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Interview with Mikhail Shubov: Guided self replicating factories, orbital fuel depots, hydrogen production on Mars and other visions for space settlement

Vintage 1980 artist depiction of a self replicating factory on the Moon. Credits: NASA

Earlier this year SSP covered self replicating factories for space settlement. An innovative paper on this topic with a simpler approach was submitted by Mikhail Shubov to ArXiv.org in August that shows how to accelerate efforts in this area.

A fully autonomous self replicating factory in space requires significant advancements in artificial intelligence, robotics, and other fields. Such facilities are mainly theoretical at this point and may not be feasible for many decades. But if humans could “guide” the operation remotely via computer control, a colony on the Moon could be started relatively soon.  This could be the proving ground for establishing such facilities on other worlds which Shubov believes could be set up on Mercury, Mars and in the Asteroid Belt eventually leading to exponential growth allowing humanity to expand out into the solar system and beyond.  He suggests that rather then using the usual definition of self-replication in which a factory would make a duplicate copy of itself, until this capability is realized, a better figure of merit would be the “doubling time”. This is how long it takes to double the facility’s mass, energy production, and machine production.

I reached out to Dr. Shubov about this article and discovered that he has been busy with a variety of scholarly papers on several technologies needed for space settlement. He agreed to a wide ranging interview via email about these topics and his vision of our future in space.

SSP: Thank you Dr. Shubov for taking the time for this interview.  With respect to your work on Guided Self Replicating Factories (GSRF), there are already companies developing semiautonomous robots for in situ resource utilization on other worlds.   OffWorld, Inc. states that “We envision millions of smart robots working under human supervision on and offworld, turning the inner solar system into a better, gentler, greener place for life and civilization.”  Their business model is focused on developing a robotics platform for mining and construction on Earth, then leveraging the technology for use in space.  Do you think this is a good approach to get started?

MS: Thank you Mr. John Jossy for taking interest in my work!

In my opinion, remotely guided robots will be very effective for construction of a colony on the Moon. These robots could be guided by thousands of remote operators on Earth. They would be linked to Earth’s Internet via Starlink which is already being deployed by Elon Musk via SpaceX. Starlink will consist of thousands of satellites linked by lasers and providing broadband Internet on Earth. About 1,646 satellites are already orbiting the Earth.

Hopefully, it would be possible to produce [an] Earth-Moon Internet Connection of about a Terabit per second. That would enable people on Earth to remotely operate hundreds of thousands of robots.

Using these robots on Asteroids and other planets of Solar System will be much more difficult due to low bandwidth and high delay of communication. For example, latency of communication between Earth and Mars is 4 to 21 minutes.

SSP: Obviously, establishing outposts on other worlds where astronauts could teleoperate robots to build a GSRF would eliminate the latency problem, which you address in your paper.

You’ve envisioned four elements of a GSRF: an electric power plant, a material production system (ore mining, beneficiation, smelting), an assembly system in which factory parts are shaped and fabricated, and a space transportation system.  With respect to the space transportation system you cover both launch vehicles and in-space propulsion systems.  The space transportation element of a GSRF, although vital for its implementation, seems to be an external part of the system.  In fact, you stated that “Initially, spaceships will be built on Earth. Fuel for refueling spaceships will be produced in space colonies from the beginning.”  So, when calculating the doubling time of a GSRF, we are not including the production of space transportation systems, correct?

MS: In my opinion, [the] space transportation system may become part of GSRF at later stages of development. How soon space transportation becomes a part of GSRF depends on the speed of development of different technologies.

If inexpensive space launch from Earth becomes available, then there will be less reliance on self-replication and more reliance on transportation of materials from Earth. In this case, space transportation system will not be part of GSRF for a long time.

If rapid growth of a Space Colony by utilization of in situ resources is possible, then many elements of space transportation system would be produced at the colony. In this case, [the] space transportation system will become a part of GSRF relatively soon.

SSP: You suggest that an important product produced by a GSRF in the Asteroid Belt would be platinum group metals to be delivered to Earth, and that they would help finance expansion of space colonization.  Some space resource experts, including John C. Lewis, believe that “…there is so vast a supply of platinum-group elements in the NEA [Near Earth Asteroids] … that exploiting even a tiny fraction of them would cause the market value to crash, bringing to an end the economic incentive to mine and import them.”  Some suggest the market for these precious metals may be in space not on Earth.  When you say “delivered to Earth” what markets were you envisioning to generate the profits needed to finance the GSRF?

MS: In my opinion the main applications of platinum group metals would be in industry. First, PGM are very important as chemical reaction catalysts. In particular, platinum is used in hydrogen fuel cells and iridium is a catalyst in electrolytic cells. It is likely that demand for platinum, iridium and other PGM will grow along with hydrogen economy. Second, platinum and palladium is used in glass fiber production.

Third, Iridium-coated rhenium rocket thrusters have outstanding performance and reusability. Rhenium is also used in jet engines. These thrusters will also provide a market for iridium and rhenium metals.

SSP: As the need for PGM grows exponentially in the future, especially with energy and battery production needs on Earth in the near future, the environmental impacts of mining these materials on Earth may be another reason to source these materials off world.

Mining water to produce hydrogen for rocket fuel is a theme throughout your writings.  In a paper submitted to the arXix.org server last month entitled Feasibility Study For Hydrogen Producing Colony on Mars, you propose that a technologically mature Martian factory could produce and deliver at least 1 million tons of liquid hydrogen per year to Low Earth Orbit.  Does placing a hydrogen production facility on Mars for fuel used in near-Earth space make sense from a delta-v perspective?  You acknowledge that initially it will be cheaper and easier to access the Moon’s polar ice to produce hydrogen.  But in the long term, Near Earth Asteroids (NEA) or even the Asteroid Belt are easier to access and they include CI Group carbonaceous chondrites which contain a high percentage (22%) of water.  Can you reconcile the economics of sourcing hydrogen on Mars over NEAs?

MS: Delivery of Martian hydrogen into the vicinity of Earth may be necessary only when the space transportation technology is relatively mature. In particular, as I mention in my work, Lunar ice caps contain between 48 million and 73 million tons of easily accessible hydrogen. Until at least 16 million tons of Lunar hydrogen is used, hydrogen from other sources would not be needed.

As I calculate in my work, delta-v for transporting hydrogen from Low Mars Orbit to LEO is 3.5 km/s accomplished by rocket engines plus about 3.2 km/s accomplished by aerobreaking. This would be economic if vast amounts of electric energy will be produced on Mars easier than on asteroids. An important and renewable resource on Mars is the heat sink in the form of dry ice. This may enable production of vast amounts of electric energy by nuclear power plants.

Even if delivery of hydrogen from Low Mars Orbit to Earth turns out to be economically infeasible, hydrogen depots in near-Mars deep space would still play a very important role in transportation to and from Asteroid Belt as well as [the] Outer Solar System.

