Conceptual illustration of three stages in the construction of an Artificial Gravity Orbital Station (AGOS), envisioned to be a potential replacement for the International Space Station. Credits: Werner Grandl and Clemens Böck
In this month’s post we explore a few concepts and challenges related to artificial gravity (AG) that when explored and understood will enable human’s to live healthy lives and thrive in space. First up, Austria-based architect and civil engineer Werner Grandl, a researcher of space stations and space colonies, and mechanical engineer Clemens Böck describe their concept for the evolving construction of a spinning Artificial Gravity Orbital Station (AGOS) in this Research Gate working paper. AGOS is envisioned as a potential successor to the International Space Station (ISS).
The primary aim of AGOS is to mitigate the adverse health effects of microgravity on humans by providing AG. This includes preventing bone density loss, muscle atrophy, and other physiological issues associated with long-duration spaceflight (more on this later). The station would also serve as a platform for scientific research under varying gravity conditions, potentially including zero-gravity, Mars-like gravity (0.38 g), and Earth-like gravity.
AGOS is proposed as a modular, rotating space station with an initial stage composed of four living modules for a crew of 24 and four zero-gravity central modules. The station is designed to be 78 meters in length, span 102 meters, have a rotation radius of 40 meters and rotate at 4.2 rpm to provide approximately 0.9 g of AG for comfortable living conditions. A non-rotating central hub would carry solar panels providing power as well as docking modules, connecting tubes, and a structural framework to maintain stability. The next stage would double the living quarter modules to eight for 48 occupants. The final configuration would finish out the station with 32 modules for 180 inhabitants.
While the ISS operates in microgravity, which is ideal for certain types of research, AGOS would provide a dual environment where both microgravity and AG conditions can be studied. This dual capability could enhance research in life sciences, materials research, and space technology development.
There are difficulties associated with the concept though, which will have to be resolved. The paper acknowledges that the engineering complexities of maintaining a rotating structure in space, ensuring stability, and dealing with the dynamics of spin gravity on the human body, especially disorientation caused by Coriolis forces, will be quite challenging to overcome.
Still, the future benefits made possible by AGOS will make overcoming these challenges worth the effort. When realized, AGOS would help enable more ambitious space exploration goals, including using the facility for human missions to Mars, where AG may be necessary and beneficial for long-term crew health during transit. It also could open avenues for commercial space ventures in Low Earth Orbit (LEO), including tourism and manufacturing under partial gravity conditions. Ultimately, AGOS could be a significant leap in space station design, enhancing both the scientific output and the prospects for human health in space for extended periods.
In a recent update on their concept penned by Grandl in ResearchOutreach, along with collaborator Adriano V. Autino, CEO of Space Renaissance International, they extend the possibility of constructing self-sustaining colonies in space via utilization of lunar and asteroid materials. Asteroids, in particular, could be hollowed out to serve as natural shields against cosmic radiation and micrometeoroids while mining for resources like metals and water.
Grandl describes a feasible design where a mined-out asteroid provides radiation shielding for a rotating toroidal habitat built inside the body for a population of 2000 people. Rotationally driven by magnetic levitation and natural lighting provided by reflected sunlight, the facility would mimic Earth gravity and environmental conditions for healthy living. This colony could sustainably support human life with integrated systems for air, water, food, and waste management.
Artistic rendition and cross sectional layout of an asteroid habitat for 2,000 colonists with a rotating torus driven by magnetic levitation while sunlight is reflected into the enclosure along the central axis illuminating the living space via a mirror cone. Credits: Werner Grandl
This approach would only work for larger solid body asteroids which are fewer in abundance and tend to be further away from Earth in the main asteroid belt. Smaller “rubble pile” bodies that are loose conglomerations of material like the Near Earth Object (NEO) Bennu recently sampled by the spacecraft OSIRIS-REx, could be utilized in an innovative concept covered a couple of years ago by SSP. The asteroid material is “bagged” with an ultralight carbon nanofiber mesh enclosure creating a cylindrical structure spun to create AG on the inner surface. Physicist and coauthor on this work Adam Frank, mentioned this approach when he recently appeared on the Lex Friedman podcast (timestamp 1:01:57) discussing (among many other space related topics) the search for life in the universe and alien civilizations that may have established space settlements throughout the galaxy and beyond (highly recommended).
A cylindrical, spin gravity space settlement constructed from asteroid rubble like that from the NEO Bennu. The regolith provides radiation shielding contained by a flexible mesh bag made of ultralight and high-strength carbon nanofibers beneath the solar panels. The structure is spun up to provide artificial gravity for people living on the inner surface. Credits: Michael Osadciw / University of Rochester
SSP has covered a scenario conceived by Dr. Jim Logan similar to Grandl’s but going big using several O’Neill Island One rotating colonies strung end-to-end in a tunnel drilled through the Martian moon Deimos.
Left: Artist impression of an Island One space settlement. Credits: Rick Guidice / NASA. Right: To scale depiction of 11 Island One space settlements strung end-to-end in a cored out tunnel through Deimos providing sea level radiation protection and Earth normal artificial gravity. Credit: Jim Logan
The authors see the creation of these permanent spin gravity settlements in space as the next step in human evolution. This vision, once considered science fiction, is grounded in realistic engineering and scientific principals.
Back to the near future, Joe Carroll addresses two topics pertinent to how AG might help mitigate deterioration of human health in space in a couple of articles in the December 9, 2024 issue of the Space Review. In the first piece, Carroll poses the provocative question “What do we need astronauts for?”, and argues that robotic spacecraft have surpassed human astronauts in space exploration due to their ability to travel farther, endure harsher conditions, and deliver more data over longer periods at lower costs. This advantage will become even greater as robotic technology and AI progress in the near future.
As an aside, for the foreseeable future there will be a debate over humans vs. machines in space. Regardless of concerns related to risks to safety, costs, and physical limitations, humans will still have the edge over robots for a while when it comes to adaptability/problem solving, complex task execution, spontaneous scientific decisions and public inspiration. A collaborative approach, leveraging the strengths of both humans and robots to achieve more efficient and effective outcomes may be better for space development in the near term.
That being said, Carroll suggests that human spaceflight activities should be focused on assessing the viability of settlements off Earth, particularly by studying human health in lunar and Martian gravity. He emphasizes the lack of data on long-term health effects in low-gravity environments and proposes the use of AG systems in LEO to simulate lunar and Martian gravity for research purposes. Carroll concludes that understanding human health in low-gravity environments is crucial for future space settlements and that humans will play a vital role in this research.
This leads into his second article which provides suggestions on how to quickly test AG in LEO. He suggests launching and deploying a long, duel dumbbell variable gravity station composed of a Crew Dragon capsule tethered to a Falcon 9 second stage that rotates to produce AG. Providing lunar gravity at one end and Martian gravity at the other, the facility would provide an on orbital laboratory where researchers could study human adaptation to these conditions. Such tests would be more cost-effective and less risky than conducting experiments directly on the Moon or Mars.
Illustration depicting a SpaceX Crew Dragon spacecraft tethered to a Falcon 9 second stage which could be spun up (in direction of down arrow) to test centrifugal force artificial gravity. Credit: Joe Carroll
But there are challenges associated with determining appropriate spin rates. This is vital as they influence the station’s radius and cost. Previous studies using vertical-axis rotating rooms on Earth have shown that higher spin rates can cause discomfort, including nausea and headaches. However, these ground-based tests may not accurately represent the sensory effects experienced in space-based AG facilities, where the spin axis is perpendicular to the direction of gravity.
