Humans on Callisto within 15 Years

Human colonies on the Moon and Mars are almost inevitable, but that is simply because of their proximity to Earth. But the best location for the first human colonies beyond our planet may not be the Moon or Mars. It could well be one of Jupiter's ice moons. The intense radiation in the inner Jovian system is a major problem, but one of the largest outer moons, Callisto, has great potential.

Callisto, the second largest of Jupiter's moons, and the easiest and safest one on which to establish a human colony

As far as human colonisation is concerned Callisto offers much the same resources as the other three Galilean moons, but there is one thing it offers that the others cannot: a low radiation environment. Such an environment, which is still protected by Jupiter's magnetosphere,  means that crewed spacecraft will need minimal radiation shielding, and habitats on the surface of Callisto are possible. On top of that, its old surface indicates that it is geologically stable. And there is also strong evidence of significant amounts of liquid water beneath the surface (which itself contains plenty of water ice).

As well as water ice, the surface is made up of significant amounts of carbon dioxide ice, rock, silicates and hydrocarbon compounds, all of which can be mined to help a colony achieve self-sufficiency (water oxygen, fuel, metals etc.).

Callisto appears to be an almost perfect choice for colonisation, and also as a base to launch the colonisation missions of many of the other outer Solar-System bodies, such as Enceladus, Titan,  Triton, and the trans-Neptune objects beyond.

An aggressive, but achievable, time line for Callisto colonisation is as follows:

• 2019: the Callisto orbiter launched. Construction of crewed spacecraft begins.
• 2020 - 2022: an unmanned supply spacecraft is launched with surface habitats and supplies for the future Callisto colony.

An unmanned Callisto supply spacecraft is prepared for launch in Earth orbit

• 2024: the orbiter arrives and begins detailed visual and radar mapping of the Callisto's entire surface.
• 2025 - 2027: the supply spacecraft arrives and enters orbit around Callisto. Two surface locations are chosen for the first colonies. The equipment for the two surface bases lands at the desired locations. The equipment includes human habitats, power generators, food and food growing bays, drilling machines, and oxygen/fuel creators (to extract hydrogen and oxygen from the surface water ice to create fuel for return journeys, and of course to make oxygen for breathing). The now empty supply spacecraft returns to Earth.
• 2027: the first crewed spacecraft launches with eight occupants.
• 2029: as the empty supply spacecraft arrives back in Earth orbit, the second crewed spacecraft launches, again with eight occupants.
• 2030: an unmanned Europa lander launches from Earth.
• 2031: the first crewed spacecraft arrives in orbit around Callisto. Six of the occupants land on the moon, three at each location, and set up the habitats. The drilling of underground habitats, and mining, begins. The two remaining crew members stay in orbit in the detached orbital station section. The empty crewed spacecraft returns to Earth.

The first colonists explore the crevasses and caves of Callisto

• 2032: The unmanned supply spacecraft leaves Earth orbit and heads back to Callisto.
• 2033: the second crewed spacecraft arrives and docks with the first one in Callisto orbit. Six of the occupants land on the moon and join the earlier colonists. There are now six at each location. The orbital station is enlarged with a new module.  It now has a permanent crew of four. The empty crewed spacecraft returns to Earth.
• 2034: the Europa lander arrives and lands on the moon's surface. The crew orbiting Callisto take control of the Europa mission, using tele-operation to control the surface rover and the penetrator to explore the ocean beneath. They will do this for all future unmanned Jovian missions.
• 2035: the underground habitats on Callisto are now occupied. They consist of large pressurised caves with habitat domes within, and also greenhouses for growing food. Tunneling continues to expand the habitats. The surface habitats are now used solely for science purposes. The first launch from Callisto with two occupants, and using fuel maufactured on Callisto, successfully docks with the orbital station.

Large man-made and pressurised caverns beneath the surface of Callisto would make ideal human habitats

• 2036: the unmanned supply spacecraft arrives. Supplies are sent to the surface colonies and the orbital station, and then the spacecraft heads back to Earth.
• 2037: the third crewed spacecraft with eight occupants leaves Earth and heads for Callisto.
• 2038: the fourth crewed spacecraft launched from Earth.
• 2039: the first baby is born in the Callisto colony.
• 2041 - 2042: the two new crews arrive in Callisto orbit and dock with the orbital station. New modules are added to the orbital station. The now very large station keeps a permanent crew of eight, while the rest head for the two surface colonies. The empty crewed spacecraft return to Earth.

One of the manned spacecraft arrives in the Jovian system and, after a close pass of Jupiter, closes in on Callisto

• 2042: with fuel on Callisto now plentiful regular round trips from the surface to the orbital station begin. Crew rotations are performed, giving all the chance to work on the surface and in orbit.
• 2043: two more children are born in the Callisto colonies.  There are now 27 colonists on the surface.

If the above plan were to be followed there would a sizable and thriving human colony on Callisto within 30 years. As it grows over the following decades humans would have an ideal base from which to launch colonisation missions to other outer Solar-System regions, and from which to conduct science and exploration work, manned and unmanned, from within a much more manageable gravity well.

SpaceX has recently presented its concept for a large and fully reusable interplanetary manned spacecraft. It's a highly impressive proposal, with a long term goal of having 100 or more passengers per trip. It would be an incredibly efficient and fast way of building a colony.

SpaceX's interplanetary spacecraft, which could eventually carry 100 passengers to colonies on Mars and the moon's of Jupiter. The image shows the spacecraft after landing on Enceladus, a moon of Saturn.

Although the initial target planet is Mars, SpaceX has said that the vehicle is suitable for use on the moons of the outer planets, too. With the extreme ambitions of organisations like SpaceX, a colony on Callisto is possible within the lifetimes of many who are reading this.  Let's hope more organisations, and some governments, rise to this challenge.

It is essential for our survival as a species.