There are numerous reasons that force us to expand our habitat beyond the borders of the Earth. Our planet is overpopulated, with resources that are not only limited but diminishing over time (drinking water, fossil fuels, fertile land, habitable areas). Some of these resources can be found somewhere in the solar system, giving our quest to reach the stars a strong economic boost. As an example, the small asteroid Amun, no larger than two kilometers in diameter, is often cited as the largest percentage composed of iron, nickel, cobalt, platinum and other precious metals. This seemingly insignificant rock, one of countless in the solar system, has more pure metal in it than has been mined and processed in all of human history. The value of the ore in this seemingly insignificant pebble is currently estimated at about 20.000 billion dollars. In addition, the ecological aspect is not negligible either: it would be healthier for us mortals to have steel mills, mines and tailings on Mars or the Moon, than on Earth.
On the other hand, today's civilization does not have its own "backup", so it is constantly in danger of being completely wiped out by some catastrophe of cosmic proportions (an indefensible meteorite strike, an epidemic or its own stupidity in the form of a nuclear war or global warming). Such a possibility is more the rule than the exception - most plant and animal species are now extinct, including the dinosaurs that ruled the earth until 60 million years ago. Even if all these plagues pass us by, the Earth is doomed in the long run. And that doom will happen long before the Sun uses up its nuclear fuel reserves. Slowly approaching its end, our star is getting bigger, hotter and brighter every day. In less than a billion years, the Earth will overheat and life on it will no longer be possible.
But where to go? When our imaginations take us away, we often forget how dangerous and essentially inhospitable the solar system is. Our first neighbor, the Moon, is very poor in materials that would be useful to future colonists. Although a significant amount of ice has recently been detected in the hidden shadows of craters near the poles, the large temperature differences during the Moon's day and night make our satellite a second-rate destination. The Moon is not much different in this respect from Mercury, which is equally inhospitable due to its proximity to the Sun and the infernal solar wind. What can we say about Venus, which can only be compared to the biblical hell. Temperatures there exceed 450 degrees with atmospheric pressure that is 100 times higher than on Earth, as at 1000 meters of sea depth. The atmosphere is almost entirely composed of carbon dioxide, and the sky is covered with clouds that rain sulfuric acid.
FROM EVIL TO WORSE: Once you pass the asteroid belt between Mars and Jupiter, things get even more complicated. The distances are getting bigger, the sunlight is getting weaker and the temperatures are getting lower. Solar panels that generate electricity become weak and useless, you will need some other source of energy, with nuclear reactors being the most logical choice. You encounter gas giants that have no solid surface to land on. If you are not willing to build floating cities similar to Miyazaki's "Laputa", you will have to settle on one of the satellites that represent a more or less hospitable habitat. But such places are also very few: Jupiter is surrounded by intense radiation belts that would kill an unprotected traveler within a few minutes. This radiation eliminates most of Jupiter's numerous satellites, including the most famous ones such as Ganymede and Io. You will have to seek refuge either on dark Callisto or Europa, under whose thick ice crust there is probably a water ocean in the depths of which, in the vicinity of thermal columns connected to the warm core of the satellite, some other life may be hiding. But to reach those warm depths, you'll have to dig through miles of ice, which is harder than granite at extremely low temperatures.
In the vicinity of Saturn, you have several advantages: less radiation, two "handy" satellites, but also even less light and even more cold. Titan is the only satellite that has a thick atmosphere and an abundance of chemical elements necessary for the survival of the colony, including lakes of liquid hydrocarbons. Even more interesting is Enceladus, the brightest object in the solar system, a small lump of ice whose cryo-volcanoes spew ice instead of lava and suggest that beneath the shiny crust there is probably a huge reservoir of water, similar to Europa. Beyond Saturn's orbit, conditions are even more drastic. Once you get past "boring" Uranus, Neptune is the last stop. Barely a fraction of the light that reaches Earth reaches this planet. This is a vestibule of absolute darkness and unimaginable cold where temperatures go as low as -230°C, with winds reaching 2000 km/h.
