The biggest challenge in building a civilization on Mars is getting a large number of people there who may choose to stay permanently.

The next big step is to get people to Mars and become a space-faring civilization.

A Mars city must be able to survive independently if spaceships from Earth stop coming, which means it needs all critical resources.

To ensure the longevity of civilization, we need to become a multiplanetary species, which would greatly increase the probable lifespan of consciousness and intelligence, both biological and digital.

Freeman Dyson's paper on the Dyson Sphere proposes that an advanced civilization would need to harness energy from a star, as Earth cannot provide enough energy for their needs.

To be a multi-planetary species, we must ensure that we can return to Mars regularly, not just leave flags and footprints like we did on the Moon.

If we don't become a multi-planetary species, we risk facing calamities that could threaten humanity's existence on Earth.

To create a self-sustaining city on Mars, we need to improve the cost of transportation by at least a factor of a thousand.

Space exploration is essential for preserving Earth; we need to utilize resources in space to reduce our impact on the planet.