I've said this many times before:

As the United States sets its sights on a manned mission to Mars, Australian astrobiologist Paul Davies says he has the perfect way to cut costs - don't bring the astronauts back...

"I see no particular reason that the astronauts who go to Mars should come back again," Professor Davies said.

"I'm in favour of a one-way mission to Mars. It would dramatically cut the costs.

"You might think that's terrible - you're sending them to their deaths. But that's not what I had in mind.

"I have in mind resupplying them every two years as a sort of cycle of the Martian orbit.

"We could send on the food parcels from home and other things that are required to keep a tiny colony, maybe four or six people, going perhaps for many years."

Though that's not precisely my idea -- I would send another permanent crew every launch opportunity, along with additional supplies and hardware for building up a beachhead on the planet. These early settler-astronauts could do some exploration, but their primary role would be the construction of a semi-self-supporting base (including food production greenhouses, atmosphere synthesis for inhabitants, fuel production for surface vehicles, machine shops, extraction/refining of common useful materials, etc.). Once the base has crossed a threshold point, defined by the number of settlers and the degree of development of the base's "mini-economy", wide-ranging exploration could begin. All the while, at every launch opportunity, an increasing number of settlers and equipment could be ferried out to Mars.