Supplies necessary for life and a functional lab for surface research should be prepositioned on Mars. The lab would be used during a manned visit, and the supplies would be there in case their short visit became unexpectedly much longer. A serious mechanical failure could easily strand a crew there for at least 2-3 years, and there is no where to get spare parts.
The "emergency" 3 year supply cache, lab, and living space could be confirmed landed and functional before any manned ship left earth.
Another cache and "space station", or a ship with return capabilities, could be placed in orbit, and confirmed to be functional (or at least functional with known reparable problems), again before any ship left earth. If you can't send a pair of ships together, you can at least pre-position the life raft.
Voyages of this length will have to have engineering crewmen capable of making repairs of vital subsystems, and they will have to have a supply of parts. If they have a serious failure on the way, they may be able to get where they are going, but unable to return. They would be forced to wait (27 months) for the rescue ship to get there, at the very least.
Thousand tons to orbit heavy lift capability, plllt, problem solved.
Can't handle the forbes webpage. The Enterprisemission webpage is bad, but this is worse.