Swiss perspectives in 10 languages
After a landmark year for red planet exploration, University of Geneva astrophysicist Sylvia Ekström and designer Javier Nombela argue that our journeys to Mars should and will remain the task of robots.This content was published on April 7, 2021 - 15:12
Can humans manage a trip to Mars?
The human body was formed through millions of years of evolution on earth. It is therefore perfectly adapted to an environment subject to a certain value of gravity and pressure, protected from solar and galactic radiation by the double protection of the earth's atmosphere and magnetosphere. If it leaves this environment, it is exposed to great physiological stress.
The first problem is microgravity, which has many consequences:
Bone decalcification: Astronauts lose bone mass 12 times faster than a postmenopausal woman;
Loss of muscle mass: Our muscles have it too easy in zero gravity and they melt away;
Weakening of the heart: With less exertion, it becomes weaker and rounder;
Fluids (blood, lymphatic system) flow up into the upper parts of the body. Our entire vascular system is designed to fight gravity and pump upwards, which it continues to do when gravity is gone;
Danger of thrombosis: Due to the two points mentioned above, the blood circulates less quickly and can clot;
Disorder of the inner ear: Our organ of balance functions thanks to the weight of small crystals on hair cells and without losing gravity.
The loss of muscle mass and weakening of the heart can be partially counteracted by strict discipline in daily exercise. On the ISS, astronauts do two hours of intense fitness (cardio and strength training) every day, yet are very weak when they return to Earth. Bone decalcification is also slowed down by strength training, but remains one of the most worrying health issues for potential Mars astronauts, as a fracture on Mars could prove fatal. Vascular problems are also considered extremely dangerous.
The limits of artificial gravity, radiation and the human psyche
Could gravity be replicated on the Mars spacecraft? It is known that in a rotating system, centrifugal force creates an acceleration that can be used to mimic the equivalent of gravity. Unfortunately, there is not enough space on a spacecraft to fit a centrifuge that cosmonauts could spend a few hours a week in, which would be enough to reduce the physiological damage of microgravity.
Could the spaceship itself be rotated? In Hollywood, yes, it's easy! But in real life it's a different story. Given that a spinning spacecraft would solve all the problems of weightlessness, the fact that no space agency is counting on such a development shows that it is conceptually, technically and financially completely beyond our reach.
The second major problem facing potential future Mars astronauts is radiation in space. The Earth's dual protection (atmosphere and magnetosphere) partially blocks or deflects UV rays and completely blocks X-rays and gamma rays, as well as solar wind particles and cosmic rays. This protection has been compared to the equivalent of a 30 meter thick concrete wall or a wall of 80 centimeters of lead. Once outside this natural barrier, it is imperative that astronauts are protected in other ways, through spacecraft isolation and/or individual shields. Despite these protective measures, it is estimated that over the course of their mission, Martian astronauts would receive the maximum acceptable level of radiation for an astronaut's entire career, with just over half of that occurring during the round trip.
A third major problem identified by space agencies is human psychology. French astronaut Thomas Pesquet gives a good example of the psychological pressures astronauts face on the ISS: you know that there will inevitably be problems during your stay, but you don't want to be the one causing them. The pressure on a Mars crew would be infinitely greater as they would have no help available should a major problem arise. On the ISS, astronauts can be brought back to earth within three hours. The Mars astronauts would be left to their own devices for the two and a half years of their mission, knowing that the slightest mistake or error, whether technical or human, could result in the death of the entire crew. It is impossible to test such a psychological situation on Earth. The Mars 500 psychological isolation experiment, conducted by the European Space Agency, has developed conflict resolution methods, but is in no way representative of real-world conditions of a trip to Mars.
MoreJoin the discussionScienceMarc-André MiserezIs human exploration of Mars worth the costs and risks?Should humans try to set foot on the red planet, or should it be left to the work of robots?
Can humans cope with a stay on Mars?
Mars is not a habitable planet. This is not an exaggeration but reflects the impossibility of normal life for organisms like ours on the Red Planet. The main problem is the weak atmosphere on Mars: it has 0.6% of the Earth's pressure at sea level, which is the pressure of Earth 35 kilometers up. This means that water on Mars is not found in a liquid state. The surface layer of the planetary soil is covered with regolith (rock dust) that was recently discovered to be contaminated with perchlorates, which are very harmful to living organisms.
