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Biosphere X, Y and Z: The future of farming in space – guest post by Marshall Martin

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/MissionCost/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.
  • Oxygen production:  Greenfluidics[7] (algae farm subsystem)
  • Improved windows:  2DPA-1 polycarbonate[8]  vs. ISS windows[9]
  • Robots vs. manual labor.  (and better tools)
  • Soil vs. regolith vs. aeroponics vs. hydroponics vs. ??
  • Improved animal and plant selections

Cost of a Biosphere X compared with other ground-based facilities:

FacilityArea
(Acres)		Cost
(USD)
Biosphere 23.14$150M[12]
Regional Mall5.7$75M [13]
Walmart0.22$2.5M
Biosphere X1.0$10M 
Special building issues – SWAG: $20M

Biosphere X design options:

  • Crops: Wheat, Oats, Barley, Rye, Corn, Rice, Milo, Buckwheat, Potato, …
  • Animals: Fish, Goats, Chickens, Sheep, “Beyond Meat”, cultured meat …
  • Insects: Honeybees, edible Insects, Meal worms, Butterflies, …
  • 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

========

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.

References:

  1. B. Venditti, The Cost of Space Flight Before and After SpaceX, The Visual Capitalist, January 27, 2022
  2. M. Williams, How to make the food and water Mars-bound astronauts will need for their mission, , Phys.org, June 1, 2020, Paragraph 4
  3. Perseverance (Rover)/Cost, Wikipedia
  4. Perseverance (Rover) – Dry Mass, Wikipedia
  5. Biosphere 2, Wikipedia
  6. 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.
  7. L. Blain, Algae Biopanel Windows Make Power, Oxygen and Biomass, and Suck Up CO2, New Atlas, July 11, 2022
  8. A. Trafton, New Lightweight Material is Stronger than Steel, MIT News, February 2, 2022
  9. Cupola (ISS module) -Specifications, Wikipedia
  10. Biosphere 2 (Planning and Construction), Wikipedia
  11. How much does it cost to develop a shopping mall?, Fixr, October 13, 2022
  12. J. Jossy, The Space Show with Dr. David Livingston, Broadcast 4061, July 25, 2023
  13. J. Jossy, The Impact of the Gravity Prescription on the Future of Space Settlement, Space Settlement Progress, March 29, 2024; J. Jossy and T. Marotta, The Space Show with Dr. David Livingston, Broadcast 3852, April 5, 2022
  14. Atmosphere of Venus (Structure and Composition), Wikipedia, “…total nitrogen content is roughly four times higher than Earth’s…”
  15. KREEP, Wikipedia
  16. Habitable zone (i.e. “Goldilocks Zone”), Wikipedia, Picture/graph, Top-right.
  17. Gerald R. Ford-class aircraft carrier (Design features, displacement), Wikipedia
  18. 16 Psyche (Mass and bulk density), Wikipedia – Note: the mass of all main asteroids are available on Wikipedia
  19. D. M. Scott, The Religious Origins of Manifest Destiny, Divining America, TeacherServe©. National Humanities Center, 2024
  20. Bible: Genesis 1:28 (Adam & Eve), Genesis 9:1 (Noah), Genesis 35:11 (Jacob), and generally repeated elsewhere in the book.
  21. B. Wang, Mass Production Rate of SpaceX Starship Costs, May 28, 2020

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The desert moss that could help terraform Mars

AI generated image of Mars in the process of being terraformed. Credit: Image Creator

Mars is currently not very hospitable to life, although it may have been billions of years ago. Many Mars settlement advocates and science fiction writers dream of the turning the Red Planet green by terraforming its atmosphere to make it more Earth-like. Even partially changing smaller regions, i.e. para-terraforming, would be a good first step.

To get things started it would be helpful if there were organisms that could survive the frigid temperatures, low ambient pressure and harsh radiation on Mars while helping to boost the oxygen levels in the atmosphere and assisting with soil fertility. Fortunately, there is a desert moss called Syntrichia caninervis that fits the bill. In a report in the journal The Innovation a team* of Chinese researchers present results of a study that demonstrate the extremotolerance of this plant to conditions on the Red Planet. This hardy organism can withstand temperatures down to a frosty -197°C, has extreme desiccation tolerance recovering within seconds after losing 97% of its water content and is super resistant to gamma radiation.

S. canivervis is a pioneering organism that has wide distribution in extreme biomes on Earth, from the Gurbantunggut Desert in China to the Mojave Desert in the California . It plays a key role in development of biological soil crust, a type of widespread ground cover which is the precursor of fertile soil. A major source of carbon and nitrogen in arid regions, these so called “living skins of the Earth” are responsible for a quarter of the total nitrogen fixation of terrestrial ecosystems. As stated in the paper, this resilient moss “…has evolved several morphological mechanisms to adapt to extreme environments, including overlapping leaves that conserve water and shield the plant from intense sunlight and white awns at the tops of leaves that reflect strong solar radiation and enhance water utilization efficiency.”

To test the desiccation tolerance of S. caninervis the researchers subjected the organism to air-drying treatment followed by measurements of plant phenotypes, water content, photochemical efficiency and changes in leaf angle. The mosses exhibited an exceptional ability to recover rapidly after being dehydrated. Incredibly, the plants were observed to be green when hydrated, turned black as water was gradually extracted, then returned to green only after 2 seconds upon rehydration.

Extended low temperature tolerance was tested by placing two samples of the plants in a freezer set at -80o C for 3 and 5 years, respectively. Short duration extreme cold was studied by subjecting the samples to -196o C in a liquid nitrogen tank for 15 and 30 days. The plants were then cultivated normally to determine their ability to regenerate. Remarkably, in the 3 and 5 year long duration freezer cohorts, both sample branch regeneration rates recovered to approximately 90% of that observed in the control group after 30 days of growth. Similar results were noted for the plants subjected to the 15 and 30 day -196o C treatment with 95% regeneration rate when compared to the controls.

For radiation resistance, samples of S. caninervis were subjected to gradually increasing levels of gamma radiation from 500 Gy up to 16000 Gy. At the upper end of the range the plants died. However, the organism survived exposures up to 2000 Gy with regeneration of branches slightly delayed when compared to controls with no radiation exposure (most plants can’t tolerate more than 1000Gy). A surprising result was noted when exposure to 500 Gy actually increased the regeneration of branches vs no exposure. Humans are sickened by exposure to 2.5 Gy and die upon exposure to 50 Gy. These results demonstrate that S. caninervis has exceptional radiation tolerance.

Finally, simulated Mars conditions were tested by placing S. caninervis in an environmental chamber called the Planetary Atmospheres Simulation Facility operated by the Chinese Academy of Sciences. Parameters were set in the chamber to mimic Mars conditions in mid-latitude regions with temperatures dipping down to −60oC at night and rising to +20oC during the day; atmospheric pressure pegged at 650 Pascals ( 0.09 PSI); Martian atmospheric gasses set to match Martian conditions ( 95% CO2, 3% N2, 1.5% Ar, 0.5% O2); and the expected ultraviolet radiation flux tuned across the UVA, UVB, and UVC wavelength bands. The treatments were applied for 1, 2, 3, and 7 days and then regeneration of branches was measured and compared to control samples. The results showed that S. caninervis can survive in a simulated Mars environment regenerating branches after 15 days of recovery. This hardy moss, having evolved to colonize extremely dry, cold environments on Earth make it ideally suited as a pioneer species to start the process of greening Mars, helping to establish an ecosystem through oxygen production, carbon sequestration, and generation of fertile soil.

Graphical illustration depicting extremotolerant properties of the moss Syntrichia caninervis showing superior desiccation and freezing tolerance, radiation resistance and pioneering benefits for terraforming Mars (slight modifications made to text of Public Summary). Credits: Xiaoshuang Li et al., under creative commons license CC BY-NC-ND 4.0

Of course terraforming Mars may take many years, perhaps centuries. In the near term, an ancient farming method called intercropping could help boost the yields of vegetables grown on Mars to sustain a healthy settler’s diet. The technique coordinates the cultivation of two or more crops simultaneously in close proximity. In a research article in PLOS ONE scientists at the Wageningen University & Research in the Netherlands describe the method of soil based food production using Martian regolith simulate. The researchers acknowledge that some processing of Martian regolith will be required to remove toxic components such as perchlorates. Research on these techniques is already underway. The study found that intercropping “…shows promise as a method for optimizing food production in Martian colonies.”

