A submarine for ... Titan. Or maybe a time machine?

Titanium is Saturn’s super-cold satellite: the average temperature on its surface is around minus 180 degrees Celsius. Water here does not exist in any form other than deep-frozen ice. Conditions are completely unsuitable for human life.

However, oddly enough, Titan has a greater number of similarities to the Earth than any other planet in the solar system, despite the gigantic differences in temperature and other climatic conditions.

The surface of Titan is very reminiscent of the earth. It discovered mountain ranges, dunes, numerous lakes and peaks, among which there are many volcanoes. As on Earth, the atmosphere on Titan seems to have erased the traces of most meteorite craters. Titanium is the only natural satellite known to man on which there is a dense atmosphere, and the only known celestial body (besides the Earth) on the surface of which there are stable liquid lakes. And the role of water in the hydrological cycle on Titan is played by methane and ethane; they fall in the form of rain and snow, they also form lakes and rivers.

There is a good chance that the chemical composition of Titan’s atmosphere is very similar to that on Earth at the time it appeared on our planet. If it turns out that the current chemical processes taking place on Titan support prebiological chemistry, similar to the one that accompanied the development of life on Earth, then by studying Titan we can study the deep past of the Earth and, perhaps, better understand how it originated on our planet a life.

Most of the information about this planet to date has been obtained using the Cassini automatic station, which has been exploring Saturn and its moon for five years. In addition, Cassini played the role of the base ship for the Huygens apparatus of the European Space Agency, which in 2005 landed on the surface of Titan.

As a result of the expedition, many new incredible things were discovered, for example, evidence of the existence of ice (water) and ammonia “cryovolcanoes” on Titan. Judging by the photographs transferred to Cassini, these volcanoes throw ammonia onto the surface of the planet.

It is not surprising that interest in exploring this mysterious planet does not fade even today, as part of the revived in 2010 NIAC project, which is now part of the NASA Space Technology Program, a submarine concept for exploring the Titan seas is being developed. Strictly speaking, it would be more correct to call it a Western-style submarine, because the seas on Titan are by no means composed of water, but of hydrocarbons - mainly methane and ethane.

Let's try to go over the history of the issue together and evaluate the feasibility of this project based on the current level of technology.

Back to the Future

Let's talk about the predecessors of this concept, including those that haven’t gone anywhere and, apparently, will remain unrealized projects. This is right the past in some past!

The closest technical detail is the Titan Mare Explorer (TiME) - which was supposed to examine the Ligei Sea or the Kraken Sea to determine the organic components. The device was supposed to descend by parachute, just like the Huygens did in 2005. After several hours of planning in the atmosphere, it is brought to a liquid surface. The device was planned in the form of a floating platform, the main mission of which is to search for the simplest forms of life for three to six months, including six hours of atmospheric descent.



Despite the fact that the TiME project was planned as a low-cost mission with financing of only $ 425 million, it lost the competition with a more successful rival - the InSight program for the study of Mars. However, from 5 to 10 million dollars were spent on the development of the project concept, and many interesting solutions found during this process can be used in other missions, the most real of which is the Titan Saturn System Mission (TSSM) today. This is a joint project of NASA and ESA to study Saturn and its moons: Titan and Enceladus. According to NASA, the project will cost $ 2.5 billion. TSSM is scheduled to launch in 2020. The TSSM device includes one orbital and two descent modules: a balloon that will fly in the sky of Titan, and a landing module, which should be splashed to the surface of one of the methane lakes. Upon arrival at Saturn in October 2029, a chemical engine will launch the device into orbit of Saturn. A two-year plan of work for the planet should take place “according to the situation”. The phase will include at least seven flights and rapprochements with Enceladus and sixteen with Titan. During this period, the gravity maneuver will be repeated, which will give the necessary energy to move to the orbit of Titan. As soon as the device completes the flight of Enceladus, it will begin to analyze unusual cryovolcanic formations at its south pole. The phase will include at least seven flights and rapprochements with Enceladus and sixteen with Titan. During this period, the gravity maneuver will be repeated, which will give the necessary energy to move to the orbit of Titan. As soon as the device completes the flight of Enceladus, it will begin to analyze unusual cryovolcanic formations at its south pole. The phase will include at least seven flights and rapprochements with Enceladus and sixteen with Titan. During this period, the gravity maneuver will be repeated, which will give the necessary energy to move to the orbit of Titan. As soon as the device completes the flight of Enceladus, it will begin to analyze unusual cryovolcanic formations at its south pole.