In order to survive in such conditions, a habitable bladder would have to be built, which could perform a number of functions: reestablishing a viable atmosphere with the right level of oxygen, maintaining a pressure that preserves the integrity of the human body, protection from radiation and for everyday use need.
The size of the bubble would depend on the number of people and length of stay. Astronauts would need at least one pressurized spacesuit that would allow a person to survive for a few hours (e.g. for a spacewalk outside the ISS or on the moon). For multiple people over a period of several months, the bladder must be the size of an entire apartment (including kitchen, rest areas, plumbing, etc.) and have an air and water recycling system, as well as food and equipment reserves. The bigger the bubble, the more complex and expensive the technical challenges would become, to the point of being unsustainable.
What's the point of going to Mars?
Nothing? One of the arguments for sending humans to Mars is that they are more efficient on the ground than a robot and could therefore learn more about the planet. However, the advances made over successive generations of robotic probes show that the knowledge they provide is advancing rapidly, despite their limitations. The undeniable advantage of robotic probes is that they don't need to eat, drink, or work in Earth's pressurized conditions. A minimal protection of your electronics is sufficient. The estimated cost of a single human mission would be equivalent to 40 robotic missions like Perseverance.
Additionally, upon leaving Earth, these probes can be sterilized in accordance with the standards of the Planetary Protection Act, which aims to avoid contamination of places we visit in the solar system. In humans, this is impossible: by bringing a few individuals of our species to Mars, we are also depositing billions of bacteria from Earth. While their chance of survival on Mars is infinitesimal, it is not zero and risks confusing the answer to the main question motivating our study of Mars: could life have evolved there in the early stages of its evolution?
Sylvia Ekströmexternal linkhas been a PhD in astrophysics since 2008, specializing in stellar physics. She is responsible for communications at the Department of Astronomy at the University of Geneva.
Javier G. Nombelais a graphic designer specializing in the visual representation of time. He is also the author of numerous popular works in the field of astronomy.
MoreIn space research, Switzerland outperforms Nobel Prize winners, an exoplanet telescope and instruments on board 50 space missions: In space, Switzerland is everywhere.
article in this story
- People on Mars: Possible or pipe dream? A live debate.
- Tomorrow's people will live on Mars
- Is human exploration of Mars worth the cost and risk?
- In space research, Switzerland punches above its weight
In accordance with JTI standards
More:SWI swissinfo.ch certified by the Journalism Trust Initiative
Join the conversation!
MoreSwiss company says this content was published on February 19, 202119. February 2021NASA's Perseverance science rover has landed safely on Mars as part of its search for traces of microbial life on the red planet.
MoreIn space research, Switzerland outperforms Nobel Prize winners, an exoplanet telescope and instruments on board 50 space missions: In space, Switzerland is everywhere.
MoreSwiss film selection SWI swissinfo.ch offers a selection of Swiss films in English, handpicked by the Swiss streaming platform Play Suisse.
Is there another planet we can live on? ›
Astronomers have observed a pair of exoplanets about 100 light-years from Earth, and they say one, which has never been seen before, is a strong candidate for supporting life.Why is it impossible for humans to live on Mars? ›
The air on mars is thinner than that on Earth. On Earth, 21 percent of the air is oxygen, which is what makes it the ideal place for human life. But on Mars, oxygen makes up 0.13 percent of the air. The majority is carbon dioxide, which is harmful to humans.Why is life possible on Earth and not on other planets? ›
What makes the Earth habitable? It is the right distance from the Sun, it is protected from harmful solar radiation by its magnetic field, it is kept warm by an insulating atmosphere, and it has the right chemical ingredients for life, including water and carbon.What planet is most likely to support life? ›
1. Mars. Mars takes the top spot for several reasons. We know it was once habitable billions of years ago, when it had lakes and rivers of liquid water on its surface.How many times did life start on Earth? ›
IN 4.5 billion years of Earthly history, life as we know it arose just once. Every living thing on our planet shares the same chemistry, and can be traced back to “LUCA”, the last universal common ancestor.Can Mars support life? ›
Despite its smaller size, the planet's land area is also roughly equivalent to the surface area of Earth's continents—meaning that, at least in theory, Mars has the same amount of habitable real estate. Unfortunately, the planet is now wrapped in a thin carbon dioxide atmosphere and cannot support earthly life-forms.Can we plant trees on Mars? ›
As mentioned earlier, Mars's open air is just too cold for plants to survive.Could we live on Mars if we successfully landed there? ›
Human survival on Mars would require living in artificial Mars habitats with complex life-support systems. One key aspect of this would be water processing systems. Being made mainly of water, a human being would die in a matter of days without it.Why does life only exist on Earth? ›
Earth is at an adequate distance from the sun which gives us heat that is neither too hot nor too cold. Earth has enough amount of water, food, and air for the survival of living organisms. Earth has a protective ozone layer which protects us from the harmful rays.What's outside the universe? ›
If the universe is infinite, there is nothing beyond it, by definition. A finite expanding universe conjures up the idea that it would have a boundary or edge, separating it from something beyond.