And in case you missed it, Kasper Kupica shared with SSP his Spacelife Direct approach to quickly getting started by selling AG real estate in LEO.
Implementing AG in space habitats could enhance human health and improve various aspects of space station operations (e.g. fluid flow, heat conduction, fire safety) while enabling studies of human physiology under low gravity conditions. Conducting AG tests in LEO is a prudent step toward understanding human health, determining biology related requirements for future lunar or Martian colonies and may ultimately determine the long term strategy for space settlement.
Artist rendering of the Lunar Outpost Eagle Lunar Terrain Vehicle. Credit: Lunar Outpost
Space News recently reported that Colorado-based Lunar Outpost has signed an agreement with SpaceX to use Starship to deliver their lunar rover, known as the Lunar Outpost Eagle, to the Moon. Announced November 21, the contract supports the Artemis program with surface mobility and infrastructure services. The agreement positions Starship as the delivery vehicle for Lunar Outpost’s Lunar Terrain Vehicle (LTV), which is a contender for NASA’s Lunar Terrain Vehicle Services (LTVS) program. The exact terms of the contract, including the launch schedule, were not disclosed in the announcements. Lunar Outpost has assembled a contractor team under the banner “Lunar Dawn” to execute the company’s LTV solution. The collaborative development program includes in industry leaders Leidos, MDA Space, Goodyear, and General Motors.
Rover Design Features
Mobility and Functionality: The Lunar Outpost Eagle is designed to support both crewed and autonomous navigation on the lunar surface. It’s built to operate even during the harsh lunar night, exhibiting resilience against the Moon’s extreme temperature changes.
Collaborative Development: The Lunar Dawn team brings expertise in spacecraft design, robotics, automotive technology, and tire manufacturing, ensuring a robust and versatile design.
Size and Capacity: Described as truck-sized, the Eagle LTV is intended to be a valuable vehicle for lunar operations, capable of transporting heavy cargo to support NASA’s Artemis astronauts and commercial activities.
Testing and Refinement: The design has undergone human factors testing at NASA’s Johnson Space Center, with feedback from astronauts being used to refine the vehicle’s usability and functionality.
Future Plans
NASA’s LTV Program: Lunar Outpost is one of three companies selected by NASA for the LTV program to develop rovers to support future Artemis missions. The other two companies are Intuitive Machines and Venturi Astrolab. After a preliminary design review (PDR), NASA will select at least one company for further development and demonstration, with the goal of having a rover operational in time for Artemis 5, currently scheduled for 2030.
Commercial Operations: Beyond NASA’s usage, the rovers will be available for commercial operations when not in use by the agency, aiming to support a sustainable lunar economy. This includes plans for infrastructure development and scientific exploration.
Series A Funding: Lunar Outpost has recently secured a Series A funding round to accelerate the development of the Lunar Outpost Eagle, ensuring that the rover project moves forward regardless of the outcome of NASA’s selection process.
Long-Term Vision: The company’s vision extends to enabling a sustainable human presence in space, with plans to leverage robotics and planetary mobility for development of infrastructure to harness space resources.
This partnership with SpaceX and the development of Eagle under the Lunar Dawn program are pivotal steps in advancing both NASA’s lunar exploration goals and commercial activities on the Moon.
Once delivered to the Moon by Starship, the Eagle rover will drive over harsh regolith terrain which, as discovered by Apollo astronauts when driving the Lunar Roving Vehicle, presents several unique challenges due to the Moon’s distinct environmental conditions. First, lunar dust is highly abrasive and can become electrostatically charged sticking to surfaces and mechanisms resulting in wear and degradation of wheels, bearings, and sensors potentially leading to equipment failure. The Moon’s low gravity can make traction difficult. Rovers might slip or skid becoming less stable when accelerating, braking or turning. Terrain variability and nonuniformity on loose powdery dust or sharp, rocky outcrops could cause stability issues.
These problems can be solved by creating roads with robust, smooth surfaces for safe and reliable mobility on the Moon. Initially, the regolith could be leveled by robots with rollers to compact the regolith to make it less likely to be kicked up by rover wheels. Eventually, technology being developed by companies like Ethos Space for infrastructure on the Moon using their robotic system for melting regolith in place for fabricating lunar landing pads, could be used to build smooth, stable roads.
A network of roads could be constructed to transport water and other resources harvested at the poles to where it would be needed in settlements around the Moon extending from high latitudes down to the equatorial regions. As envisioned by the Space Development Network, this system of roads could be created to provide access to a variety of areas to mine valuable resources as well as thoroughfares to popular exploration and tourism sites. The development of the highway system could start at the poles with telerobots, then eventually be expanded to include equatorial areas and would be fabricated autonomously prior to the arrival of large numbers of settlers.
Longer term, a more efficient method of transportation on the Moon could be magnetic levitation (maglev) trains. Research into this technology has already been proposed by NASA which is actively developing a project named “Flexible Levitation on a Track” (FLOAT), which aims to create a maglev railway system on the lunar surface. This system would use magnetic robots levitating over a flexible film track to transport materials, with the potential to move up to 100 tons of material per day. The FLOAT project has advanced to phase two of NASA’s Innovative Advanced Concepts (NIAC) program.
Artist’s rendering of the Flexible Levitation on a Track (FLOAT) maglev lunar railway system to transport materials on the Moon. Credit: Ethan Schaler / Jet Propulsion Laboratory
Artist’s depiction of a space farm in a 56m radius rotating space settlement. Credits: Bryan Versteeg / Spacehabs.com
Editors Note: This post is a summary of a presentation by Marshall Martin that was accepted by the Mars Society for their conference that took place August 8 – 11th in Seattle, Washington. Marshall was not able to attend but he gave me permission to publish this distillation of his talk. There are minor edits made to the original text with his permission. Marshall is an accomplished Software Engineer with decades of experience managing multiple high tech projects. He has Bachelor’s Degree in Mathematics and Physics from Northwestern Oklahoma State University and an MBA in Management of Information Systems from Oklahoma City University. He is currently retired and farms with his in-laws in Renfrow, Oklahoma. The views expressed by Marshall in this post are his own.
The Earth is a Biosphere supporting life which has evolved and thrived on sunlight as an energy source for more than 3.4 billion years.
Therefore!
You would think a few smart humans could reverse engineer a small biosphere that would allow life to exist in deep space on only sunlight.
Furthermore, eventually the sun will run short of hydrogen and transition into a red giant making the Earth uninhabitable in a few hundred mission years. Long before that time, we need to have moved into biospheres in space growing crops for food. But for now….
The cost of food in space (when launched from Earth) is too high. My Estimates: [1,2]
Launch Vehicle/Mission
Cost/pound (USD)
Cost/Person/Day* (USD)
Space Shuttle to ISS
$10,000
$50,000
Falcon 9 to ISS
$1134
$5670
Atlas V[3] to Mars (Perseverance[4] Mars Rover)
>$100,000
$500,000
2 year mission to Mars based on Atlas V costs
>$100,000
$365,000,000
* Assuming average consumption rate of 5 pounds/day
If we assume that the SpaceX Starship will reduce launch costs to Mars by at least two orders of magnitude, the cost/person/day for a two year mission would still exceed $3 million dollars.
Solution: farming in space
Starting with a rough estimate, i.e. a SWAG (Scientific wild-ass guestimate): – A space station farm sized at 1 acre producing 120 bushels per acre of wheat, 60 pounds per bushel, 4 crops per year, yields 28,000 pounds of wheat per year. Using Falcon 9 launch costs, this produces a crop valued at $31.7M per year. If your space farm is good for 50 years, the crops would be worth $1.585B when compared to an equivalent amount of food boosted from Earth at current launch costs.
