The tyranny of the rocket equation, combined with Earth's deep gravity well, and the higher efficiency of rocket engines in vacuum makes it seem much worse than

The tyranny of the rocket equation, combined with Earth's deep gravity well, and the higher efficiency of rocket engines in vacuum makes it seem much worse than it is. E.g. for a lunar mission: it takes 9.4 km/s Δv to get to low Earth orbit (LEO), but only 5.5 km/s Δv to get from there to the Moon [1]. Raptor (the engine used on Starship) has an exhaust velocity of 3.2 km/s on Earth, and 3.7 km/s in vacuum [2]. Plugging those numbers in the rocket equation, to get to LEO you need about 19x your payload mass in fuel. However, to get from LEO to the moon surface, you only need 4x your payload mass in fuel. So while a tanker can indeed only bring a small fraction of its launch mass as fuel to orbit, once you're in orbit you don't need that much fuel to get to the moon. In reality the numbers to get to LEO are lower because of staging and the vacuum engines on Starship which can be used in the upper atmosphere, and you also need fuel to get back from the moon, but it probably won't add up to a full Starship. [1] https://www.reddit.com/r/space/comments/29cxi6/i_made_a_deltav_subway_map_of_the_solar_system/ https://www.reddit.com/r/space/comments/29cxi6/i_made_a_delt... [2] https://en.wikipedia.org/wiki/SpaceX_Raptor https://en.wikipedia.org/wiki/SpaceX_Raptor [3] https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation