Now imagine if this planet was a bit more dense or bigger. Let's say 2g instead of 1. I wonder if we had any space vehicles at all right now, in that case. EDI

Now imagine if this planet was a bit more dense or bigger. Let's say 2g instead of 1. I wonder if we had any space vehicles at all right now, in that case. EDIT: Nevermind, FTA: > If the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built. Let us assume that building a rocket at 96% propellant (4% rocket), currently the limit for just the Shuttle External Tank, is the practical limit for launch vehicle engineering. Let us also choose hydrogen-oxygen, the most energetic chemical propellant known and currently capable of use in a human rated rocket engine. By plugging these numbers into the rocket equation, we can transform the calculated escape velocity into its equivalent planetary radius. That radius would be about 9680 kilometers (Earth is 6670 km). If our planet was 50% larger in diameter, we would not be able to venture into space, at least using rockets for transport. Anthropic principle my a$$. This Universe can barely support an expanding civilization. We barely became self-aware, and the useful lifespan of the Sun is almost over - it will only make things more difficult for the Earth from now on. If the planet is too small, it's not stable enough to support life. If it's too big, you're trapped there forever. And the range in between is narrow.