After 50 years, mankind plans to return to the moon, and a little later predicts a flight to Mars. However, it is unlikely that people in the near future are destined to significantly move away from the earth's orbit: many factors prevent this.
Space is not only the last but also the most dangerous frontier. This is the most extreme of possible environments, but it is through it that the path to new worlds lies. To get to them, a person will have to invent new engines, learn to withstand radiation, not die from an accidental scratch and not go crazy. Is it possible?
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When traveling to exoplanets (space bodies outside the solar system), the main problem for modern researchers - both living and automata - will not be the unexplored conditions of the objects of study, but the time itself required for such an enterprise. NASA highlighted the main problems that will arise due to the fact that with the most optimal development of technical means, the journey will take years.
Nowadays, the main engines are based on chemical processes: fuel and oxidizer are burned to form hot gas. Due to the heating, exhaust gases flow out at high speed from the rocket nozzle, pushing the rocket in the opposite direction. Alas, such engines leave little room for maneuver for a person, since the rate of gas flow is limited by the combustion temperature. Even theoretically, a trip to the stars on engines with chemical propulsion is unrealistic with the current level of technology. So, the spacecraft, the most distant from the Earth, Voyager-1, which was launched in 1977, covered over 21 billion km in 40 years. This is, without exaggeration, an astronomical figure, but even in this state of affairs, Voyager-1 will reach the star AC +79 3888 (17 light years from the Sun), towards which it flies at a speed of about 62,000 km / h, only after 40,000 years old.
Modern space probes are capable of developing even higher speeds. For example, Jupiter's artificial satellite Juno is capable of reaching about 250,000 km / h, while the recently launched Parker Solar Probe will accelerate to 692,000 km / h. But in these projects, high speed is achieved, among other things, due to gravitational maneuvers: the probe passes near the planet, and it carries it away "with it", accelerating it to its orbital speed. This is convenient within our system, but not enough for fast travel to the stars: there will be no objects for gravitational maneuver outside the solar system. In addition, the farther a planet is from a star, the slower it moves.
One possible solution to the problem is an ion drive. The principle of its operation is based on the creation of jet thrust based on ionized gas: electrons are torn from molecules, and the resulting charged ions are accelerated in an electric field. Thus, it is possible to achieve higher flow rates of the substance from the nozzles, in addition, this approach is more energy efficient (less fuel is spent on acceleration). As a result, ion engines theoretically make it possible to achieve unprecedented speeds: according to researchers, Mars can be reached in just 39 days instead of seven months, which in total will be spent on the way to the Red Planet by the InSight module, which is to land on Mars in November this year. Unfortunately, the existing ion thrusters are too weak and can only be used for orbit correction.
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In Russia, the state corporation "Rosatom" is engaged in the project of a nuclear engine for cosmonautics, details have not been disclosed
A more radical approach, at least for the colonization of the solar system, can be nuclear rocket engines. A nuclear source is heated by the decay of a radioactive substance, heating the working fluid, which can flow out at a much higher rate than that resulting from the combustion of fuel and oxidizer in a chemical engine. They tried to apply this approach at the beginning of the space age, during the Cold War. However, until now, their use is constrained by two factors. It is undesirable to throw a large amount of radioactive substances into orbit: as practice shows, sometimes it can fall back. In addition, such an engine requires serious cooling, and in space, heat can be given off only by radiation, which carries away energy relatively slowly, which limits the power of nuclear engines. Weak nuclear engines are easier to replace with ion engines that are less dangerous for the Earth or more familiar jet engines powered by chemical fuel.
Using modern materials and technologies, different countries are now trying to develop more powerful models of nuclear and ion engines. Potentially, they will allow for several months to get to Saturn (for the Cassini mission, this path took seven years). Today, nuclear engines are being developed, for example, in the United States: in 2017, NASA and BWXT Nuclear Energy signed a contract to develop the engine. In Russia, the state corporation Rosatom is engaged in the project of a nuclear engine for cosmonautics, details have not been disclosed.
Dangerous environment
Even with engines that can reach distant planets or even stars in a matter of months or years, the question of the safety of the crew of such a ship remains open. And the main threat will not be aliens or asteroids, but radiation. Ionizing radiation can damage DNA, cause problems in the operation of almost all body systems and nullify any, even the most thoughtful, space enterprise involving a person.
If we talk about the more affordable option today (flight to Mars), then it is radiation that is becoming one of the main problems that astronauts will face. If on Earth a person is protected by the atmosphere and the magnetic field of the planet, then already on the ISS cosmonauts are exposed to radiation ten times stronger. The flight to the Red Planet with the current level of technology development will take about 7 months. To this must be added the time spent on Mars, which does not have a protective magnetic field and a dense earth's atmosphere, and also the way back must be taken into account. Summing up all the risks, only a radiation threat can make a ticket to the fourth planet from the Sun deadly. Therefore, for example,The Orion being developed by Lockheed Martin will be equipped with a special protected shelter in case of excessive solar activity and large release of radioactive particles. Note that a similar solution is currently used on the ISS.
Since ancient times, volcanic activity on the Moon and Mars could have left many kilometers of tunnels up to 1 km wide.
If we are talking about planetary expansion, then for this, scientists propose to use magnetic shields or terraforming in the future. There is a budget option: Italian researchers proposed a concept for the settlement of the so-called lava tubes - channels in the thickness of the planet, formed during uneven cooling of lava. Radiation from outer space in them will be minimal, as it will be weakened by the upper layers of Mars. In this case, storms and other threats on planets with an atmosphere are also not afraid.
It is assumed that since ancient times of volcanic activity on the Moon and Mars, many kilometers of tunnels up to 1 km wide could remain, in the darkness of which the history of the colonization of celestial bodies by man could well begin.
In addition to radiation, a person still has to solve many problems: to ensure an uninterrupted and reliable supply of oxygen, to solve the problem with nutrition, to learn to get along with the same people for a long time, etc. Needless to say that during a conditional mission even to the nearest planets, astronauts will have to solve medical problems on their own, for example, removing appendicitis? At the moment, everyone going into space undergoes numerous tests, but it is simply impossible to insure against everything. As the researchers pointed out, a six-man team during a 900-day voyage to Mars will almost inevitably face at least one case when one of the crew members needs urgent help. Some hope is given by the Russian-European experiment "Mars-500"during which the crew of six people in a closed room on Earth successfully lived "in flight" for 520 days, coping with psychological and medical problems.
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Funding is the backbone of space projects, and the vast majority of unrealized space projects have failed at this stage. Even fully automated projects like the Curiosity rover are worth billions of dollars. The flight of a man to Mars is estimated at times more expensive.
Even projects where there is no need to think over life support systems for people often face funding problems due to the high cost of technology. For example, the cost of the James Webb Orbiting Telescope has already exceeded $ 9 billion, and it was planned to launch it into space 10 years ago. If we talk about the cost of manned missions, the most striking example was the project of the International Space Station. It is estimated at $ 150 billion and is one of the most expensive engineering structures in the world.
Moreover, funding one project by itself does not ensure its success. Such projects require a well-developed scientific base, as well as production facilities and infrastructure capable of supporting the station. The US alone spends $ 3 billion on this annually.
According to NASA calculations, the cost of developing, preparing and implementing a mission to Mars within 30 years may exceed $ 450 billion. According to some estimates, the total cost of the project will be $ 1.5 trillion! A fantastic amount against the background of the budget of the American Aerospace Agency, which averages about $ 20 billion annually. Even the entire volume of the modern market for space services and technologies reaches $ 350 billion. So the cost of an expedition is no less a problem than space radiation.
