Extracting resources from space, and expanding to Mars or space colonies are likely non-starters due to simple physics. No matter how you do it, it takes aroun

Extracting resources from space, and expanding to Mars or space colonies are likely non-starters due to simple physics. No matter how you do it, it takes around 100 MJ/kg to get something into orbit, which translates into about 28kWh of electricity per kg, to offer a more relatable comparison [0]. It costs roughly the same amount to land the equivalent amount of mass on Earth without making an impact crater. One single, average human weighs somewhere around 65kg. So, not counting the mass of the fuel and vehicle necessary to do so, evacuating one human costs the energy equivalent of around 1820kWh of electricity. The average American household uses just over 10000kWh per year [1], just for comparison. Now, let's get to the bad news. Remember the weight of the vehicle and fuel that we just conveniently forgot about? Let's not forget about it anymore. Falcon 9 weighs around 550,000 kg [2]. So, just to put it in orbit, empty, costs the equivalent of over 1.5x10^6 kWh of electricity, or, roughly the yearly consumption of 1500 years worth of the average American household's energy consumption. That energy has to come from somewhere. Tell me, how is space going to save us again? On the other end, in less than 20 years, we need to not only offset the trend of 50% increase in global energy consumption, but also cut back an additional 50% from where we are today. In other words, in 20 years, in order to simply break even in terms of sustainability, we need to become 3x more efficient than we ever have over any 20 year period, if we want to maintain current levels of economic growth. And you don't find that hard to imagine? Edit: Alternatively, do you see us supporting 2 billion more people on this planet in 2050 with lower levels of economic growth than we've had the past few decades? See https://en.wikipedia.org/wiki/Projections_of_population_growth#2050 https://en.wikipedia.org/wiki/Projections_of_population_grow... for population growth estimates. --- [0]: https://space.stackexchange.com/questions/4330/how-much-energy-is-required-to-put-1-kg-in-leo https://space.stackexchange.com/questions/4330/how-much-ener... [1]: https://www.eia.gov/tools/faqs/faq.php?id=97&t=3 https://www.eia.gov/tools/faqs/faq.php?id=97&t=3 [2]: https://www.spacex.com/vehicles/falcon-9/ https://www.spacex.com/vehicles/falcon-9/