SSP: Your first choice of a power source for the colony on Mars is an innovative heat engine utilizing dry ice harvested from the vast cold reservoirs at the planet’s polar caps. You suggest that the initial heat source for this sublimation engine be a nuclear reactor. Why not simply use the nuclear reactor to produce electricity? Nuclear reactors coupled to high efficiency Stirling engines for electricity generation like NASA’s Kilopower project have very high power density per unit weight and the technology will be relatively mature soon. Your second choices are solar and wind which are not as reliable as a nuclear power source, especially with reduced solar flux at Mars’s orbit and the problem caused by dust in the atmosphere. Why was a more mature nuclear power technology for direct electricity production not considered?

MS: Thank you.  As I understand now, a regular nuclear reactor with a heat engine using water or ammonia as a working fluid is the best choice for energy production on Mars.  Dry ice should only be used as a heat sink and not as working fluid.  Given the very low temperature and ambient pressure of Martian dry ice, it is likely that power plants will have thermal efficiency of at least 50%.

Almost all components of Martian power stations can be manufactured from in situ resources.  Only the reactors themselves and the nuclear fuel will have to be delivered from Earth.

SSP: A booming space transportation economy will need cryogenic fuel depots to store hydrogen for rocket fuel in strategic locations throughout the inner solar system.  You’ve got this covered in your recent paper Hydrogen Fuel Depot in Space.  Some start ups like Orbit Fab have already started work in this area, albeit on a smaller scale, and United Launch Alliance integrated cryogenic storage into their Cislunar-1000 plans a few years back, but this initiative seems to have slowed down due to delays in ULA’s next generation Vulcan launch vehicle.  In this paper you calculate the required energy to refrigerate hydrogen in one smaller (400 tons) and another larger (40,000 tons) depot.  In both cases, a sun shield is required to block sunlight to prevent boil off.  You don’t mention the method of power generation to provide energy for the refrigeration units.  Could the sun shield have a dual use function by incorporating photovoltaic solar cells on the sun facing side to generate electricity to power the refrigeration system?

Diagram depicting a cryogenic liquid hydrogen storage depot with 40,000 ton capacity. Credits: Mikhail Shubov

MS: Power for the refrigeration system will be provided by an array of solar cells placed on the sun shield.  As I mention in my work, the 400 ton depot requires 80 kW electric power for the refrigeration system, while the 40,000 ton depot requires 840 kW electric power.  This power can be easily provided by photovoltaic arrays.

SSP: SpaceX has proven what was once believed impossible: that rockets could be reused and that turnaround times and reliability could approach airline type operations.  Although we are not there yet, costs continue to come down.  In your paper entitled Feasibility Study For Multiply Reusable Space Launch System you calculate that with your proposed system in which the first two stages are reusable and the third stage engine can be returned from orbit, launch costs could be reduced to $300/kg.  Musk is claiming that with the projected long term flight cadence, eventually Starship costs could be as low as $10/kg.  Even if he is off by a factor of 10 that is still lower than your figure.  What advantages does your system offer over Starship? 

MS: The main advantage of the Multiply Reusable Space Launch System is the relatively light load placed on each stage. As I mention on p. 10, the first stage has delta-v of 2.6 km/s and the second stage has delta-v of 1.85 km/s. The engines have high fuel to oxidizer ratio and a low combustion chamber temperature of 2,100oC. These relatively light loads on the rocket airframes and engines should make these rockets multiply reusable similar to airliners. The launch system should be able to perform about 300 space deliveries per year.

Hopefully Elon Musk would succeed [in] reducing launch costs to at least $100 per kg. Unfortunately, many previous attempts at drastic reduction of launch costs did not succeed. Hence, we may not be sure of Starship’s success yet.

SSP: You state in several of your papers that:

“A civilization encompassing the whole Solar System would be able to support a population of 10 quadrillion people at material living standards vastly superior to those in USA 2020. Colonization of the Solar System will be an extraordinary important step for Humankind.”

Why do you think that colonization of the solar system is important for humanity and when do you think the first permanent settlement will be established on the Moon or in free space?  Here I use the National Space Society’s definition of a space settlement:

‘ “A space settlement” refers to 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 as a part of a larger network of space settlements. “Space settlement” refers to the creation of that larger network of space settlements. ‘

MS: In my opinion colonization of Solar System will bring unlimited resources and material prosperity to Humankind.   The human population itself will be able to grow by the factor of a million without putting a strain on the available resources.

As for the time-frame of establishment of human settlements on the Moon and outer space, I have both optimistic and pessimistic thoughts.  On one hand, Humankind already possesses technology needed to establish rapidly growing space settlements.  This means that Solar System colonization can start at any time. On the other hand, such technology already existed in 1970s.  This technology is discussed in Gerard K. O’Neill’s 1976 book “The High Frontier: Human Colonies in Space”.  Thus, space colonization can be indefinitely delayed by the lack of political will.  Hopefully space colonization will start sooner rather then later.

Credits: Gerard K. O’Neill / Space Studies Institute Press
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Saving Earth and opening the solar system with the nuclear rocket

The NERVA solid core nuclear rocket engine. Credits: NASA

James Dewar believes it is time to reconsider the solid core nuclear thermal rocket, like what was developed in the 1960s under the NASA’s Nuclear Engine for Rocket Vehicle Application (NERVA) Project, as a high thrust cargo vehicle for opening up the solar system and for solving problems here on Earth. A tall order, as he explained in his appearance on The Space Show (TSS) October 26, because nuclear propulsion within the atmosphere and close to the Earth was taken off the table by NASA over 60 years ago and research on nuclear rockets was put on ice after 1973 until recently. Dewar worked on nuclear policy at the Atomic Energy Commission and its successor agencies, the Energy Research and Development Administration and the Department of Energy. He has documented his views in a paper linked on TSS blog.

What is old could be new again. NERVA had a very light high power solid core reactor with Uranium 235 fuel in a graphite matrix creating nuclear fission to heat hydrogen to produce rocket thrust. The specific impulse (efficiency in conversion of fuel to thrust) of the first iteration of NERVA was about 825 seconds, or almost twice that of chemical rockets. More efficient versions were on the drawing board. The compact design (35×52-inch core) lends itself to low development costs and would be inexpensive to fabricate and operate. It has the potential to lower launch costs significantly and research could pick up where it left off nearly 50 years ago.

So why is NASA announcing development of new nuclear thermal propulsion systems for missions to Mars in the distant future? The reactor cores like those used in Project NERVA are known technologies that can it be adapted for other useful applications and it can be done safely on Earth. There could be a large niche market for energy production in remote rural areas such as Alaska or Canada, or supplementing base load utilities during power disruptions due to severe weather events. With their high operating temperatures, these reactors can replace fossil fuel power generation for manufacturing industries that require process heat such as steel/aluminum or chemical production, which cannot be powered efficiently by wind or solar energy. There may also be a cost advantage and environmental benefit to replacing carbon based fuels for powering maritime oceangoing vessels.

“Even the Greens may support it…What if a reestablished program included making a nuclear propelled 1000-foot tanker sized skimmer to rid the oceans of plastic?”

