Mars continues to capture the imagination of mankind. But no wonder, since the Moon has proved to be a lifeless rocky desert and Venus an acid hell. Mars, however, is - or was once - a planet like Earth. In any case, its current state, devoid of atmosphere and life, has given rise to bold plans to colonise Mars, to build cities on the red planet, and Elon Musk himself has often said that the future of humanity lies on Mars. One of homo sapiens' missions is to settle there.
Away from Earth, but why?
We are living in a time of climate crisis, overpopulation, the collapse of ecosystems. Today, thanks to global news, more and more people are concluding that there is no way around it and that we must start this experiment called Earth society all over again. The less radicals are content to rethink the paradigms of the past, to reform society and relations between people, to protect the environment or to play with the idea of redistributing resources.
Not so truly forward-looking people: many of them (driven by a kind of pessimism) claim that the Earth is finished, that we have ruined it for good, that we should start the story from Adam and Eve, that we should go to Mars!
These ideas are, of course, compounded by the fact that homo sapiens is curious and constantly driven onwards and further by the desire to explore. Yesterday's knowledge and skills are not enough. Having traversed the Earth on expeditions, we know every nook and cranny, and thanks to satellites there are no secrets left - perhaps only the oceans, the depths of the Earth - we must look upwards, they claim. We need to know the Solar System and its planets. This idea is even more widespread because, thanks to the films, we know the dangers of a stray asteroid that could hit the Earth. To avoid a real Armageddon, we should at least transport some of humanity to other planets.
The other planets in the Solar System orbit too far from the Sun (and from us) to be considered for human habitation for the time being. The same is true of the Moon, which is not suitable for colonisation.
Mars, on the other hand, is terraformable - a term first used by American science fiction writer Jack Williamson in a 1942 novel, and adopted by science. After Earth, Mars is our narrowest cosmic neighbour, the friendliest planet in the Solar System. Although it has only a third of Earth's gravity, experts imagine that in the distant future we could make its atmosphere denser by heating its surface. With an average surface temperature of -53 degrees Celsius, it has frozen water beneath its surface, which, along with Martian debris, could be a good source of raw materials for long-term terrestrial settlers. Mars is rich in minerals such as zinc and germanium, and the possibility of ancient microbial life has been raised.
If all this is true, why are there still no settlements on Mars founded by humans? Why has Mars not yet been colonised?
The first problem to overcome: the cost
Although the legendary engineer Wernher von Braun outlined the details of a trip to Mars in 1969, after the first successful moon landing, his proposal was rejected by NASA. Various calculations have been made over the decades on the cost (mainly to NASA) of a manned space mission to Mars. In the 1970s they came out at $40-100 billion, in the first half of the 1980s the figure at the Planetary Society was set at $38 billion. Add to this: one of the highlights in the history of space travel, the moon landing at that time would have cost around $150 billion in today's prices. The reality is that NASA's current budget is less than €23 billion, and this is fragmented between several important projects. The European ESA - which is funded by contributions from the Member States of the space agency and does not rely on the governments of any single country - has even less money, €6.5 billion, or roughly $8 billion. Back in 2007, the then NASA chief estimated the cost of the Mars programme at $156 billion.
But let's go beyond that and assume that, say, several billionaires and governments are putting the money together. Can we go now? Unfortunately, still no.
The second problem to overcome: physics
Although the new US-China Cold War has now boosted traffic between the Earth and the Moon, it's been a long time since we sent a man to another celestial body. So, on the one hand, there is a lack of expertise and experience. On the other hand, we do not have the equipment: we need a robust rocket to take us there and back, a reliable system (computing, propulsion, biological, etc.), logistics (food, water, oxygen storage), something to do with waste and hygiene, and a robust suitcase lander that can operate well for a long time in the harsh conditions of Mars.
The real overwhelming difficulty is the length of the journey. While the Moon is astronomically next door, the trip to Mars alone can take up to nine months. No human has ever travelled so far, and astronauts face many more unknowns along the way. Without a self-sufficient base on Mars, we should not even start, as the optimal return journey is only every 26 months to save energy. We are talking about a three-year journey, with a drastically increased risk of accidents and death. In addition, the ideal Hohmann orbit would allow astronauts to return more quickly, but this does not consider the fact that they would land on Mars.
At present, we do not have a rocket or spacecraft capable of such a task in which we can safely put people. There are alternative ideas for shortening the journey, but they exist only on paper, none of them has been tried in practice. But let's not give up so easily on colonising Mars!
