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.
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.
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.”
“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
“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.”
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
Conceptual illustration of the Minerva Space Settlement in orbit around Jupiter’s moon Ganymede. Credits: Minerva Project Team
Space Settlement Progress typically features the latest advancements in technology that are enabling the settlement of space. This post will be a little different. When attending the International Space Development Conference last May I was impressed by a team of students from Highschool Colegiul National Andrei Saguna in Romania, who had conceived of a space settlement in orbit around Jupiter’s satellite Ganymede which they call Minerva. The project was an entry in the National Space Societies’ Space Settlement Contest, and for which they won a second place award for 9th graders. While admiring their poster I was approached by Maria Vasilescu, who proudly described their project and agreed to collaborate with me on this post. She spoke perfect English, shared marketing materials (key chains, buttons and bookmarks with QR codes linking to their website) and explained that the primary purpose of Minerva would be a deep space location for a University of Space Exploration. I was intrigued by the concept and was struck by Maria and her teammates’ enthusiastic vision of humanity’s future in space. I wanted to know more about what motivated this group of teenagers to come together and create such an imaginative project, as youths like them will be future pioneers on the High Frontier. Maria agreed to coordinate with her team on an interview via email about Minerva.
The Minerva Project Team and their poster session at ISDC 2023, a second prize winner for 9th graders of the NSS Space Settlement Contest. Credits: Minerva Project Team: clockwise from lower right: Bodean Mircea-Sorin, Ana Radus, Andrei Ioan Prunea, Alexandra Nica, Alexandra Maria Nemes, Maria Vasilescu
SSP: How did the team come up with this Minerva concept?
Minerva: We took inspiration from our school which gave us a lot of opportunities to which we owe a lot and we wanted to build such a university in the final frontier.
SSP: You mentioned stumbling across some obstacles during your journey but sticking together by motivating each other. Is this an experience you feel comfortable sharing?
Minerva: One of the hardest things was to think about all the aspects that go into making a space settlement as ninth graders, such as the form [Forum on the website], which was decided in the last week, or the economical part. But we managed to meet often and brainstorm to come up with better ideas.
SSP: You said that the project helped you discover your true selves. Can you explain how this came about?
Minerva: We developed ourselves and our passions and we found out what we like because it covers a broad area of subjects beyond science. We managed to see by which area we are drawn to and enjoy actually researching.
SSP: You’ve stated that one of the reasons for building Minerva is to invent new lifestyles different from those that exist on Earth. How do you envision lifestyles changing in space?
Minerva: The university can prepare you for life in space, which will be an important part in the humans’ future, therefore we don’t want to invent new lifestyles, but incorporate space in the ones that already exist.
SSP: You’ve proposed auctioning a Minerva NFT to fund your efforts and future experiments. Would this be the sole source of financing for the project, and will it be sufficient? What about simply charging tuition for the USE?
Minerva: Everything on our settlement is given and made by us for the people so they don’t need to have money to buy material things. And because we have worked to make almost everything renewable and green, the funds MinervaNFT will bring are more than sufficient for everything else. And as for tuition, we feel like putting students through an exam such as the one that defines their attendance to USE is stressful enough as it is. However, the students will need to pay for the transport from Earth to the settlement.
SSP: There does not appear to be any trade or economic activity on Minerva, only academic studies. Students may choose to return to Earth or stay on the space station after they complete their studies. If they stay, have you considered the possibility of graduates developing and marketing other industries such as software development, robotics, mining water from Ganymede as rocket fuel, intellectual property on life support systems, or many other potential industries that could arise from scientific innovation that would take place on a space settlement? Or would this be totally an academic institution?
Minerva: It is not a totally academic institution because we have two thirds of the ship which will be occupied by students that remained on the settlement. But here, you don’t need money, everything being provided by us, so people don’t work for money, they work to occupy time, for enjoyment. If they do develop other industries, it will be fully for the greater good of humanity and the future of our kind, not for money.
SSP: The location chosen for Minerva is very challenging from an engineering perspective. Although Ganymede is not deep in Jupiter’s magnetosphere, and has its own magnetic field which could help mitigate exposure, the location will still have high levels of radiation if unprotected, which complicates the design because much more mass is needed to provide adequate shielding to be safe for humans. In addition, travel times to Jupiter are quite long even with improved propulsion which you’ve indicated would be as high as four years for students wanting to make the journey. Finally, solar energy at Jupiter’s remote distance from the sun requires that photovoltaic arrays be enormous to provide sufficient energy. A good compromise might be the asteroid Ceres, which is believed to be 25% water and does not have a magnetic field generating high radiation like what would be experienced at Jupiter. Others have proposed this asteroid as a good destination for space settlement. Why not locate the settlement in a more accessible and hospitable environment that might reduce costs?