But in order to embark on such a path, we have to solve countless problems, primarily economic and technical. We need to provide funds that, in the simplest version of the journey to Mars and back, range between 10 billion and 1000 billion dollars (the upper limit is much more likely), which is too much even for our friends from the Emirates. In today's time of economic crisis, when all developed countries are cutting budgets and introducing rigorous austerity measures, it is hard to imagine that anyone will risk being sent to the insane asylum by proposing the cost of 500 billion just to set foot on Mars. Even if there is money, it is necessary to perfect the existing rocket engines because the current chemical ones have long been surpassed, to determine how the passengers will endure a journey of several months in a confined space and weightlessness, to protect them from the ubiquitous cosmic radiation and to provide a closed living ecosystem, both during the flight and at the destination itself, capable of maintaining the conditions necessary for human life with minimal or no assistance from Earth.
On the other hand, traveling between the planets of the solar system is child's play compared to traveling between the stars. The cosmos is, in essence, a vast empty space in which isolated oases of matter are separated by colossal distances whose true dimensions can only be understood with the help of mathematics. Let's forget about our desire to reach the center of the Milky Way, where, at a distance of about 27.000 light years, resides a super-massive black hole. It would be even more difficult for us to jump the abyss two and a half million light years wide and visit Andromeda, our closest galaxy. Let's limit ourselves to the relatively modest goal of traveling to the nearest star (Proxima Centauri), from which we are only a little more than four light-years away (let's ignore for a moment the fact that this star is not an ideal target for settlement, given that in its vicinity up to no planets are now observed).
CONQUERING THE VOID: Many intelligent minds have thought about this, and the British Interplanetary Society went the furthest, which developed the project of the first interstellar vehicle - "Daedalus" in the mid-seventies. It is a space ship of colossal dimensions with a mass of over 50.000 tons, most of which is spent on fuel. The number of crew members is not predefined, but it is limited by the relatively modest amount of useful equipment that the ship can carry (less than 1 percent of the total mass). Instead of the classic chemical drive, which is ineffective and inapplicable here, "Daedalus" uses energy released by the thermonuclear fusion of heavy hydrogen (deuterium) and light helium (He-3). This isotope of helium is impossible to produce on Earth in the necessary quantities, so it will be provided from Jupiter's atmosphere, using robotic balloons that will do the "mining" job for at least 20 years. The fuel will be packed in capsules that will be compressed under the influence of ultrafast electron beams to the pressure and temperature required to start a nuclear reaction.
Although controlled nuclear fusion represents a technological challenge that we have not yet overcome, the designers of Daedalus thought of everything else. Given that the spacecraft needs to travel at speeds comparable to the speed of light, its collision with even low-mass particles could cause catastrophic damage. For this purpose, an ultra-hard beryllium shield was designed, which should provide all the necessary protection. The flight to the stars is at the same time a flight into the unknown, and that is why "Daedalus" will be equipped with powerful telescopes and a fleet of auxiliary ion-powered spacecraft designed to explore the destination many years before reaching the goal. The 40-meter-diameter exhaust nozzle of the engine will be used simultaneously as an antenna for the crew's communication with Mother Earth.
And that's where imagination ends, and harsh reality begins. When to start a journey that will last for decades? It is quite possible that the aircraft that would go on the road today would at some point be overtaken by the aircraft that will take off in 20 years, which will certainly have a stronger and more advanced engine. However, let's assume that a round trip to Proxima Centauri or some distance beyond Barnard's Star would take one human's working life, some 40 years. And for that to be possible, "Daedalus" would have to travel at an average speed of at least 20 percent of the speed of light. At this speed, relativistic phenomena do not yet have a dominant influence, so you can estimate the kinetic energy of "Daedalus" using the formula from school physics: mass times speed squared divided by two. The required energy is actually several times higher: the average speed is less than the maximum, plus you will need energy not only to accelerate, but also to slow down the aircraft. On the other hand, keep in mind that the entire annual energy production of the United States of America is about 27.000 billion kilowatt-hours.
The prize question is: how many "Daedalus" could be sent to the first next star using this gigantic amount of energy? The correct answer is: none! At today's level of energy production, America would not produce the energy needed for just one short-range interstellar spacecraft in a thousand years.
Populating the cosmos is incomparably more difficult than it appears in science fiction novels and movies. The various "vorps," tachyon and antimatter engines, "wormholes," and other exotic artefacts of the universe that enable faster-than-light travel through shortcuts in space and time are more a result of our frustration with our own limits than a demonstration of an idea based on scientific fact. We are where we are and we will stay there for a long, long time.
