> Terraforming and space mining are absolute necessities for human survival. Is that so? Which timeframe are we talking about then, because for the entirety of

> Terraforming and space mining are absolute necessities for human survival. Is that so? Which timeframe are we talking about then, because for the entirety of humankind's existence, including its ancestors (so going back at least 4 million years), Earth was a mighty fine place to be. The occasional ice age didn't stop our non-technological ancestors from spreading all over the globe either. > You really only can argue that maybe it is one or two centuries too early to think about colonizing Mars, but you gotta start somewhere. How about closer targets then? The Moon is just a few days o travel away, can be evacuated at short notice if need be and communication delay allows for near-realtime information exchange. This obsession with Mars and "colonising" it is really quite baffling to me. It's not even clear whether the physical conditions (especially gravity, which no amount of "terraforming" can change) would allow for long-term human settlement. Instead of planning (permanent) research outposts to find answers to these questions, Musk is already fantasising about "1 million people on Mars by 2050", which is just bonkers. Considering that our species developed in an environment with 1g gravity, 1 atm of air pressure, plenty of water and moderate temperatures, I find it quite astonishing how anyone in their right mind would find Mars of all places to be necessary for human survival. A civilisation capable of modifying an entire planet's atmosphere, temperature, and magnetic field would much more easily (in terms of energy required) be capable of creating free floating habitats with orders of magnitude more living space, carefully tuned parameters (air, temperature, artificial gravity, etc.) and versatility than a small cold, barren rock like Mars. It would be much quicker to create such artificial worlds, worlds, too than to slowly heat up and build up an entire breathable atmosphere. By the way - where are all the required elements for a proper atmosphere and ecosystem (e.g. nitrogen and phosphorus) supposed to come from? Even extraction from minerals (assuming sufficient presence) would be incredibly costly: 1 m³ of air is appr.1 kg of nitrogen and given a similar composition of Mars and Earth, about 0.03% of the crust would be nitrogen. That'd be about 3300 kg of soil to process per m³ of air to get the nitrogen for an Earth-equivalent atmosphere at sea-level. If you want a column of just 100m of air with a density in that ballpark, that'd already be 300 tons of soil to process per m², or (given an average density of 4 tons/m³) 70 metres of the entire surface of Mars... Just to give you an idea of what the scope of such an undertaking (e.g. "terraforming" Mars) would be. It's something that a post-scarcity society can do as a vanity project, but most certainly not as a "necessity for survival".