Additionally, a nuclear reactor of this type could service manufacturing centers in both space and on Earth. It could inexpensively launch satellites and provide power for environmental and solar weather stations to monitor and protect Earth’s health. Dewar even thinks that the solid core nuclear reactor could be used to address the growing global problem of industrial waste by melting it down to its chemical constituents and then separating out commercially valuable components from the actual waste prior to permanent disposal. The low launch costs of the nuclear rocket may actually make disposal of waste off Earth economically feasible. Whole clean industries could spring up around these process centers. So this type of reactor could address many national goals and objectives rather than just crewed missions to Mars or deep space.

But what about the elephant in the room? Safety, radiation and fear of all things “nuclear”? Would the public support ground based testing if a NERVA type solid core nuclear thermal rocket program were restarted? Dewar covers this in detail in his book The Nuclear Rocket, Making Our Planet Green, Peaceful and Prosperous. As reported by the EPA in 1974, “…It is concluded that off-site exposures or doses from nuclear rocket engine tests at [the] NRDS [Nuclear Rocket Development Station] have been below applicable guides.”

What about regular launches of a nuclear rocket in the Earth’s atmosphere? First, the launch range proposed would be in an isolated ocean area over water to eliminate the possibility of failure or impact in populated regions. Second, the nuclear core would be enclosed in a reentry vehicle type cocoon for safe recovery in the event of an accident. Third, the nuclear engine is envisioned as an upper stage and would not be “turned on” until boosted high in the stratosphere, thus emission of gamma rays and neutrons from the fission reaction would not be any different then the radiation already impinging on our atmosphere from cosmic and solar radiation.

“…the best way to banish fear is for citizens to profit from the program.”

There is also the potential for the U.S. and its citizens to profit from this venture. Dewar suggests a governance framework for creating a public/private corporation in which the private sector is in charge, but leases assets from NASA and DOE. The government would support the venture via isolated testing sites, providing technical advice, supplying the uranium fuel and security to guard against potential nuclear proliferation. The public/private partnership would be set up to incentivize citizen participation through stock purchases and distribution of dividends in addition to providing jobs and funding the missions.

“Another source of funding would exist beyond the government or private billionaires: the public now has access”

Dewar concludes his paper with an inspirational statement: “…a new space program emerges based on science, not emotion, one that maximizes the technology for terrestrial applications, one that neuters the rocket equations and democratizes the space program, allowing citizens to participate and profit, and one that ever integrates Earth into the Solar System.”

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Reproduction off Earth and its implications for space settlement

Launch of the Space Shuttle Atlantis (STS-66) on November 3, 1994. The mission carried an experiment called NIH.Rodent 1, the first of only two study’s to date on rats launched at mid-pregnancy and landed close to full term to study the effects of microgravity on reproduction. Credits: NASA

In a MDPI Journal Life paper, Alexandra Proshchina and a team* of Russian researchers summarize the research that has been performed thus far on reproduction of invertebrates in space. As mentioned in the article, the only data we have on mammalian reproduction in microgravity since the dawn of the space age is from two experiments carried out over 26 years ago. The studies looked at pregnant rats launched aboard the Space Shuttle on missions STS-66 and STS-70 in 1994 and 1995 respectively, and there have never been any births of mammals in space. This huge knowledge gap on reproduction in space is problematic for human space settlement. Yet Elon Musk, The Mars Society, and other groups are charging ahead with plans for cities on Mars. What if we discover that humans cannot have healthy babies in 0.38g? SSP has covered the quest for determining the gravity prescription before looking at JAXA’s effort to at least start experimenting with artificial gravity in space, albeit on adult mammals (mice). We are still waiting for JAXA’s published results of 1/6g experiments carried out in 2019.

The data from the Space Shuttle program only looked at part of the gestation period (after 9 days) and only in microgravity. The results did not bode well for reproduction in space. Some findings “…clearly indicate that microgravity, and possibly other nonspecific effects of spaceflight, can alter the normal development of the brain itself.”

Histological cross section through a representative rat brain from NIH.Rodent 1 experiment from STS-66. Left side (a) is low magnification and right side (b-d) are high magnification. Red arrows show areas of neurodegeneration. 1 – Nasal cavity, 2 – olfactory nerve, 3 – olfactory bulb, 4 – eye, 5 – cortex telencephali, 6 – hippocampus, 7 – fourth ventricle, 8 – cerebellum. Credits: Alexandra Proshchina et al.*

So we have this one piece of data for reproduction in microgravity and nothing in higher gravitational fields except what we know here on Earth in 1g.

Would partial gravity like on the Moon or Mars be sufficient for normal fetal development in rats (or mammals in general, especially humans) during the full gestation period? If problems are identified could it be extrapolated to human reproduction? The fact that homo sapiens and their ancestors evolved on Earth in 1g for hundreds of thousands of years is a big red flag for future space colonists that hope to settle on the surface of planetary bodies and have children.

We don’t know how lower gravity conditions could affect embryonic cell growth. How would the changes in surface tension and embryo cell adhesion be altered in these environments? We have very little data on cellular mechanisms and embryonic alterations that lower gravity may induce that could affect fetal development.

“There are also many other questions to be answered about vertebrate development under space flight conditions.”

A recent report on giving birth in space by SpaceTech Analytics looks at many of the factors that need to be considered for human reproduction off Earth. Most problems could be potentially mitigated through engineering solutions such as radiation protection, medical innovations tailored for space use, life support technology, etc. In this entire presentation the authors gave very little consideration to partial gravity affects on human embryos and child birth. One slide (number 70) out of 85 discusses these issues.

It is clear that more and longer term experiments will be necessary to determine how partial gravity affects the reproduction and development of mammals before humans settle space. Some researchers are actually considering genetic modification to allow healthy reproduction in space, and the ethical considerations associated with this course of action. Obviously, such a drastic methods would come only if there was no other alternative. One would think that building O’Neill type habitats rotating to produce 1g of artificial gravity would be preferable to such extreme measures.

Clearly, we need a space based artificial gravity laboratory to carry out ethical clinical studies on the gravity prescription for human reproduction, starting with rodents and other lower organisms. SSP recently covered a kilometer long version of such a facility that could be deployed in a single Falcon Heavy launch. And don’t forget Joe Carroll’s proposal for a LEO partial gravity test facility. Doesn’t it make sense to invest in such a facility and do the proper research before (or at least in parallel to) detailed engineering studies of colonies on the Moon or Mars intended for long term settlement? This research could inform decision making on where we will eventually establish permanent space settlements: on the surface of smaller worlds or in free space settlements envisioned by Gerard K. O’Neill. Elon Musk may want to consider such a facility before he gets too far down the road to establishing cities on Mars.

* Authors of Reproduction and the Early Development of Vertebrates in Space: Problems, Results, Opportunities: Alexandra Proshchina, Victoria Gulimova, Anastasia Kharlamova, Yuliya Krivova, Nadezhda Besova, Rustam Berdiev and Sergey Saveliev.

