“You would send a little bit older folks, around 60 or something like that,” Schulze-Makuch said, bringing to mind the aging heroes who saved the day in the movie “Space Cowboys.”

That’s because the mission would undoubtedly reduce a person’s lifespan, from a lack of medical care and exposure to radiation. Radiation could also damage reproductive organs, so sending people of childbearing age is not a good idea, Schulze-Makuch said.

Mars is a six-month flight away, and it has surface gravity, a thin atmosphere, frozen water, carbon dioxide and essential minerals. The two scientists propose the missions begin with two two-person teams, in separate ships that would serve as living quarters on the planet. More colonists and regular supply ships would follow.

The technology already exists, or is within easy reach, they wrote. By not taking the extra fuel and provisions necessary for a return trip to Earth, the mission could cut costs by 80 percent.

Davies and Schulze-Makuch say it’s important to realize they’re not proposing a “suicide mission.”

“The astronauts would go to Mars with the intention of staying for the rest of their lives, as trailblazers of a permanent human Mars colony,” they wrote.