* Authors of the Report The extremotolerant desert moss Syntrichia caninervis is a promising pioneer plant for colonizing extraterrestrial environments:

Xiaoshuang Li 1, Wenwan Bai 1 2, Qilin Yang 1 2, Benfeng Yin 1, Zhenlong Zhang 3, Banchi Zhao 3, Tingyun Kuang 4, Yuanming Zhang 1, aoyuan Zhang 1
1 – State Key Laboratory of Desert and Oasis Ecology, Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
2 – University of Chinese Academy of Sciences, Beijing 100049, China
3 – National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
4 – Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

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Proposal for an International Lunar Resource Prospecting Campaign

Artist’s depiction of the NASA Volatiles Investigating Polar Exploration Rover (VIPER) locating and assessing the concentration of ice and other resources near the Moon’s South Pole. Credits: NASA / Daniel Rutter

NASA and space settlement advocates are justifiably excited about resources on the Moon, especially water ice known to be present in permanently shadowed regions (PSR) at the lunar poles, because of it’s potential as a source of oxygen and fuel that could be sourced in situ saving the costs of transporting these valuable commodities from Earth.  But how much ice is actually available, accessible and can be processed into useable commodities?  In other words, in terms defined by the U.S. Geological survey, what are the proven reserves?  A reserve is a subset of a resource that can be economically and legally extracted. 

By way of background, under NASA’s Moon to Mars (M2M) Architecture where the agency is defining a roadmap for return to the Moon and then on to the Red Planet, an Architecture Definition Document (ADD) with the aim of creating an interoperable global lunar utilization infrastructure was released last year.  The goals articulated in the document are to enable the U.S. industry and international partners to maintain continuous robotic and human presence on the lunar surface for a robust lunar economy without NASA as the sole user, while accomplishing science objectives and testing technology that will be needed for operations on Mars. 

Of the nine Lunar Infrastructure (LI) goals in the ADD, LI-7 addresses the need to demonstrate in situ resource utilization (ISRU) through delivery of an experiment to the lunar South Pole, the objective of which would be demonstrating industrial scale ISRU capabilities in support of a continuous human lunar presence and a robust lunar economy.  LI-8 aims to demonstrate a) the capability to transfer propellant from one spacecraft to another in space; b) the capability to store propellant for extended durations in space and c) the capability to store propellant on the lunar surface for extended durations – defining the objective to validate technologies supporting cislunar orbital/surface depots, construction and manufacturing maximizing the use of in-situ resources, and support systems needed for continuous human/robotic presence.

To accomplish these goals NASA initiated a series of Lunar Surface Science Workshops starting in 2020.  The results of workshops 17 and 18  held in 2022 were summarized last January in a paper by Neal et al. in Acta Astronautica and discussed recently at a Future In-Space Operations (FISO) Telecon on 2/14/2024 in a presentation by Lunar Surface Innovation Consortium (LSIC) members Karl Hibbitts, Michael Nord, Jodi Berdis and Michael Miller.  These efforts identified a conundrum: there is not enough data to establish how much proven reserves of lunar water ice are available to inform economically viable plans for ISRU on the Moon.  Thus, a resource prospecting campaign is needed to address this problem.  International cooperation on such an initiative, perhaps in the context of the Artemis Accords, makes sense to share costs while enabling the signatories of the Accords (39 as of this post) to realize economic benefits from commerce in a developing cislunar economy.

The campaign concept proposes a 3-tiered approach. First, confirming ice is present in the PSRs near potential Artemis landing sites – this could be done by low altitude orbital reconnaissance using neutron spectroscopy, radar and other techniques. Next, surface rovers already on the drawing board such as the Volatiles Investigating Polar Exploration Rover (VIPER), would be deployed to locate specific reserves.

Finally, detailed characterization of the reserve using rovers leveraging capabilities learned from VIPER and optimized for reconnaissance in the PSRs. Some technological improvements would be needed in this final phase to address power and long duration roving under the expected extreme conditions. Nuclear power sources and wireless power beaming from solar arrays on the crater rims, both requiring further development, could solve these challenges. This technology will be directly transferrable to equipment needed for excavation, which will face the same power and reliability hurdles in the ultra cold darkness of the PSRs.

As mentioned in the FISO presentation and pointed out by Kevin Cannon in a previous post by SSP, how water ice is distributed in lunar regolith “endmembers” is a big unknown and could be quite varied.  Characterization during this last phase is paramount before equipment can be designed and optimized for economic extraction.

Artist’s impression of different types of lunar water ice / regolith endmembers, characterization of which will be required before extraction methods and equipment can be validated. Credits: Lena Jakaite / strike-dip.com / Colorado School of Mines

The authors of the paper acknowledge that coordinating an international effort will be difficult but involving all stakeholders will foster cooperation and shape positive legal policy within the framework of the Artemis Accords to comply with the Outer Space Treaty.  

From the conclusion of the paper:

“If the reserve potential is proven, the benefits to society on Earth would be immense, initially realized through job growth in new space industries, but new technologies developed for sending humans offworld and commodities made from lunar resources could have untold important benefits for society back here.”

George Sowers, whose research was referenced in the paper and covered by SSP, believes that “Water truly is the oil of space” that will kickstart a cislunar economy.  Once reserves of lunar water ice are proven to exist through a prospecting campaign and infrastructure is placed to enable economically feasible mining and processing for use as rocket fuel and oxygen for life support systems, technology improvements and automation will reduce costs.    If it can be made competitive with supply chains from Earth lunar water will be the liquid gold that opens the high frontier.

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The impact of the Gravity Prescription on the future of space settlement

Artist rendering of a family living in a rotating free-space settlement based on the Kalpana Two design, with a length of 110m and diameter of 125m. Credits: Bryan Versteeg / Spacehabs.com

This post summarizes my upcoming talk for the Living in Space Track at ISDC 2024 taking place in Los Angeles May 23 – 26. The presentation is a distillation of several posts on the Gravity Prescription about which I’ve written over the years.

Lets start with a couple of basic definitions. First, what exactly is a space settlement? The National Space Society defined the term with much detail in an explainer by Dale L. Skran back in 2019. I’ve extracted this excerpt with bolded emphasis added:

Space Settlement is defined as: ​

​“… a habitation in space or on a celestial body where families live on a permanent basis, and that engages in commercial activity which enables the settlement to grow over time, with the goal of becoming economically and biologically self-sustaining …”

​The point here is that people will want to have children wherever their families put down roots in space communities. Yes, a “settlement” could be permanent and perhaps inhabited by adults that live out the rest of there lives there, such as in a retirement community. But these are not biologically self-sustaining in the sense that settlers have offspring that are conceived, born and raised there living out healthy lives over multiple generations.

Next we should explain what is meant by the Gravity Prescription (GRx). First coined by Dr. Jim Logan, the term refers to the minimum “dosing” of gravity (level and duration of exposure) to enable healthy conception, gestation, birth and normal, viable development to adulthood as a human being…over multiple generations. It should be noted that the GRx can be broken down into at least three components: the levels needed for pregnancy (conception through birth), early child development, and adulthood. The focus of this discussion is primarily on the GRx for reproduction.

We should also posit some basic assumptions. First, with the exception of the GRx, all challenges expected for establishment of deep space settlements can be solved with engineering solutions (e.g. radiation protection, life support, power generation, etc…)​. The one factor that cannot be easily changed impacting human physiology after millions of year of evolution on Earth is gravity. We may find it difficult or even impossible to stay “healthy enough” under hypogravity conditions on the Moon or Mars, assuming all other human factors are dealt with in habitat design.

Lets dive into what we know and don’t know about the GRx. Several decades of human spaceflight have produced an abundance of data on the deleterious effects of microgravity on human physiology, not the least of which are serious reduction in bone and muscle mass, ocular changes, and weakening of the immune system – there are many more. So we know microgravity is not good for human health after long stays. Clearly, having babies under these conditions would not be ethical or conducive for long term settlement.

The first studies carried out on mammalian reproduction in microgravity took place in the early 1990s aboard the Space Shuttle in a couple of experiments on STS-66 and STS-70. 10 pregnant rats were launched at midpregnancy (9 days and 11 days, respectively) on each flight and landed close to the (22 day) term. The rat pups were born 2 days after landing and histology of their brain tissue found spaceflight induced abnormalities in brain development in 70% of the offspring.