SWAG #2 – I believe a space farm of this size can be built using the von Braun “Wet Workshop” approach applied to a spin gravity space station composed of several Starship upper stages at a projected cost of $513M. More on that later.
Do we know how to build a space farm? NO!
So how do we get there?
Biosphere X would be the next generation of ground-based Biospheres. You may consider the original Biosphere 2[5] as the first prototype. As an initial SWAG, it was marginally successful. As the design basis of a working space farm, it is nowhere close.
Image of the iconic Biosphere 2 experiment that attempted two missions, between 1991 and 1994, sealing a team of nine and seven Biospherians, respectively, inside the glass enclosure. The facility is now used for basic research to support the development of computer models that simulate the biological, physical and chemical processes to predict ecosystem stability. Credits: Biosphere 2 / University of Arizona
Biosphere Y will be placed in Equatorial Low Earth Orbit (ELEO) and will be based on the best iteration of Biosphere X.
Biosphere Z will be a radiation hardened version of Biosphere Y for deep space operations.
Key Metrics:
People per acre is an important metric. Knowing how many people are going to be on a space station or spaceship will imply the size of the farming operations required. [6]
Labor per acre is important. It determines how many farm workers are needed to feed the space population (assuming there will be no automation of farm operations). Note: every American farmer feeds about 100 people. Obviously, if it takes 11 farmers to support 10 people in the biosphere, that is a failure. If it takes 2 farmers to support 10 people that implies that 8 workers are available to work on important space projects. Like building the next biosphere that is bigger and better.
Cost per acre will be the major cost of supporting a person in space. There will be a huge effort to reduce the cost of space farmland.
Water per acre required to grow the crops. Since there is a metric for people per acre, the water per acre would include the water in the sewage system. I would think the water for fish farming would be separate or an option.
Soil per acre is literally the amount of dirt needed in tons. This gets fun. Will Biosphere X use hydroponics, aeroponics, light weight dirt, or high quality top-soil? It could be just standard sandy loam. The quality of the soil will have a big impact on what crops can be grown, which in turn, has a big impact on People per acre.
Watts per acre is the power required to operate a farm. Another major cost of food grown in space. Direct sunlight should be very cheap via windows, at least for biospheres in ELEO. In deep space far removed from the protection of Earth’s magnetic field, radiation would pose a problem for windows unless some sort of angled mirror configuration could be used to reflect sunlight adjacently. Electricity from solar panels has been proven by ISS. Power from a small modular nuclear reactors might be a great backup power for the first orbiting biosphere. Note, diesel fuel would be extremely expensive and emissions would cause pollution to the biosphere in space; that implies, farming would be done using electrical equipment.
Improvements based on the Biosphere 2 experience to make a successful Biosphere X:
Updated computers for: better design, data collection, environmental control systems, subsystem module metrics, communication.
Humans: I suggest 2 men & 2 women and work up from there.
Remote ground support: start big and reduce as fast as possible, goal = zero.
Testing Biosphere X:
Can a team live in the biosphere for two years? (See Biosphere 2 test which was 2 years, i.e. a round trip to Mars and back) How much food was produced? Debug the biosphere. Make upgrades and repeat the tests. Calculate Mean Time to Failure (MTTF), Mean Time to Repair (MTTR), system flexibility, cost of operations, farming metrics (see above). etc.
With enough debugging, Biosphere X will become a comfortable habitat for humans of all ages. This will include old people, children, and perhaps babies. I think a few babies should be born in a Biosphere X (e.g. a few dozen?) before proceeding to Biosphere Y. Obviously, it may be challenging to find motivated families willing to make the generational commitment for long term testing required to realize this noble goal of space settlement. Alternatively, testing of Biosphere X could be simplified and shortened by skipping having babies, deferring this step to the next stage.
Biosphere Y potential configuration:
Once a reasonably well designed Biosphere X has been tested it will be time to build a Biosphere Y. This will require figuring out how to launch and build the first one – not easily done! Let’s posit a reasonably feasible design using orbital spacecraft on the near-term horizon namely, the SpaceX Starship. Using nine upper stages with some modifications to provide spin gravity, sufficient volume could be placed in ELEO for a one acre space farm. Here’s one idea on what it would look like:
A central hub which we will call the 0G module will be composed of three Starship upper stages. Since they would not be returning to Earth, they would not need heat shield tiles, the aerodynamic steerage flaps, nor the three landing rockets. Also, there would not be a need for reserve fuel for landing. These weight reductions would allow the engineers to expand Starship and/or make more built-in structure and/or carry more startup supplies.
We will assume the current length of 165 feet with a 30 foot diameter. Three units placed nose-to-tail make 495 feet. But internally there would be 3 workspaces per unit: Oxygen tank, methane tank, and crew cabin. Times three units makes 9 chambers for zero gravity research.
The three units are connected forward and aft by docking hatches. Since the return to Earth engines have been deleted, the header tanks in the nose of Starship (the purpose of which is to offset the weight of the engines) would be eliminated allowing a docking port to be installed in front. In addition, with the 3 landing engines eliminated, there should be room for a tail end docking port. This will allow crew to move between the three Starship units in the 0G hub.
An aside: I am assuming that the nose of the station is always pointing towards the sun. The header tanks in the nose of the first unit could be retained and filled with water to provide radiation shielding to block solar particle events for the trailing units.
The 0G-units will need access ports on each of their sides to allow a pressurized access and structural support tube extending out to the 1G-units located at 100 meters on either side of the hub. This distance is calculated using Theodore W. Hall’s SpinCalc artificial gravity calculator with a spin rate of 3 rpm. There would be three access tubes extending out to connect to each of the 3 Starship 1G units. I assume the standard Starship has an access door which can be modified to connect to the tube.
Conceptual illustration of a possible configuration of an initial Biosphere Y in LEO using modified SpaceX Starship upper stages docked nose to tail. The station spins at 3 rpm around the central 0G hub with the outer modules providing 1G artificial gravity and enough volume for an acre of space farm. Credits – Starship images: SpaceX. Earth image: NASA
One or more standard Starships would deliver supplies and construction materials. They would also collect the three Raptor engines from each modified unit (36 in total) for return to Earth.
I note that the engineering modifications, methods and funding for operations in space to construct Biosphere Y have yet to be determined. However, applying a SWAG for launching the primary hardware to LEO:
This would require 18 starship missions. Using Brian Wang’s estimates of $37M per Starship[21] we get the following cost:
9 Starships times $37M per starship = $333M
18 Starship launches times $10M per launch = $180M
Total SWAG cost: $513M
What’s on the inside?
As mentioned previously, the interior of Biosphere Y will be a Wet Workshop utilizing the empty oxygen and methane tanks in addition to the payload bay volume (roughly 60ft + 39ft + 56ft long, respectively, based on estimates from Wikipedia), for a total length of 155 feet by 30 feet wide for each individual Starship unit. With six 1G Starship units this amounts to about 657, 000 cubic feet of usable volume for our space farm experiencing normal gravity and its associated support equipment (half that for the 0G hub).
Note: Biosphere Y is designed to be placed in Equatorial Low Earth Orbit (ELEO). This orbit is below the Van Allen belts where solar particle events and galactic cosmic ray radiation are reasonably low due to Earth’s protective magnetic field.
Since the first Biosphere Y will spin to produce 1G, eventually experiments will need to be performed to determine the complete Gravity Prescription[12, 13]: 1/2g, 1/3g, 1/6g and maybe lower. You would think this would be required before trying to establish a permanent colony on the Moon and/or Mars in which children will be born. This will probably require several iterations of Biosphere Y space stations to fine tune the optimum mix of plants, animals, and bio-systems.