FERMI'S PARADOX: Will one day we still leave the known environment of the mother star and start to populate our near and far cosmic environment similar to how we once colonized the distant ends of our own planet in the past? Looking at the speed at which science, technology and the human mind are advancing, one would say we will. Take, for example, magnificent projects such as "Moravia to Thessaloniki" or "Belgrade on Water" - until yesterday only a crazy person would have thought that this could be done, and today these ideas are winning elections. The first airplane took off a little over a century ago, and today our aircraft are already in all parts of the solar system, even outside of it. But what appears to us to be a logical step forward seems to contradict immediate observations.
The famous nuclear physicist Enrico Fermi was the first to notice and formulate the paradox that today bears his name: the moment you acquire the ability to move between stars, even at minimal speed, you will populate the entire Milky Way for a period of time not exceeding 250 or 300 million year. That's a ridiculously short period for a galaxy as old as ours and the age of the universe estimated at 13,7 billion years. If we agree that Earth is only one of several billion similar planets, if humanity is only one of the intelligent civilizations that inhabit the Milky Way, the simple question arises: "Where are they all?" from various civilizations and cultures that interpenetrate each other as in Star Wars or Star Trek? In reality, we have no good clue or even an indication that somewhere in our environment, what we predict has already happened to others.
This can only mean two things: either colonizing the cosmos (just like the canal to Thessaloniki) is an incomparably more complex (perhaps impossible) endeavor, or we are completely alone in space. How is it that the universe is so finely "tuned" to spawn only one civilization and no more? The answer may lie in the so-called "anthropic principle": if everything was just a little different, if everything was not "happened" as finely as it is, there would be neither "Belgrade on the Water", nor "Vremen", nor you as readers, and for God's sake, neither the author of this text.
When the moment comes to take the first step in colonizing space, it is almost certain that it will happen on Mars. In many respects, Mars resembles Earth: a day on it lasts almost as long as on Earth, and due to the tilt of its axis of rotation, Mars has seasons that change regularly. And most importantly, Mars has huge reserves of water in the form of ice deposits at the poles or at a relatively shallow depth below the surface. But somewhere the similarities end and the differences begin that make our flight to Mars difficult and risky.
Today, for example, no one knows what long-term effect the reduced gravity of Mars, three times weaker than Earth's, would have on the human body. All previous researches are limited to weightlessness. There is no liquid water on Mars, the soil is barren and unsuitable even for the hardiest and most extreme living organisms from Earth. The temperature is very low (on average, it does not exceed -5°C anywhere, and it drops to -100°C), while the solar radiation is much more intense than on Earth. Mars does not have a protective magnetic field, so an astronaut on Mars would, within a few years, receive the dose of radiation expected for his entire working life. The Martian atmosphere is very thin (about 30-40 kilometers above Earth) and is almost entirely made of carbon dioxide. The partial pressure of carbon dioxide is higher on Mars than on Earth, so the Martian atmosphere is extremely toxic to both plants and humans. And finally, much less sunlight reaches Mars than Earth: the most beautiful day on Mars looks like a very gloomy day on Earth.
Getting to Mars is neither quick nor easy. The "window" for the flight (related to the optimal position of Earth and Mars) opens approximately once every two years. From the point of view of minimal fuel consumption, the most economical is the so-called A Hochmann trajectory, an elongated ellipse that approximates the orbits of Earth and Mars, but such a trajectory requires at least 6-9 months of travel through empty space exposed to killer cosmic radiation. With a higher fuel consumption, you can reach Mars in a much shorter time, but a higher amount of fuel automatically means less payload. Landing on Mars is even more challenging: Mars has enough gravity to make landing significantly more difficult than on the Moon. On the other hand, the Martian atmosphere is too thin so that parachutes cannot be used in the final stage.
What awaits astronauts on Mars? First of all, the habitat must be absolutely isolated from the outside world with a closed system of production and recycling of food, water and oxygen. Mars has little to offer settlers: except for water reserves, there is only solar energy, which is not easy to exploit due to constant dust-filled winds that can envelop the entire planet for several weeks. Communication with colonists would not be possible in real time: even at the speed of light, a radio signal from Mars takes 5–30 minutes to travel the distance to Earth. At the time when the Earth and Mars are on the opposite side of the Sun, this communication is practically impossible for several months at a time.