It was not until 2017 that the first mammalian study of rodents with artificial gravity was performed on the ISS. Although not focused on reproduction, the Japan Aerospace Exploration Agency (JAXA) performed a mouse experiment in their Multiple Artificial-gravity Research System (MARS) centrifuge comparing the impact of microgravity to 1g of spin gravity. ​The results provided the first experimental evidence that mice exposed to 1g of artificial gravity maintained the same bone density and muscle weight as mice in a ground control group while those in microgravity had significant reductions.

Diagram depicting an overview of the first JAXA Mouse Project in the MARS centrifuge with photos of the experiment on the ISS. Credits: Dai Shiba et al. / Nature. http://creativecommons.org/licenses/by/4.0/

In 2019 JAXA carried out a similar study in the MARS centrifuge adding lunar gravity levels to the mix. This study found that there were some benefits to the mice exposed to 1/6g in that Moon gravity helped mitigate muscle atrophy, but it did not prevent changes in muscle fiber or gene expression​.

Just last year, a team led by Dr. Mary Bouxsein at Harvard Medical School conducted another adult mouse study on the MARS centrifuge comparing microgravity, .33g, .67g and 1g. They found that hind quarter muscle strength increased commensurate with the level artificial gravity concluding, not surprisingly, that spaceflight induced atrophy can be mitigated with centrifucation. The results were reported at the American Society for Gravitational and Space Research last November.​

Returning to mammalian reproduction in space, an interesting result was reported last year in the journal Cell from an experiment by Japanese scientists at the University of Yamanashi carried out on the ISS in 2019. The team, headed up by Teruhiko Wakayama, devised a way to freeze mouse embryos post conception and launch them into space where they were thawed by astronauts and allowed to develop in microgravity. Control samples were cultured in 1g artificial gravity on the ISS and Earth normal gravity on the ground. The mouse embryos developed into blastocysts and showed evidence of cell differentiation/gene expression in microgravity after 4 days​. The researchers claimed that the results indicated that “Mammals can thrive in space”. This conclusion really can’t be substantiated without further research.

Which brings us to several unknowns about reproduction in space. SSP has explored this topic in depth through an interview with Alex Layendecker, Director of the Astrosexological Research Institute. Yet to be studied in depth is (a) conception, including proper transport of a zygote through the fallopian tube to implantation in the uterus. Less gravity may increase the likelihood of ectopic pregnancy which is fatal for the fetus and could endanger the life of the mother; (b) full gestation through all stages of embryo development to birth​; and (c) early child development and maturation to adulthood in hypogravity​. All these stages of mammalian reproduction need to be validated through ethical clinical studies on rodents progressing to higher primate animal models before humans can know if having children in lower gravity conditions on the Moon or Mars will be healthy and sustainable over multiple generations.

AI generated image of an expectant mother with her developing fetus in Earth orbit after mammalian reproduction has been validated via higher animal models through all stages of pregnancy for a safe level of gravity. An appropriate level of radiation shielding would also be required and is not shown in this illustration. Credit: DALL-E-3

Some space advocates for communities on the Moon or Mars have downplayed the importance of determining the GRx for reproduction with the logic that a fetus in a woman’s uterus on Earth is in neutral buoyancy and thus is essentially weightless. Therefore, why does gravity matter? ​ I discussed this question with Dr. Layendecker and he had the following observations paraphrased here: True, gravity may have less of an impact in the first trimester. But on the cellular level, cytoskeletal development and proper formation/organization of cells may be impacted from conception to birth​. Gravity helps orient the baby for delivery in the last trimester​ and keeps the mother’s uterine muscles strong for contractions/movement of the baby through the birth canal​. There are many unknowns on what level of gravity is sufficient for normal development from conception to adulthood.

Why does all this matter? Ethically determining the right level of gravity for healthy reproduction and child development will inform where families can safely settle space​. The available surface gravities of bodies where we can establish communities in space cluster near Earth, Mars and Moon levels​. These are our only GRx options ​on solar system bodies.

Gravity level clustering of solar system bodies available for space settlement. Credit: Joe Carroll

The problem is that we don’t yet know whether we can remain healthy enough on bodies with gravity equivalent to that on the Moon or Mars, so we can’t select realistic human destinations or formulate detailed plans until we acquire this knowledge​. Of course we can always build rotating settlements in free space with artificial gravity equivalent to that on Earth. Understanding the importance of the GRx and determining its value could change the strategy of space development in terms of both engineering and policy decisions. The longer we delay, the higher the opportunity costs in terms of lost time from failure to act​.

What are these opportunity cost lost opportunities​? Clearly, at the top of Elon Musk’s list is “Plan B” for humanity, i.e. a second home in case of cataclysmic disaster such as climate change, nuclear war, etc. This drives his sense of urgency. From Gerard K. O’Neill’s vision in The High Frontier, virtually unlimited resources in space could end hunger and poverty, provide high quality living space for rapidly growing populations​, achieve population control without war, famine, or dictatorships​. And finally, increase freedom and the range of options for all people​.

If humans can’t have babies in less than Earth’s gravity then the Moon and Mars may be a bust for long term (biologically sustainable) space settlement.​ There will be no biologically sustainable cities with millions of people on other worlds unless they can raise families there​.

Spin gravity rotating space settlements providing 1g artificial gravity may be the only alternative​. If Elon Musk knew that the people he wants to send to Mars can’t have children there, would he change his plans for a self-sustaining colony on that planet?​ Having and raising children is obviously important to him. As Walter Isaacson wrote in his recent biography of Musk, “He feared that declining birthrates were a threat to the long-term survival of human consciousness.”

So how could he determine the GRx quickly? One solution would be to fund a partial gravity facility in low Earth orbit to run ethical experiments on mammalian reproduction in hypogravity. Joe Carroll has been refining a proposal for such a facility, a dual dumbbell Moon/Mars low gravity laboratory which SSP has covered, that could also be marketed as a tourist destination. Spinning at 1.5 rpm, the station would be constructed from a combination of Starship payload-sized habitats tethered by airbeams allowing shirt sleeve access to different gravity levels​. Visitors would be ferried to the facility in Dragon capsules and could experience 3 gravity levels with various tourist attractions​. The concept would be faster, cheaper, safer and better than establishing equivalent bases on the Moon or Mars to quickly learn about the GRx​. The facility would be tended by crews at both ends that live & collect health data for up to a year or more​. And of course, ethical experiments on the GRx for mammalian reproduction would be carried out, first on rodents and then progressing to higher primates if successful.

Left: Conceptual illustration depicting a LEO Moon-Mars dumbbell partial gravity facility constructed from Starship payload-sized habitats tethered by airbeams and serviced by Dragon capsules. Rectangular solar arrays deploy by hanging at either end as spin is initiated via thrusters at Mars module. Center: Image of an inflated airbeam demonstration. Right: diagram of an airbeam stowed for transport and after deployment. Credit: Joe Carroll

What if these experiments determine that having children in lower gravity is not possible and our only path forward are free-space rotating settlements? Physics and human physiology require that they be large enough for settlers to tolerate a 1g spin rate to prevent disorientation. As originally envisioned by O’Neill, the diameter of his Island One space settlement would be about 500 meters.

Conceptual illustration of an Island One space settlement. The living space sphere is sized at about 500m in diameter. Credits: Rick Guidice / NASA

As originally proposed, these settlements would be located outside the Earth’s magnetic field at the L5 Earth-Moon Lagrange Point necessitating that they be shielded with enormous amounts of lunar regolith to protect occupants from radiation. Their construction requires significant technology development and infrastructure (e.g. mass drivers on the Moon, automated assembly in space, advances in robotics, power sources, etc…)​. Much of this will eventually be done anyway as space development progresses…however, knowing the GRx (if it is equal to 1g) may foster a sense of urgency​.

Some may take the alternative viewpoint that if we know that Earth’s gravity works just fine we could proceed directly to free-space settlements if we could overcome the mass problem. This is the approach Al Globus and Tom Marotta took in their book The High Frontier: An Easier Way with Kalpana One​, a 450m diameter cylindrical rotating free-space settlement located in equatorial low Earth orbit (ELEO) protected by our planet’s magnetic field, thereby reducing the mass significantly because there would be far less need for heavy radiation shielding.