What other things can be done with a Biosphere Y?
Replace International Space Station
Astronomy
Space Force bases in orbit
Repair satellites
Fueling station
De-orbit space junk
Assemble much larger satellites from kits (cuts cost)
Lunar material processing station
Families including children and babies[13] in space
Biosphere Z:
Once Biosphere Y is proven, it is ready to be radiation hardened to make a Biosphere Z. I assume the radiation hardening material would come from lunar regolith. It is much cheaper than launching a lot of radiation shielding off Earth.
Biosphere Z will be able to do everything that Biosphere Y can do – just further away from Earth.
After an appropriate shake-down cruise (2 years orbiting the Moon, Lagrange 1, and/or Lagrange 2), a Biosphere Z design should be ready to go to Mars. Note several problems will have been solved to ensure positive outcomes for such a journey: • What does the crew do while going to Mars — farming. • Building Mars modules to land on Mars • The crew has been trained and tested for long endurance flights • Other typical Biosphere Y, Z activities
Biosphere S — Major Milestone:
Eventually a biosphere will be manufactured using only space material, thus the designation Biosphere S. Regolith can be processed into dirt. Most metals will come from the Moon and/or Mars surface material. Oxygen is a byproduct of smelting the metals. Carbon and Oxygen can come from the Martian atmosphere. Water can be obtained from ice in permanently shadowed regions at the Moon’s poles or from water bearing asteroids. The first Biosphere S units will probably get Nitrogen from Mars. Later units could get nitrogen, water, and carbon-dioxide from Venus[14]. From the Moon we get KREEP[15]. (potassium, Rare Earth Elements, and Phosphorus) found by the Lunar Prospector mission.
People, plants, livestock, microbes, etc. will come from other Biospheres.
Electronics will probably still come from Earth, at least initially, until technology and infrastructure matures to enable manufacturing of integrated circuits in space.
Artist’s depiction of an agricultural section of Biosphere S, which could be of the Stanford Torus design built mostly from space resources. Credits: Bryan Versteeg / Spacehabs.com
At this point, humans will have become “A space faring species”
In a century, the number of Biospheres created will go from zero to one hundred per year.
Marshall’s Conjecture:
“400 years after the first baby is born in space, there will be more people living in space than on Earth.” After all, from the time of the signing of The Mayflower Compact to present day is about 400 years and we have 300+ million US citizens vs. the United Kingdom’x 68 million.
The explosion of life:
On Earth there are relationships between the number of humans, the number of support animals and plants. There are currently 8 billion people on Earth and about 1 billion head of cattle. I estimate that there are 100 billion chickens, a half billion pigs, etc.
As the number of Biospheres increases in number, so will the number of people, and the number of support plants and animals. To state it succinctly, there will be an explosion of life in space.
So how many Biosphere S colonies can we build?
Let us assume that they will be spread out evenly in the solar “Goldilocks Zone” (GZ). Creating a spreadsheet with Inputs: inside radius (IR), outside radius (OR) and minimum spacing; Output: Biosphere slot count.
Using: IR of 80,000,000 miles, OR of 120,000,000 miles, (120% to 33% Earth light intensity[16], respectively) and spacing of 1000 miles between Biospheres (both on an orbit and between orbits) you get: 40,000 orbits with the inner orbit having 502,655 slots and the outer orbit having 753,982 slots. This works out to over 25 billion slots for Biospheres to fill this region. Assuming 40 people per Biosphere S implies a space population of over a trillion people. And that is only within the GZ. With ever advancing technology like nuclear power enabling settlement further from the sun, there is no reason that humans can’t expand their reach and numbers throughout the solar system, implying many trillions more.
Can we build that many Biospheres?
Let us assume each Biosphere S has a mass of one million tons (10 times larger than a nuclear powered aircraft carrier[17]) That implies 25.1×1015 tons of metal for all of them. 16 Psche’s mass is estimated at 2.29×1016 tons[18]. There are the larger asteroids, e.g. Ceres (9.4×1017tons), Pallas, Juno, Vesta (2.5×1017 tons) and several others. Assuming the Moon (7.342×1019 tons) is reserved for near Earth use. If the asteroids are not enough, there are the moons of Mars and Jupiter. The other needed elements are readily available throughout the solar system, e.g. nitrogen from Venus, water from Europa, dirt from everywhere, so…
YES! My guess is that it will take 100,000 years to fill the GZ assuming a construction rate of about 250,000 Biospheres per year. That implies an expansion of the population by about 2 million people a year ( I acknowledge these estimates don’t take into account technological advances which will undoubtedly occur over such long stretches of time that may lead to drastically different outcomes. Remember! Its a SWAG!)
Is this Space Manifest Destiny? Is it similar to the Manifest Destiny[19] in America from 1840 to 1900? In my opinion, yes! But this is a very high-tech version of Manifest Destiny. The bottom line assumption is that the Goldilocks Zone is empty — therefore — we must go fill it! Just like the frontiersman of the 1800s.
The First Commandment:
This gives a new interpretation of the phrase from the Book of Genesis,
“Go forth, be fruitful and multiply“[20].
Not only are we people required to have children; but we are required to expand life in many forms wherever we go. For secular readers, this may be interpreted as the natural evolution of life to thrive in new ecosystems beyond Earth. Therefore, the big expansion of life will be in space.
It all starts with Biospheres X, Y, and Z optimized for farming in space
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When considering humanity’s expansion out into the solar system, look at the concepts put forward above and ask: “Is this proposal missing a key step or two in the development of biospheres in space?”
Editor’s Note: Marshall appeared on The Space Show on August 27 to talk about his space farming vision. You can listen to the archived episode here.
G.K. O’Neill, The High Frontier, 1976, p. 71 – based on Earth-base agriculture – 25 People/Acre; p72 – Optimized for space settlement (i.e. predictable, controlled climate) – 53 People/Acre.
Concept illustration of Offworld’s Prospector 1 Mobile Excavator. Credits: Dallas Bienhoff / Offworld, Inc.
At the intersection of AI, swarm robotics and mining technology lies the key to sustainable, affordable space development. Offworld, Inc. is on the cutting edge of this frontier with their suite of diverse robot species that when coordinated with collective intelligence, will enable sustainable in situ resource utilization (ISRU) thereby lowering the cost of establishing settlements on the Moon and beyond, while kickstarting a thriving off Earth economy. In a presentation to the Future In-Space Operations (FISO) Telecon on July 24, Space Systems Architect Dallas Bienhoff described Offworld’s plans for an ambitious demonstration mission called Prospector 1.
In April 2023, OffWorld Europe entered into an agreement with the Luxembourg Space Agency to collaborate on a Lunar ISRU exploration program commissioned by the European Space Agency. The multi-year initiative will develop a processing system focused on harvesting and utilizing lunar ice resources. The program will develop a Lunar Processing Module (LPM) to be integrated into a mobile excavator that will be launched to Moon’s south pole on the Prospector 1 mission currently scheduled for late 2027. The goal of Prospector 1 is to demonstrate the capability of processing icy lunar regolith to produce oxygen and hydrogen. The LPM when loaded with icy regolith will process the lunar soil to extract water, then via electrolysis produce oxygen and hydrogen. The module’s hopper is designed to receive up to 50 kg of regolith and batch process 2.5kg/hour. The unit will be housed on a mobile excavator massed at 2500 kg. Offworld has already completed TRL4 testing on the LPM in their Luxembourg office.
