Now it will take me several months to fly to Mars.

If it takes more than 250 days according to the route of Curiosity and the spacecraft has to carry three people, then it needs to prepare 250×3 days of food. In terms of water use, you can maximize the use of circulating water, and you should be able to bring less, but you still need water for bathing and washing your face. 250 days without a bath seems quite unacceptable.

In addition, there is the problem of coming back. Assuming it needs to come back, it should take more than 200 days, less than going, because coming back is equivalent to inner planet exploration.

So in order to be reliable, it is necessary to prepare food for three people for 500 days. Even if the rocket thrust is large enough in the future, I think 400 days is a limit.

The circuit diagram of the round trip is something like this:

Adults eat about 2 kilograms of food every day, so 500*3*2=3000, which is about 3 tons.

Of course, the above is the safest scheme, and there are many ways to actually implement it:

First of all, the launch site can be chosen on the moon. Regardless of the cost, the moon can launch rockets and provide a larger payload, because the gravity of the moon is much smaller than that of the earth.

Secondly, you can launch the food for the return trip first, or even launch a freight orbital module to fly around Mars first, so that you can carry half the materials less. Of course, this is risky. For example, if there is a problem with the orbital module and it explodes, or if there is a problem when it is docked with the orbital module, it will take 200 days to fly hungry. I believe that people will eat people.

As for the idea of using spacecraft to make food or recycle it, I don't think it is advisable. Although there is plenty of sunshine, the space is very limited, and you need to carry soil and a lot of water (although it can be recycled). Whether the output is enough is also a problem. It is very troublesome to get a set of ecological recovery measures in such a narrow and precious space of spacecraft.

According to the above analysis, if we can launch on the moon (such as putting Saturn V on board) to shorten the travel time, and then arrange the cargo hold to reduce the take-off load, then I estimate that the round trip may only take 300 days or even 200 days. If there is food, it is enough to prepare 150 days.

If you want to stay all your life, that is, to immigrate to Mars, you must never prepare yourself by eating for a lifetime, but you must be self-sufficient.

Mars immigrants need greenhouses first. Mars has carbon dioxide, but less oxygen, water shortage and low temperature (the highest temperature in summer is about 20 degrees, and it is cool and cold in winter). Plants can be planted by transporting materials, and even some poultry and livestock can be raised.

Building some affiliated factories, medical equipment and power generation equipment based on greenhouses can ensure the long-term survival of human beings on Mars.

Mars has low atmospheric pressure and thin air. Some plants can survive, but animals are more difficult to survive. If you want to stay on Mars all your life, you need energy, food, air, water and other infrastructure.

In terms of energy, large-area solar panels are not particularly realistic, because there are many sandstorms on Mars, and it is very difficult to maintain large-area solar panels. If pollution is not considered, isotope nuclear battery is a good choice, which can provide power for at least several years or even longer. At present, no oil, natural gas, coal and other resources have been found on Mars, so it is best to choose materials with high energy density to transport to Mars, and nuclear batteries may be the only choice.

Food, air and water can only be produced in a closed greenhouse, because the air on Mars is thin and dry. If it is an open greenhouse, precious water resources are easily lost. Because the technology of simulating the biosphere is not developed at present, this greenhouse may have to continuously obtain resources from the earth to continue its operation.

If Mars can survive stably for a period of time, such as months or even years, then the long-term consideration should be to obtain resources directly from Mars. At present, it is not ruled out that there is water inside Mars, so it would be much better if water can be obtained directly on Mars. Mars also has some minerals, ores and so on. If we can make full use of these resources, then Mars will be self-sufficient to some extent. However, it should be emphasized that self-sufficiency requires a lot of manpower and tools, and the transportation cost of these manpower and resources is still very huge at present.

The most important part of acquiring resources is cost. If the cost of 2 yuan is invested in order to obtain resources with a value of 1 yuan, then this acquisition is not cost-effective. There are also resources on the moon, but they are not used by human beings, because the input is too high, the output is low and the risk is high. After all, the people who colonized Mars are living people, and the risk is too high, which is tantamount to murder.