Artist impression of Kalpana One rotating free-space settlement located in equatorial low Earth orbit. Credits: Bryan Versteeg / Spacehabs.com

But there may be an even easier way. Kasper Kubica has proposed a 10 year roadmap to the $10M condo in ELEO based on Kalpana Two, a scaled down version of the orbital settlement described by Al Globus in a 2017 Space Review article.

Artist rendering of the inside of a rotating free-space settlement based on the Kalpana Two design, with a length of 110m and diameter of 125m. Credits: Bryan Versteeg / Spacehabs.com

Even though these communities would be lower mass, they will still require significant increases in launch rates to place the needed materials in LEO, especially near the equator​. Offshore spaceports, like those under development by The Spaceport Company, could play a significant role​ in this infrastructure. Legislation providing financial incentives to municipalities to build spaceports would be helpful, such as The Secure U.S. Leadership in Space Act of 2024 introduced in Congress last month. The new law (not yet taken up in the Senate) would amend the IRS Code to allow spaceports to issue tax-exempt Muni bonds for infrastructure improvements.

Wouldn’t orbital debris present a hazard for settlements in ELEO?​ Definitely yes, and the National Space Society is shaping policy in this area. The best approach is to emphasize “light touch” regulatory reform on salvage rights, with protection and indemnity of the space industry to encourage recycling and debris removal.​ Joe Carroll has suggested a market-based approach that would impose parking fees for high value orbits, which would fund a bounty system for debris removal. This system would incentivize companies like CisLunar Industries, Neumann Space and Benchmark Space Systems, firms that are developing space-based processes to recycle orbital debris into useful commodities such as fuel and structural components.

Further down the road in technology development and deeper into space, advances in artificial intelligence and robotics will enable autonomous conversion of asteroids into rotating space settlements, as described by David Jensen in a paper uploaded to arXiv last year.​ This approach significantly reduces launch costs by leveraging in situ resource utilization. Initially, small numbers of “seed” tool maker robots are launched to a target asteroid​ along with supplemental “vitamins” of components like microprocessors that cannot be easily fabricated until technology progresses, to complete the machines. These robotic replicators use asteroid materials to make copies of themselves and other structural materials eventually building out a rotating space settlement. As the technology improves, the machines eventually become fully self-replicating, no longer requiring supplemental shipments from Earth.

Artist impression of a rotating space settlement constructed from asteroid materials. Credits: Bryan Versteeg, spacehabs.com

Leveraging AI to enable robots to build space settlements removes humans from the loop initially, eliminating risk to their health from exposure to radiation and microgravity​. Send it the robot home builders – families then safely move in later. There are virtually unlimited supplies in the asteroid belt to provide feedstock to construct thousands of such communities.

Artist impression of the interior of Stanford Torus free-space settlement. Advances in artificial intelligence and robotics will enable autonomous self replicating machines that could build thousands of such communities from asteroid material. Credits: Don Davis / NASA

If rotating space settlements with Earth-normal gravity become the preferred choice for off-Earth communities, where would be the best location, the prime real estate of the solar system? Jim Logan has identified the perfect place with his Essential Seven Settlement Criteria.

  • Low Delta-V​ – enabling easy access with a minimum of energy
  • Lots of RESOURCES​ … obviously!
  • Little or No GRAVITY WELL​ – half way to anywhere in the solar system
  • At or Near Earth Normal GRAVITY for​
    People, Plants and Animals ​- like what evolved on Earth
  • Natural Passive 24/7 RADIATION Protection​ – for healthy living
  • Permit Large Redundant Ecosystem(s)​ – for sustenance and life support
  • Staging Area for Exploration and Expansion​
    (including frequent, recurrent launch windows)​

Using this criteria, Logan identified Deimos, the outermost moon of Mars, as the ideal location. As discussed above, AI and robotic mining technology improvements will enable autonomous boring machines to drill a 15km long core through this body with a diameter around 500 meters – sized for an Island One space settlement to fit perfectly.

Conceptual illustration of a 500 meter wide by 15km long core bored through Deimos. Credit: Jim Logan

In fact, 11 Island One space colonies (minus the mirrors) strung end to end through this tunnel would provide sea level radiation protection and Earth normal artificial gravity for thousands of healthy settlers.

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

In conclusion, the GRx for reproduction will inform where biologically self-sustaining healthy communities can be established in space. If we find that the GRx is equal to Earth’s normal level, free-space settlements with artificial gravity will be the safest and healthiness solution for humans to live and thrive throughout the solar system. The sooner we determined the GRx the better, for current plans for settling the Moon or Mars may need to be altered to consider rotating space colonies, which will require significant infrastructure development and regulatory reform​. Alternatively, since we know Earth’s gravity works just fine, we may choose to skip determination of the GRx and start small with Kalpana in low Earth orbit. Eventually, artificial intelligence will enable safe, autonomous self-assembly of space settlements from asteroids. The interior of Deimos would be the perfect place to build safe, healthy, biologically self-sustaining space settlements for thousands of families to raise their children, establishing a beachhead from which to explore the rest of the solar system and preserve the light of human consciousness.

Update June 3, 2024: Here is a recording of my presentation on this topic at ISDC 2024.

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Economic benefits from space mining

A fictional depiction of an ore ship servicing mining operations on an asteroid. Credits: DALL∙E 3

The clean energy transition away from fossil fuels promoted by the Biden Administration and other world governments will require significant increases in mining of critical materials for clean energy technology. To support the huge projected growth in solar, wind, and battery technologies over the next few decades, demand for key minerals such as lithium, graphite, nickel and rare-earth metals will balloon significantly according a 2021 report by the International Energy Agency: The Role of Critical Minerals in Clean Energy Transitions. When compared to current supply levels, sourcing of these materials will need to grow by several hundred percent, with lithium in particular predicted to explode by 4,200% to keep pace with the needed battery production for EVs and other energy storage systems. There is insufficient mining capability in the world today to meet this demand, and if capacity were ramped up to these levels, there would be serious environmental and economic consequences. If we ignore other promising alternatives (which SSP does not advocate) such as ramping up licensing of new nuclear fission power plants and funding development of fusion energy or space solar power, what can be done?

In the journal PNAS, a research article makes the case for why mining in space may be a viable solution and help lay the foundation for sustainable growth on Earth. The author’s* objective for the paper was to perform a trade study on the economic outcomes associated with the environmental and social impacts of terrestrial mining compared to the costs of sourcing from asteroids, focusing primarily on metals required for the clean energy technologies such as copper, nickel cobalt and lithium. The methodology of the paper used a neoclassical Ramsey economic model to predict economic growth under those two scenarios. The study quantifies the economic benefits and projected timelines of mining in space for increasing metal use in clean technologies on Earth for the rest of this century and concludes that the reduction in costs due to environmental damage to our planet’s biosphere may be worth the investment in asteroid mining.

Along similar lines another economic analysis by Matthew Weinzierl makes the potential case for an expanding space economy as a solution to secular stagnation, that condition that some economists fear is happening in the US: a chronic lack of demand as if the economy is operating below capacity even when it appears to be booming. Weinzierl says “In simple terms, secular stagnation is the idea that a sluggish outlook for the economy causes people to save more and firms to invest less, and if interest rates cannot fall enough to spur investment (perhaps because of the sluggish outlook), the lack of investment makes the low-growth prospects all the more likely to be fulfilled, initiating a vicious cycle.” How could space development help prevent this problem? Space settlement, i.e. world building, would unlock abundant resources in the solar system to sustain not only capital investment in expanding economic activity, but robust population growth without limits.

An interesting perspective on off-Earth mining as a commercial engine driving a space economy, with a focus on a thriving Martian colony, was proposed a few years ago in a paper by Robert Shishko and others. The study examined the role of space mining in an economy based on mineral extraction, ice/water, and other resources obtained in situ on the Red Planet. The analysis provided a better understanding of the market conditions and technology requirements for that economy to grow and prosper. This approach would definitely benefit from the recent discovery of massive amounts of subsurface water ice under the Medusae Fossae Formation near the equator of Mars.

Mars Express radar image of subsurface water ice beneath the Medusae Fossae Formation near the equator of Mars. Credits: ESA

If an economic case can be made for space mining and funding secured, it will be dependent on the location of the most profitable and accessible space resources in terms of energy and abundance of useful material. Where will this motherlode for space mining be? SSP has covered this debate.

One of the companies on this frontier is UK based Asteroid Mining Corporation which has the goal of becoming the first profitable space resources business. The startup is working on an autonomous robotic platform call Space Capable Asteroid Robot Explorer with a roadmap that plans for revenue payout at each milestone with eventual return of asteroid resources in the mid-2030s.