Mars has been thought of as our next space destination for decades. The first serious study called "Project Mars" was made by Wernher von Braun, a genius rocket designer who made the infamous "Fau-2" rockets for Hitler, and "Saturn V" for the Americans, the biggest rocket of all time, which took man to the moon. . For the expedition to Mars that would precede its full colonization, von Braun envisioned a fleet of a dozen ships that would be built in orbit using 1000 three-stage rockets. This fleet would take the first group of 70 settlers to Mars. The project was revised several times as our knowledge of the Red Planet progressed, but was definitely pushed aside when Richard Nixon liquidated the Apollo program and prioritized the development of a space taxi. Not long after, disillusioned and depressed, Wernher von Braun ended his career at NASA.
The conquest of Mars gained publicity again in 1989 when George W. Bush, then US president, announced his "space exploration initiative" outlining a long-term vision for US exploration of the solar system. The multi-decade saga was supposed to culminate in the human conquest of Mars. NASA thus received a long-needed tailwind. The very next year, the National Space Administration produced a study titled "Moon and Mars Exploration," which looked at the next few decades in space and predicted costs of about $450 billion. Unfortunately, the document was met with a knife by influential congressmen and senators who did not want to support the largest American investment since the end of World War II. In just one year, the Bush initiative was liquidated, and NASA turned to incomparably cheaper automated probes.
Many distinguished NASA engineers were disappointed, among them Robert Zubrin. After a detailed analysis of all the projects proposed up to that point, he determined that they all suffer from the same fundamental flaw: the huge costs are mainly the result of our effort to bring everything we need to live and work on Mars with us from Earth. Instead, Zubrin proposed a much cheaper alternative that was later formalized under the title "Mars, Direct." His project advocates faster and easier travel with incomparably less equipment, with some critical resources being produced on Mars. In the first phase, Zubrin envisages sending a spacecraft to Mars that will carry a ship for the return of future astronauts to Earth, a small nuclear reactor, eight tons of hydrogen and a small chemical laboratory similar to the one in the "Breaking Bad" series. Over the next ten months, the automated laboratory would chemically produce 110 tons of methane and oxygen using hydrogen and carbon dioxide from the Martian atmosphere. In this way, on-site fuel will be provided for the return flight to Earth and the propulsion of the Mars exploration vehicle. Only two years later, the astronauts will start their journey to Mars, along with their habitat, which will be grounded near the laboratory. Everything they need to return to Earth will already be waiting for them on the surface of Mars. After that, the expeditions should rotate every two years.
Zubrin invested a lot of energy in the promotion of his concept, which received positive reviews from the professional public. He had the opportunity to present his project in the appropriate committees of the Senate, and on several occasions he was granted modest funds to continue his work. Although Barack Obama has repeatedly announced that he hopes to "be there" when Americans land on Mars sometime in the fourth decade of this century, his words have not been followed by concrete actions. The last financial faucets that kept Zubrin's project alive were turned off in 2011. Zubrin dedicated himself to writing books and working in the "Mars Society" organization, which he founded in 1998 with the aim of promoting research and colonization of Mars, primarily with private funds.
In the absence of any government initiative, Mars is left to the interests of private investors who are just taking their first steps in space. Such a concept is bearing its first fruits: the SpaceX corporation has already imposed itself with its low-cost Falcon 9 rocket carrier and the Dragon capsule, which reunited America with the International Space Station. But even for such successful companies, Mars is still far away, which does not mean that it has been completely forgotten.
Dutch businessman Bas Lansdorp launched the non-profit organization Mars One in 2012 with the goal of sending an expedition to Mars in 2023 with a one-way ticket. By 2033, Mars should have a colony of about 20 astronauts. As things stand, the project will be financed by the sale of television rights for a "reality" show that will follow the selection, training and journey of astronauts to the Red Planet (the first round of selection has already been completed, and there are ours among the chosen ones). The cost is estimated at around six billion dollars, which is quite "ridiculous" compared to NASA's 2009 estimates, which are at least 20 times higher. The project met with fierce criticism from the professional public, including Zubrin himself. To them, Mars One is a simple hoax behind an organization that has nothing: no knowledge, no concept, no spaceport, no rocket, no astronauts, nothing but the desire to make money by sending people to almost certain death. Even so, there is no shortage of adventurers who would gladly stick their heads in a bag for a moment of glory. There is (only) money missing: only $300.000 has been collected so far.
