How long does it take for humans to immigrate to Mars?

Recently, a piece of news about Mars has become a hot spot of public concern: the Dutch non-profit enterprise "Mars No.1" has published a list of 100 candidates (including 4 from China) selected from the global 200,000 applicants. These candidates will continue to compete, and the final four candidates will be sent to Mars for settlement in 2025. According to the plan announced by the company, they will launch a communication satellite to Mars in 20 16, and then set up a permanent base in 2023 after several stages of tasks.

Is this project that allows the selected people to embark on the journey of "going back" reliable? What technical problems should human beings solve when they immigrate to Mars? Is it necessary for human beings to immigrate to Mars in the foreseeable future? The reporter interviewed relevant experts in this regard.

The Martian environment is only relatively "friendly"

Mars is the fourth closest planet to the sun and one of the four Earth-like planets. The ancients in China thought it was as bright as fire, and its position and brightness often changed, which made people unpredictable, so it was called "flicker". With the help of astronomical telescope, we can see that Mars is orange, which is caused by iron oxide widely distributed on its surface. Among the eight planets in the solar system, Mars is slightly larger than Mercury, making it the second smallest planet. Its diameter is about half of the earth's diameter, and the rotation period of its tilt from the axis is equivalent to that of the earth. Its day and night are slightly longer than the earth, about 37 minutes longer, but it takes twice as long to orbit the sun.

Why are researchers and the public always most interested in Mars when discussing the topic of "moving to other planets in the future"? Bian Yulin, a famous popular science writer and visiting researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, said: Humans have the ability to land on the moon, but there is no atmosphere on the surface of the moon, which is in an ultra-high vacuum state and is not suitable for living. Look further, look at the two neighboring planets of the earth-Venus and Mars. The environmental conditions of the former are too harsh, the surface temperature exceeds 450℃, and the extremely dense atmosphere is full of sulfuric acid droplets. In contrast, the environment of Mars is much more "friendly": there is an atmosphere, and water ice and the remains of lakes and rivers have been found, providing basic conditions for biological survival.

However, this "friendliness" is relative, and the natural environment of Mars is actually very unfavorable to people; Only in the solar system, Mars is more livable than any planet or satellite except the Earth. Xuan Shi, deputy secretary-general of the Shanghai Astronomical Society, said that although Mars has an atmosphere, its main component is carbon dioxide, accounting for 95%. Other components include: 3% nitrogen, 1.6% argon, little oxygen and water vapor. And the atmosphere is very thin, which is only equivalent to the atmospheric pressure at an altitude of more than 30 kilometers on the earth. So the air on Mars can't be directly breathed by people. In terms of temperature, Mars is also not suitable for human habitation. The average temperature of its surface is lower than that of the earth.

Above 30℃. Like the earth, there are four seasons in a year. In summer, the temperature in the equatorial region can exceed 20℃ during the day, but it will drop below -50℃ at night.

It can be seen that if human beings live on Mars, they must live in a closed living cabin and wear special spacesuits when they go out. The complexity of these facilities and equipment can be imagined.

How many technical barriers are there to immigrate to Mars?

Today, "Mars One" company claims that it will establish a permanent base on Mars in 2023, and send four people there in 2025 to become the first generation of space immigrants, which really makes people sweat for the company and human "pioneers".

Academician Ye Peijian, chief scientist of space science and deep space exploration of China Academy of Space Technology, said that this Dutch institution has neither planes nor rockets, and it does not have the ability to survive on Mars. Trying to implement the plan in 2025 is like a scam and a joke.

Ye Peijian said that the launch cycle between Mars and the Earth is only once every 28 months. Because the two planets orbiting the sun are 55 million kilometers apart at the nearest time and 400 million kilometers apart at the farthest time, in order to save fuel, space agencies all over the world choose to launch the two planets at the nearest time. Based on the strongest space flight capability in the world, it takes hundreds of days to fly from Earth to Mars. At present, the astronauts of the space shuttle and the space station will rotate after a period of time, and how to survive the flight for hundreds of days is a big problem in itself.