Asteroid Mining Corporation’s Space Capable Asteroid Robotic Explorer. Credits: Asteroid Mining Corporation.

And of course readers of SSP are familiar with AstroForge, the company focusing on returning precious metals to Earth from asteroids.

Upon full maturation of AI and space-based robotics technology, it will be possible to autonomously restructure an asteroid to construct spin gravity space settlements using materials in situ.

Artist impression of a rotating space settlement under construction using material from an asteroid. Credits: Bryan Versteeg, spacehabs.com

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* Authors of research article in PMAS Mining in Space Could Spur Sustainable Growth: Maxwell Fleming, Ian Lange, and Sayeh Shojaeinia of the Colorado School of Mines; Martin Stuermer of the International Monetary Fund.

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Curriculum for Astrochemical Engineering

An engineer pondering chemical processes for use in space learned in an advanced postgraduate course in Astrochemical Engineering. Credits: DALL∙E 3

In a paper in the journal Sustainability a global team of researchers has created a two year curriculum to train the next generation of engineers who will design the chemical processes for the new industrial revolution expected to unfold on the high frontier in the next few decades.

Current chemical engineering (ChE) training is not adequate to prepare the next generation of leaders who will guide humanity through the utilization of material resources in space as we expand out into the solar system.

Astrochemical Engineering is a potential new field of study that will adapt ChE to extraterrestrial environments for in situ resource utilization (ISRU) on the Moon, Mars and in the Asteroid Belt, as well as for in-space operations. The body of knowledge suggested in this paper, culminating in Master of Science degree, will provide training to inform the design ISRU equipment, life support systems, the recycling of wastes, and chemical processes adapted for the unique environments of microgravity and space radiation, all under extreme mass and power constraints.

The first year of the program focuses on theory and fundamentals with a core module teaching the physical science of celestial bodies of the solar system, low gravity processes, cryochemistry (extremely low temperature chemistry), and of particular interest, circular systems as applied to environmental control and life support systems (ECLSS) to recycle materials as much as possible. Students have the option to specialize in either process engineering or a more general concentration in space science.

For the process engineering option in year one, students will learn how materials and fluids behave in the extreme cold of space. This will include the types of equipment needed for processes in a vacuum environment including microreactors and heat exchangers, as well as methods for separation and mixing of raw materials.

In the space science specialization, year one will include production of energy and its utilization in space. Applications include solar energy capture and conversion to electricity, nuclear fission/fusion energy, artificial photosynthesis, and the role of energy in life support systems.

In the second year, students learn basic chemical processes for ISRU on other worlds. Processes such as electrolysis for cracking hydrogen and oxygen from water; and the reactions Sabatier, Fischer-Tropsch and Haber-Bosche for production of useful materials.

The second year process engineering specialization focuses on ISRU on the Moon with ice mining, processing regolith and fluid transport under vacuum conditions. Propulsion systems are also covered including methane/oxygen engines, hydrogen logistics, cryogenic propellent handling in space and both nuclear thermal and electric propulsion. Space science specialization in year two covers life support systems and space agriculture.

A design project is required at the end of each year to demonstrate comprehension of the concepts learned in the curriculum, and is split between an individual report and a group project.

Coupled with synthetic geology for unlocking a treasure trove of space materials in the Periodic Table, innovative equipment for ISRU on the drawing board and research on ECLSS, Astrochemical Engineering will be a valuable skill set for the next generation of pioneers at the dawn of the age of space resource utilization.

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Progress on mammalian reproduction in microgravity

AI generated image of an expectant mother with her developing fetus in Earth orbit after mammalian reproduction has been validated via higher animal models through all stages of pregnancy for a safe level of gravity. An appropriate level of radiation shielding would also be required and is not shown in this illustration. Credits:DALL∙E 3

We are one step closer to determining the gravity prescription for human reproduction in space. Okay, so we still don’t have the green light for having children at destinations in space with less than normal Earth gravity or higher radiation environments….yet. But a team of Japanese scientists report positive results after running an experiment aboard the International Space Station in 2019 that examined mouse embryos cultured in both microgravity and artificial gravity in space, then compared them to controls on Earth after a few days of development. The researchers published their results in a paper in iScience.

The researchers developed equipment and a protocol for freezing two-cell embryos after fertilization on the ground and launching them to the ISS where they were thawed then split into two groups, one allocated to growth in microgravity, the other treated with spin gravity to artificially simulate 1g. A control group remained on Earth. The procedure was designed to be executed by untrained astronauts. Cultured growth continued for 4 days after which the samples were preserved and refridgerated until they could be returned to Earth for analysis.

The samples were also monitored for radiation with a dosimeter and as expected aboard the ISS, were exposed to radiation levels higher then developing fetuses experience on the ground but far lower than those known to exist in deep space outside the Earth’s atmosphere and protective magnetic field. Still, this can be a “worst case” data point for radiation exposure to developing embryos as it is unlikely that pregnancy would be ethically sanctioned at higher levels.

Upon thawing by astronauts, the embryos were cultured through initial mitosis to eventual cell differentiation and blastocyst formation. A blastocyst is the multicellular structure of early embryonic development consisting of an an outer layer of cells called the trophectoderm surrounding a fluid-filled cavity in which an inner cell mass (ICM) called the embryoblast eventually develops into the embryo.

The study was concerned with how gravity may influence cell differentiation, the placement of the ICM within the blastocyst and if radiation effects gene expression in the these cells which will later develop into the fetus. Gene expression within the trophectoderm is also critical for proper development of the placenta.

The results were very promising as the data showed that there were no significant effects on early cell differentiation during embryo development and that proper gene expression manifested in microgravity when compared to 1g artificial and normal Earth gravity.

A human blastocyst with the inner cell mass at upper right. Credits: Wikipedia

A highlight of the paper implied that the results indicate that “Mammals can thrive in space.” It is too early to make such a bold statement with only this one study. It should be noted that this experiment only focuses on one early stage of embryo development. Conception in microgravity is not addressed and as pointed out by Alex Layendecker of the Astrosexological Research Institute, may have a whole other set of problems that raise ethical concerns as may the effects of lower gravity on later stages of gestation, in actual live birth and in early child development.

No matter how positive these recent results appear to be for early embryo development, as was determined by a landmark experiment on pregnant mice during the Shuttle era, we already have a data point on mammalian fetal development in later stages of gestation in microgravity: serious brain developmental issues were discovered in mice offspring born after exposure to these conditions. So mammalian reproduction in microgravity may start out relatively normally (assuming conception is successful) but appears to have problems in later stages, at least according to the limited data we have so far. On the bright side, the recent study found that 1g artificial gravity had no significant effects on embryo development.

Clearly more data is needed to determine which level of gravity will be sufficient for all stages of mammalian reproduction in space. Fortunately, SpaceBorn United is working on this very problem. They have plans for research into all stages of human reproduction in space to enable independent human settlements off Earth. SpaceBorn CEO Egbert Edelbroek in a recent appearance on The Space Show described upcoming missions later this decade that will study mammalian conception and embryo development using the company’s assisted reproductive technology in space (ARTIS). They have developed a space-embryo-incubator that will contain male and female mouse gametes, which upon launch into orbit, will initiate conception to create embryos for development in variable gravity levels. After 5-6 days the embryos would be cryogenically frozen for return to Earth where they would be inspected and if acceptable, placed in a natural womb for the rest of pregnancy and subsequent birth. If successful with mice the the company plans experiments with human stem cell embryos and eventually human gametes.

The gravity prescription for human reproduction in less than normal Earth gravity is still not known. But at least researchers are starting to gather data on this critical factor for long term biologically sustainable space settlement.

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Why settle space?

Artist depiction of the interior of a cylindrical space colony during an eclipse of the sun. Credits: Don Davis / NASA Ames Research Center

This question has come up a lot lately in the press, usually in the context of how public funds should be spent in space.  On the affirmative side, the answer has been addressed well by many space advocates over the years. Elon Musk wants to make the human race a multi-planetary species in case of a catastrophe on Earth and to expand consciousness out into the cosmos starting with Mars. Jeff Besos wants to move industrial activity off world and eventually fulfill Gerard K. O’Neill’s vision of trillions of people living in free space colonies. When asked the question last year by American Enterprize Institute’s James Pethokoukis, Robert Zubrin said: “In order to have a bigger future. In order to have an open future. In order to open the possibility to create new branches of human civilization that will add their creative talents to the human story. ” He thinks Intellectual Property will be the main export of a Mars colony and he’s already kickstarting that process with the Mars Technology Institute. And of course, The National Space Society (NSS) provides clear rationale in the introduction to their Roadmap to Space Settlement.

