Question

What is the minimum amount of compressed hydrogen rocket fuel that would be necessary to get a Dragon2 space capsule from the surface of the Earth to the surface of Mars ?

Answer 1

The delta v to Low Mars Orbit is about 4.1 km/s. The delta V to get to Earth from there is 2.9 km/s (Earth C3 to Low Mars Orbit).The key focus is 2 points.Bottom line is, you need to lift 3 people and supplies and provide it with a delta v of about 6.0 km/s. I'm not an expert in the supplies category, so let's just pick a number, say, let's carry a Dragon capsule fully loaded. Wikipedia gives about 7500 kgs, which is probably a fair starting point. That's not quite as much as required for an Earth Launch, but would be similar to a Falcon 9 launch from Mars to Earth. Let's call it half of one. In fact, The Case for Mars states that around 96 tons of fuel is required to make the trip for 4. First of all, fuel the rocket on the surface of Mars. If you take hydrogen from Earth, you can easily combine it with carbon dioxide and have methane and oxygen, which is a very good rocket fuel. And that requires only 16 tons of fuel, not too bad to manage