Several conceptual studies provide foundations for the development of space habitats:
O’Neill’s The High Frontier (1974–76)
Near the end of Project Apollo (1961–72), Princeton physicist Gerard K. O’Neill and his students discovered in 1970 space habitat cylinders made of steel and glass 5 miles in diameter and 20 miles long were feasible.
O’Neill’s Princeton students solved issues such as radiation protection from cosmic rays, natural sun angles, power, pest free farming, and orbital attitude control without reaction motor problems.
O’Neill’s visionary space age findings can be found in Physics Today (1974) and The High Frontier: Human Colonies in Space (1976). O’Neill called his work an “assault on the academic publication establishment.”
O’Neill’s space habitats included Earth simulated and zero gravity areas, closed system agricultural greenhouses, seasons, variable indoor-outdoor living scenarios, solar powered construction sites, mass driver, and rotory pellet launchers for shipping and processing of valuable minerals on the space colony.
Inexpensive solar power from space can be microbeamed back to Earth. The Moon and asteroids will yield highly valuable resources such as carbon, nitrogen, hydrogen, and silicon. Ultimately, libraries, cinemas, restaurants, rain, and birds will develop on the space colonies of the future and a system of trade involving extraction, processing, and shipping will develop between the Moon, asteroids, other near space bodies, and Earth in the twenty-first century.
NASA Ames-Stanford Summer Study (1975)
NASA sponsored O’Neill summer workshops in space habitat design concepts for 100 to 10 million people. These space age habitat designs included the Stanford Torus, the Bernal Sphere, Toroidal Colony, and Cylindrical Colony. O’Neill influenced NASA to construct solar power satellites from lunar materials by demonstrating orbital manufacturing from lunar materials could generate profits, spur the development of new uses for such facilities, become self-supporting, and then build additional colonies. O’Neill and his colleague concluded it was better to build colonies near planets, moons, and asteroids instead of on them.
Space Studies Institute
Founded in 1977 by O’Neill, the Space Studies Institute (SSI) focused on space colonization feasibility studies as well as prototypes for a mass driver to move ores from the Moon to space colony orbits.
NASA Space Habitation Concepts
NASA concepts for space habitation include:
- Island One: A Bernal sphere habitat for 10–20,000 people with 900,000 square miles of planned agriculture.
2. Stanford Torus: Alternative to Island One.
3. O-Neill Cylinder: Island Three: The O’Neill cylinder, improvement on Islands One and Two is comprised of two counter-rotating cylinders five miles in diameter and and scalable to twenty miles long. Each cylinder has six equal-area stripes running the length of the cylinder. Three stripes are transparent windows. Large mirrors hinged on back of each stripe of window. Unhinged edge of the windows points to Sun to reflect sunlight into cylinders through the windows. Night is simulated opening mirrors to allow viewing of empty space and permits heat to radiate to space. Three stripes are habitable “land” surfaces. An outer agricultural ring twenty miles in diameter rotates at a different speed for farming. Angular velocity reduces motion sickness and Coriolis forces. Central axis allows for recreation with zero gravity.
The habitat’s industrial manufacturing block is in the middle for minimized gravity for some manufacturing processes. To save high costs of rocketing materials from Earth, habitats would be built with materials launched into space from the Moon’s lunar base with a magnetic mass drive.
4. Lewis One: 450-mile-long rotating cylinder with 250-mile radius plus several inner cylinders used for agriculture.
5. Kaplana One: Short cylinder 325 miles long and a 250-mile radius. Inner cylinders used for agriculture. Radiation shielding for 3000 residents.
6. Bola: Habitat or spacecraft connected by cable to a counterweight or habitat. Long with slow rotational radius for small station mass. Designed for Mars ship, initial construction shack for a space habitat, or orbital hotel. Heavy long-term habitation radiation shield requiring heavy cable rotates with the habitat.
7. Beaded Habitats: Small mass-produced single habitat bolas set for interconnection. They can be grouped into dumbbells, then bow-ties, ring, cylinder beads, and a framed array of cylinders. With even incremental investments, each stage expands safety and reduces cost per person as it adds more radiation shielding, and capital equipment. Larger rotating radiation shields grow more economical as colonial radius, population, habitats, and radiators
- Bubbleworld: Dandridge Cole’s (1964) Inside-Outside concept of drilling a tunnel thru the longest asteroid axis of iron or nickel and iron and filling it with a volatile substance like water. Solar reflector constructed nearby to focus solar heat onto asteroid to weld and seal tunnel ends and then to slowly diffuse heat across outer surface. Solar reflectors require significant human industrial presence to direct solar energy where needed. Water inside cylinder expands and inflates mass as metal softens. Rotation shapes cylinder. Centrifugation produces artificial gravity and the interior fills with soil, air, and water. Ring shaped lake creates slightly bulging middle of cylinder. Based on science fiction author Larry Niven’s Known Space stories of colonizing asteroid belt.
2. Asteroid Terrarium: Like the Bubbleworld design, an idea appearing in hard science fiction writer Kim Stanley Robinson’s novel 2312.
3. Bishop Ring: 100 km wide. 1000 km radius with 200 km high retention high walled Torus. Nanotube designed roofless habitat open to outer space on inner rim.
4. McKendree Cylinder: Paired cylinder like Island Three but much larger at 460 km in radius and 4600 km long. Also uses nanotubes.
Current space habitation projects and proposals include:
- Nautilus X-Multi-Mission Space Exploration Vehicle (MMSEV): NASA proposed (2011) long duration up to two  years, space transport vehicle with artificial gravity compartment for six (6) crew members. Partial-g-torus centrifuge with standard metal frame and inflatable spacecraft structure.