On the negative side, there are many naysayers. Some even say humans will never live in space. NSS Board Member Al Globus does a great job of refuting these viewpoints.

In an effort to gain deeper insights and clarify the vision of space settlement, SSP reached out to several space advocates, academicians and entrepreneurs to gather as many viewpoints as possible. They were asked if they agreed with the viewpoints above or if they had a different take.  Regardless of if we are asking for public support for government efforts through space agencies, if the efforts will be funded by private individuals or through a combination of public/private partnerships, why should humanity settle space? Here are their answers:

Doug Plata MD MPH, President & Founder of the Space Development Network, makes the case that there is no need to convince the public of the value of space:

“Many space advocates argue that the general public needs to be convinced of the value of space if we are ever going to see space development occur. So, these advocates come up with a wide variety of arguments including: the necessity of securing large amounts of public funding, the value of satellites in our everyday lives, the potential for a huge “space economy”, inspiring the next generation, and even for the survival of the human species.

“But is convincing the general public actually necessary? Put another way, will off-Earth settlement be impossible unless polls show a large percentage of the public supports space settlement?

“Secondly, it is not the general public who will be deciding whether they will settle on the Moon and Mars. Specifically, the uninterested, the cynical, nor the leftist opponent will need to be convinced over their objections. The ones who will decide will be countries choosing to send their hero astronauts to represent their own people and also private citizens who have saved up enough money. If countries have national pride (practically all) and if there are any “early adopters” with enough savings to pay for their ticket and stay, then it will be those who will decide to go. From Elon’s first BFR presentation (Guadalajara), this has been his business case and I find it to be sufficient. We don’t have to imagine some sort of unobtanium to trade with Earth to figure out where the funding will come from.

“For starters, much of the recent progress in space has not been the result of a groundswell of support from the public. Both Elon Musk and Jeff Bezos started their path to radically reducing the cost of launch independent of any groundswell of support for space by the public. And it is significant to note that they obtained their considerable wealth thanks to their Internet companies that had little, if anything, to do with space. It is their vast wealth that now gives them the ability to develop the reusable rockets which will make space development and settlement affordable and, as a result, inevitable. Even if NASA’s budget is cut to zero, Bezos will still have 20 X the wealth of NASA’s annual human spaceflight budget with Musk’s wealth at 30 X. And both are making progress with their heavy lift vehicles in a significantly more cost-effective manner than NASA.

“In conclusion, the cynic cannot be convinced, and it is probably a waste of time to try. But for those who have their own reasons for wanting to go, so long as the price has been brought down low enough…it is they who will inherit the stars. To each his own.”

Image of the Space Development Network’s full-scale mockup of an inflatable permanent habitat for the Moon or Mars at ISDC 2023. The concept is intended to demonstrate how a 100 tonne SpaceX Starship payload could be delivered and deployed to create a habitat with a 1 acre footprint. Credits: Doug Plata / Space Development Network

Dr. Daniel Tompkins, an agricultural scientist and founder of GrowMars weighs in:

“To address the term settlement from a biological view, for me it means to settle on a process or methodology to sustain and expand water/food/housing. There is settling the land to provide these things (where and how to get clean water, grow/harvest food, get building material). there is settling on practices that are reproducible with multi generational intent. Building schools, planning for expanding population. Different than an oil platform or remote research center which aren’t considered sea steading or settling Antarctica for the multigenerational intent reason.

“To answer directly on various views, mixed on positions:

“Musk- agree Mars is “easy” and most scaleable [sic]. Disagree that sustainable cites or a million people is a magically successful benchmark. Showing ability to support expanding population regardless of scale is important. How do you go from the resources to support 2 people, to 4 people.

“Zubrin- practical and pragmatic about challenges for human missions to Mars and how they can potentially accelerate the science and search for life beyond Earth. Agree IP is best export to support Mars economy lb for lb., particularly genetic engineering and synthetic biomanufacturing. Also agree on term resource creation vs term ISRU.

“Bezos- Moon is more difficult then Mars to “settle” lacking useful carbon and nitrogen than Mars, but opens a bigger range of options for where we can, the trillion people in the solar system model. The thermodynamics of habitats and greenhouses in these places isn’t well established or realized and there are misconceptions to this point of Mars being too cold.

“NSS- disagree with undertone of unlimited power needed to solve for space and earth to bring post scarcity. Unlimited biology vs unlimited power argument.

“O’Neill mostly addressed in above views, specifically cylinders are inspiring, but the process to make them not shown to make people think reproducible. Also, micrometer impacts.

“My short response to the space community and wider is that regardless of where in space (orbit, lunar, Mars etc.), space settlement is about learning to thrive independent of Earth’s natural resources in extreme environments. Whether we go to space or not, we are going to have to solve the same problem sets, i.e. clean air, water, food, materials on Earth in 50-100 years, if not sooner. It means you don’t have to fight with [your] neighbor or chop down the rainforest for more resources, you can do resource creation anywhere on Earth and meet basic needs.

“Space settlement level hardware should not be an eventually, it can be smaller than traditional mission payloads and de-risk certain mission architectures. Which is less mass/volume. Food for 3 years, greenhouses, or a machine to make greenhouses? Some of all three would be good, especially in certain scenarios.

“With sustainable independent settlement as a benchmark, practices and processes need to be inherently reproducible and serviceable. Similar and inspired methods could be used on Earth with limited resources in extreme environments to bootstrap resource creation to meet basic needs.”

Conceptual illustration of a habitat on Mars constructed from self-replicating greenhouses. Credits: GrowMars / Daniel Tompkins

Dr. Tiffany Vora, VP of Innovation Partnerships at Explore Mars and Vice Chair of Digital Biology and Medicine at Singularity University, had the following take:

“In my mind, there are three big arguments in favor of humans moving off-planet for extended, if not permanent, habitation.

“First, we more or less have the technologies that we need in order to do so, as well as a burgeoning space economy. I view crewed space habitation and settlement as further spurs to technological and economic development that will drive deeper understanding of the world around us while creating jobs and, hopefully, prosperity beyond a privileged few. That technology development has the added benefit of improving life on Earth, for example by contributing to solutions to the UN SDGs—on the way to setting the stage for sustainable human habitation off Earth.

“Second, as a biologist, I simply cannot believe that we are alone in the universe. I can’t even bring myself to believe that we’re alone in the Solar System! I view exploration and long-term settlement as key components of finding life off Earth, learning how it works, and learning from how it works. Serving as stewards of non-Terran life would be a momentous responsibility for humanity; although we have a dismal record of that here at home, I believe that life anywhere in the universe is a precious thing that would be worth a deep sense of obligation on the part of humans. Alternatively, failing to locate life elsewhere in the Solar System could provide strong messaging about the fundamental science of life—and hammer home the precarity and beauty of life on Earth.

“Third, I still believe in the capacity of space to inspire people, across generations and boundaries and even ideologies. The goal of settling space isn’t only about setting boots on exotic landscapes: it’s about staring at unbelievably complicated and dangerous challenges and saying, “Let’s do this—and here’s how I’m going to help.” I grew up in Florida, standing in my backyard watching shuttle launches. I have never lost the feeling that I had as a kid, witnessing that. I want every child on Earth to feel that sense of inspiration, of desperate excitement about the future—as well as a compelling urge to be part of it. Sure, I’d love for that to inspire STEMM careers, but there are so many other ways to contribute!

“Obviously, every word that I’ve written here comes with its own caveats. But just as I believe in these words, I also believe in our ability to make choices that open up an abundance of possible futures to bring prosperity and peace, not just to as many people around the world as possible, but to our own planet. The key is choices, and those choices have to be made starting today.”

Science journalist and historian Robert Zimmerman in his book Genesis, The Story of Apollo 8, wrote this:

“The new century will see a renaissance of space exploration as exciting and as challenging as the space race in the 1960s. And this rebirth will happen under the banner of freedom and private property, the very principles for which the United States fought the Cold War.”