The company is exploring a variety of options for generation of power for the mission. Of course landers provide some minimal power but not nearly enough for processing lunar regolith. One promising system under consideration is the Vertical Solar Array Technology (VSAT) under development by Astorbotic which will provide 10kw of power (only in sunlight). But wait, there’s more! Astrobotic announced this month that they were just awarded a Small Business Innovation Research (SBIR) award by NASA to develop a larger version of the array called VSAT-XL capable of delivering 50kw. Designed to track the sun, VSAT is ideal for location at the lunar south pole where the sun’s rays are at very low elevation and provide semi-permanent illumination on the rims of permanently shadowed craters.
Comparison of relative sizes of the two VSAT solar arrays. Credit: Astrobotic
Another innovative alternative is a power source called the Nuclear Thermionic Avalanche Cell (NTAC ) under development by Tamer Space, a company providing a range of power and construction resources for settlements on the Moon, the Cislunar economy and sustainable pioneering of Mars. The device is an electrical generator that converts nuclear gamma-ray photons directly to electric power in a compact, reliable package with high power density capable of long-life operation without refueling. NTAC can provide higher power levels (e.g. starting at 100kw) and is not dependent on the sun to enable operations through the lunar night should Offworld elect to locate their facility far from the Moon’s poles or in permanently shadowed regions. Tamer described their technology at the 2023 Space Resources Roundtable
Image of a research prototype of the Nuclear Thermionic Avalanche Cell: Credit: Tamer Space
After Propector 1, Offworld’s follow on plans envision a second Prospector 2 to be launched in the 2029 timeframe. This mission will ramp up capability to include multiple robot species such as an excavator, hauler, and processor. In addition, liquefaction will be added to the process stream (not just gaseous products) and pilot plant capabilities will be demonstrated to reduce risk for the next mission. In 2031, a formal pilot plant will be established with multiple excavators and haulers. The facility will have a fixed processing plant and storage facilities capable of producing tons of water, oxygen, and hydrogen. By the end of 2034, OffWorld plans to launch an industrial scale ISRU plant with output of 100s of tons of volatiles, elements and bulk regolith per year.
Bienhoff said at the conclusion of his presentation that Offworld’s long term vision for lunar operations include: “Industrial scale ISRU, 10s – 100s of tons of product per year – by product [I mean] that’s processed regolith, that’s oxygen, that’s hydrogen, that’s water, that’s perhaps metals. We plan to monetize or use every gram we excavate. That’s a tall order, but in order to have a thriving lunar community, we need to produce as much as we can on the Moon, for the Moon, before we think about exporting from the Moon.”
Conceptual illustration showing the first iteration of the proposed design of a GE⊕ Lunar Power Station beaming power to facilities on the Moon. Credit: Astrostrom
In response to ESA’s Open Space Innovation Platform Campaign on Clean Energy – New Ideas for Solar Power from Space, the Swiss company Astrostrom laid out a comprehensive plan last June for a solar power satellite built using resources from the Moon. Called the Greater Earth Lunar Power Station (GE⊕-LPS, using the Greek astronomical symbol for Earth, ⊕ ), the ambitious initiative would construct a solar power satellite located at the Earth-Moon L1 Lagrange point to beam power via microwaves to a lunar base. Greater Earth and the GE⊕ designation are terms coined by the leader of the study, Arthur Woods, and are “…based on Earth’s true cosmic dimensions as defined by the laws of physics and celestial mechanics.” From his website of the same name, Woods provides this description of the GE⊕ region: “Earth’s gravitational influence extends 1.5 million kilometers in all directions from its center where it meets the gravitational influence of the Sun. This larger sphere, has a diameter of 3 million kilometers which encompasses the Moon, has 13 million times the volume of the physical Earth and through it, passes some more than 55,000 times the amount of solar energy which is available on the surface of the planet.”
GE⊕-LPS would demonstrate feasibility for several key technologies needed for a cislunar economy and is envisioned to provide a hub of operations in the Greater Earth environment. Eventually, the system could be scaled up to provide clean energy for the Earth as humanity transitions away from fossil fuel consumption later this century.
One emerging technology proposed to aid in construction of the system is a lunar space elevator (LSE) which could efficiently transport materials sourced on the lunar surface to L1. SSP explored this concept in a paper by Charles Radley, a contributor to the Astrostrom report, in a previous post showing that a LSE will be feasible for the Moon in the next few decades (an Earth space elevator won’t be technologically possible in the near future).
Another intriguing aspect of the station is that it would provide artificial gravity in a tourist destination habitat shielded by water and lunar regolith. This facility could be a prototype for future free space settlements in cislunar environs and beyond.
Fabrication of the GE⊕-LPS would depend heavily on automated operations on the Moon such as robotic road construction, mining and manufacturing using in situ resources. Technology readiness levels in these areas are maturing both in terrestrial mining operations, which could be utilized in space, as well as fabrication of solar cells using lunar regolith demonstrated recently by Blue Origin. That company’s Blue Alchemist’s process for autonomously fabricating photovoltaic cells from lunar soil was considered by Astrostrom in the report as a potential source for components of the GE⊕-LPS, if further research can close the business case.
Most of the engineering challenges needed to realize the GE⊕-LPS require no major technological breakthroughs when compared to, for example (given in the report), those needed to commercialize fusion energy. These include further development in the technologies of the lunar space elevator, in situ lunar solar cell manufacturing, lunar material process engineering, thin-film fabrication, lunar propellent production, and a European heavy lift reusable launch system. The latter assumes the system would be solely commissioned by the EU, the target market for the study. Of course, cooperation with the U.S. could leverage SpaceX or Blue Origin reusable launchers expected to mature later this decade. With respect to fusion energy development, technological advances and venture funding have been accelerating over the last few years. Helion, a startup in Everett, Washington is claiming that it will have grid-ready fusion power by 2028 and already has Microsoft lined up as a customer.
Astrostrom estimates that an initial investment of around €10 billion / year over a decade for a total of €100 billion ($110 billion US) would be required to fund the program. They suggest the finances be managed by a consortium of European countries called the Greater Earth Energy Organization (GEEO) to supply power initially to that continent, but eventually expanding globally. Although the budget dwarfs the European Space Agency’s annual expenditures ( €6.5 billion ), the cost does not seem unreasonable when compared to the U.S. allocation of $369 billion in incentives for energy and climate-related programs in the recently passed Inflation Reduction Act. The GE⊕-LPS should eventually provide a return on investment through increasing profits from a cislunar economy, peaceful international cooperation and benefits from clean energy security.
The GE⊕-LPS adds to a growing list of space-based solar power concepts being studied by several nations to provide clean, reliable baseload energy alternatives for an expanding economy that most experts agree needs to eventually migrate away from dependence on fossil fuels to reduce carbon emissions. Competition will produce the most cost effective system which, coupled with an array of other carbon-free energy sources including nuclear fission and fusion, can provide “always on” power during a gradual, carefully planned transition away from fossil fuels. The GE⊕-LPS is particularly attractive as it would leverage resources from the Moon and develop lunar manufacturing infrastructure while serving a potential tourist market that could pave the way for space settlement.
Artist impression of an asteroid smelting operation. Credits: Bryan Versteeg / spacehabs.com
When humanity migrates out into the solar system we’ll need a variety of elements on the periodic table to build settlements and the infrastructure needed to support them such as solar power satellites. But before that future becomes a reality, there may be a near term market on Earth for precious metals sourced in space as transportation costs come down. There is also the added benefit of moving the mining industry off planet to preserve the environment. Could the asteroid belt provide these materials? Kevin Cannon, assistant professor at the Space Resources Program at the Colorado School of Mines describes the prospects for mining precious metals and building materials for space infrastructure asteroids in a recent paper in Planetary and Space Science. Coauthors on the paper Matt Gialich and Jose Acain, are CEO and CTO, respectively, at the asteroid mining company AstroForge which just came out of stealth mode last year.
