Life on the moons of our Solar System
Spreading out among the stars and building new colonies has long been a dream for humanity, but we shouldn’t just looked at neighbouring planets as potential future homes. Scientists have been collecting information on the moons in our Solar System for decades, and they are often just as interesting as the planets they orbit.
Our Solar System is home to over 200 moons, orbiting every planet except for Mercury and Venus. Moons vary widly in size, shape, and in their environments. They are inhospitable to humans, but as our technology continues to develop, perhaps one day human life might be possible there with appropriate habitat structures. Terraforming a moon (artificially engineering an Earth-like environment) would enable us to live relatively normal lives, although this still lies somewhat within the realms of science fiction. Which of the Solar System’s moons is our best hope for an off-world colony?
A multitude of moons
Jupiter and Saturn have the most moons: the latest count for Saturn is 82! Many would be too small for extensive human habitation at only a few kilometres in diameter, and have bare rocky surfaces. The larger moons have been extensively studied over the years and seem much more promising as potential locations for human settlement.
Which of the Solar System’s moons is our best hope for an off-world colony?
Volcanic moons
One of Jupiter’s largest moons is considered the most volcanically active place in the solar system. Io is home to hundreds of volcanoes where erupted lava reaches kilometres above the surface of the planet. It has limited atmosphere and no water, making it extremely unlikely that life as we know it could have developed there. If proven beyond doubt, this lack of life could make Io a potential body for terraforming, as there would be limited ethical considerations around altering the environment to suit humans.
There are other volcanic moons that could be good colony candidates. Enceladus, one of Saturn’s moons, has a very different type of volcanic activity. Beneath its white icy crust is a global ocean of water, complete with hydrothermal seafloor vents. Plumes of water vapour erupt from fissures in the crust, carrying materials into space. Enceladus is already considered to be strong candidate for discovering other forms of life, so terraforming should not be considered until we know for certain.
Hidden oceans
Enceladus, along with Jupiter’s moons Europa, Callisto, and Ganymede, all hide massive global liquid-water oceans beneath their icy crusts. Having large amounts of liquid water available could be a huge support to a human colony. Their atmospheres are too thin to support life but oxygen has been detected, and NASA is already running experiments to see how an oxygen-rich atmosphere could be created artificially from gases like carbon dioxide. But perhaps one of the best options is Titan, Saturn’s largest moon. As well as a subsurface global water ocean, Titan has a thick atmosphere and experiences a host of continuous reactions that might provide chemical components essential for supporting life.
Ruth Kirk is a science writer based in the UK.