At the moment, there are many flaws for this type of settlement in space due to movies showing the incorrect timelines to built somethings similar to that of Earth however, I will talk about some ways to possibly live in this megastructure in the future centuries, and what challenges need to be overcome by future generations.
Many people argue that a centripetal force generating gravity will harm humans in the long-run however, it might be able to shield you from the effects of rapid space-acceleration and to give you a constant pull â€œdownwardâ€ without needing to accelerate it, it will be as if somehow you discovered a type of negative gravitational mass.
If antimatter has negative gravitational mass, then by setting up a ceiling of antimatter and a floor of normal matter, we could create an artificial gravity field that always pulled you down by spinning very-fast which in turn would create/simulate artificial gravity. (again this is all a theory/speculation which has yet to be proven) Sooner or later in the future we are bound to create strong/firm artificial gravity.
The first challenge in developing an Oâ€™Neill cylinder is that it will be way too expensive. It will cost billions and trillions of dollars since we will need to build infrastructure. The bigger the colony the harder it becomes to manage and the more money it will cost to build, sustain. It will require funding from multiple nations/people.
The Second challenge is to make artificial gravity stay same in all directions inside the cylinders at all times by rotating the cylinders in 360 degrees. Gravity distortion will be a major issue to solve. We would need to develop technology that will allow us to perfectly simulate gravity in a way that we are able to stay still without being affected by Earthâ€™s gravity.
The third challenge will be powering the station with vast amounts of energy. The cylinder will be facing the sun directly. Several different types of energy will be required to operate this megastructure such as solar, electric, fusion, and even fission.
The fourth challenge would be to overcome engineering that prevents from any space debris which can cause a deep tear/hole in these type of space colonies. Having clear of space debris is a must since any hole caused can become a catastrophe for habitants living inside. Strong resistant materials from wear and tear is a must.
Oâ€™Neill colony will be more like a super-large orbital station in space. It would need many properly thought-out ventilation systems that will retract carbon emissions, hydrogen, with proper sewage systems.
We would need thousands of workers manpower to build this.
We would be solely dependent on the strength of the materials acquired to build this cylinder.
We would need abundant amount of materials with abundant amount of supplies.
Keeping any plant/animal life alive in this type of habitat will be a real challenge in the long-term. It will act as an artificial bio-dome habitat for other life-forms. We would need to be able to control bacteria growth from any diseases and prevent causes of long-term space-radiation effects.
Colonists inside would use solar power for electrical energy and for growing crops. The outer walls of an O’Neill colony are generally pictured as a transparent material, so that mirrors can aim sunlight through its walls as needed to provide light and energy as well as a strong thick structure that gives protection from any space debris and any tear.
This type of structure will be built on by multiple layers of resistant materials and periodical maintenance will be mandatory. It is essential to build this mega-structure by lightweight materials/properties that are very resistant from breaking. Layers of encapsulated pressurized carbon nanotubes will be used by, 3d-printing a mined asteroid resources. Nanotechnology will play a vital role in converting and shaping resources at the molecular level efficiently.
Asteroid belts include rich source of raw materials, already exposed, and differentiated. We would need to mine resources at very large amounts by drones/machines or space probes who will be doing almost 70% of the transport and labor through special tools, equipmentâ€™s, and transportation of materials in abundant amounts.
In the future, we will need to mine raw chemical substance, elements, and materials like oxygen, nitrogen, aluminum, and even metal which are plentiful in the solar system, and mining for resources in space is a common theme across space settlement discussions.
Because of their size, the colonies should be able to act as fully independent ecosystems, with plants to cycle air and water and resource cycles not so dissimilar from Earth. Machines will be doing almost all of the work to progress work at a faster rate. We would need many space-shuttles/rockets to mine, create, and transport materials at a significantly faster rate.
The central-part of the cylinder could be powered by nuclear/fission propulsion technology to prevent it from constantly falling into low earth orbit or to stop moving away from Earth’s direction. It needs to be able to move like a space ship yet remain stationary in a way to create a simulated firm-gravity, as well as having a proper docking stations for continuous launching and landing of space shuttles.
I personally think that the O’Neill colony may not be bigger than 4-6 miles of circumference maximum and that is because of the amount of generated power will be required to run it would be way too astronomical. There will be major issues facing a colony size this big for maintenance issues such as carbon emissions and oxygen consumption and control.
Sooner or later with the progression and advancements of human technology from the last 200 years, humans will be capable of designing and building this technology inevitably within the next few centuries. We might even be able to build a blueprint by the end of this century. Humans are already trying to build a space-hotel next to ISS for tourism so O’Neill colony in a couple of centuries is definitely plausible.
In order to achieve this, the earth would have to be near a type 2 civilization on Kardashev scale to acquire this type of energy and resources to create something as vast and self-sufficient.