Minerva: The main reason we chose such a far away location is precisely because we want to explore as much as possible of the cosmos. It’s not that we don’t want a closer location, it’s just that we know very little about Jupiter and its surrounding moons and further and this university can offer humanity an opportunity to explore it and send the research back to Earth. At the same time, we have taken the radiation into consideration and just how today’s spaceships have protection against it, so how [sic] our settlement, but ten times more efficient.
SSP: The sources of power for Minerva include solar arrays and nuclear fission, but you excluded fusion energy because it is currently experimental. By the time it will be technologically possible to travel to Jupiter and establish infrastructure that far out in the solar system, we will have developed fusion energy for use on Earth as well as in space. The preliminary design work for a Direct Fusion Drive for rapid transit to the outer planets has been started by Princeton Satellite Systems and the Fusion Industry Association just came out with their third annual report stating that the industry has now attracted over $6 billion in investment. When it is feasible to begin work on Minerva, fusion power sources will likely be available. Will you be updating your project plan as new technologies become available?
Minerva: Of course, we are sure that many aspects of our settlement can be improved by future developments in science, engineering and many other fields. As much as possible, we will incorporate them into our settlement. As mentioned in our paper, when talking about technological advances that may happen, we have to keep up with innovation and incorporate them to help us fulfill every need when travelling to space.
SSP: You raised the concern that Earth is approaching a major crisis with population growth putting a strain on Earth’s vital resources. You also said that the purpose of the space community is to sustain humanity if Earth’s environment became unfavorable for life. In selecting the location of Minerva, when considering Mars and its orbital distance, you said that even though it fulfills most of your requirements “…the disadvantage of Mars its it proximity to Earth…” and it “…is too close to our planet in order for us to choose it as the proper placement for the spacecraft.” Why must Minerva be distant from Earth if the planet is in crisis in the future and why isn’t the orbit of Mars, at 56 million kilometers, considered not far enough away?
Minerva: Mars wasn’t a viable option because, as we have stated before, the purpose of the USE is to gather information and scientific news that can only be found in the farther cosmos. We already know a lot about Mars and planets in close proximity to Earth, we want to venture further, discover and experiment with more than we already have.
SSP: Some surveys say that young people live in fear of the future due to climate change. Many media outlets amplify this doom and gloom. However, some economists point out that using the United Nation’s own data from the Intergovernmental Panel on Climate Change, with the predicted increase in temperature by the year 2100, global GDP will be reduced by only 4% to deal with climate related impacts. Although it is clear that we should eventually reduce our dependance on fossil fuels this is not an existential threat. Plus, technological innovation continues to improve efficiency in resource utilization, energy development and agriculture, enabling higher standards of living notwithstanding increasing population growth.
The viewpoint that the Earth is in “crisis” is closely aligned with Elon Musk’s motivation, who believes it is urgent that we become a multiplanetary species, to have a “Plan B” in case of a planetwide catastrophe. Jeff Bezos has a different perspective, that heavy industrial activity could be moved off world to preserve the Earth’s natural environment and to improve humanities’ standard of living though utilization of unlimited space resources.
Gerard K. O’Neill saw the promise of space settlement as a way to solve Earth’s problems through the humanization of space. He saw it as a way to end poverty for all humans, provide high-quality living space that would continue to grow robustly, to moderate population growth without war, famine, dictatorship or coercion; and to increase individual freedom. Does your team share the same anxiety about the future as other young people: that life on Earth is doomed and therefore, we need to build Minvera as a sanctuary to preserve humanity? Or do you see it as one among many options for space settlement to improve life on Earth and beyond, as outlined in O’Neill’s vision?
Minerva: We see Minerva as a place where people that are smart and passionate about space have a chance to make scientific discoveries that would be impossible to do on Earth. Aligned with Gerald O’Neil’s [sic] view, we believe that humans should expand into space whether it is as a Plan B or by harvesting resources from other planets or celestial objects. With the help of Minerva, the smartest children of their generation will be able to experience these scenarios and be closer to the future. We don’t see Minerva as a Plan B for humanity, students that have finished their 4 years being able to return to earth, but rather as a place where people can enjoy a stress free and enjoyable environment. Therefore Minerva is preparing smart youngsters to be able to take advantage of any of the two cases. If they choose to remain on Earth, the knowledge that they acquired while in the USE will definitely increase humanity’s survivability against the existential threats mentioned.
SSP: You’ve created a survey [what was earlier referred to as a “Form” and can be found at the “Forum” link on the Minerva website] for anyone to express their opinion about your project and the prospect of living in space. Will you use this feedback to improve your project?