How did life first exist on the Earth? ›
The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.What planets Cannot support life? ›
Uranus cannot support life as we know it.What is the closest possible habitable planet? ›
Proxima Centauri is known to host one planet for sure—the roughly Earth-size Proxima b, which completes one orbit every 11 Earth days. That puts Proxima b in the star's “habitable zone,” the just-right range of orbital distances where liquid water could exist on a world's surface.Is there a planet like Earth found? ›
Scientists at NASA have recently announced that they found a planet that is almost identical (about 95%) to Earth's size and shape and has a rocky surface. Named TOI 700 e, this new planet orbits within its star's habitable zone, which also hints at the presence of water on its surface.When did Earth have no life? ›
Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. The oldest known fossils, however, are only 3.7 billion years old.Who was the first human on Earth? ›
Homo sapiens, the first modern humans, evolved from their early hominid predecessors between 200,000 and 300,000 years ago. They developed a capacity for language about 50,000 years ago. The first modern humans began moving outside of Africa starting about 70,000-100,000 years ago.Who was the first person on Earth? ›
Adam is the name given in Genesis 1-5 to the first human. Beyond its use as the name of the first man, adam is also used in the Bible as a pronoun, individually as "a human" and in a collective sense as "mankind".Will Venus ever be habitable? ›
If it's too much or too little, then liquid water can't exist on the surface, and thus the planet is not a good candidate for life. According to this simple criterion, Venus is habitable; that is, it can potentially support liquid water. But it obviously doesn't.Can life exist on Moon? ›
For life to exist, water is very essential. However, there is no water as well as no atmosphere on the Moon. Hence, life cannot exist on Moon.Did Mars used to be like Earth? ›
Early Mars was not only wetter and warmer than it currently is, it also had a similar magnetic field to Earth's, which weakened over time, causing water loss. Knowing that Mars had water isn't a new thing. As mentioned in the previous story, we've seen evidence of river beds, stream flows, and lakes.
Does Mars have gold? ›
In addition, lithium, cobalt, nickel, copper, zinc, niobium, molybdenum, lanthanum, europium, tungsten, and gold have been found in trace amounts.What animal can live on Mars? ›
Of all the animals on Earth, the tardigrade may be the only animal that could survive on Mars.Did Mars ever had water? ›
The red planet once had a global ocean, rivers, and lakes. Then, the solar wind — charged particles from the Sun — stripped away the Martian atmosphere. As the planet's protective shield faded, all liquid water on the surface evaporated into space, merged with minerals, or fled underground to become water ice.How long would it take to make Mars habitable? ›
Depending on whom you talk to, terraforming could take anywhere from 50 years to 100 million years to complete. The surface might one day look like our own Earth. It could also resemble a massive metropolis with people unable to live outside of domes or other manmade structures for hundreds of years.Why does Elon Musk want to go to Mars? ›
Tenets. As early as 2007, Elon Musk stated a personal goal of eventually enabling human exploration and settlement of Mars, although his personal public interest in Mars goes back at least to 2001 at the Mars Society. SpaceX has stated its goal is to colonize Mars to ensure the long-term survival of the human species.Why is Mars the most habitable planet? ›
Of all the planets in the solar system, Mars is the most Earth-like in terms of its water patterns. Mars has polar ice caps that grow and recede with the seasons and has evidence of water channels similar to those on Earth today.What is the one thing you can't survive without? ›
Water is essential to our lives – 50 – 65 percent of our bodies are composed of it. We not only consume water, we need it for so many important functions in our life.What's the purpose of life? ›
Inherent to our existence is that we learn, adapt, and grow. Health, happiness, and longevity are the payoffs for this. Since our biological evolution is the foundation of our existence, a purpose of our lives is to continue to "evolve" during our lifetime by learning and growing.What is the purpose of humans? ›
From an evolutionary perspective, the purpose of human life (and most animals) is to survive long enough to reproduce and ensure the propagation of the species. A capitalist might seek to generate as much wealth as possible, while a selfless person will tell you their purpose is to help others.What was before the universe? ›
“Inflation tells us that the period of time before the Big Bang was extremely cold, almost at absolute zero, and it was empty of everything but empty space, and that empty space carried energy that stretched the universe out to this enormous size and into the initial state before the Big Bang.
