The earth, our only home, has been home to life for billions of years, and over those billions of years, countless creatures have appeared on the planet, and of course, countless creatures have disappeared from it. It may be that some creatures had difficulty adapting to the earth's environment and so were eliminated, or it may be that some creatures had simply too many natural predators and they were eventually wiped out by them. Humans are now at the top of the earth's food chain, and apart from viruses, there are basically no creatures that can threaten our survival. However, just because there are no creatures that can threaten humans, it does not mean that humans can rest on their laurels. Because there are many threats to the planet itself, there are issues that could lead to the end of our species.

For example, the risk of an asteroid striking the earth. Although the likelihood of an asteroid striking the earth is very small, and we often see asteroids fly safely past the earth and rarely see an asteroid strike the earth, with so many asteroids, there is always the possibility that some could slip through the net and eventually strike the earth. Once an asteroid strikes the earth, the damage caused would be potentially devastating and the human race could come to an end. Another example is that the sun has a lifespan. The sun is now in its youthful stage, and as it ages, its temperature and brightness will increase, and in time the temperature of the earth will increase with it. Scientists predict that the sun's light may cause the earth to become less habitable by the time it is expected to do so in a billion years. So, in the long run, civilisation on earth will always be destroyed, and the only way out for us humans is to migrate to an alien planet.

Within our solar system, there are 2 planets in the habitable zone of our solar system, one of which is our home planet earth and the other is mars. Although mars is as far away from earth as 400 million kilometres, compared to those distant exoplanets, mars is just around the corner.

Is mars habitable or not?

The proximity to our planet does not mean that it is the ideal planet, because a planet that is habitable for us must have a better environment, and not all planets can be a second home for us humans. So what is the environment of mars like, and can it be inhabited or not?

Mars is the fourth earth-like planet in our solar system from the inside out, and is further away from the sun than the earth is from the sun, plus the surface of mars has a very thin atmosphere, so the surface of mars is cooler than our planet. The relatively low temperature is not really a big problem, if the temperature is very high it is a bigger problem. Just like mercury and venus, the surface temperature of the planet is up to more than 400°c. With such a high temperature, even probes, not to mention humans, would have difficulty surviving. From this point of view, mars is indeed much more habitable than mercury or venus.

The surface of mars, where the air is thin and extremely cold, is littered with all kinds of impact craters and all kinds of canyons, sand dunes, gravel and rocks, just like those desert and gobi desert areas of our home planet, so desolate that not a trace of life can be seen at all. Judging from the surface environment of mars, it does not seem to be suitable for us to live in, the environment in very harsh.

However, we should not be deceived by the surface of mars, although the surface of mars looks very desolate and without a trace of life, the rover has found that mars still has a large amount of water ice material, which is present in the polar regions of mars and some mid-latitude regions, and some water ice material is also present under the landing area of our zhu rong mars rover. Some scientists believe that the water-ice material on the surface of mars could meet our needs for human migration to mars, but only if we could exploit it and use it for drinking water, or decompose it to obtain oxygen and hydrogen.

Nasa: Sending humans up by 2040

As a potential "Second home", mars is now the focus of much exploration. Musk's space transportation company spacex has announced that it will stop producing new manned dragon spacecraft in order to focus its resources on developing interplanetary spacecraft. The development of a reusable starship is the focus of spacex, and their goal is to achieve a migration to mars with the help of such a starship. As envisaged, mr musk wants to build 1,000 starships, launching three starships a day, carrying 100 people each time, eventually aiming to send one million people to mars by 2050 and carrying a martian city on board.

This goal may seem unattainable, but much progress has been made in the development of the starship, which is currently on track for an orbital flight test as early as may this year, with more complex tests to follow if the test goes well.

Before spacex's starship was about to launch for testing, nasa administrator bill nelson also proposed the idea of a manned landing on mars, with bill nelson stating that the us plans to send humans to mars by 2040. Compared to spacex's vision, the us plan to send humans to mars in 2040 is probably a little more realistic. After all, with the current level of technology, it is still very difficult to achieve a manned landing on mars, what the astronauts will face during the flight to mars, how the astronauts will solve various problems living on mars (including the problem of resupplying food, water, oxygen and other supplies), and the technical problems of how the astronauts will take off from mars and return to earth. Not to mention the return of astronauts to earth from the surface of mars, there have not even been any experiments with rovers taking off from mars to return to earth. This series of tests will take a long time, as mars is too far away from earth to launch a probe to test these technologies at any time. So it is still not realistic to send a million people to mars before 2050, but in a few decades, a hundred years or more it will still be feasible for humans to migrate to mars.