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Freedom Engineering in Space

A tongue-in-cheek Freedom Engineering poster encouraging space settlers to produce oxygen through plant growth as an alternative to dependency on centralized oxygen production facilities. Credits: Charles Cockell

At the 24th Annual International Mars Society Convention held October 14 – 17, Dr. Charles Cockell, professor of Astrobiology in the School of Physics and Astronomy at the University of Edinburgh, gave a talk on what he calls Freedom Engineering. His viewpoint was also published in a paper via the journal Space Policy in August of 2019. Cockell makes the case that due to the extreme constraints imposed by the laws of physics on living conditions in space settlements, freedom of movement will necessarily be restricted. Such conditions could be exploited by tyrannical governments to limit social, political and economic freedoms as well. To address these concerns Cockell suggests that colony designers utilize proactive engineering measures in planning off Earth communities to maximize liberty in the space environment. For example, rather then one centralized oxygen production facility or method that may be leveraged by a despot to control the population, it is suggested that settlements be designed with multiple facilities distributed widely and if possible, other types of oxygen production (e.g. greenhouses) be employed to minimize the chance of monopolization.

This engineering philosophy raised many questions among colleagues of mine so I reached out to Dr. Cockell for an interview via email to provide answers. He graciously agreed and I’m very grateful for his responses.

SSP: How is Freedom Engineering different from standard engineering practices of designing for redundancy to prevent single point failure?

CC: There is a strong overlap. For example, if you want redundancy, you multiply oxygen production. That would also be a desired objective to minimize the chances of monopolistic control over oxygen. So often the objectives are the same. However, I suggest that freedom engineering is a specific focus on engineering solutions that cannot be used to create coercive extraterrestrial regimes, which is not always the same as redundancy. For example, we might minimize the use of cameras and audio devices to monitor habitats for structural integrity, an objective consistent with general engineering demands, but potentially antithetical to human freedoms.

SSP: Since the added costs are significant and we may not be able to follow these practices initially, how do we get around the problems you mention after being on the Moon a decade or two? Wouldn’t the forces of tyranny have already won?

CC: Liberty is never cheap in resources and human effort. You can take a cost-cutting approach and hope that tyrannical regimes don’t take hold in a settlement or you can plan before hand to minimize their success, even if that involves more cost. However, as many freedom engineering solutions are compatible with redundancy, it is not necessarily the case that introducing measures like maximizing oxygen production and spacesuit manufacture motivated by considerations on liberty would add significantly to a cost already incurred by ensuring redundancy.

Liberty is never cheap in resources and human effort.

SSP: How do we avoid centralized control of transportation? Will we have two or more landing pads, several sets of rockets? – e.g., Musk, Bezos, and ULA?

CC: I would say that maximizing the number of entities with transportation capabilities is a good idea. Here too, we would want to achieve this for redundancy, but it would also reduce the chances of monopolization and the isolation of a settlement (particularly if leaving the settlement can only be achieved with one provider). This could also include multiplying the physical number of rocket launch and arrival points.

SSP: There are always non-redundant systems, which you acknowledge. At some level there are critical infrastructures that cannot be made redundant because then we get into an infinite loop. If a tyrannical power wanted to control everything on the Moon, for example, that is where they would focus their control. Can you comment?

CC: That’s true. It goes without saying that, as on Earth, a determined despot with enough support can find ways to take over a society. However, as the framers of the US Constitution understood, if you can introduce enough checks and balances you can make tyranny an outcome that requires many of those to fail. You reduce the risk. So by minimizing the number of single point controls in an extraterrestrial society you never eliminate the chances of tyranny, but you reduce the number of options open to those with tyrannical tendencies.

It goes without saying that, as on Earth, a determined despot with enough support can find ways to take over a society.

SSP: How would a tyrannical off-Earth settlement get its citizens when moving to such a settlement would seem like a terrible idea?

CC: It’s true that an overtly tyrannical settlement may eventually find it difficult to recruit people and might therefore fail. One might hope that this would be a feedback loop that would discourage tyranny in space. However, when building free government[s], it’s a good idea to assume the worse to achieve the best, i.e. assume that people will attempt to, and can, create a tyranny, and then build a system that minimizes this possibility. It’s also worth pointing out that once people are in a settlement, they will be physically isolated under some governance power. Just as it isn’t trivial to remove a tyranny on Earth that has a population corralled under it once it is established, it may not be easy to free a settlement once it has a population under its control. It is worthwhile to attempt to design societies that avoid this possibility from the beginning.

SSP: Would a space settlement economy with multiple competing companies providing essential needs such as life support, obviate the requirement for engineering redundancy since it would be more difficult for a tyrannical government to take over all the means of production?

CC: Yes, I think in many ways multiple competing companies is a form of redundancy – providing many conduits for production and minimizing single points of control or failure. Maximizing productive capacity is essential. I would mandate some basic level of oxygen production capability, for example, that any settlement must be capable of producing to keep people alive, and then try and stimulate a private market in fashionable oxygen machines of various kinds, different oxygen production methods etc. Of course, one should not be utopian. A coercive monopoly could still control a lot of this, but in general the more entities that produce vital resources, the more likely real choice can emerge in some form.

SSP: One reasonable measure that can be taken that doesn’t fall under normal engineering approaches is standardizing data transparency. It might make sense that it should be a matter of public record, and easily assessable, the records of who does what with vital resources and how activities that seriously impact human safety are managed. This can be done without compromising anyone’s intellectual property. The full light of day can be good protection especially when used proactively, and establishing such standards would head off the opportunity to wave things away as bias or smear campaigns. Open-source approaches to data are already a big thing for all the space agencies and may be the best course of action. Do you have an opinion on this philosophy?

CC: I think this is essential. The freedom engineering approach I suggest is just one mechanism for reducing coercive governance, but a free society is constructed from many other needs. In some of my previous papers I have discussed exactly this – the need for transparency in information about oxygen production, who is funding it, and how etc. A general culture of openness is necessary. There may be some novel approaches such electing members of the settlement by lot to take part in meetings to do with oxygen or water production, for instance, and write public reports. Corporations will find all this very annoying of course, but the wider culture of liberty will be enhanced by a very ‘leaky’ society with respect to information. Other essential things are a free press (even if that is just informal lunar or Martian newspapers), transparency in elections for running the settlement, and perhaps maximum terms on people involved in health and safety tasks to create fluidity in the network of officialdom that oversees the potentially large number of health and safety concerns with respect to radiation, dust, production of essential items.

Corporations will find all this very annoying of course, but the wider culture of liberty will be enhanced by a very ‘leaky’ society with respect to information.

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Astrosettlement Development Strategy for human expansion into the solar system and beyond

Conceptual illustration of a Habitat Autonomous Locomotive Expandable (HALE) mobile self sustaining habitat under propulsion near a planetary destination. Credits: unknown artist via Thomas Matula

Dr. Thomas Matula, Professor at Sul Ross State University Uvalde, Texas, has developed an economically based strategy for space settlement. His plan addresses the deficiencies in many proposed visions of human expansion beyond earth, namely the missing economic and legal aspects needed for sustainable settlement of the solar system. Matula discussed his approach with David Livingston on The Space Show September 14 and in a paper entitled An Economic Based Strategy for Human Expansion into the Solar System attached to the show blog.

