The whole Mars thing seems feasible:
1. Imagine living with 2 people for the rest of your life in a cave.
2. Mars has polar ice caps with solid carbon dioxide, not frozen water like on earth.
3. Has Mars ever been in the Goldilocks zone to support life or will it ever be? Its current mean temperature is: 210 K, -63°C, -81.5°F
4. With the thin atmosphere and the Suns radiation levels on the surface, living on Mars would be about the same as living on Earth's moon. Its mean surface level pressure of 0.087 psi, compared to Earth's sea level average of 14.69 psi. That means water boils at 0.01°C on the surface of Mars.