# Gravity on a spaceship

What if you lined the lower hull of a spaceship with osmium metal plating, would enough osmium plating create enough pull to simulate earths gravity?

• This wouldn't be "simulating" Earth's gravity but reproducing it. You're basically taking the Earth on the journey with you... – Przemek D Jun 5 '18 at 7:05

## 2 Answers

You need a LOT of material to create natural gravity. Earth weighs ~1024 kg, so that's the ballpark figure you need to create 1 g.

Suppose you stand on the surface of a sphere of material of average density $\rho$ (and that the density distribution inside the sphere is spherically symmetric) then the mass increases in proportion to $\rho r^3$ so the surface gravity increases as $\rho r$ (inverse square law). Since Osmium is roughly four times denser than the Earth, you could need a sphere of it $1/4$ the size of the Earth. You might gain a small factor by making it a different shape but it will still need to be hundreds or thousands of kilometres in size. So not really anything you could call "plating".