Astrosettlement Development Strategy (ADS) can be boiled down into a four step economically based roadmap for space settlement which could be started with minimal private funding. Each step would achieve economic success before moving on to the next level. The four levels are Earth based research, industrialization of the Moon, developing and settling the solar system and interstellar migration.

In the first step of Earth based research, Matula suggests developing a subscription based online role playing computer game with the purpose of creating a virtual simulation of a space settlement to model the social and economic aspects of communities beyond Earth. SSP has been following similar efforts already underway by Moonwards. Further research in this phase would look into space agriculture to understand the types of plants and dietary needs of space settlers and improving the efficiency of crop growth paving the way for self sustaining habitats. Matula has penned a different paper along these lines called The Role of Space Habitat Research in Providing Solutions to the Multiple Environmental Crises on Earth, also attached to the Space Show Blog, which could have duel use applications in addressing environmental problems on our home planet. There are already efforts underway in this arena with Controlled Environment Agriculture (CEA) utilizing greenhouse automation through the Internet of Things leading to reduction of water needs and an increase in crop yields.

“Developing the technology
to green the Solar System will also green the Earth for future generations”

Next on the roadmap is lunar industrialization. The focus of this step is to use robotics and in situ resource utilization to minimize the mass of materials lifted from Earth and to create lunar manufacturing capability in a cislunar economy that can be leveraged to build space based habitats for expansion into deep space.

Developing the solar system comes next. Once an economic foundation of industrialization of the Moon has been established, large mobile habitats can be built at the Earth-Moon Lagrange points L1 and L2. Called HALE, for Habitat Autonomous Locomotive Expandable, these are 1km wide self sustaining habitats with 1G artificial gravity capable of low energy transit throughout the solar system including out to the Kuiper Belt, where they can use the resources there to add to their size or build copies of themselves.

The final phase combines mobile free space settlement with advanced propulsion to develop the capability of expansion into the Oort cloud and on to the stars.

“…propulsion technology could advance to a point that would allow mobile space habitats designed for the Oort Cloud to be transformed into the first generational starships.”

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Enabling a multiplanetary civilization with photonic laser thrusters

Illustration of photonic laser thruster infrastructure for in-space transportation in cislunar space. Credits: Young K. Bae

Y.K. Bae Corp is on the verge of testing a revolutionary photonic laser thruster (PLT) that could be a game changer for in space propulsion and interplanetary travel. Founder and Chief Scientist Young K. Bae Ph.D described the technology in a recent Future In-Space Operations (FISO) Telecon presentation. The secret is generating thrust through photon pressure of a recycled laser beam enabling high energy to thrust efficiency without onboard propellant. Y.K. Bae Corp’s Continuous-Operation laser thruster or PLT-C is capable of delivering continuous thrust for long periods of time (e.g. days – years). The crew/payload section of the craft contains no power supplies, fuel or rocket engines. A power source is needed at the destination to generate a velocity reversal and stopping beam.

Dr. Bae believes an in-space “photonic railway” using this technology could open the solar system to commercialization and laid out a timeline for development of the photonic laser thruster. He believes that a 1 Newton (N) thrust PLT demonstration on the ISS could be accomplished within 3 years, a 50-N thrust PLT suborbital lunar launch is possible within 10 years, transits to the Moon can be done within 20 years and trips to Mars/Asteroids are projected to be in the 30 – 40 year timeframe.

When scaled up, super high ∆v can be achieved using the PLT. With a total electric laser power of 1000MW, travel times from the Earth to Mars could be achieved in less then 20 days for a 1-ton ship with 50% payload. From Mars out to Jupiter, a trip would take about 45 days for a craft with the same mass. The PLT spacecraft could be the main mode of rapid in-space transportation for humans and high price or lighter commodities after conventional thrusters (e.g. chemical rockets) establish the initial infrastructure and continue as the transportation choice for low cost or heavier payloads.

Illustration of a photonic railway using PLT infrastructure for in-space propulsion established at (from right to left, not to scale) Earth, Mars, Jupiter, Pluto and beyond. Credits: Young K. Bae.

Y.K. Bae Corp has demonstrated the photonic laser thruster technology in the lab. Check out their cubesat demo video.

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Update on SHEPHERD, an innovative spacecraft architecture for asteroid capture, mobilization and resource extraction

Artist renderings of an autonomous pneumatic handling system using SHEPHERD technology. An asteroid is first carefully enclosed in a touchless manner within a sealed fabric envelope, de-spun and de-tumbled through friction with an introduced controlling gas, then driven by continuous gas flow to introduce delta-V and deliver the asteroid to a target destination. Chemical and thermal interaction between the introduced atmosphere and the asteroid will permit fuel and water extraction, 3D electroforming of parts from metal sources and the creation of in-space biospheres to feed large habitats. Concept depicted by: Bruce Damer and Ryan Norkus with key design partnership from Peter Jenniskens and Julian Nott. Note: all of the illustrations in this post are credited as above unless otherwise indicated

The SHEPHERD concept for gentle asteroid retrieval with a gas-filled enclosure, an SSP favorite open source technology, has been covered in a previous post.  Dr. Bruce Damer, one of the coinventors of the system, recently appeared on SpaceWatch.Global’s Space Café podcast where he revisited this promising technology for capturing asteroids, mobilizing them and extracting key materials to support space settlement (which can be found near the end of the recording).  SHEPHERD could solve the three main sourcing problems of sustainable spaceflight and habitation: harvesting volatiles, building materials, and sources of food.  Dr. Damer has also been busy with his (and UCSC Prof. David Deamer’s) Hot Spring Hypothesis, a testable theory regarding the place and mechanism of the life’s origins on the Earth, which was the main focus of the podcast.  In fact, the arc of his career has tied these two endeavors together in interesting ways.  SSP reached out to Dr. Damer for an exclusive interview via email on these groundbreaking topics.

SSP: Dr. Damer, thank you so much for taking the time to answer my questions about SHEPHERD.  I’ve been excited and intrigued with the technology ever since I saw the initial paper and your 2015 TEDx talk.  Can you give our readers an overview of the concept?

Damer: The goal for SHEPHERD is to provide a universal technology to open the solar system to sustainable spaceflight and beyond that, to large scale human colonization (see figures and explanations for Fuel, Miner and Bio variants below). Enclosing an asteroid (or Near-Earth Object-NEO) within a fabric membrane and introducing a controlling gas would turn that asteroid into a “small world”. The temperature of the gas, its chemical composition and gas pressure forces set up within it can enable multiple in-situ resource utilization (ISRU) scenarios. Initially, the extraction of water and other volatiles from icy NEOs could provide fueling stations with deliveries throughout the solar system. Next, the use of the Mond-process carbonyl gas extraction from high-metallic NEOs can provide electroform 3D printing of large parts in space for construction of habitats. Lastly, melting the ice content of a NEO to a liquid phase surrounding its rocky core enables the introduction of microbes, algae and even some aquatic animals into a biosphere, a mini-Earth terrarium sustained in space. This one invention could provide many of the elements necessary for sustainable spaceflight but also for the construction and support of in-space and surface-located planetary and lunar habitats for thousands or millions of inhabitants. Co-inventor of the design, Dr. Peter Jenniskens at the SETI Institute, calls this the “sailing ship for space” harkening back to how his Dutch ancestors helped open the Earth to commerce centuries ago.

