Gravity’s smothering hold on Earth’s inhabitants means that eighty to ninety percent of the mass of current rockets must be taken up by the actual propellant burned to lift the rocket into space! According to Pettit, this means that sitting atop a rocket is more precarious than perching oneself atop a bottle of gasoline. It also means that there isn’t much room for stuff like food, computers, scientific experiments, and astronauts.

Despite these drawbacks, we should count ourselves lucky.

“If the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built,” Pettit says.