Guardian:

A few months before he died, Carl Sagan recorded a message of hope to would-be Mars explorers, telling them: "Whatever the reason you're on Mars is, I'm glad you're there. And I wish I was with you."

On Monday, 17 years after the pioneering astronomer set out his hopeful vision of the future in 1996, a company from the Netherlands is proposing to turn Sagan's dreams of reaching Mars into reality. The company, Mars One, plans to send four astronauts on a trip to the Red Planet to set up a human colony in 2023. But there are a couple of serious snags.

Firstly, when on Mars their bodies will have to adapt to surface gravity that is 38% of that on Earth. It is thought that this would cause such a total physiological change in their bone density, muscle strength and circulation that voyagers would no longer be able to survive in Earth's conditions. Secondly, and directly related to the first, they will have to say goodbye to all their family and friends, as the deal doesn't include a return ticket.

...Nevertheless, the project has already had 10,000 applicants, according to the company's medical director, Norbert Kraft. When the official search is launched on Monday at the Hotel Pennsylvania in New York, they expect tens of thousands more hopefuls to put their names forward.

A human colony on Mars? Does this mean raising children on Mars? If so, this presents a profoundly troubling ethical question. It's fine if an adult woman or man wants to go to Mars and spend the rest of his/her life being bored to death by a planet that has little to nothing going for it. But to be born in this world, to realize it's not your world, and to feel everyday the frustrated instincts for a world that has rising from its buzzing surface a warm and biotic halo. What if these stranded children demanded that we on Earth come right away and rescue them from a boredom that has no beginning or end? They did not ask to be born on Mars. They are being punished for a crime they never committed. And what if they sue us Earth humans for trillions? What are the rights of these Martian brats? And finally there is this...

But the Mars One website states: "While a cosmonaut on board the Mir was able to walk upon return to Earth after 13 months in a weightless environment, after a prolonged stay on Mars the human body will not be able to adjust to the higher gravity of Earth upon return.

"There is a point in time after which the human body will have adjusted to the 38% gravitation field of Mars, and be incapable of returning to the Earth's much stronger gravity. This is due to the total physiological change in the human body, which includes reduction in bone density, muscle strength, and circulatory system capacity."

One solution is to make a Truman Show of the lives of these Martian children. They can never know of Earth, never know where their parents really come from. They have to believe this is all there is and will ever be...