The asteroids have accessible mining volume that exceeds that available on the Moon or Mars. This is because only the thin outer crust of these bodies is reachable by excavation, whereas the asteroids are small enough to be totally consumed resulting in higher accessible mining volume.
To-scale accessible mining volume of terrestrial bodies, calculated as the total volume for the asteroids (main belt mass of 2.39 x 1023 kg, mean bulk density of 2000 kg/m3), and as the volume for an outer shell 1.2 km in thickness for the Moon, Mercury, and Mars, equivalent to the deepest open pit mine on Earth. Note the combined volume of the near-Earth asteroids (~5 x 1012 m3) is too small to be visible at this scale. Figure 1 in paper. Credits K.M. Cannon et al.
The authors take a fresh look at available data from meteorite fragments of asteroids. Their analysis found that for Platinum Group Metals (PGMs), the accessible concentrations are higher in asteroids than ores here on Earth making them potentially profitable to transport back for use in commodity markets.
“Asteroids are a promising source of metals in space, and this promise will mostly be unlocked in the main belt where the Accessible Mining Volume of bodies greatly exceeds that of the terrestrial planets and moons”
PGMs are indispensable in a wide range of industrial, medical, and electronic applications. Some examples of end-use applications include catalysts for the petroleum and auto industries (palladium and platinum), in pacemakers and other medical implants (iridium and platinum), as a stain for fingerprints and DNA (osmium), in the production of nitric acid (rhodium), and in chemicals, such as cleaning liquids, adhesives, and paints (ruthenium).
It has been pointed out by some analysts that flooding markets here on Earth with abundant supplies of PGMs from space will cause prices to plummet, but the advantage of reducing carbon emissions and environmental damage associated with mining activities may make it worth it. The authors also point out that there are probably various uses where PGMs offer advantages in material properties over other metals but are not being used because they are currently too expensive.
Asteroids are rich in other materials such as silicon and aluminum which would be economically more useful for in-space applications. As the authors point out, some companies are already planning for use of metals and manufacturing in space such as Redwire Corporation with their On-Orbit Servicing, Assembly and Manufacturing (OSAM) and Archinaut One, which will attempt to build structural beams in LEO. Another example mentioned in the paper has been covered by SSP: the DARPA NOM4D program with aspirations to develop technologies for manufacturing megawatt-class solar arrays and radio frequency antennas using space materials. Finally, another potential market for aluminum sourced in space is fuel for Neumann Thrusters (although spent upper stage orbital debris may provide nearer term supplies). And of course, silicon will be needed to fabricate photovoltaic cell arrays for space-based solar power.
AstroForge will test their asteroid mining technology on two missions this year. Brokkr-1, a 6U CubeSat just launched on the SpaceX Transporter 7 mission last April, will validate the company’s refinery technology for extracting metals by vaporizing simulated asteroid materials and separating out the constituent components. Brokkr-2 will launch a second spacecraft on a rideshare mission chartered by Intuitive Machines attempting their second Moon landing later this year. Brokkr-2 will hitch a ride and then fly on to a target asteroid located over 35 million km from Earth. The journey is expected to take about 11 months and will fly by the body and continue testing for two years to simulate a roundtrip mission.
Conceptual rendering of a Blue Alchemist solar cell fabrication facility on the Moon. Credits: Blue Origin
Jeff Bezos’ new initiative called Blue Alchemist made a splash last month boasting that the team had made photovoltaic cells, cover glass and aluminum wire from lunar regolith simulant. This is an impressive accomplishment if they have defined the end-to-end process which (with refinements for flight readiness) would essentially provide a turnkey system to fabricate solar arrays to generate power on the Moon. The announcement claimed that the approach “…can scale indefinitely, eliminating power as a constraint anywhere on the Moon.” Actually, this may not be possible at first for a single installation as surface based solar arrays can only collect sunlight during the lunar day and would have to charge batteries for use during the 14 day lunar night, unless they were located at the Peaks of Eternal Light near the Moon’s south pole. But if scaling up manufacturing is possible, coupled with production of transmission wire as described, a network of solar power stations in lower latitudes could be connected to distribute power where it is needed during the lunar night.
Very few details were revealed about the design outputs of the end products (not surprisingly) in Blue Origin’s announcement, particularly the “working prototype” solar cell. An image of the component was provided but it was unclear if the process fabricated the cells into a solar array or if the energy conversion efficiency was comparable to current state of the art (around 21%). Nor do we know how massive the manufacturing equipment would be, how much periodic maintenance is needed or if humans are required in the process. Still, if a turnkey manufacturing plant could be placed on the Moon and it’s output was solar arrays sourced from in situ materials, it would significantly reduce the costs of lunar settlements by not having to transport the power generation equipment from Earth. This particular process has the added benefit of producing oxygen as a byproduct, a valuable resource for life support and propulsion.
Research into production of solar cells on the Moon from in situ materials is not new. NASA was looking into it as recently as 2005 and there are studies even dating back to 1989. Blue’s process produces iron, silicon, and aluminum via electrolysis of melted regolith, using an electrical current to separate these useful elements from the oxygen to which they are chemically bound. Solar cells are produced by vapor deposition of the silicon. The older studies referenced above proposed similar processes.
It would be interesting to perform an economic analysis comparing the cost of a solar power system supplied from Earth by a company focusing on reducing launch costs (say, SpaceX) with that of a company like Blue Origin that fabricated the equipment from lunar materials. Peter Hague has done just that in a blog post on Planetocracy using his mass value metric.
Hague runs through the numbers comparing SpaceX’s predicted cost per kilogram delivered to the Moon by Starship with that of Blue Origin’s New Glenn. At current estimates the former is 5 times cheaper than the latter. Thus, to best Starship in mass value, Blue Alchemist would have to produce 5kg of solar panels for every 1kg of equipment delivered to the Moon, after which it would be the economic winner. Siting a recent analysis of lunar in situ resource utilization by Francisco J. Guerrero-Gonzalez and Paul Zabel (Technical University of Munich and German Aerospace Center (DLR), respectively) predicting comparable mass output rates, Hague believes this estimate is reasonable.
Perhaps we should not get ahead of ourselves as Blue Origin’s timeline for development of their New Glenn heavy-lift launch vehicle is moving a glacial pace and one wonders if they have the cart before the horse by siphoning off funds for Blue Alchemist. Jeff Bezos is free to spend his money any way he wishes and definitely seems to be in no hurry.
Conceptual illustration of New Glenn heavy-lift launch vehicle on ascent to orbit. Credits: Blue Origin
But SpaceX’s Starship has not made it to space yet either and after we see the first orbital flight, hopefully as early as next week, the company will have to demonstrate reliable reusability with hundreds of flights to achieve economies of scale commensurate with their predicted launch cost of $2M – $10M. As SpaceX has demonstrated with it’s launch vehicle development process it is not a question of if, it is one of when.
Image of full stack Starship at Starbase in Boco Chica, TX. Credits: SpaceX
As both companies refine their approach to space development, will it be the tortoise or the hare that wins the mass value price race for the cheapest approach to power on the Moon? Or will each company end up complementing each other with energy and transportation infrastructure in cislunar space? Either way, it will be exciting to watch.
