Reply #55: One proposal I saw years ago suggested sending an unmanned "factory" ahead [View All]

[csziggy]

To produce fuel for the take off and return trip. I am not technological knowledgeable enough to understand or remember the details, but they were making assumptions about the composition of the soil based on early Mars missions and what elements and compounds they could harvest and produce.

The basic idea was that before the manned mission ever took off there would be enough fuel stockpiled on Mars for a return trip. How much easier if there only had to be enough to power a chemical rocket to get the return vessel into orbit and let the ion rocket power the interplanetary trip!

ETA: Here it is: Mars Direct. My memory of the details is not quite right: http://www.nss.org/settlement/mars/zubrin-promise.html