Minerva: Maybe in the future, yes. We have encouraged people to complete the survey honestly and there’s always place for improvement for anything. And the second reason is to observe humanity’s view on such a settlement. In creating such a complex space settlement, you need to align your view with the society’s beliefs, them being the ones who will eventually populate it.
SSP: Does your team expect to remain engaged with the project as you progress in your education and after you eventually establish your careers here on Earth?
Minerva: It was certainly an experience we will treasure for a long time, but not everything has to be drawn out. I think this project took a lot of work and effort and we want to invest into something new, see this contest from as many angles as possible while we can. This project like no other can incorporate so many aspects of society from which you can discover your biggest passions. Talking to everyone in our group, we found that each one of us enjoyed a different part of the project and we believe that that was the key to our win. We were all doing something we are passionate about and therefore worked even harder for the final result. Now that we’ve learned what topics intrigue us, we can start doing even more work in that domain. We believe that this project is the perfect opportunity and will open numerous doors in any future career path. We strongly recommend this contest to anyone wondering whether they should put their effort into it or not.
Artist’s impression of the interior of an O’Neill Cylinder space settlement near the endcap. Credits: Don Davis courtesy of NASA
Its a given that space travel and settlement are difficult. The forces of nature conspire against humans outside their comfortable biosphere and normal gravity conditions. To ascertain just how difficult human expansion off Earth will be, a new quantitative method of human sustainability called the Panscosmorio Theory has been developed by Lee Irons and his daughter Morgan in a paper in Frontiers of Astronomy and Space Sciences. The pair use the laws of thermal dynamics and the effects of gravity upon ecosystems to analyze the evolution of human life in Earth’s biosphere and gravity well. Their theory sheds light on the challenges and conditions required for self restoring ecosystems to sustain a healthy growing human population in extraterrestrial environments.
“Stated simply, sustainable development of a human settlement requires a basal ecosystem to be present on location with self-restoring order, capacity, and organization equivalent to Earth.”
The theory describes the limits of space settlement ecosystems necessary to sustain life based on sufficient area and availability of resources (e.g. sources of energy) defining four levels of sustainability, each with increasing supply chain requirements.
Level 1 sustainability is essentially duplicating Earth’s basal ecosystem. Under these conditions a space settlement would be self-sustaining requiring no inputs of resources from outside. This is the holy grail – not easily achieved. Think terraforming Mars or finding an Earth-like planet around another star.
Level 2 is a bit less stable with insufficient vitality and capacity resulting in a brittle ecosystem that is subject to blight and loss of diversity when subjected to disturbances. Humans could adapt in a settlement under these conditions but would required augmentation by “…a minimal supply chain to replace depleted resources and specialized technology.”
Level 3 sustainability has insufficient area and power capacity to be resilient against cascade failure following disturbances. In this case the settlement would only be an early stage outpost working toward higher levels of sustainability, and would require robust supplemental supply chains to augment the ecosystem to support human life.
Level 4 sustainability is the least stable necessitating close proximity to Earth with limited stays by humans and would require an umbilical supply chain supplementing resources for human life support, and would essentially be under the umbrella of Earth’s basal ecosystem. The International Space Station and the planned Artemis Base Camp would fall into this category.
Understanding the complex web of interactions between biological, physical and chemical processes in an ecosystem and predicting early signs of instability before catastrophic failure occurs is key. Curt Holmer has modeled the stability of environmental control and life support systems for smaller space habitats. Scaling these up and making them robust against disturbances transitioning from Level 2 to 1 is the challenge.
How does gravity fit in? The role of gravity in the biochemical and physiological functions of humans and other lifeforms on Earth has been a key driver of evolution for billions of years. This cannot be easily changed, especially for human reproduction. But even if we were able to provide artificial gravity in a rotating space settlement, the authors point out that reproducing the atmospheric pressure gradients that exist on Earth as well as providing sufficient area, capacity and stability to achieve Level 1 ecosystem sustainability will be very difficult.
Peter Hague agrees that living outside the Earth’s gravity well will be a significant challenge in a recent post on Planetocracy. He has the view, held by many in the space settlement community, that O’Neill colonies are a long way off because they would require significant development on the Moon (or asteroids) and vast construction efforts to build the enormous structures as originally envisioned by O’Neill. Plus, we may not be able to easily replicate the complexity of Earth’s ecosystem within them, as intimated by the Panscosmorio Theory. In Hague’s view Mars settlement may be easier.
Should we determine the Gravity Rx? Some space advocates believe that knowledge of this important parameter, especially for mammalian reproduction, will inform the long term strategy for permanent space settlements. If we discover, through ethical clinical studies starting with rodents and progressing to higher mammalian animal models, that humans cannot reproduce in less than 1G, we would want to know this soon so that plans for the extensive infrastructure to produce O’Neill colonies providing Earth-normal artificial gravity can be integrated into our space development strategy.
