If we are going to send people then we are going to have to at least make a show of bringing them back. To do this they are going to have to land with enough fuel to get them back off the surface and join the mother ship. The Mothership is going to have to carrying enough fuel to get them home.

Mars has a higher gravitational pull than the moon and an atmosphere to hinder you. Getting enough fuel up there is going to be difficult, landing with it on board could be classed as suicidal.

Fuel is going to be a major problem, even with improved engine technologies.

What we really need is a lighter OS...