SSP has addressed the gravity prescription (GRx) in previous posts as being a key human factor affecting where long term space settlements will be established. It’s important to split the GRx into its different components that could effect adult human health, child development and reproduction. We know that microgravity (close to weightlessness) like that experienced on the ISS has detrimental effects on adult human physiology such as osteoporosis from calcium loss, degradation of heart and muscle mass, vision changes due to variable intraocular pressures, immune system anomalies…the list goes on. But many of these issues may be mitigated by exposure to some level of gravity (i.e. the GRx) like what would be experienced on the Moon or Mars. Colonists may also have “health treatments” by brief exposures to doses of 1G in centrifuge facilities built into the settlements if the gravity levels in either location is found to be insufficient. We currently have no data on how human physiology would be impacted in low gravity (other then microgravity).
The most important aspect of the GRx with respect to space settlement relates to reproduction. How would lower gravity effect embryos during gestation? Since humans have evolved in 1G for millions of years, a drastic change in gravity levels during pregnancy could have serious deleterious effects on fetal development. Since fetuses are already suspended in fluid and can be in any orientation during most of their development, it may be that they don’t need anywhere near the number of hours of upright, full gravity that adults need. How lower gravity would affect bone and muscle growth in young children is another unknown. We just don’t know what would happen without a clinical investigation which should obviously be done first on lower mammals such as rodents. Then there are ethical questions that may arise when studying reproduction and growth in higher animal models that could be predictive of human physiology, not to mention what would happen during an accidental human pregnancy under these conditions.
Right now, we only know that 1G works. If space settlements on the Moon or Mars are to be permanent and sustainable, many space settlement advocates believe they need to be biologically self-sustaining. Obviously, most people are going to want to have children where they establish permanent homes. If the gravity of the Moon or Mars prevents healthy pregnancy, long term settlements may not be possible for people who want to raise families. This does not rule out permanent settlements without children (e.g. retirement communities). They just would not be biologically self-sustaining.
SSP has suggested that it might make sense to determine the GRx soon so that if we do determine that 1G is required for having children in space, we begin to shape our strategy for space settlement around free space settlements that produce artificial gravity equivalent to Earth’s. Fortunately, as Joe Carroll has mentioned in recent presentations, the force of gravity on bodies where humanity could establish settlements throughout the solar system seems to be “quantized” to two levels below 1G – about equal to that of the Moon or Mars. All the places where settlements could be built on the surfaces of planets or on the larger moons of the outer planets have gravity roughly at these two levels. So, if we determine that the GRx for these two locations is safe for human health, we will know that we can safely raise families beyond Earth in colonies on the surfaces of any of these worlds. Carroll proposes a Moon/Mars dumbbell gravity research facility be established soon in LEO to nail down the GRx.
But is there an argument to be made for skipping the step of determining the GRx and going straight to an O’Neill colony? After all, we know that 1G works just fine. Tom Marotta thinks so. He discussed the GRx with me on The Space Show recently. Marotta, with Al Globus coauthored The High Frontier: An Easier Way. The easier way is to start small in low Earth orbit. O’Neill colonies as originally conceived by Gerard K. O’Neill in The High Frontier would be kilometers long in high orbit (outside the Earth’s protective magnetic field) and weigh millions of tons because of the amount of shielding required to protect occupants from radiation. The sheer enormity of scale makes them extremely expensive and would likely bankrupt most governments, let alone be a challenge for private financing. Marotta and Globus suggest a step-by-step approach starting with a far smaller version of O’Neill’s concept called Kalpana. This rotating space city would be a cylinder roughly 100 meters in diameter and the same in length, spinning at 4 rpm to create 1G of artificial gravity and situated in equatorial low Earth orbit (ELEO) which is protected from radiation by our planet’s magnetic field. If located here the settlement does not require enormous amounts of shielding and would weigh (and therefore cost) far less. Kasper Kubica has proposed using this design for hosting $10M condominiums in space and suggests an ambitious plan for building it with 10 years. Although the move-in cost sounds expensive for the average person, recall that the airline industry started out catering to the ultra-rich to create the initial market which eventually became generally affordable once increasing reliability and economies of scale drove down manufacturing costs.
What about all the orbital debris we’re hearing about in LEO? Wouldn’t this pose a threat of collision with a free space settlement given their larger cross-sections? In an email Marotta responds:
“No, absolutely not, I don’t think orbital debris is a showstopper for Kalpana.
… First, the entire orbital debris problem is very fixable. I’m not concerned about it at all as it won’t take much to clean it up: implement a tax or a carbon-credit style bounty system and in a few years it will be fixed. Another potential historical analogy is the hole in the ozone layer: once the world agreed to limit CFCs the hole started healing itself. Orbital debris is a regulatory and political leadership problem, not a hard technical problem.
Second, even if orbital debris persists, the technology required to build Kalpana…will help protect it. Namely: insurance products to pay companies (e.g. Astroscale, D-Orbit, others) to ‘clear out’ the orbit K-1 will inhabit and/or mobile construction satellites necessary to move pieces of the hull into place can also be used to move large pieces of debris out of the way. In fact, I think having something like Kalpana…in orbit – or even plans for something that large – will actually accelerate the resolution of the orbital debris problem. History has shown that the only time the U.S. government takes orbital debris seriously is when a piece of debris might hit a crewed platform like the ISS. Having more crewed platforms + orbital debris will drastically limit launch opportunities via the launch collision avoidance process. If new satellites can’t be launched efficiently because of a proliferation of crewed stations and orbital debris I suspect the very well-funded and strategically important satellite industry will create a solution very quickly.”
To build a space settlement like the first Kalpana, about 17,000 tons of material will have to be lifted from Earth. Using the current SpaceX Starship payload specifications this would take 170 launches to LEO. By comparison, in 2021 the global launch industry set a record of 134 launches. Starship has not even made it to orbit yet, but assuming it eventually will and the reliability and reusability is demonstrated such that a fleet of them could support a high launch rate, within the next 20 years or so there will be considerable growth in the global launch industry. If larger versions of Kalpana are built the launch rate could approach 10,000 per year for space settlement alone, not to mention that needed for rest of the space industry. This raises the question of where will all these launches take place? Are there enough spaceports in the world to support it? Marotta has an answer for this as well. As CEO of The Spaceport Company, he is laying the groundwork for the global space launch infrastructure that will be needed to support a robust launch industry. His company is building distributed launch infrastructure on mobile offshore platforms. Visit his company website at the link above for more information.
Conceptual illustration of a mobile offshore launch platform. Credits: The Spaceport Company
For quite some time there has been a spirited debate among space settlement advocates on what destination makes the most sense to establish the first outpost and eventual permanent homes beyond Earth. The Moon, Mars or free space O’Neill settlements. Each location has its pros and cons. The Moon being close and having ice deposits in permanently shadowed craters at its poles along with resource rich regolith seems a logical place to start. Mars, although considerably further away has a thin atmosphere and richer resources for in situ utilization. Some believe we should pursue all the above. However, only O’Neill colonies offer 1G of artificial gravity 24/7. With so many unknowns about the gravity prescription for human health and reproduction, free space settlements like Kalpana offer a safe solution if the markets and funding can be found to make them a reality.
Conceptual illustration of a Moon base composed of inflatable habitats near one of the lunar poles. Credits: ESA / Pneumocell
The European Space Agency (ESA) recently published a report on a design study of an inflatable lunar habitat. The work was done by Austrian based Pneumocell in response to an ESA Open Space Innovation Platform campaign. The concept utilizes ultralight prefabricated structures that would be delivered to the desired location, inflated and then covered with regolith for radiation protection and thermal insulation. The main components of the habitat are toroidal greenhouses that are fed natural sunlight via a rotating mirror system that follow the sun. Since the dwellings are located at one of the lunar poles, horizontal illumination is available for most of the lunar night. Power is provided by photovoltaic arrays attached to the mirror assemblies. During short periods of darkness power is provided by batteries or fuel cells.