Zimmerman continues:

“In a larger more philosophical perspective, we settle space because that’s what humans must do. It is the noblest thing we can do. To quote myself again, this time from my 2003 history, Leaving Earth:

‘Our hopes and dreams are a definition of our lives. If we choose shallow and petty dreams, easy to accomplish but accomplishing little, we make ourselves small. But if we dream big, we make ourselves great, taking actions that raise us up from mere animals.’ “

“Earthrise” image taken by astronaut Bill Anders from Apollo 8 on Christmas Eve 1968. Note that this is the original orientation of the image. As pointed out by Zimmerman, it was rotated 90o by the press for dramatic effect. Credits: William Anders/NASA

Entrepreneur and inventor Ryan Reynolds had a refreshingly unique perspective:

“So, why should humanity settle space (remotely and in-person)?:

  • To be confronted with a new set of challenging environments.
  • Feel the struggle to understand and adapt to them. 
  • Benefit from the effort through shared insights and tangible gains for all. 
  • To observe ourselves outside of the cradle, and know better what we are. 
  • To gain a broader view of our kinship with all that exists. 
  • To be surprised and appalled at our behavior out there. 
  • To ensure that the story does not end here. 
  • To extend biology’s reach.”

Dr. Peter Hague, an astrophysicist in the UK who blogs on Planetocracy had this to say:

“The solar system can and will, eventually, support civilisation on a more larger scale than exists on Earth. There is 2 billion times as much energy available from the Sun in the wider solar system as falls on the Earth alone, and huge reserves of raw materials. The composition of this civilisation will be determined by which nations make investments now – they will get to populate the new society, set the rules and inspire the culture. So it’s in the interests of nations to have a stake in the future, or be irrelevant in a few centuries.”

Haym Benaroya, Distinguished Professor of Mechanical and Aerospace Engineering at Rutgers University and author of Building Habitats on the Moon provided these views:

“I often have to defend the efforts and resources that have been used, and will continue to be allocated, for the space program, and especially the manned space program. While one can rightly say that the funds expended is miniscule as compared to other things that governments and people spend vast sums on, this argument rings hollow. I prefer to point to space, its exploration and its settlement, as an open-ended human adventure and imperative that provides young generations a positive vision of their future, one that gives hope to them and their decedents. Simultaneously, it offers the likely significant technical developments that would not occur otherwise. These technologies will impact how humans will live. Their health will improve, their lives will be longer, more fulfilled, and with the potential for great achievements. There is also the hope that with greater abundance for all on Earth, which a potentially vast space economy can provide, the tolerance for wars will decline. This last idea is a bit utopian given the history of the human race, but it is not a fantasy. It is a potential. Space can increase that potential in a major way.”

Dr. David Livingston, creator/host of The Space Show and one of today’s foremost authorities on the New Space economy, had this thought-provoking vision:

“Space settlement is a visionary long-term project.  In addition, I’m confident that be the inevitable outcome pushed by a global humanity wanting to go to space for off-Earth experiences, living off-Earth and eventually creating off-Earth communities.  I see it as a natural outgrowth of innovation, advancements in all walks of life and in our desire to see and check out what lies just around the corner.  Over time this will happen within the private commercial section of our economy with government mostly working to provide enabling rules of the road to mitigate some risks and uncertainty through establishing order and reasonable protocols. To breathe life into this vision so that it becomes reality, collectively we need to anchor our vision in science, engineering, medical development, behavioral science and most likely many more foundational components so that what we build and stands the test of time on solid footing. Having a dream and a vision for space settlement is one thing but to work on it, to enable it, to develop it, to make it come about implies we are a free people able to pursue dreams, to turn them into reality and to create amazing outcomes that were not even in existence yesterday. But its not enough to just have a good dream or vision for the future. We need to be able to make it happen which to me implies having a solid foundation not Bay Mud, plus realistic, plausible outcome expectations that are only possible when we can explore, build, and develop as we see fit. When we can take risks.  Being free to push forward to what lies beyond Earth is as essential as all the other ingredients that will go into making space settlement happen because without that freedom, we will have our dreams but without the ability to make them real.

“I’m fully aware that the settlement discussions like to focus on operational timelines, rockets, engineering, medical, food, and all sorts of challenges.  While all of this is critical to developing space settlement, these discussions must not sidetrack us into a world of hypotheticals and perspectives suggesting this or that technology is best given our present state of settlement R&D. Since I firmly believe that the private sector should make settlement happen, more so than the government, I would like to see viable commercial projects and startups designed to enable and support the goal of settlement. Government too has an important role in establishing space settlement. Rules of the road and policies are needed to provide order, structure, and safety.  One of our primary relationships with government must be oversight so that we enable not curtail settlement development.

“Space Settlement is fraught with challenges, with naysayers and those that think they know best for others.  I have every confidence that we will in time be overcome these obstacles.  By showing and doing, not by talking and promising.  I’m in less of a hurry to see the first settlement than I am in seeing us get started with essential precursors such as long-term commercial project financing as an example.  Space settlement will likely evolve because of a step-by- step methodical approach to information and fact gathering, problem solving, testing, development, and more testing. Risk taking will play a very large role in our ability to move forward.  As for risk taking, it can only be taken by those with the freedom to do so. As we advance step by step, innovation and forward thinking by those on the front lines will play an increasingly valuable role in turning our vision into reality.

“Space settlement is and should be a global endeavor with unlimited motivating and inspiring reasons driving thousands if not millions of us to our goal. As we move forward, we are sure to uncover and use many of the tightly held secrets of our universe. For sure it will be a very exciting and rewarding adventure as we figure out how to live, work, and play off-Earth, all the while making sure the process and our off-Earth communities are sustainable and independent on an ongoing basis.  This will happen if we remain focused and avoid distraction. Having patience will help us stay the course and to develop and maintain our needed drive into the future.  A future that to me lies ahead of us with as much certainty as does our daily sunrise and sunset.”

Tom Marotta, CEO of The Spaceport Company and Brett Jones, Strategic Marketer and Frontier Tech investor cowrote this inspiring response:

“Reimagining the Stars: A Multiplanetary Mindset for a Flourishing Future
The challenges humanity faces today are vast. From the instability of our global systems to the dwindling resources and fading hopes, there’s an undeniable sense of stagnation. Yet, within this atmosphere of despondency lies a beacon of hope, a path toward rejuvenation: the cosmos. Imagine a world where resources are not just abundant, but practically infinite. Where our collective potential is not limited by the boundaries of our blue planet, but instead, expanded by the boundless wonders of space. Such a vision is not mere science fiction; it is a future within our grasp.

“Space: An Oasis of Resources and Possibilities
Outer space is not just about twinkling stars and distant planets. It’s a treasure trove waiting to be explored. The vast quantities of materials and energy floating in the cosmic expanse can fuel economies, revitalize our planet, and secure prosperous futures for generations. And it’s not just about physical resources. The challenges of space exploration will drive advancements in healthcare, technological innovation, and even the social fabric of society.

“New Frontiers, New Beginnings
Space offers a fresh canvas, an opportunity to redefine human existence. For those yearning for change, be it a new environment, companionship, or the thrill of exploration, the cosmos holds endless possibilities. It’s not just about survival; it’s about thriving in ways we have yet to envision.

“Redefining NASA’s Mission: From Pride to Purpose
NASA has always been a symbol of American pride. Its achievements, from landing on the moon to exploring the distant reaches of our solar system, are testament to human ingenuity. Yet, its true potential lies not just in exploration, but in transformation.

“For NASA to truly leave an indelible mark on every individual, it needs to shift its vision. Instead of focusing solely on exploration and scientific endeavors, the emphasis should be on providing direct benefits for every citizen. This involves prioritizing space settlements, harnessing energy from space, and leveraging cosmic resources.

“An Invitation to the Stars
As we stand on the cusp of a new era, we must choose the trajectory of our future. By adopting a multiplanetary mindset, we’re not just securing a better life for ourselves but ensuring the continued growth and prosperity of all humankind for millennia to come. The universe beckons, offering hope and possibilities. It’s up to us to answer the call.”

Conceptual illustration of a mobile offshore launch platform as part of a robust launch industry infrastructure servicing thousands of launches in the near future to support space development. Credits: The Spaceport Company

Daniel Suarez, author of Delta-V and Critical Mass, believes we should rephrase the question:

“The question of ‘why’ humanity should settle space has been debated ever since it became technologically possible in the late 1960’s and early 1970’s. And the question has renewed relevance here in 2023 with the launch of a new space race — both public and private. A frequent objection is: “Why should we spend precious resources on space development when we have pressing problems to solve down here on Earth?”