SHEPHERD-Fuel variant with volatiles such as water ice sublimating from the NEO into a warming gas, the resulting water vapor pumped down and condensed into liquids in storage tanks and then separated into hydrogen and oxygen. These tanks become the fuel source for a self-propelling tanker block which can be delivered to a refueling rendezvous point such as Earth cislunar space or Mars orbit
SHEPHERD-Miner version with an introduced carbonyl gas and an electric field dipole drawing off ions from a metallic NEO and layering them on a mandrel (shown on the left) to create a precision 3D part such as blocks, beams or tanks for space habitat construction
SHEPHERD-Bio variant sustaining a liquid biosphere around the rocky core of a NEO, with a lit interior and boom to introduce and extract organic materials. A balance of microbes, algae, and even small aquatic animals could maintain this small world, a “terrarium in space” to support large populations in habitats and at surface colonies
SHEPHERD-Fuel variant in Mars orbit or at some distance away showing the delivery of re-fillable tanker block sections to a Mars mission, the nearly empty block propelling itself for refilling. In this way ample fuel is provided in-situ prior to the craft arriving at Mars, with mission lander fuels, water for human consumption, shielding and return propellant provided in orbit in advance without having to extract volatiles from the Mars atmosphere or regolith
Vision of SHEPHERD Miner and Bio variants supporting a large habitat in LEO with the mantra of: “built in space, and fed in space”

SSP: Have there been any developments or updates to the concept since the initial TEDx talk and NewSpace Journal paper which both came out in 2015?

Damer: Back then we thought that no company or government had the will or capability to invest in such an opportunity, but this is now changing. The roaring success of NewSpace ventures such as SpaceX and their dual award of NASA’s Artemis Program returning humans to the moon based on reusable crewed launches and their recent successful low altitude testing rounds for Starship, has totally changed the space landscape of the near future. Jeff Bezos’ vision for megastructures in space based on the O’Neill colonies of the 1970s would require substantial asteroid resourcing. Elon Musk’s vision for large surface colonies on Mars would be equally well supported by simple, automated space based ISRU which overcomes substantial mining and manufacturing hazards attempting to process bulk materials on the surface of Mars or the moon. In addition, Bigelow’s success with inflatables, China’s surging space program with a new crewed station and rovers on the moon and Mars, all point to much more traffic and demand, especially for fueling depots, as early as the mid-2030s. Reducing the cost of lifting heavy and bulky materials from Earth may never be competitive to extraction, electroforming and farming in space with low-cost delivery directly to points of demand.

Earlier this year I determined that the time was right to place our invention out into the field again and seek partners to join in a development roadmap that will provide a solid financial and technical ladder for SHEPHERD’s maturation.

At a NASA/SETI meeting in January 2019 I was discussing SHEPHERD with members of the Luxembourg Space Agency and was overheard by space entrepreneur Carlos Calva. He approached me and offered that he would work with me to make SHEPHERD into a business. Subsequent meetings at SETI with my co-designer Peter Jenniskens (Julian Nott had died tragically in a ballooning accident) gave us early insights into SHEPHERD’s developmental timeline.

In that spring of 2019 Carlos and I engaged in a rapid-fire series of meetings developing a short-term cash business model for SHEPHERD which would provide a financial lever for the technology. Capturing, moving, and extracting resources from asteroids is a longer-term (15+ years) play, with no immediately apparent buyer for the first potential products: volatiles for propulsive fuel, air, water, and other crew consumables. Elon Musk and SpaceX might reach a point in this decade when they would buy a futures contract for hundreds, or thousands of tons of water and fuel delivered into Earth and Mars orbits sometime in the 2030s. Jeff Bezos may also want to finance the development of SHEPHERD as a technology for delivery of resources to build space habitats much as he has with Amazon’s funding of drone and other robotic fulfillment innovations.

But how to prove SHEPHERD as a technology and then sustain it as a business for long enough to be ready for either of these clients? We settled on two emerging market opportunities: 1) satellite servicing and decommissioning, and 2) hazardous debris removal and deorbiting. Both are potential cash businesses that could provide us achievable milestones to support the multiple investment rounds required. Satellite servicing and debris removal or de-risking is an urgent unmet market need for both governments and commercial operators worldwide. Along with the CubeSat revolution, SpaceX’s reusable launch platform and Bigelow Aerospace’s success with the inflatable Genesis and BEAM module on the ISS, many core technologies were maturing.

Making SHEPHERD into a viable sailing ship for space will not be without its challenges. Designing and flying a fabric enclosure which can open, admit an object (a satellite, a chunk of debris, or a space rock) and then closing it tight, sealing it well enough to fill it with a controlling gas was a major technical challenge which NASA identified  in their review of our 2014 Broad Agency Announcement proposal for the asteroid redirect program (since cancelled). The tried-and-true way to make a new space system work reliably is to build scale models, test them to failure, and test them again.

SSP: You mentioned that some of the capabilities of the system could be tested in LEO with CubeSats. Since the technology is open source, has anyone reached out to you to develop hardware for such an experiment? What would be tested and how?

Damer: Carlos and I made a bee-line for the world-renowned annual CubeSat Developer Conference meeting at Cal State San Luis Obispo in April of 2019 where we were able to interact with many of the leading thinkers and solution providers in the CubeSat industry. We devised a back-of-an-envelope LEO test vehicle flight series and made some key contacts. For a small investment (2-4 million USD), an effective six test flight series with a 4U CubeSat would first deploy a gas filled bag into which we could release a target object (such as a real meteorite which would be returned to space). The images below depict this scenario. Later flights in the series could have the target released to space and then the CubeSat would match orbits, track, enclose and seal the object into the enclosure. Key for any test is the ability to manage the object within the enclosure such that it does not contact the fabric. This would not be an issue for our small CubeSat, but it would be a potentially catastrophic encounter for a satellite or NEO. The key to safety (SHEPHERD stands for Secure Handling through Enclosure of Planetesimals Headed for Earth-Moon Retrograde Delivery) is that the system is touchless. In the image below we see gas jets firing to move the object toward and hold it in the center of the enclosure.

SHEP Cube test vehicle
Inflation of bag enclosure using controlling gas, introduced target object (perhaps a meteorite returned to space)
Management of target object position with gas jets
Lit interior showing target centered safely in the enclosure

All of this early effort to build and fly the CubeSat missions would mature our IP including: tracking, gas fluid dynamics for handling and enclosure deployment and sealing. We could then value the company and seek a round of investment from governmental or commercial partners in the satellite servicing and debris removal markets.