The balloon will be launched into the atmosphere of Titan during the first flyby. It will be in the airspace of the satellite for six earth months: from April to October 2030. Based on data from Cassini-Huygens, the ball will float in the sky of Titan until the end of its service life at 20 degrees north latitude and 10 kilometers above the surface.

Mysteries of the Titan Seas

Scientists know that along the coastline on Titan lies a sedimentary layer left by evaporated liquid hydrocarbons; this indicates sharp fluctuations in sea level.

Changes in the orbit of Titan lead to the fact that the liquid components of its atmosphere every 30 thousand years move from one pole to another. Currently, they are concentrated in the polar northern regions of the satellite.

On Titan, the main task is to obtain information on such aspects as: surface composition and geographical distribution of various organic elements, identifying the methane cycle and methane basins, whether cryovolcanism and tectonism are active, ammonia is present or absent, studying the subsurface ocean, magnetic fields and much more. The submersible could study the bottom of the shallow seas of Titan, which, according to planetologists, is a giant ancient meteorite crater.



Scientists also speculate about the presence of stratification of the layers in the Titan Ocean - similar to what is observed in the Black Sea, where under the surface layer there are layers of more salty water with a high content of hydrogen sulfide.
Thus, the submarine will have to face very serious problems, the main of which is working in ultra-low temperatures and a very chemically aggressive environment.

Will the Pentagon contribute?

Today it became clear that many tasks to study the seas of the Titan can only be done by a submersible robot, so a space submarine with a high degree of probability can replace a floating platform during the TSSM mission, or complement it. At the same time, descent to the surface of the sea, apparently, will be carried out by parachute - the most logical way for a planet with an atmosphere.



However, there are other options, the most exotic of which is the proposal to use the existing X-37B reusable warship, which was created by order of the Pentagon and recently passed a series of tests, to deliver the device to Titan.

If there was a sea of ​​vodka, I would become a submarine!

One of the most serious problems that the designers of the submarine needs to solve is energy supply. From the side of the layman, the situation probably looks absurd - to swim in a sea of ​​hydrocarbons and look for energy! However, an oxidizing agent is required to release energy from the seas of the Titan. On Earth, oxygen plays its role, which is too little on Titan, so you will have to postpone diesel generators until better times and look for other solutions.



Unfortunately, solar panels, widely used at present for shorter flights, unfortunately, will not work either. They cannot be used even after surfacing due to the foggy atmosphere of the satellite and the great distance to the Sun. There seems to be no alternative to using an isotopic energy source today. Typically, plutonium-238, which releases heat as a result of half-life, is used as an energy source in such devices. And there is a serious problem along this path - in the USA, the production of this isotope was discontinued in the 1980s, and its reserves are now coming to an end. The fact is that for the most part this isotope is a by-product of the production of nuclear weapons, the program of work on which has been greatly reduced recently.



Laboratory prototype of the Stirling radioisotope generator.

As part of the TiME project mentioned above, it was planned to use a new energy system called the Stirling Radioisotope Generator, which provided the most efficient extraction of energy from plutonium-238, but its development was suspended with this project.

Earth, Earth, as you hear? Reception mm.

So far, the developers have not identified a set of devices that could be carried by the submersible. But the obvious candidates are a sonar, a video camera and a soil sampling system.

Communication with the Earth is important for the success of this expedition. The TiME project involved direct data transmission, as the North Pole of Titan has been oriented toward the Earth during the current decade.



But as the end of the decade approaches, the Earth shifts lower and lower to the horizon of Titan, which makes direct communication difficult. Therefore, this type of communication will now be possible only during the expedition, which is planned for 2040, when the inclination of Titan's orbit will again become favorable.

However, another option is also possible - the landing of the device can be carried out from the orbital block, which will remain in orbit around Titan and will transmit signals from the submarine to Earth. The same in turn will transmit information during the ascent to the surface. This option leads to a significant increase in the cost of the entire project, but on the other hand fits perfectly into the TSSM program.

Is there a place for Russia?

In my opinion, ambitious TSSM interplanetary missions should be carried out in close cooperation with as many countries as possible. Today, the United States and Europe are participating in it. An agreement on the participation of Roscosmos in the mission is being discussed, but in connection with the country's current course on the “special path,” the chances of this are decreasing every day. Of course, I want to believe in miracles, because our Energy Superpower is not indifferent to hydrocarbon sources, no matter how difficult they are. Maybe when the victorious exploration of the Arctic is accomplished, our government will turn its gaze to space, and the supplies of polonium will go to fuel for the space program, and not to improve the specific properties of individual varieties of tea? And suddenly, a miracle happens, and I still have to participate in the development of electronics for the space submarine,

PS I express gratitude to the user zv347 for help in editing the text.