“However, to address that concern I think it’s vital to re-frame the question as not just ‘why’ we should settle space, but why we must urgently settle space. And the answer is compelling: we must settle space in order to deliver economic opportunity and clean energy to all the people of Earth, particularly if we are to have a reasonable chance of resolving the existential threat of climate change. One may question how expanding human society and industry into space accomplishes that, but the answer is straightforward…

“Yes, developed nations have made progress in reducing their carbon emissions in an effort to address climate change. And yes, more consumers are buying electric cars. However, social media and mainstream news reports tend to suggest climate change will soon be under control if we just continue installing solar & wind farms, and keep buying electric cars. However, the truth is that human civilization as a whole is not reducing carbon emissions. In fact, for all our efforts over the past 30 years all we’ve done is slow the growth of emissions. For example, global carbon emissions increased yet again (0.9%) in 2022 and that increase was above the 6% increase from the year before (source: National Oceanic & Atmospheric Administration). Pointedly, carbon emissions have increased almost every year since the dawn of the industrial age in 1850 (a notable exception being 2020, during the height of the pandemic).

“The amount of CO2 in the atmosphere today was last experienced 4.3 million years ago, during the mid-Pliocene epoch when sea levels were 75 feet higher than today, and average temperatures were 7 degrees Fahrenheit warmer than pre-industrial times. Even if we reduced annual global carbon emissions to zero tomorrow, average global temperatures would still continue to rise each year for a century or more because of the trillion tons of CO2 that we’ve already released into our atmosphere since 1850. That CO2 will take a century or more to be sequestered by the natural carbon cycle, which means there will be a surplus of heat absorbed by the planet each and every year no matter how many solar panels, wind turbines, and hydro power stations we install.

“No, in order to truly address climate change, we’re going to need to remove CO2 from Earth’s atmosphere, reducing concentrations from the present 418ppm down to at least 350ppm, a level more suitable to global civilization. But coming up with the terawatts of clean energy required to remove all that CO2 is going to be nearly impossible here on Earth, especially as economic and political turmoil continues to spread in response to climactic chaos.

“Adding to the challenge of resolving climate change is the fact that over 2 billion people currently live in poverty and billions more experience meager living standards. They are eagerly trying to improve their circumstances through economic development and increased energy usage. India, China, nations of Africa, and elsewhere want to improve the lives of their citizens just as developed nations of the West did over the past 150 years. They need energy to do so, and new coal and gas-fired power plants are coming online in the developing even as they continue to roll out solar and wind.

“How can we possibly increase the energy and resources available to the people of Earth without further polluting our already ailing home world — especially in time to stave off the worst effects of climate change, which will itself cause more conflict, uncontrolled migration and food shortages, reducing cooperation on global issues? Earth is a finite system, and the solution to climate change and continued economic development worldwide lies in going beyond Earth’s atmosphere to obtain the energy and resources we need.

“One answer is to expand carbon-intensive industry and energy generation into cislunar space. By using in-situ resource utilization in deep space (as opposed to launching all our working mass from Earth), we can start to rapidly build out an offworld industrial infrastructure & economy, using resources harvested from our Moon and near-Earth asteroids. By refining these materials in space, we can build enormous solar power satellites, place them in geosynchronous orbit, and beam at first gigawatts and later terawatts of clean solar power to rectennas on the Earth’s surface 24-hours a day, rain or shine anywhere in the hemisphere beneath them. The technology to accomplish this has existed since the mid-1970’s. And Earth’s geosynchronous orbit, safely populated with solar power satellites could return well over 300 terawatts of continuous clean energy — and for reference we currently consume a bit over 20 terawatts of energy worldwide.
Plus, the economic growth made possible by expanding industry and energy generation into cislunar space will be critical for all the people of Earth. This could include industries only possible in the microgravity and/or near-perfect vacuum of space, from ultra-clear ZBLAN fiber optics, exotic alloys, pharmaceutical discovery, astronomy — the list goes on.

“So ‘why’ should we settle space? I contend that’s the wrong question. The right question is ‘why should we urgently‘ settle space? And the answer is to avoid an existential catastrophe and instead make possible a promising and dynamic future for countless generations to come.”

Artist depiction of a space-based solar power satellite collecting sunlight and converting the energy to microwaves for beaming to rectennas on Earth to be fed into a country’s power grid. Credits: © ESA – Andreas Treuer

Finally, here are the reasons for space settlement articulated as goals in 1976 by Gerard K. O’Neill from his blueprint for migration off Earth, The High Frontier:

  • Ending hunger and poverty for all human beings
  • Finding high-quality living space for a world population which will double withing forty years, and triple with another thirty, even if optimistic estimates of low-growth rate are realized
  • Achieving population control without war, famine, dictatorship, or coercion
  • Increasing individual freedom and the range of options available to every human being
Cutaway view revealing interior of a toroidal space settlement. Credits: Rick Guidice / NASA Ames Research Center
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Artificial photosynthesis for production of oxygen and fuel on the Moon and Mars

Image of ice in a crater on the Martian plain Vastitas Borealis captured by the European Space Agency’s Mars Express orbiter. Credits: ESA/DLR/Freie Universitat Berlin (G. Neukum)

When we establish outposts and eventually, settlements on the Moon or Mars it would be economically beneficial if we did not have to create supply chains from Earth for water, breathable air and the fuel we will need for our rockets. This is why sources of water ice in the permanently shadowed craters at the lunar poles and in glaciers in the equatorial regions on Mars are so attractive as early destinations. Once we get there what equipment will we need to process this valuable resource? The typical way envisioned for cracking water in situ on the Moon or Mars to produce oxygen and hydrogen is through electrolysis. But this method requires a lot of power. There may be a more efficient way. New ESA sponsored research by scientists* in the UK and Europe examines a novel method that mimics photosynthesis in plants using a photoelectrochemical (PEC) device. The findings were published June 6 in Nature Communications.

PEC reactors are currently being studied on Earth for water splitting to produce green hydrogen from sunlight. Since they only rely on solar energy for power they are ideal for space applications. One type of device consists of a semiconductor photocathode immersed in an electrolyte solution that absorbs solar energy for a reaction to split hydrogen from water molecules. Oxygen is produced at the anode of the cell. PEC devices can be fabricated as panels similar to photovoltaic arrays. For use on Mars, the authors analyze another similar PEC technology using a gas-diffusion electrode to reduce atmospheric carbon dioxide in a reaction producing methane for rocket fuel.

The authors modeled the performance of these devices subjected to the expected environmental conditions on the Moon and Mars. Specifically, they looked at attenuation from the accumulation of dust on the PEC cells caused by micrometeorites pulverizing the lunar surface, coupled with the solar wind inducing an electrostatic charge in the resulting dust. And of course dust storms are relatively frequent on Mars which could significantly degrade performance. To address this problem self cleaning coatings are suggested as a solution. Solar irradiance was also considered as it would be reduced at the orbit of Mars. It was concluded that the PEC performance could be significantly boosted with solar concentrators by a factor of 1000 enabling higher production rates and power densities, especially on Mars.

An added advantage for space-based application of this technology is the elements needed to construct PEC devices are readily available on these worlds obviating the need to transport them from Earth and thereby significantly reducing costs.

“…in-situ utilization of elements on both, the Moon and Mars, is feasible for the construction of PEC devices.”

The technology is ideal to augment the production of oxygen in environmentally controlled life support systems of habitats that may not initially be 100% closed and cannot easily be resupplied with consumables from Earth. A competing technology for oxygen production which was recently demonstrated on Mars is the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) which functions via solid oxide electrolysis of carbon dioxide. This process requires high temperatures and therefore, more energy presenting a challenge when increased production of oxygen will be required for large settlements. The author’s analysis show that the PEC devices are more energy efficient and can easily be scaled up.

“Oxygen production via unassisted PEC systems can … be carried out at room temperature … suitable to be housed in temperature controlled space habitats.”

* Authors of the Nature Communications article Assessment of the technological viability of photoelectrochemical devices for oxygen and fuel production on Moon and Mars: Byron Ross at the University of Warwick, UK; Sophia Haussener at Ecole Polytechnique Fédérale de Lausanne, Switerland; Katharina Brinkert, University of Bremen, Germany