Given all the logistics involved, it is unlikely that mankind will ever see outside the solar system to colonize exoplanets. But the possibility of living elsewhere within the solar system is not so far-fetched.
NASA is planning an outpost on the moon. Crew missions to Mars are not far away. Heck, we even have people living off the planet (albeit temporarily) in the International Space Station.
So are there people elsewhere in the solar system who can make us at home? 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 hangs in the asteroid belt between Mars and Jupiter, and with a diameter of 952 kilometers it is considered the largest known asteroid in the solar system, and as the only dwarf planet closer to the sun than Neptune.
Why Ceres? This marks very desirable boxes, Janhunen thinks.
‘The motivation’, he writes in a pre-print article published on arXiv, ‘is to have a settlement with artificial gravity that enables growth outside the Earth’s habitat, while the inhabitants also have an easy journey between inhabitants and’ provides a fairly low population density of 500. [people per] square kilometers. ‘
Mars and the moon, according to him, may not be the best places for human colonies, because their natural gravity is so different from the earth. We know that astronauts experience health problems when they return to Earth from a low or no G environment; we have very little idea of the consequences of low gravity to maturity.
An alternative to the planetary colony model is an artificial space colony orbiting the sun – a space station that revolves around generating enough centrifugal force to mimic one g: the gravity of the earth.
It would also be logistically awful. If the population becomes too large for one settlement, several settlements may be needed. If multiple colonies are in an orbit around the sun, it can drift apart and cause other problems, such as travel between settlements. If they revolve around a common body, collision avoidance becomes a problem.
Janhunen’s solution is quite neat, at least conceptually: use Ceres as a base around which the rotating settlement knots can rotate, connected by a fixed frame.
This would not only solve the problem of holding the settlement nodes together without the possibility of collision, but also solve the problem of the material neatly, as it could be collected directly from the dwarf planet. Nitrogen is of particular importance, Janhunen said, as it forms so much of the Earth’s atmosphere.
But we also know that Ceres is quite salty, and recent research suggests that it can also have a lot of water below the surface. Solar panels on the surface of the dwarf planet can easily propel a spacecraft to the satellite.
“The removal of Ceres’ material is energy-efficient compared to its processing into habitats, when a spacecraft is used,” explains Janhunen. “Because Ceres has low gravity and rotates relatively quickly, the spacecraft is achievable.”
According to him, radiation protection can be built from 80 percent silicate regolith (rock of Ceres) and water. The habitats would be divided into rural and urban spaces, 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 can be used to direct sunlight toward the habitat, for the purpose of growing crops, for lighting and for solar power. These mirrors would hang like a makeup compact on one side of the disk-shaped satellite and could be adjusted to collect most of the sunlight as the dwarf planet moves around the sun.
“We use a disk geometry for the megasatellite because the symmetry eliminates the tidal moment so that reaction wheels are not needed to maintain the posture,” writes Janhunen.
“The habitats are illuminated by natural sunlight. The sunlight is collected on the disk by two flat mirrors that are inclined at an angle of 45 degrees and concentrated by parabolic mirrors to the desired intensity.”
It can be cultivated, if necessary, by simply adding more habitats on the edge of the first to potentially millions of habitats, for a lifestyle that might be even better than life on earth.
After all, there would be no natural disasters or unwanted weather, and its modular action would mean that it could only continue to grow with the population. In principle, Ceres, Janhunen believes, can support the current population of the earth 10,000 times.
Of course, this is all very speculative and has yet to be tested. In addition, Janhunen notes that artificial gravity around the orbit is still a goal that has yet to be realized.
As for the case, space elevators, giant mirrors and radiation protection are sufficient to protect a space colony. Orbital simulations for Ceres, and the logistics of transporting many people past Mars, are also factors that still need to be considered.
Once these kinks are ironed out, it will only take about 22 years to build a human satellite into orbit around Ceres, Janhunen calculates.
“The overall difficulty of carrying out this project is likely to be similar to the establishment of Mars,” he writes.
“The delta-v and the travel time to Ceres are longer, but on the other hand one avoids planetary landings and the atmospheric weather and dust. On Ceres, it takes a bit of effort to lift the material to lift with the elevator “But it’s energetically cheap. Once the materials are in a high Ceres orbit, the thermal environment is uniform and it’s easy to get energy due to the absence of eclipses.”
It’s definitely worth thinking about, right?
Janhunen’s paper, written under the framework of the Finnish Center for Excellence in Sustainable Space Research, is available on arXiv.
H / T: Phys.org