re: Earth Return Vehicle
What about the Earth Return Vehicle?
If the astronauts can return back to Earth, in a fully loaded ERV, doesn't it mean this scenario needed TWO Mars bound spaceships, adding their respective Delta Vs? The ERV also needed to leave Earth's gravity well (earlier) with fuel from Earth and slow down (with fuel) to land on Mars.
The Moon scenario requires one rocket for one crew, both to and from the Moon.
Raoul