The third problem to overcome: getting there
But what awaits us on the journey? Well, nothing good. Micrometeorites, small pieces of interplanetary debris, hurtle through space at more than 10km per second, and if they hit and knock a spacecraft over, they punch a hole in its body the size of a mass-dependent hole that can lead to decompression. If the hole is large, the air is expelled from the spacecraft at an astonishing rate, and the low pressure has a fatal effect on the human body: water in the soft tissues evaporates, the body starts to swell, the mouth and airways cool. Bubbles form in the bloodstream travelling around the body, obstructing circulation. Blood circulation stops within a minute and, due to a lack of oxygen to the brain, astronauts lose consciousness within 15 seconds and die within a short time. Micrometeorites are very common in the solar system, even smaller than 1 cm in diameter pose a huge threat to spacecraft, and there is currently no radar that can detect such small objects in space.
The technology to enter, land and land in the Martian atmosphere is critical. The planet's atmosphere starts to build up at an altitude of 131 km, so a system is needed that can protect the spacecraft from the thermal effects of friction and heating for a long time on entry. The unevenness of the atmosphere, density variations and winds can be very damaging to the lander, so the ability to correct for this is essential. The unevenness of the Martian terrain is a further risk: the landing site must have a relatively flat surface, and there is no technology to warn a human lander of accident-prone rock formations during landing and to correct the lander's trajectory on the fly.
Landing takes 5-8 minutes and is almost impossible to test on Earth with the same environmental parameters as on Mars. In 1997, the Mars Pathfinder space probe was surrounded by a complex airbag system to ensure that its expensive development survived what engineers called "six minutes of terror".
The high speed also requires a huge heat shield to reduce the maximum mass of the payload; the installation of an extra heavy-duty parachute is also inevitable, capable of safely landing much more than the current one - under one tonne - up to 20 or 30 tonnes of cargo on the surface of Mars. These have not even started development and such a system would need several years of testing on Mars.
The fourth problem to overcome: the colony
With a crew of six and a 600-day stay, the Martians need more than 100 tonnes of water, 3.6 tonnes of air and 10.8 tonnes of air at a pressure suitable for Martian conditions to survive and work. The water consumption is so high because it will be used not only for drinking, but also for washing hands, flushing toilets, washing, and showering. The system will also need to provide 0.5 kg of air and the same amount of food per day. We can't get that much to Mars, so obviously, only a self-sufficient recycling system like the one on the International Space Station can help. But, as we have seen, there is no quick return from Mars and no spacecraft can be sent to resupply, so it is a much bigger logistical challenge. Support for the colony is vital. Such a mechanism can only be made operational with long tests and a huge budget - estimated at around $10 billion - for this purpose.
The fifth problem to overcome: the human
The 2015 movie "The Martian", shot in Hungary, is one of the most realistic Mars movies. Its writer has worked out almost every detail to make the story of the botanist stranded on Mars as believable as possible. In one sequence, the character played by Matt Damon repeatedly explores the surface of the red planet to find out how he can survive until the team that rescues him arrives.
Unfortunately, this is the point where all our best hopes die a short death.
The human body and outer space are incompatible. The astronauts are perhaps the fittest people in the world, selected and trained to rival the elite commandos. Yet, even in the short term, damage to the body can be observed: on the International Space Station - which is in near-Earth orbit, nearby! - a significant number of people on the International Space Station, which is close to the Earth's surface, later reported visual problems, and some had not recovered after five years. Cataracts, and ultimately blindness, can be expected for those who live in weightlessness for extended periods. Luckily, astronauts don't spend so much time in weightlessness. In addition, calcium starts to be leached out of the body, leading to reduced muscle mass and weakened bones. The heart muscle also loses strength, and the natural regeneration that occurs in space on Earth is painfully slow due to the abnormally slow rate of blood vessel formation. The nervous system is also damaged by deep-space radiation, with deterioration of cognitive abilities and short-term memory impairment.
Speaking of radiation, we don't have a spacecraft that can protect humans from DNA-damaging radiation for that long. Those who arrive on Mars would be likely to have already developed cancer and other neurological or haematological diseases. So, there are plenty of challenges on the road to conquering the red planet.
Despite all this, the dream of colonising Mars is still on the agenda, and it may be the next big step for our species, the first of which began on the Moon with Armstrong's footprint. Mars is not yet a home. But space is waiting to be conquered.