Gravitational Energy

Far from the ground, $\relax mgh$ no longer works. A mass at distance $r$ from the centre has:

$$U = -\frac{GMm}{r}$$

The zero is very far away, so $U$ is negative everywhere else.

$U$ climbs toward zero as $r$ grows, and $U \cdot r$ is the same at every distance. Moving out takes the work $\Delta U = U_2 - U_1$.

U is negative and climbs toward zero as r grows.