The Apollo 11 astronaut Buzz Aldrin proposes in the Washington Post:
Let the lunar surface be the ultimate global commons while we focus on more distant and sustainable goals to revitalize our space program. Our next generation must think boldly in terms of a goal for the space program: Mars for America's future. I am not suggesting a few visits to plant flags and do photo ops but a journey to make the first homestead in space: an American colony on a new world.
There's no doubt about the excitement of Mars exploration. And it's certainly possible that astronauts would be able to conduct investigations and perform experiments that robots could not match. Nor does the word "colony" bother me; contrary to centuries of speculation there were no Native Martians to be dispossessed by us (or to invade Earth), in fact no unambiguous sign of present Martian surface life, though who knows what aquatic organisms might exist in the planet's interior.
One expression is unnerving: homestead. And it's worrisome precisely because it summarizes what are otherwise attractive attributes: courage, perseverance, willingness to take risks. There is also the belief that self-sustaining Mars colonies could perpetuate human society if the earth became uninhabitable, an idea endorsed at the very highest levels of science: