Given all the logistics involved, it is unlikely that humanity will ever see our way outside the solar system to colonize exoplanets. But the possibility of settling elsewhere within the solar system is not so discouraged.
NASA is planning an outpost on the moon. Crew missions to Mars are not far away. Heck, we already have people living off the planet (albeit for temporary periods) on the International Space Station.
So is there somewhere else in the Solar System that can make our home human? Well, according to physicist and astrobiologist Pekka Janhunen of the Finnish Meteorological Institute in Finland, the dwarf planet Ceres is not entirely unlikely.
Ceres is an interesting piece of rock. It is located in the asteroid belt between Mars and Jupiter and, with a diameter of 952 kilometers, is considered both the largest known asteroid in the solar system and the only dwarf planet closer to the Sun than Neptune.
Why Ceres? Janhunen thinks he ticks a lot of desirable boxes.
“The motivation,” he writes in a prepress paper published on arXiv, “is to have a settlement with artificial gravity that would allow it to grow beyond the Earth’s habitable zone, while providing an easy journey inside the settlement for the inhabitants. and a reasonable population density of 500 [people per] square kilometer. “
Mars and the Moon, he argues, may not be the best places for human colonies because their natural gravity is so different from that of Earth. We know that astronauts face health problems when they return to Earth from a low or zero G environment; we have very little idea of the effects of growing to underweight.
An alternative to the planetary colony model is an artificial space colony, which orbits the Sun – a space station that rotates to generate enough centrifugal force to mimic a g: the Earth’s gravity.
And that would be logistically awful. If the population grows too much for one settlement, multiple settlements may be required. If several colonies are in orbit around the Sun, they could move away, creating other problems, such as travel between settlements. If a common body orbits, collision avoidance becomes a problem.
Janhunen’s solution is quite neat, indeed, at least in concept: use Ceres as a base around which could rotate the rotating nodes, connected by a fixed frame.
This would not only solve the problem of holding the nodes together without the potential for collision, but would also solve the problem of materials, as they could be collected directly from the dwarf planet. Nitrogen is very important, Janhunen said, because it represents a large part of the Earth’s atmosphere.
But we also know that Ceres is quite salty and recent research suggests that it may also have a lot of water under its surface. Solar panels on the surface of the dwarf planet could easily power a space elevator to the satellite.
“Lifting Ceres materials is energy-efficient compared to processing them in habitats if a space elevator is used,” explains Janhunen. “Because Ceres is lightweight and rotates relatively quickly, the space elevator is feasible.”
Radiation protection, he said, could be built from regular 80% silicate (Ceres rock) and water. Habitats would be divided into rural and urban areas, with a soil depth of 1.5 meters to 4 meters, as required for trees and gardens.
(P. Janhunen, arXiv, 2020)
Because Ceres is so far from the Sun, mirrors could be used to direct sunlight to habitat for crop cultivation, lighting, and solar energy. These mirrors would be articulated on a disk-shaped side of the satellite, like a makeup compact, and could be adjusted to collect the most sunlight as the dwarf planet moves around the Sun.
“We use a disk geometry for the megasatellite, because its symmetry eliminates tidal torque, so the reaction wheels are not needed to maintain the attitude,” writes Janhunen.
“Habitats are illuminated by natural sunlight. Sunlight is gathered on the disk by two flat mirrors inclined at a 45-degree angle and concentrated to the intensity desired by the parabolic mirrors.”
This could be cultivated, as needed, by simply adding more habitats to the edges of the first, to millions of potential habitats, for a lifestyle that could perhaps be even better than life on Earth.
After all, there would be no natural disasters or unwanted weather, and its modularity would mean that it could continue to grow with the population. In principle, Ceres could support, Janhunen believes, 10,000 times the current population of the Earth.
Of course, everything is very speculative and has not yet been tested. In addition, Janhunen finds that orbital artificial gravity is still a goal that has not yet been achieved.
In fact, so are space elevators, giant mirrors and radiation shielding enough to protect a space colony. Orbital simulations for Ceres and the transport logistics that many people surpass on Mars are also factors that should not be taken into account.
However, once these tricks are removed, it would only take 22 years to build a human satellite in orbit around the city of Ceres, Janhunen calculates.
“The overall level of difficulty in executing this project is probably similar to installing on Mars,” he writes.
“Delta-v and triptime to Ceres are longer, but on the other hand planetary landing and weather and dust are avoided. At Ceres an effort is needed to lift the materials into orbit using the elevator, but it is cheap in terms of “Once the materials are in high Ceres orbit, the thermal environment is uniform and the energy is easy to obtain due to the absence of eclipses.”
Definitely worth thinking about, right?
Janhunen’s work, written at the Finnish Center of Excellence in Sustainable Space Research, is available on arXiv.
H / T: Phys.org