Anyone fancy a 39-day trip to Mars?

[Smivs]

You still have to launch all of it, in relatively tight launch windows (which come about two years apart).

By sending the descent/ascent module separately, you can send it within reason when you like. As it's un-manned it doesn't matter if it takes an age to get there, as long as it's there before the manned module arrives. With a long timescale like this for a Mars mission, you can spread the effort over time, and even ensure the 'Lander' is safely in Mars orbit before the manned module even sets off.

[Chrisfs]

aye, why the return = harder bit.

The hardest part of an interplanetary flight is the first couple of hundred kilometres, getting off the planet.

For a return trip from Mars, you need to bring the rocket for that plus the launch facility with you.

This increases the mass of your initial launch by a factor of, say, 50.

You don't really need a launch facility, just a flat area and a ship that can lift off again. Fuel would be the biggest problem.
It worked with the Moon. Gravity on Mars is 38% of Earth which is about twice of that on the Moon. So in that respect, it would be easier to take off from Mars than from Earth.

[JensAyton]

You don't really need a launch facility, just a flat area and a ship that can lift off again.

By “launch facility”, I don’t mean Cape Canaveral. Just a predictable launch surface – like the Apollo descent module.

Gravity on Mars is 38% of Earth which is about twice of that on the Moon.

Atmospheric drag is not negligible.

And yes, it’s easier than launching from Earth. If it wasn’t, no-one would even be considering it.