Will Mars ever become like Earth? No. Why? For the same reason, Kansas City will never be New York. If we want to envision the progression of our presence into space, we simply have to look at how cities have evolved on this planet. There are even studies that show how slime spreads in a similar manner. Of the 50 largest cities in the world, except for Mexico, Theran, Bogota, and Bengaluru, all are located either by the ocean or on a major river that leads to the ocean. Major cities are built where it makes economic sense. Meaning that the costs to access and move the resources needed to live and trade are not larger than the value of those same resources and trades. The longevity of cities like Las Vegas, where it never made sense to build from the beginning, is open for debate – only time will tell if they survive as the world changes. On paper, unfortunately, their future is almost certainly gloomy.
The Earth is a resource-super-rich planet in a Universe where Life is scarce. We believe, and logically so, that there are many other planets like ours in space. Places that are rich in resources. And between these planets and the Earth are millions of lifeless celestial bodies. Some of those places are simply dangerous and incapable of hosting Life. Some have resources we need for trade without having the resources we need to live. Others have resources we need to live but the extraction of those resources is a challenge.
Like the oceans that unite the world, water will unite our space expansion. It was believed that water was almost nonexistent outside of what is found on Earth but now we know that it abounds in the Universe. There is ice on the Moon and on Mars. Recently a cloud of vapor 140 trillion times the amount of water in all the seas and oceans here on Earth was discovered 12 billion light-years away.
The two biggest cities in the United States of America are New York (created in 1624) and Los Angeles (created in 1781). The former is located on the East Coast and the latter on the Pacific Coast. Los Angeles, also known as America’s Port, is the largest port in North America. Long Beach, which is located less than 30km from Los Angeles is the US’s second-largest port. Third, on the list is New York’s port. In between these two cities and ports, and scattered across the country, cities of all sizes can be found. And most are located near a river or a lake. If there are not, then they must somehow find a way to connect to a body of water. While there are 19,495 incorporated cities in the US (as of 2018), there is only one New York and one Los Angeles.
The same will happen in space. Civilizations will settle on other Earth-like planets but terraforming a planet like Mars will never make economic sense. Plus we simply wouldn’t have the time to wait for what evolution took billions of years to do. Even if we nuked a planet, it would take way too much time to create Earth-like conditions. Places like the Moon and Mars will be outposts or cities where water can be found, in a network of settlements that connect special resource-rich planets. In other words, going to space is not going to reinvent the wheel. The only thing changing is going to be the scale of that wheel.