In the near future, humanity has a good chance of expanding its presence beyond the earth. This includes building an infrastructure in Low Earth Orbit (LEO), on the surface (and in orbit around the moon) and on Mars. This presents numerous challenges as life in space and on other celestial bodies brings with it all sorts of risks and health hazards – not the least of which is radiation and long-term exposure to low gravity.
These problems require innovative solutions. and several have been suggested over the years! A good example is Dr. Pekka Janhunen's concept for a megasatellite settlement in orbit around Ceres, the largest asteroid in the main belt. This settlement would provide artificial gravity to its residents, while the local resources would enable the creation of a closed ecosystem inside, thereby "terraforming" a space settlement.
Dr. Janhunen – a theoretical physicist from Helsinki, Finland – is no stranger to advanced concepts. In addition to being a research manager at the Finnish Meteorological Institute, he's also a visiting professor at Tatu University and senior technical advisor to Aurora Propulsion Technologies, where he oversees the commercial development of the solar electric wind sail (E-Sail) concept he proposed back in 2006.
Exterior view of a Stanford torus. At the bottom center is the non-rotating primary solar mirror, which reflects sunlight onto the angled ring of secondary mirrors around the hub. Photo credit: Donald E. Davis
The paper describing his concept was recently published online and submitted to the scientific journal Elsevier for publication. It's a concept that Dr. Janhunen describes Universe Today as “(T) flawed from the user's point of view: creating an artificial environment near Ceres and Ceres materials that can be scaled to the same and larger population than today's earth. ”
Rotating space habitats are a tried and true proposition and suggested alternative to (or in conjunction with) habitats on other celestial bodies. The first recorded instance was Konstantin Tsiolkovsky's 1903 book Beyond Planet Earth, in which he described a wind turbine station in space that would rotate to provide artificial gravity.
This was followed by Herman Potonik's expanded proposal in The Problem of Space Travel (1929), the Von Braun Wheel (1952), and Gerard K. O & # 39; Neill's revolutionary proposal in The High Frontier: Human Colonies in Space (1976) called for a rotating one Cylinder in Space – aka. the O & # 39; Neill cylinder. However, all of these concepts concerned stations in Low Earth Orbit (LEO) or at an Earth-Sun Lagrange point.
As Dr. Janhunen emailed Universe Today, a mega-satellite constellation in orbit of Ceres could use local resources to create Earth-like conditions:
“They provide an earth-like gravity of 1 g, which is essential for human health, especially children, to grow into healthy adults with fully developed muscles and bones. Ceres has nitrogen to create the habitat atmosphere, and it's large enough to provide nearly unlimited resources. At the same time, it's also small enough that its gravity is rather low, so lifting material from the surface is cheap. "
Artist's impression of a pair of O'Neill cylinders. Photo credit: Rick Guidice / NASA Ames Research Center
According to his study, the mega-satellite settlement would consist of rotating habitats attached to a disc-shaped frame by passive magnetic bearings. This would allow for simulated gravity within the habitats, make travel within the settlement easier, and ensure that population density remains low.
Dr. Janhunen estimates that it could be kept at 500 people per km2 (190 people per mi2) while cities like Manhattan and Mumbai have densities of around 27,500 and 32,303 people per km2 (or 71,340 and 83,660 people per mi2, respectively). The settlement was initially to be provided with a depth of 1.5 m (~ 5 ft), which could be upgraded to 4 m (~ 13 ft).
This would allow for green spaces with gardens and trees that produce the settlement's oxygen and scrub the CO2 atmosphere (as well as additional radiation shielding). Similarly, Ceres is known to have abundant ammonia salts on its surface (especially around the bright spots in Occator Crater) that could be imported into the settlement and converted to nitrogen for use as a buffer gas.
Planar and parabolic mirrors, which are located around the frame, would direct concentrated sunlight onto the habitats, provide lighting and enable photosynthesis. While creating such a settlement poses many technical challenges and would require a massive investment of resources, in many ways it would be easier to colonize the moon or Mars.
A view of Ceres in natural color, pictured from the Dawn spacecraft in May 2015. Photo credit: NASA / JPL / Planetary Society / Justin Cowart
Incidentally, it would also be a lot easier than terraforming the moon or Mars. As Dr. Janhunen stated:
“Easier in some aspects (no need to land a planet, no dust storms, no long night). In all cases, the biggest challenge is likely to be getting the industry booted in a remote place – you need some robotics and AI, but they're by and large emerging now. "
But perhaps the most exciting aspect of this proposal is the fact that it enables a space elevator! On Earth, such a structure remains impractical (and also extremely expensive) as Earth's gravity (9.8 m / s2 or 1 g) seriously limits space exploration. In short, a missile must reach an escape speed of 11.186 km / s (40,270 km / h) to free itself from Earth's gravity.
On Ceres, however, gravity is a fraction of what it is here on Earth – 0.28 m / s2 (less than 3%), resulting in an escape speed of only 510 meters per second (1.8 km / h) . . In combination with its fast rotation, a space elevator is completely feasible and energetically cheap (compared to transport from other places).
Of course, such a settlement also has the advantage of exploring (and colonizing) the outer solar system. With a large population and infrastructure around Ceres, ships destined for Jupiter, Saturn, and beyond would have a layover to refuel and pick up supplies. Possible targets for colonies could be the Galilean moons, Saturn's moons or orbiting habitats in both systems.
This would give humanity access to the abundant resources of these systems and usher in an age of post-scarcity. In the meantime, this Ceres mega-constellation would provide an Earth-like environment for a sizeable population within the main asteroid belt that could be improved to make way for many more people. As Dr. Janhunen said:
“The Ceres mega-satellite could probably grow to hundreds of billions of people, so it would be sufficient for at least a few centuries. Beyond that, discussing the future is difficult, but in general what life in general does is spreading to multiple places. On the other hand, people like to live in a networked world, parts of which (all) can be accessed through travel. "
At its core is Dr. Janhunen's concept of combining space construction and in-situ resource use (ISRU) with some key elements of terraforming. The end result is a design for a scalable settlement that could allow humans to colonize otherwise uninhabitable parts of the solar system. When grappling with the future of humanity in space, both the challenges and the rewards are clear.
In order to get the rewards, we need to be powerfully creative and ready to get involved!
Further reading: arXiv