SSP: How do you foresee these two potential near term commercial applications generating sufficient revenue to “pay the way” for SHEPHERD to achieve its long-term goals?

A much larger SHEPHERD version with an enclosure for capture and servicing of a high value large satellite. Servicing could either be carried out with a robotic bay or by astronaut mechanics flying on SpaceX Dragon, who enter through an airlock and can breathe a low-pressure Earth atmosphere negating the need for bulky EVA/space suits

Damer: Paying the way for SHEPHERD could come from a mixture of satellite servicing (expensive “big birds” for the US DOD or communication satellite operators), orbit graveyarding (for GEO, or de-orbiting from LEO), and of course mitigation of dangerous space debris to head off Humanity’s disastrous  encounter with the “Kessler syndrome” as depicted in the movie Gravity. In-space satellite servicing via robotic spacecraft is problematic, requiring very high-risk grappling procedures between vehicles which have no built-in standard grappling mechanism. SHEPHERD provides a gas-based “pneumatic” way to safely envelop and control spacecraft without hard contact. Early computational studies at the SETI institute in 2014 established that a shape model of multi-ton asteroid 2008 TC3 could be de-tumbled and de-spun in less than 24 hours if the object was interacting within a gas at 10% Earth atmosphere pressure. The friction of the satellite or chunk of debris with the gas will bring it to a standstill, then gas jets can be used to rotate and position the enclosed spacecraft for servicing. Imparting a continuous driving force onto the craft using these same jets can create sufficient delta-V to change its orbit. Such safe handling and mobilization of objects in space is key to a whole range of future space operations. The irregularity of satellite shapes (including long booms or antennae) presents fewer challenges to SHEPHERD’s scale and size-independent gas handling system than they would to a robotic or crewed “jet pack” style EVA servicing as we saw with the Space Shuttle’s Hubble servicing missions.

If a satellite servicing, extension of life, or safe decommissioning capability were clearly on the horizon, supporters of international treaties and reinsurance companies could create guaranties, service contracts and insurance instruments which would finance a first generation of SHEPHERD vehicles.

SSP: What do you see as the full vision for the sustainable space architecture which SHEPHERD could enable?

A full vision of the architecture enabled by SHPHERD supporting near-Earth habitats, interplanetary missions, and a class of continuously cycling robotic and crewed spacecraft. Cycling visits of SHEPHERD ISRU supply depots could capture, relocate and extract from asteroids of all sizes and compositions. Eventually a mature SHEPHERD architecture could scale up enclosure sizes to provide the Earth a comprehensive planetary protection shield from larger NEO impact hazards

Damer: The image above depicts the enabling of SHEPHERD-derived spacecraft and processing facilities to support both near Earth space stations and larger megastructure colonies, robotic and human exploration of the inner solar system and beyond. I envision the SHEPHERD business being most akin to the mining industry I was raised around in British Columbia and as depicted in the Sci Fi series The Expanse. Some companies would fly prospecting (and orbit determination) missions to NEO targets, file claims and then sell them on to development companies. Those companies would license or build SHEPHERD-class spacecraft financed through contracts for future deliveries of commodities to companies and governments. Buyers would eventually acquire the risk-taking development companies and leverage them to support much larger projects such as space settlement megastructures or to supply Mars surface colony operations. Over time, scaling of the SHEPHERD system enclosure sizes would permit the safe handling and redirection of Earth-threatening asteroids giving us all a planetary protection shield. A great deal of Astrobiology science could also be supported such as the delivery of a pristine carbonaceous asteroid to Lunar orbit (see below) for astronaut geologists to sample. These samples might give us clues as to how life began on the Earth through the delivery of abundant organics from asteroids like this.

Release of pristine asteroid into Lunar orbit to support sampling by Astrobiologists looking for clues to life’s origins on the Earth, four billion years ago

SSP: What are the next steps for SHEPHERD?

Damer: The COVID-19 pandemic caused a pause on SHEPHERD’s development both as an engineering concept and a business. When I was invited to appear on the Space Café podcast in April (of 2021), I decided to bring it up again to gauge public interest and bring it to leaders in New Space. This interview with you is the next step in developing that interest, calling forward a development team. What I am also seeking is critical input from the community on the concept, leadership in research, and the formation of a company or university research program with financial support for the early on-ground computational and test-article studies leading up to CubeSat flights.

I specifically “open sourced” the basic concept of SHEPHERD on behalf of the three co-inventors in my 2015 TEDx talk, but IP developed by one or more implementers of this core concept can provide them and their investors with protectable value. The seal closure will be one key patentable innovation. Together with a team of keen and willing supporters including myself and Carlos, we produced a pitch deck which was first premiered at the Space Resources Roundtable held at the Colorado School of Mines in May of 2019. This deck concisely lays out the initial cash business in satellite servicing and debris removal and the engineering we have done around the CubeSat and larger variants. Carlos is back at work on the key steps of recruiting engineering leadership and funding for the ground-based development. I am open to inquiries from qualified contacts who wish to discuss their involvement seriously.

SSP: As you described above, of the three key applications of SHEPHERD, one could be food production for space settlements by creating a fully self-contained biosphere out of an asteroid, a mini-Earth if you will.  This complements your Hot Springs Hypothesis for life’s beginnings in its method for seeding space with life beyond Earth.  Is there an underlying principle linking the origin of life and humanity’s role in extending it beyond the cradle of the Earth?

Series of three images showing cellular mitosis beginning with fission of the nucleus, mitosis underway and completion of the process with daughter cells separated
SHEPHERD Bio with image of Earth overlain on its 500m diameter terrarium world
Mitosis of the Earth into “daughter worlds” represented by the arising of SHEPHERD-Bio in the solar system

Damer: Thank you for asking this question! A couple of years ago I literally sat bolt upright in bed having had a dream of a future vision of the solar system, possibly from the year 2100. A ring of asteroids had become enclosed with SHEPHERD craft or some derivative thereof, and thousands to millions of “new worlds” were orbiting the sun. In nearby orbits were the sharply geometric and tubular shapes of space settlements under construction, housing billions of humans and the organisms with which they cohabitate. Evolution had a future path, moving off our birth world by first creating many new ones. Like the first living cells, the Earth had undergone a spectacular mitosis! I realized in a flash that this future solar system was a huge scale evolution of the ancient hot spring pool cycling with membrane-enclosed protocells which Dave Deamer and I have proposed for life’s beginning. The principal of membranous encapsulation enabling chemical activity and resource sharing acted out four billion years ago in hot spring pools would return to enable life to emerge from the womb of the Earth into a long evolutionary future in the cosmos. It was truly gratifying. You can see how I then wove together these stunning parallel visions in my two TEDx talks below.

