Now more than ever, space agencies and star-eyed billionaires have their minds set on finding a new home for humanity beyond Earth’s orbit. March is an obvious candidate, due to its relatively close proximity, 24-hour day / night cycle and CO2-rich atmosphere. However, there is a school of space travel that suggests that colonizing the surface of another planet – any planet – is more of a problem than it is worth.
Now, a new paper published on January 6 date to the prepress database arXiv offers a creative counter-proposal: Discard the Red Planet, and build a giant floating habitat around the dwarf planet Cereso, instead.
In the journal, which was not yet a colleague, astrophysicist Pekka Janhunen of the Finnish Meteorological Institute in Helsinki describes his vision of a “megasatellite” of thousands of cylindrical spacecraft, all connected within a disk-shaped frame that orbits constantly around Ceres. – the largest object in the asteroid belt between Mars and Jupiter. Each of these cylindrical habitats could accommodate more than 50,000 people, maintain an artificial atmosphere and generate Earth’s gravity by the centrifugal force of its own rotation, Janhunen wrote. (This general idea, first proposed in the 1970s, is known as O’Neill cylinder).
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But why Ceres? Its average distance from Earth comparable to that of Mars, Janhunen wrote, facilitating travel – but the dwarf planet also has a large elemental advantage. Ceres is rich in nitrogen, which would be key to developing the orbiting atmosphere of the settlement, Janhunen said (the Earth’s atmosphere is about 79% nitrogen.) Instead of building a colony on the surface of the tiny world – Ceres has a radius of about 1/13 of the Earth – settlers could use space elevators to deliver raw materials from the planet directly to their orbiting habitats.
This orbital lifestyle would also address one of the biggest warnings Janhunen sees in the idea of Martian surface colony: the health effects of low gravity.
“My concern is that children on a Martian settlement will not grow up to healthy adults (in terms of muscles and bones) due to the too low Martian gravity,” Janhunen told Live Science via email. “That’s why I was looking [an] an alternative that would provide [Earth-like] gravity but also an interconnected world. “
Despite this, Janhunen’s proposal comes with its own warnings that could work against a successful Ceres colony, a foreign researcher pointed out.
Welcome to disco world
According to Janhunen’s proposal, each cylinder of the Ceres megasatellite would produce its own gravity by rotation; each cylindrical habitat would measure approximately 6.2 miles (10 kilometers) long, have a radius of 0.6 miles (1 km), and complete full rotation every 66 seconds to generate the centrifugal force necessary to simulate terrestrial gravity.
A single cylinder could comfortably hold about 57,000 people, Janhunen said, and would be held in place next to its neighboring cylinders by powerful magnets, such as those used in magnetic levitation.
That interconnectedness points to the other great advantage of megasatellite life, Janhunen said: New habitat cylinders could be added to the edges of the colony indefinitely, allowing for almost unlimited expansion.
“The surface of Mars is smaller than that of Earth, and therefore it cannot give rise to significant population and economic expansion,” Janhunen told Live Science. Ceres colony, on the other hand, “grows from one to millions of habitats.”
Seeing the light
In addition to the cylinders and their massive disk frame, the main features of the colony will be two huge glass mirrors, angled at 45 degrees relative to the disk to reflect just enough natural sunlight into each habitat. Part of each cylinder will be dedicated to growing crops and trees, planted in a 5-foot-thick (1.5-meter) bed of soil derived from Ceres ’raw materials, Janhunen wrote. The natural sunlight must strengthen them. (The “urban” part of each cylinder would meanwhile depend on artificial light to simulate a terrestrial day-night cycle. Janhunen does not condition where the oxygen from the settlement comes from.)
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This society of floating cylindrical utopias may sound a bit extravagant, but it has its supporters. In 2019, Jeff Bezos (CEO of Amazon and founder of the private space company Blue Origin) spoke at Washington, DC on the merits of building “O’Neill colonies” similar to that described by Janhunen here. Bezos was skeptical that such a colony could exist in our lifetime, and asked the audience, “How are we going to build O’Neill colonies? I don’t know, and no one in this room knows.”
However Janhunen is more optimistic. In an email to Live Science, he said the first human settlers could set out for Ceres in the next 15 years.
Next year at Ceres?
Manasvi Lingam, an assistant professor of astrobiology at the Florida Institute of Technology, which studies planetary habitability, said Ceres’ proposal presents a “credible alternative” to colonizing the surface of Mars or the Moon, but some key considerations are still missing.
“I would say there are three main warnings,” Lingam, who did not participate in the journal, told Live Science. “The first is a question of other essential elements besides nitrogen.”
One key element that is not mentioned in the newspaper is phosphorus, Lingam said. The human body depends on phosphorus to create DNA, RNA and ATP (an essential form of energy conservation in cells). All organisms on Earth – including any plants that colonists might hope to grow in their floating habitats – need it in one way or another, but Janhunen’s proposal does not address where or how this critical element would be obtained.
The second warning is the technology, Lingam said. Collecting nitrogen and other raw materials from Ceres would require mining the planet’s surface and extracting those crucial elements from the rocks themselves. This operation probably would not have been possible without a fleet of autonomous mining vehicles ready to deploy on Ceres, other than satellites to guide them to the most viable food-rich deposits. The idea is believable, Lingam said, but technologically, we’re not there yet; recently (January 15), a NASA Martian robot was declared dead after it failed to bury itself just 16 feet (5 meters) into the Martian surface, ending a two-year mission.
These technological limitations point to Lingam’s third warning, which is the proposed time frame. Janhunen’s proposal suggests that the first cluster of orbiting habitats of the megasatellite could be completed 22 years after mining begins on Ceres. But this estimate assumes that the available electricity supply of the settlement is growing exponentially every year, starting immediately and never stopping due to technological or logistical problems. That assessment “is unthinkable,” Lingam said, but should not be considered certain.
“That 22-year time scale could be the lower limit under optimal conditions, but I would argue that the actual time scale could be much longer,” Lingam said.
Originally published in Life Science.