by the atmosphere, which means that it is a safe environment for humans. The atmosphere of Mars is not dense enough to provide reliable protection from GCR and the Earth.

People living on Titan can walk (or,rather, bouncing - since gravity is 14 percent of Earth's gravity, slightly less than on the Moon) in suits to keep warm. It is cold on Titan (surface temperature around -290 degrees Fahrenheit). And people will need to wear respirators in order to breathe oxygen, since the atmosphere is mostly nitrogen. Light on Titan is a bit dim, like just after sunset here on Earth, due to haze particles in the dense atmosphere. People living in the same hemisphere of Titan, always facing Saturn, will have a wonderful view of the ringed planet.

Really funny (and potentially useful)The thing is, thanks to the low gravity and dense atmosphere, people on Titan can easily fly under their own power if they tie their wings to their hands! In the future, people can go boating on lakes and seas, which are mostly in higher latitudes.

Because it's so cold on Titan, all the waterfrozen - lakes and seas are composed of liquid methane and ethane. These hydrocarbons (like natural gas here on Earth) are abundant on Titan - not only in lakes and seas, but also on the surface and in the atmosphere. They are a ready-made source of materials for creating building materials such as plastics. Humans can burn methane to produce energy, possibly using a nuclear reactor to electrolyze water (since Titan's atmosphere does not contain the oxygen we need to burn methane).

Astronomers recently measured the depth ofthe big sea of ​​methane on Titan. It turned out that it is at least 0.3 km long: this is enough to study it on a robotic submarine. It turned out that the depth of the small Sinus Sea, which is located on Titan, is 85 m. And the largest Kraken Sea has not yet been measured. Both reservoirs consist of a mixture of ethane and methane, the second component predominated. This is a huge amount of energy.

Another option for chemical energy is the hydrogenation of acetylene (ie 3H 2 + C 2 H 2); both hydrogen and acetylene are present in Titan's atmosphere.

In addition, we may consider the possibilityusing wind turbines as an alternative source of energy. The air density on Titan is about five times that on Earth, so the potential wind energy is significant. Although there is not much wind on Titan's surface (Cassini measurements show a wind speed of about 1 m / s; for comparison, the typical wind speed on Earth is about 4 m / s), measurements of the Huygens probe showed a wind speed of about 20 meters per second on an altitude of 40 km - this means that the tethered aerial wind farms can generate hundreds of megawatts of energy.

What is the problem?

If Titan is so good and interesting, then why hasn't it been mastered yet? Why are most missions directed to Mars and the Moon? The problem is distance.

Flight time to Saturn can vary from 4years up to almost 7 years, depending on the orbital relationship to Earth at the time of launch. Without significant advances in energy, this would mean an extremely long journey to and from any potential colony.

In addition, there are manyobstacles, not least of which is the study of how people will live and work in microgravity. In addition, growing food on Titan using crops like we do here on Earth will not be efficient, given the lower solar flux reaching Titan's surface and the already low efficiency of photosynthesis here on Earth. The people on Titan will need biotechnology and unconventional products. Perhaps future humans on Titan will be able to employ some kind of artificial photosynthesis.

It remains only to wait for a breakthrough in science.

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