Sunday, 15 March 2015

Colonies Under the Ice Moons

Deep beneath the surface of many of our Solar System's worlds are hidden oceans. Jupiter's moon Europa is probably the best known, but two of its other moons, Ganymede and Callisto, also have significant subsurface oceans.
Geysers on Saturn's moon, Enceladus

Saturn's moon Enceladus has very recently been shown to have liquid water beneath its icy surface, its active geysers, over a hundred of them, being the most compelling evidence for this.

And even Ceres in the asteroid belt and Pluto are prime suspects for such deep oceans.

An exploration of such oceans is long overdue, and not because there may be signs of life down there. There is a much more important reason than that.  We need to know how viable such locations are for underwater human colonies.  If such colonies could be built they would have the following advantages:
  • the hundreds, and likely thousands, of metres of ice above would provide a huge amount of protection from deadly hazards such as meteor strikes, cosmic radiation, attack and supernovae
  • oxygen and hydrogen could be harvested from the water to breath and for fuel
  • if the oxygen levels are high enough there may be marine life, feeding off the minerals from volcanic vents in the moons' rocky cores, which could provide a food source
  • Earth's deep sea marine life could be introduced to further improve food stocks

A small manned submarine on Europa
Colonies could be built in different ways depending on the conditions found, but they are likely to be habitats attached to the underside of the ice cover or dug deep into the ice. Submarines would be used for transportation between the habitats, and for exploration of the oceans. Large enough submarines could even become permanent habitats themselves.

Access to the colonies would be by a shaft to the surface, with possible habitats located at various levels on the way up (as suggested by the Objective Europa proposal). A small facility would be located at the surface to receive new arrivals and supplies, and for colonists to leave the moon, or embark on surface activity.

With such a large choice of worlds to colonise in this way, once the technology and experience of one attempt is realised it would be relatively easy to colonise the others. The shelter offered by such locations is so good that research and mission planning should commence immediately.

A surface base on an ice moon of Jupiter

Titan - Our Best Subsurface Destination

There is one moon I have yet to mention, and it is probably the best location for such a colony. That moon is Saturn's largest, Titan. Like the large Jovian moons, Titan has a global subsurface ocean, but unlike all the others it also has a thick atmosphere which would offer significant protection for surface bases.

The internal structure of Saturn's moon, Titan

Titan should, in my opinion, be the focus of research for such colonies. But no proposals for manned missions or colonisation exist. The only proposal I can find regarding Titan is a NASA submarine mission to explore the moon's hydrocarbon and methane surface seas.

A submarine exploring one of Titan's seas
If this goes ahead it will indeed be fascinating, but it is unlikely to further the cause of human colonisation beyond Earth. That should be the focus of ALL future space missions.