Why is Mars the only planet humans can survive on?

Answer 1

Mars offers suitable gravity and raw materials for a colony. Mercury and Venus are too hot and the gas giants don't have livable surfaces or gravity. (Some of their moons may.)

The temperature on Mars during the summer is about 20° C to -40°C which suggests a survivable climate. In fact, at one time in the past Mars was much more hospitable to Earth-type life. There is likely a lot of water ice at the poles. And unlike asteroids and moons, there is room for lots of development.

Considering all the above points, one can say that a protective habitat is possible on Mars, but obviously one cannot live on Mars as easily as we do on Earth. The atmosphere is normally too thin to breathe and the pressure so low that blood would boil at body temperatures.

Colonies on the Moon and Mercury would essentially be in a vacuum, although like Mars there is likely a considerable amount of water ice (in deep craters on both bodies). also mars OS way to hot any other time apart from summer so it is a problem.

Answer 2

Humans cannot survive on Mars without significant life support systems due to its harsh environment, including thin atmosphere, lack of breathable air, extreme temperatures, and high levels of radiation. Earth is uniquely suited for human life due to its abundant resources, atmosphere, and moderate climate.