How many dimensions exist? ›
The world as we know it has three dimensions of space—length, width and depth—and one dimension of time. But there's the mind-bending possibility that many more dimensions exist out there. According to string theory, one of the leading physics model of the last half century, the universe operates with 10 dimensions.Where does space end? ›
No, they don't believe there's an end to space. However, we can only see a certain volume of all that's out there. Since the universe is 13.8 billion years old, light from a galaxy more than 13.8 billion light-years away hasn't had time to reach us yet, so we have no way of knowing such a galaxy exists.How did water get on Earth? ›
Nearly 4 billion years ago, during the Late Heavy Bombardment, countless meteors rained down on the Earth and the Moon. Over time, these icy asteroids and comets delivered oceans to Earth, depositing the water directly to the surface.What is the universe made of? ›
Composition. The universe is composed almost completely of dark energy, dark matter, and ordinary matter. Other contents are electromagnetic radiation (estimated to constitute from 0.005% to close to 0.01% of the total mass-energy of the universe) and antimatter.Where was human life created? ›
Humans first evolved in Africa, and much of human evolution occurred on that continent. The fossils of early humans who lived between 6 and 2 million years ago come entirely from Africa. Most scientists currently recognize some 15 to 20 different species of early humans.Is Earth the only planet with life? ›
Yet Earth remains a standout, and so far, one of a kind. Of the thousands of exoplanets – planets around other stars – confirmed by our increasingly powerful telescopes, and despite extensive probing of the solar system, ours is still the only planet known to host life.What planet can replace Earth? ›
Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin based on its characteristics; also known by its Kepler Object of Interest designation KOI-7016.01) is a super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system ...What is the next habitable planet? ›
Proxima Centauri b (or Proxima b), sometimes referred to as Alpha Centauri Cb, is an exoplanet orbiting within the habitable zone of the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of the triple star system Alpha Centauri.Can humans live on Jupiter? ›
Potential for Life. Jupiter's environment is probably not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme and volatile for organisms to adapt to.How many planets can support life? ›
Three (Venus, Earth, and Mars) out of eight planets might be able to support life. Based on recent discoveries of planets outside of our Solar System, it was estimated that 1 in 5 planets could exist in the habitable zone of their star: Average lifetime of a planet.
How much longer will Earth be habitable? ›
The evaporation of the Earth's oceans would be well underway by 1 billion years from now. We can assume that millions of years before this, Earth will have become uninhabitable.What planet has been protecting Earth? ›
While Jupiter often protects Earth and the other inner planets by deflecting comets and asteroids, sometimes it sends objects on a collision course straight toward the inner planets.What is the new planet with water? ›
Exoplanet explorers have discovered new planets, Kepler-138c and d, covered with water. According to a new study published on Thursday in Nature Astronomy, two planets 218 light years away from Earth are water worlds.Are there any Earth like planets? ›
NASA's Transiting Exoplanet Survey Satellite (TESS) has found two planets similar in size to Earth and within the habitable zone of star TOI 700 .Is there a super-Earth? ›
There are hundreds of cool dwarf stars for every star like the Sun, and scientists have found super-Earths orbiting 40% of cool dwarfs they have looked at. Using that number, astronomers estimate that there are tens of billions of super-Earths in habitable zones where liquid water can exist in the Milky Way alone.How many Earth like planets are there? ›
On 4 November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarf stars within the Milky Way Galaxy.Can humans live on Pluto? ›
Potential for Life. The surface of Pluto is extremely cold, so it seems unlikely that life could exist there. At such cold temperatures, water, which is vital for life as we know it, is essentially rock-like. Pluto's interior is warmer, however, and some think there could even be an ocean deep inside.Can humans live on Uranus? ›
Potential for Life
Uranus' environment is not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme and volatile for organisms to adapt to.
As an ice giant, Uranus doesn't have a true surface. The planet is mostly swirling fluids. While a spacecraft would have nowhere to land on Uranus, it wouldn't be able to fly through its atmosphere unscathed either. The extreme pressures and temperatures would destroy a metal spacecraft.