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 in the solar system is not that far-fetched.
NASA plans an outpost on the moon. Manned missions to Mars are not far away. Heck, in fact, we already have people living off-planet (albeit for temporary stints) on the International Space Station.
So is there anywhere else in the solar system where humans could make us home? According to physicist and astrobiologist Pekka Janhunen of the Finnish Meteorological Institute in Finland, 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 at 952 kilometers (592 miles) in diameter, it is considered both the largest known asteroid in the solar system and the only dwarf planet closer to the sun than Neptune.
Why Ceres? It satisfies many desirable boxes, Janhunen thinks.
“ The motivation, ” he writes in a preprint paper published on arXiv, “ is to have a settlement with artificial gravity that allows for growth beyond Earth’s habitat, while also making it easy for the inhabitants to live inside the settlements. to travel and a fairly low population density of 500 inhabitants. [people per] square kilometers. “
Mars and the moon, he argues, may not be the best places for human colonies because their natural gravity is so different from Earth’s. We know that astronauts have health problems when they return to Earth from a low or zero G environment; we have very little idea of the effects of maturing at low gravity.
An alternative to the planetary colony model is an artificial space colony orbiting the sun – a space station that orbits to generate enough centrifugal force to simulate one g: Earth’s gravity.
This would also be logistically terrible. If the population becomes too large for one settlement, multiple settlements may be required. If there are multiple colonies orbiting the sun, they can drift apart, causing other problems, such as travel between settlements. When they orbit a common body, collision avoidance becomes a problem.
Janhunen’s solution is actually pretty neat, at least in concept: use Ceres as a base around which the rotating settlement nodes could circle, connected by a fixed frame.
This would not only solve the problem of keeping the settlement nodes together without the possibility of collisions, but would also neatly solve the problem of materials as they can be collected directly from the dwarf planet. Nitrogen is of particular concern, Janhunen said, because it makes up so much of Earth’s atmosphere.
But we also know that Ceres is quite salty, and recent research suggests there may be a lot of water beneath the surface as well. Solar panels on the surface of the dwarf planet could easily power a space elevator to the satellite.
“Lifting the materials from Ceres is energetically inexpensive compared to processing them into habitats, when using a space elevator,” Janhunen explains. “Because Ceres has low gravity and rotates relatively quickly, the space elevator is feasible.”
Radiation shielding, he said, could be made up of 80 percent silicate regolite (Ceres rock) and water. The 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 can be used to direct sunlight towards the habitat, for growing crops, for lighting and for solar energy. These mirrors would hinge on one side of the disk-shaped satellite, as a make-up compact, and could be adjusted to capture 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 torque, so reaction wheels are not needed to maintain their attitude,” Janhunen writes.
“The habitats are illuminated by natural sunlight. The sunlight is collected on the disc by two flat mirrors that are angled at 45 degrees and are concentrated to the desired intensity by parabolic mirrors.”
This can be cultivated, if necessary, by simply adding more habitats at the edges of the former, to potentially millions of 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 due to its modularity it could just keep growing with the population. Basically, according to Janhunen, Ceres could support 10,000 times Earth’s current population.
It’s all very speculative, of course, and has yet to be tested. In addition, Janhunen notes that orbital artificial gravity is still a goal that has yet to be realized.
Incidentally, space elevators, gigantic mirrors and radiation shielding are enough to protect a space colony. Orbital simulations for Ceres, and the logistics of transporting many people along Mars, are also factors that have yet to be taken into account.
However, once these kinks are smoothed out, it would only take about 22 years to build a human satellite orbiting Ceres, Janhunen calculates.
“The overall difficulty of carrying out this project is probably comparable to establishing Mars,” he writes.
“The delta-v and trip time to Ceres are longer, but on the other hand, planetary landings and the atmospheric weather and dust are avoided. On Ceres, it takes some effort to lift the materials into orbit, but it is energetically cheap. Once the materials are in a high Ceres orbit, the thermal environment is uniform and energy is readily available due to the absence of eclipses. “
Definitely worth thinking about, right?
Janhunens paper, written as part of the Finnish Center of Excellence in Research of Sustainable Space, is available on arXiv.
H / T: Phys.org