Cutaway view of the inflatable lunar habitat. Credits: ESA / Pneumocell
The detailed system study worked out engineering details of the most challenging elements including life support, power sources, temperature control, radiation protection and more. The greenhouses would provide sustenance and an environmentally controlled life support system for two inhabitants recycling everything. The authors claim that “…it appears possible to create in the long term a closed system…” This remains to be validated.
Inflatable space habitats have many advantages over rigid modules including lower weight, packaging efficiency, modularity and psychological benefit to the inhabitants because after deployment, the interior living space is much larger for a given mass. Several organizations and individuals have already begun to investigate inflatable habitats for lunar applications. The Pneumocell study mentions ESA’s Moon Village SOM-Architects concept which is a hybrid rigid and partly inflatable structure. Also referenced is the Foster’s and Partners Lunar Outpost design which envisions a 3D printed dome shaped shell formed over an inflatable enclosure.
Foster and Partners Lunar Outpost constructed from a hybrid of 3D printed modules and an inflatable structure. Credits: Foster and Partners
Illustration of a hybrid lunar inflatable structure. Credits: Rohith Dronadula
The Pneumocell report concludes: “A logical continuation of this study would be to build a prototype on Earth, which can be used to investigate various details of the suggested components … ” Such an approach would be relatively inexpensive and could inform the future design of flight hardware.
Speaking of ground based prototypes, The Space Development Network has been exploring inflatable structures for habitats on the Moon for some time. Doug Plata, president of the nonprofit organization working to advance space development hopes to display an inflatable version of his InstaBase concept at BocaChica, Texas when SpaceX attempts its first orbital launch of Starship, hopefully within the a year or so. When comparing his design to Pneumocell’s, Plata says in an email to SSP, “One difference is that we have the modules directly attached to each other and so avoid the mass of those connecting corridors.”
Conceptual illustration of InstaBase – a fully inflatable lunar base capable of supporting an initial crew of eight. Credits: The Space Development Network
In reference to the greenhouse designs, Plata continues: “As for the GreenHabs, they have a pretty interesting design to take advantage of direct sunlight. We address the shielding conceptually by fully covering the GreenHabs and then use PV solar drapes and transport the electricity into the GreenHabs via wires. By converting sunlight to electricity to LEDs, more surface area of plants can be grown than the surface area of the solar panels powering them. This is due to the full spectrum of the sun being converted to only those frequencies that plants use.”
It is great to see such creativity and variety of designs for abodes on the Moon. When reliable transportation systems such as Starship blaze the trail, we will be ready with easily deployable, safe and voluminous habitats for lunar settlements.
Artist rendering of the interior of an inflatable toroidal greenhouse in a lunar habitat. Credits: Pneumocell
Image credit: NASA/Goddard/Arizona State University
The Cislunar Science and Technology Subcommittee of the White House Office Science and Technology Policy Office (OSTP) recently issued a Request for Information to inform development of a national science and technology strategy on U.S. activities in cislunar space.
Dennis Wingo provided a response to question #1 of this RFI, namely what research and development should the U.S. government prioritize to help advance a robust, cooperative, and sustainable ecosystem in cislunar space in the next 10 to 50 years?
In a prolog to his response Wingo reminds us that historically, NASA’s mission has focused narrowly on science and technology. What is needed is a sense of purpose that will capture the imagination and support of the American people. In today’s world there seems to be more dystopian predictions of the future than positive visions for humanity. We seem to be dominated by fear of “…doom and gloom scenarios of the climate catastrophe, the degrowth movement, and many of the most negative aspects of our current societal trajectory.” This fear is manifested by what Wingo defines as a “geocentric” mindset focused primarily within the material limitations of the Earth and its environs.
“The question is, is there an alternative to change this narrative of gloom and doom?”
He recommends that policy makers foster a cognitive shift to a “solarcentric” worldview: the promise of an economic future of abundance through utilization of the virtually limitless resources of the Moon, Asteroids, and of the entire solar system. An example provided is to harvest the resources of the asteroid Psyche which holds a billion times the minable metal on Earth, and to which NASA had planned on launching an exploratory mission this year but had to delay it due to late delivery of the spacecraft’s flight software and testing equipment.
Artist rendering of NASA’s Psyche Mission spacecraft. Credits: NASA/JPL-Caltech/Arizona State Univ./Space Systems Loral/Peter Rubin
Back to the RFI, Wingo has four recommendations that will open up the solar system to economic development and address many of the problems that cause the geocentrists despair.
First, we should make the Artemis moon landings permanent outposts with year long stays as opposed to 6 day “camping trips”. This should be possible with resupply missions by SpaceX as they ramp up Starship launch rates (assuming the launch vehicle and lander are validated in the same timeframe, which seems reasonable). Next, we need power and lots of it – on the order of megawatts. This should be infrastructure put in place by the government to support commerce on the Moon. By leveraging existing electrical power standards and production techniques, large scale solar power facilities could be mass produced at low cost on Earth and shipped to the moon before the capability of in situ utilization of lunar resources is established. Some companies such as TransAstra already have preliminary designs for solar power facilities on the Moon.
Which brings us to ISRU. The next recommendation is to JUST DO IT. This technology is fairly straightforward and could be used to split oxygen from metal oxides abundant in lunar regolith to source air and steel. Pioneer Astronautics is already developing what they call Moon to Mars Oxygen and Steel Technology (MMOST) for just this application.
Conceptual illustration of the Lunar OXygen In-situ Experiment (LOXIE) Production Prototype. Credits: Mark Berggren / Pioneer Astronautics
And lets not forget the wealth of in situ resources that could be unlocked via synthetic geology made possible by Kevin Cannon’s Pinwheel Magma Reactor.
Conceptual depiction of the Pinwheel Magma Reactor on a planetary surface in the foreground and in free space on a tether as shown in the inset. Credits: Kevin Cannon
Of course there is water everywhere in the solar system just waiting to be harvested for fuel and life support in a water-based economy.
Illustration of an ice extraction concept for collection of water on the Moon. Credits: George Sowers / Colorado School of Mines
Wingo’s final recommendation is industrialization of the Moon in preparation for the settlement of Mars followed by the exploration of the vast resources of the Asteroid Belt. He makes it clear that this is more important than just a goal for NASA, which has historically focused on scientific objectives, and should therefore be a national initiative.
“…for the preservation and extension of our society and to preclude the global fight for our limited resources here.”
With the right vision afforded by this approach and strong leadership leading to its implementation, Wingo lays out a prediction of how the next fifty years could unfold. By 2030 over ten megawatts of power generation could be emplaced on the Moon which would enable propellant production from the pyrolysis of metal oxides and hydrogen production from lunar water. This capability allows refueling of Starship obviating the need to loft propellent from Earth and thereby lowering the costs of a human landing system to service lunar facilities. From there the cislunar economy would begin to skyrocket.
The 2040s see a sustainable 25% annual growth in the lunar economy with a burgeoning Aldrin Cycler business to support asteroid mining and over 1000 people living on the Moon.
By the 2050s, fusion reactors provide power and propulsion while the first Ceres settlement has been established providing minerals to support the Martian colonies.
“The sky is no longer the limit”
By sowing these first seeds of infrastructure a vibrant cislunar economy will enable sustainable settlement across the solar system. A solarcentric development mythology may be just what is needed to become a spacefaring civilization.
Artist’s concept of an O’Neill space colony. Credits: Rachel Silverman / Blue Origin