In order to simulate hundreds of days of space flight, Russia organized the "Mars 500" experiment. The experiment was conducted in Moscow. Six young people selected from all over the world lived in a closed cabin for 520 days and completed the simulation experiment from flying to Mars, landing on Mars and returning to Earth. Shi Shen believes that the effectiveness of this experiment is questionable, because these subjects are very clear in their hearts that they are actually on the earth and their safety is guaranteed. This mentality is very different from those who really set foot on Mars. Moreover, the experiment was not carried out in weightlessness. In the weightless environment of the universe, the calcium loss in astronauts is obvious, which will be infringed by cosmic rays. Whether people can withstand these physical tests and psychological suffering when they go to Mars in the future is a problem that cannot be ignored.

After the manned spacecraft arrives on Mars, passengers will face greater challenges if they want to live on Mars for a period of time. They must use the equipment carried on the spacecraft to build a closed living cabin. There should be necessities such as oxygen, water and waste disposal devices in the cabin. "If these things are brought from the earth, the amount is very large." Xuan Shi said that in rocket launching and space navigation, the load is a key factor-the greater the weight, the more fuel it carries, and the technical difficulty rises sharply. Therefore, it is very difficult and expensive to send all the components for building a living area or base to Mars.

If we want to emigrate to Mars or live on this planet for a long time, we must build a large base with more perfect facilities. In addition, it is necessary to carry out the environmental reconstruction plan of Mars, including taking plant seeds there, using the photosynthesis of plants to absorb carbon dioxide, the main component of the Martian atmosphere, to produce oxygen, and gradually increase the oxygen content in the atmosphere, so as to get closer to the earth's environment.

"Mars Earthization" or Tourism Development?

Bian Yulin introduced that at present, Mars exploration in the United States is in a leading position in the world, and the launched rover Curiosity has successfully landed and completed the exploration mission. The US government plans to send a manned spacecraft to Mars around 2035. Of course, this is not an immigrant who goes and never comes back. Astronauts will return to Earth after landing on Mars. "So it is too early to consider immigrating to Mars."

So, is it possible for humans to immigrate to Mars in the future? Bian Yulin believes that this possibility exists. In his view, the population on the earth will continue to increase, and one day it will not accommodate everyone, so emigrating to Mars is a solution. The implementation of this plan is a long process, which is roughly divided into four stages: first, after manned landing, human beings need to complete many experiments of astronauts' short-term survival on Mars; Then, build a small base suitable for life and work on this planet; Then, gradually expand the scale of the base; When conditions are ripe, we will begin to transform the Martian environment on a large scale and realize the goal of "globalization of Mars".

The so-called "Earthization of Mars" is to transform Mars into an environment similar to Earth. In August, 2003, the International Conference on Migration Research on Mars was held in the United States. Participants suggested that in the next few centuries, Mars should be transformed into a green planet and become the second home of mankind. According to the idea, there are several technical schemes for the formation of Mars, including: adding appropriate gases (such as greenhouse gases and gases suitable for biological survival) to the atmosphere, increasing the surface temperature and pressure, melting water ice on Mars into liquid water, and then gradually increasing the oxygen content in the atmosphere through photosynthesis of plants; Dissolve a large number of underground frozen soil layers, and then lead water to the surface, gradually forming a hydrosphere; Set a huge reflector or refractor in space to reflect more sunlight to the surface of Mars; Spread sand-fixing fungi and plants to prevent sandstorms, then generate soil and expand living areas.

Many researchers believe that some technical solutions to transform Mars are feasible, and there may be some technical solutions in the future, and transforming Mars into a "second earth" will become a reality. However, many experts point out that in the foreseeable future (hundreds or thousands of years later), there is no need for human beings to immigrate to Mars, and there is no need to transform the Martian environment on a large scale. If the population on the earth is increasing, the living space can be extended to the ocean or underground. At present, although this is technically difficult, it is not unsolvable. In contrast, the cost of emigrating to Mars is too high.

Xuan Shi said that going to Mars may become a tourism project in the future, just as going to space has become a favorite tourism project for a few rich people. Isn't it interesting to take a long trip by spaceship, make a short stop on Mars and visit Mount Olympus, which is more than 27 kilometers high?