2. ISS Centrifuge Demo: Part of the 2011 Multi-Mission Space Exploration Project (MMSEV) larger torus centrifuge space habitat design. Centrifuge has 30 foot outside diameter and 30-inch ring interior cross-section diameter. Possible Sleep Module for International Space Station crew. In 2019, NASA intended to break new ground with the first all-female space walk or more accurately space float but the agency overlooked the wardrobe needs of female astronauts.
3. Bigelow Commercial Space Station: Announced in October 2010 as “Space Complex Alpha” and built in 2014–15. Designs contain up to nine (9) modules and 100,000 cu ft of habitable space. Here is a cut-away view of the habitat.
4. NASA’s Lunar Orbital Platform-Gateway (2018) is extending the human presence in deep space. Remotely operating a robotic rover, collecting lunar samples from the Moon’s surface to prospect resources, using airlocks to complete spacewalks, and conducting scientific research aboard the outpost are some of its activities. Astronauts will engage for 30–60 days in daily meals, exercise, and medical evaluations as they gain experience pressing the human presence deeper than ever to Mars and the rest of the solar system. The Moon is the gateway to Mars.
5. NASA and its commercial space partners at Next Space Technologies for Exploration Partnerships (NextSTEP) will use the Gateway to expand deep space operations including missions to the Moon with decreasing reliance on Earth. These public-private and private partnerships rapidly develop prototype systems, advance key capabilities, and validate operational concepts for future missions beyond Earth’s orbit.
Companies participating in NextSTEP include: Bigelow Aerospace, Boeing, Lockheed-Martin, Oribital AK, Sierra Nevada Corporation’s Space Systems, and Nano-Racks. NextSTEP is managed by NASA’s Advanced Explorations Systems Division (AES) in NASA’s Human Exploration and Operations Mission Directorate.
NASA began testing deep space habitation prototypes provided by five (5) companies in 2019. The Next Step Habitation effort began in 2015 with companies completing year-long concept studies. Those studies set the foundation for prototype development from 2016–2018.
Engineers, technicians, and flight operators from across the agency and space industry analyze system capabilities and human factors like layout and ergonomics to optimize efficiency and performance. Each company’s planning designs include environmental control and life support systems, avionics, sleeping quarters, exercise equipment, and communal areas.
Prototyping means design, build, test, and refine habitats long before the final flight version is developed. Such operational-driven engineering provides early understanding of precisely what we need to address the mission reducing risk and cost.
Builders, operators, and future users of the Gateway work together on this approach to evaluate concepts earlier and more completely. This helps NASA move forward to the Moon as early as possible.
The Gateway will be a temporary home and office for astronauts farther in space than humans have ever been and will serve as home base for astronaut expeditions on the surface of the Moon and for future human missions to Mars. The NextSTEP approach fortifies American leadership in space and helps drive open, sustainable, and agile lunar architecture. Now for the prototypes.
6. The Lockheed Martin prototype is based on a Multi-Purpose Logistics Module (MPLM), designed to provide logistics capabilities for the International Space Station. The design leverages capabilities of Lockheed’s robotic planetary spacecraft and Orion capsule which will transport astronauts to and from the Gateway. The prototype includes a reconfigurable space which could support a variety of missions and combines hardware prototyping and software simulation.
6. Northrop Grumman’s prototype leverages their Cygnus spacecraft which delivers supplies to the International Space Station. The Cygnus took its maiden flight in 2013 and is already human rated. Northrop Grumman’s habitat mockup focuses on a comfortable and efficient living environment and different internal configurations.
7. Boeing’s Exploration Habitat Demonstrator, which is being tested at the Marshall Space Flight Center in Huntsville, Alabama, is proven space station heritage hardware. Prime space station contractor since 1993, Boeing developed multiple space station elements. Boeing’s demonstrator leverages heritage assets while optimizing interior volume along with isolated areas with capability to use different atmospheres for payloads without impacting cabin atmosphere.
Sierra Nevada’s Large Inflatable Fabric Environment (LIFE) habitat, being tested at the Johnson Space Center in Houston, Texas, is designed to launch in a compact “deflated” configuration. It then inflates once in space. The benefit of inflatables, also called expandables, is capable in final configuration of providing a far larger living space than traditional rigid structures limited in size by payload volume of the rocket used to launch it. The LIFE Prototype inflates to 27 feet in diameter and simulates three (3) floors to live.
Bigelow of North Las Vegas, Nevada, has a B330 prototype. The B330 features an expandable module which expands in space to provide 330 cubic meters of livable area. Bigelow sent a smaller module, the Bigelow Expandable Activity Module (BEAM), to the space station in 2015 at which time they expanded the structure live on NASA Television to include compressed air tanks. The BEAM completed a two-year demonstration aboard the station proving soft-goods resilience to harsh space environment. Following the demonstration period, NASA extended BEAM’s time aboard the station so it would function as a storage unit.
NanoRacks has proposed yet another concept to optimize habitable volume for Gateway astronauts, the Independence 1. The idea is to refurbish and repurpose a spent rocket propellant tank. This will leverage the natural vacuum of space to flush the tank of residual propellants. NanoRacks completed a feasibility study outlining the concept and plans to develop full-scale prototypes demonstrating robotics development, outfitting, and systems integration to convert the tank to function as a deep space habitat.
NASA’s Space Directive 1 will be used to build more effective all electric spacecraft and to design safe high-tech long-duration deep space habitats thru the 2020s with NASA’s partners at the International Space Station. NASA’s Space Launch System rocket and Orion spacecraft are opening the door to in-space propulsion systems, in situ resource extraction and utilization, and space manufacturing.
For more on ergonimic space habitat design exteriors and interiors consult the trailblazing Computer Simulations of Space Societies (2019) by Dr. William Bainbridge of the National Science Foundation.