ELI5. If the weight of rocket fuel is so important, why do SpaceX boosters waste a ton of fuel landing themselves?

Question

ELI5. If the weight of rocket fuel is so important, why do SpaceX boosters waste a ton of fuel landing themselves?

In: Engineering

Answer 1

Adding say 5% extra fuel margin is cheaper than building a new rocket for each launch.

Rockets are built in stages.

The first stage is 80% of the cost AND the mass penalty is much smaller (because it doesn’t go all the way to space), so tail landing reuse is a no brainier (once you get it to work).

Second stage reuse has a higher mass penalty, for a smaller part of the rocket so reuse is ‘debatable’.