Why 73% of a Mars Rocket Is Fuel

[00:00:00]A chemical rocket's exhaust velocity, how fast the engine throws propellant out the back, tops out at roughly 4.4 km/s.

[00:00:09]For a delta V of 5.7, the equation demands that about 73% of the spacecraft's departure mass is fuel.

[00:00:19]Three quarters of everything headed towards Mars gets burned and discarded.

[00:00:24]Life support, crew quarters, landing vehicle, food, water, return fuel, science equipment, all fight for that remaining quarter.

[00:00:36]Transit time is locked by geometry, half the orbital period of the transfer ellipse, 259 days, about 8 and 1/2 months. No engineering improvement changes that number.

[00:00:50]Going faster means a higher energy trajectory, more delta V, exponentially more fuel. For a limited time only, >> we are giving out the first three chapters of our complete introduction to stargazing, completely free. Check our channel profile for the link.