One of the main reasons for the climate crisis is that we’ve grown too big for our britches on Mother Earth. The amount of energy humans are using, the greenhouse gas from the fossil fuels we are burning, the materials being mined and manufactured, and the waste we are generating have all become too great for the planet to handle. It should be obvious that infinite growth cannot happen on a finite planet, yet our economics seem to ignore this. Humanity has two options if we want to survive as a civilization: either a planned reduction in resource extraction and use through a process known as “degrowth,” or expansion beyond the Earth into space. Degrowth is complex and difficult to implement without crashing economies and requires a major shift in the economic thinking that has driven human civilization over the last several centuries. Expansion into space is also difficult but presents technical challenges that have multiple ancillary benefits if solved. The Apollo moon landing program gave us major advances in electronics, miniaturization, computing, engineered materials, and flight control. Modern space efforts, many driven by private industry, are solving everyday problems of suborbital and orbital flight, landing re-usable boosters, developing new materials, and figuring out how to move fuel, supplies, and people around in space. Making humanity a multi-planetary species, inhabiting the moon and Mars and other parts of the solar system in the future spreads out industry and populations and reduces impacts on any one place. Manufacturing processes that are environmentally risky can be restricted to factories in orbit or on the moon, avoiding damage to ecosystems and the environment. Humanity has reached the limits of Earth. If we want to continue to grow and develop as a species, we have no other option except space.