The SHEPHERD project is dedicated to the memory and genius of Julian Nott (right) at home in Santa Barbara during my 2014 visit

Links and Resources:

Humanity’s Next steps in Space | Dr. Bruce Damer | TEDxSantaCruz (April 15, 2015):
https://www.youtube.com/watch?v=wLMHcUg36yc

In the Beginning: The Origin & Purpose of Life | Dr. Bruce Damer | TEDxSantaCruz (April 15, 2015): https://www.youtube.com/watch?v=6qiW4aUqtvA

Peter Jenniskens’ first Asteroid Day SETI talk on the technical aspects of SHEPHERD: https://youtu.be/EnCTkUxgtZo

Update July 29, 2021: My interview of Dr. Damer along with David Livingston on The Space Show: https://www.thespaceshow.com/show/13-jul-2021/broadcast-3721-dr.-bruce-damer-john-jossy

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An efficient biological intensive oxygen and sustenance system for life support

Rendering of a toroidal space habitat with 12 centrifuges containing gardening units and four composing modules providing an environmental control life support system for a crew of 6. Credits: Thomas Lagarde / International Astronautical Federation

Fully closed environmental control life support systems for long term human space missions are difficult to achieve. But its possible to get closer using a novel approach proposed by Thomas Lagarde in a paper presented at the 69th International Astronautical Congress in Bremen, Germany which took place in October 2018. Using a combination of rotating greenhouses and worm composting units, the system would significantly reduce resupply while producing air and food with equipment that accelerates plant growth while efficiently recycling waste.

Lagarde starts with the inputs and outputs of a crew of six and determines what the surface area required for greenhouses to produce nutritious crops for sustenance and life support. He assumes that inflatable modules like Bigelow Aerospace’s B330 design could be a starting point for the enclosures and then extends the concept to a torus combining the advantages of a solid shell module with that of an inflatable. The greenhouses utilize a rotating garden concept called an “omega garden unit” (OGU) based on an Omega Garden, Inc’s rotary hydroponics system which maximizes crop yield while minimizing space requirements. Growing plants under these conditions, i.e. with artificial gravity, has been shown to activate plant hormones called auxin, thereby increasing their growth rate. The use of an organic light-emitting diode source at the axis of the centrifuge provides a commercially available solution for optimal light exposure while saving space, energy and generating less heat.

To make significant progress toward closure of the life support system recycling loop, human waste and non-edible plant parts become worm food in composting units. This natural process can be accelerated under the right conditions, achieving exponential growth of the worm population but can be self-regulated as described in detail in the paper.

Lagarde sums up the research by saying: “After studying all the different aspects of plant growth and composting, we can conclude that the combination of a rotating garden and processing of organic products by worms will provide enough food and fresh air for a crew of 6 in a minimal space.”

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Self replicating factories for space settlement

Artist’s illustration of a self replicating factory near an asteroid and serviced by a SpaceX Starship. Credits: Michel Lamontagne / Principium

The technology of self replicating machines has been gradually progressing toward maturity over the last few decades. The Space Studies Institute recognized this key enabler of space settlement as far back as the 1980s and covered the topic frequently in its newsletter updates. Now Michel Lamontagne has provided a status update in the latest issue of Principium. On page 50, he highlights the history of self replicating factories, provides a vision for the evolution of the concept for production of space settlement infrastructure and gives a summary of recent developments in key areas of research such as additive manufacturing, machine learning and cheap access to space that will be enablers of this space based industry.

The first factory will be built on the Moon after deep learning simulations prove the concept on Earth. Eventually the more autonomous versions would migrate to Mars and then to what may be the best suited location, the asteroid belt which “…may be the ultimate resource for space settlement construction.” Lamontagne believes “These factories would then follow humanity to the Stars, after having helped to build the infrastructure required for the occupation of the solar system and for Interstellar travel.”

Artist’s rendering of an early self replicating factory on the Moon with SpaceX Starships serving as basic construction elements. Credits: Michel Lamontagne / Principium
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Determining the gravity prescription for long term space settlement

Credits: Dai Shiba et al.* / Nature. http://creativecommons.org/licenses/by/4.0/

If humanity is to ever move off Earth, clearly we will need to be able to have children wherever we establish long term settlements. But, as humans have evolved over millions of years in Earth’s gravitational field, normal gestation may not be possible on the Moon or Mars. This is probably the most important physiological question to be answered before outposts are permanently occupied on these worlds. We can shield people from radiation, we can recycle wastes and use ISRU to replenish consumables for life support. But we may find that artificial gravity either in free space rotating habitats or on planetary surface settlements is required for settlers to have healthy children. In fact, when I asked Dr. Shawna Pandya, a physician and expert in space medicine about it on The Space Show, she said “…that is the million dollar question”.

Numerous studies have shown the deleterious effects of long term microgravity on human health. So we know that humans will need some level of gravity for sustainable occupation. But what level is enough to stave off the effects of lower gravity on human health and what about reproduction under these conditions? Plus, there is the problem of how to run ethical clinical studies to answer these questions? The Japan Aerospace Exploration Agency (JAXA) has started research in this area by studying mice under variable gravity conditions aboard their Kibo module on the International Space Station using a Multiple Artificial-gravity Research System (MARS). Results of this first ever long term space based mouse habitation study with artificial gravity were published in a paper called Development of new experimental platform ‘MARS’—Multiple Artificial-gravity Research System—to elucidate the impacts of micro/partial gravity on mice in Nature back in 2017. The authors* of the paper found that significant decreases in bone density and muscle mass of the mice reared under microgravity conditions were evident when compared to a cohort raised under 1G indicating that artificial gravity simulating the surface of the Earth may prevent negative health effects of microgravity in space. The next obvious step was to test the mice in 1/6 G simulating conditions on the Moon. This experiment was ran in 2019 but the results have not yet been published. SSP has reached out to JAXA with an inquiry on when we can expect a report. This post will be amended with an update if and when an answer is received.

Reproduction of mice or other mammals has not been studied in space under variable gravity conditions. The problem screams out for a dedicated space based artificial gravity facility such as the Space Studies Institute’s G-Lab and others (e.g. Joe Carroll’s Partial Gravity Test Facility ). Even if such a laboratory existed, how would ethical clinical studies on higher mammal animal models to simulate human physiology during pregnancy be carried out? Answering this question will come first before the million dollar one.

June 2, 2023 Update: JAXA finally released the results of their 2019 study on mice subjected to 1/6 G partial gravity in a paper in Nature in April. There is good news and not-so-good news. The good news is that 1/6 G partial gravity prevents muscle atrophy in mice. The downside is that this level of artificial gravity cannot prevent changes in muscle fiber (myofiber) and gene modification induced by microgravity. There appears to be a threshold between 1/6G and Earth-normal gravity, yet to be determined, for skeletal muscle adaptation.

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* Authors of Development of new experimental platform ‘MARS’—Multiple Artificial-gravity Research System—to elucidate the impacts of micro/partial gravity on mice: Dai Shiba, Hiroyasu Mizuno, Akane Yumoto, Michihiko Shimomura, Hiroe Kobayashi, Hironobu Morita1, Miki Shimbo, Michito Hamada, Takashi Kudo,
Masahiro Shinohara, Hiroshi Asahara, Masaki Shirakawa and Satoru Takahash