Rocket science

Moving stuff to outer space is super expensive and takes a lot of energy, which is part of the reason why colonizing the moon or terraforming Mars is extremely hard. To move something heavy into space you need a rocket with enough fuel. But adding fuel makes the rocket even heavier... And if you wanted to visit Mars and come back, you would need enough fuel to leave both Earth and Mars.

We can actually calculate how much fuel a rocket needs using the rocket equation: $m_\mathrm{fuel} = M \left( e^{v/v_e} - 1\right)$ where $M$ is the mass of the rocket (with no fuel), $v_e$ is the exhaust velocity of the rocket, and $e = 2.71828\dots$ is Euler's number. $v$ is the velocity the rocket needs to escape, which is different for every planet. Try to submit some code with a function rocket_fuel(v) that returns $m_\mathrm{fuel}$ for Saturn V ($M = 250,000 \; \mathrm{kg}$, $v_e = 2,550 \; \mathrm{m/s}$) as a function of $v$.

Input: The velocity $v$ the rocket needs to reach to escape the planet in meters per second (m/s).

Output: The mass of fuel $m_\mathrm{fuel}$ needed by the rocket to escape the planet in kilograms (kg).