[knowitnone]

Sure, let's remove 70kg. That'll get the ship moving...not.

[mperham]

You’re missing the fact that most of the weight of a spaceship is to support that 70kg and accelerate the whole thing. Watch this discussion about getting to Alpha Centauri.

https://youtu.be/uZN5xjoS6TU?si=05xuUdWsWADrZY-i