One of the ideas often proposed in 2012 circles is the idea that a rogue planet will come nearer to Earth and herald in a new era. Bypassing the connection of this idea to the actual prophecies of 2012, is it possible that a rogue planet could sustain life? Astronomers used to say no, but the realm of possibility has only expanded in recent years. But in order for life to be possible on a rogue planet, several factors would have to be addressed first.
First, let’s look at the biggest and most often overlooked problem of planet habitability – gravity. Gravity has always been a major limiting factor in giving us the space-faring civilization once envisioned by the likes of HG Welles and countless others since. But while gravity does leave many hurdles to be overcome in science fiction – particularly with the difficulties inherent in artificial gravity, for the purpose of planets it’s easy enough for a to have the appropriate mass to have similar gravity to Earth – just be a similar size and density.
But then comes one of the more difficult factors when it comes to the planets themselves – heat. On Earth heat is generated primarily by the sun with other heat sources coming in the form of radioactive decay heat – which is quite significant at the interior of the planet. And these other sources are one of the key ingredients to a life sustaining rogue planet. A planet hurtling through the void of space with life either on its surface or somewhere within it would need a heat source to keep water either on or in it in a liquid form. For this, it’s possible the water could be heated by naturally radioactive heat sources through the radioactive decay of materials. The heat from these power sources is so significant it is often used to heat pressurized water in nuclear power plants.
Then there is the problem of atmosphere and pressure. It’s been demonstrated that certain organisms, such as the incredible microscopic water bears can survive in a vacuum in space, but they enter into a state of dormancy. When they reenter a sustainable environment they then reawaken with little to no damage to their physical forms. To keep organisms from being in a constant state of dormancy, they would need a pressurized environment with something akin to an atmosphere – at least according to our current understanding of carbon based life forms. For that we should take a look at Mars’ moon Phobos which was discovered to have a porous interior. Such an interior could have pockets that caved in in such a way that pressurized pockets would form allowing microscopic organisms to survive.
Of course speculating on every different element that would need to come into play would be as difficult as quantifying all the different factors that came into play when life first began on Earth, but it’s clear that the simple dismissal of life on rogue planets cannot be justified any more than it can be proven. Will we see life on a planet without a star?