Others believe why bother? We know that 1G works. Is there a shortcut to realizing these massive rotating settlements without the enormous efforts as originally envisioned by Gerard K. O’Neill? Tom Marotta and Al Globus believe there is an easier way by starting small and Kasper Kubica’s strategy may provide a funding mechanism for this approach. Given the limits of sustainability of the ecosystems in these smaller capacity rotating settlements, it definitely makes sense to initially locate them close to Earth with reliable supply chains anticipated to be available when Starship is fully developed over the next few years.
Companies like Gravitics, Vast and Above: Space Development Corporation (formally Orbital Assembly Corporation) are paving the way with businesses developing artificial gravity facilities in LEO. And last week, Airbus entered the fray with plans for Loop, their LEO multi-purpose orbital module with a centrifuge for “doses” of artificial gravity scheduled to begin operations in the early 2030s. Panscosmorio Theory not withstanding, we will definitely test the limits of space settlement sustainability and improve over time.
Listen to Lee and Morgan Irons discuss their theory with David Livingston on The Space Show.
Artist’s rendering of a farming settlement on Mars. Credits: HP Mars Home Planet Rendering Challenge via International Business Times.
Space settlement will eventually require space farming to feed colonists and to provide life support. It’s clear that we will replicate our biosphere wherever we go. In that spirit, Bryce L. Meyer envisions Mars as the breadbasket of the outer solar system. In a presentation at Archon 45, a science fiction and fantasy convention held annually by St. Louis area fans, he makes the case for why the fourth planet would be the ideal spot to grow crops and feed an expanding population as part of the roadmap to agriculture in space.
Carbon dioxide and subsurface water ice are plentiful on Mars, critical inputs for crop photosynthesis. There is also evidence of lava tubes there which could provide an ideal growing environment protected from radiation, micrometeorite bombardment and temperature extremes. The regolith should provide good nutrients and there is already research on methods to filter out perchlorates, a toxic chemical compound in the Martian soil.
Image of Lava tubes on the surface of Mars as photographed by ESA’s Mars Express spacecraft. Credits: ESA/DLR/FU Berlin/G Neukum / NewScientist
Another advantage that Mars holds as a food production hub for the asteroids and beyond is its placement further out in the solar system. Since it is higher up in the sun’s gravity well, Meyer calculates that it would take less than 43% of the fuel needed to transport goods from Mars outward than from Earth. He even suggests that with its lower gravity and recent advancements in materials research, a space elevator at Mars could be economically feasible to cheaply and reliably transport foodstuff off the planet.
Meyer keeps a webpage featuring space agriculture, terraforming, and closed cycle microgravity farming where he poses the question “Why settle space?” I like his answer: “Trillions of Happy Smiling Babies!!!”
Basic input/output diagram of an environmental control and life support system like what would be expected in a space farm. Credits: Bryce L. Meyer
Meyer is the founder and CEO of Cyan React, LLC, a startup that designs compact photobioreactors and provides expertise in closed-cycle farming and life support especially for space settlement and space habitats. He is also a National Space Society Space Ambassador doing his part to educate the public about the potential benefits to humanity through the use of the bountiful resources in space. In a presentation at this year’s International Space Development Conference, he describes his research on bioreactors explaining how settlers will grow food and recycle waste sustainably on the high frontier.
Diagram depicting the flow of materials in a closed space farm habitat utilizing bioreactors. Credits: Bryce L. Meyer
Complete closure and stability of an environmental control and life support system (ECLSS) is challenging and not without limitations. As launch and space transportation costs come down in the near future and off-Earth supply chains become more reliable, complete closure will not be required at least initially. In situ resource utilization will provide replacement of some ECLSS consumables where available for colonists to live off the land. As missions go deeper into space reaching the limits of supply chain infrastructure and even out to the stars, closure of habitat ECLSS and resource planning will become more important. Meyer has done the math for farms in space to provide food and air for trillions of smiling babies…and their families as they move out into the solar system.
Artist concept of a cutaway view of the Stanford Torus free space settlement. Credits: Rick Guidice / NASA
Can humanity explore and develop space responsibly by learning from some of the mistakes made throughout history while settling new lands? In an article called “To Boldly Go (Responsibly)” on LinkedIn, CEO of Trans Astronautica Corporation Joel Sercel provides a vision for how we should conscientiously manage space settlement in a manner that respects human rights and the rule of law, but also maintains stewardship of the space environment.
“Through space settlement, we have a chance to show that humanity has learned from history and is evolving morally and culturally”
Sercel warns of the “Elysium effect”. In the words of Rick Tumlinson, who coined the term in an article on Space.com, “…as entrepreneurs like Elon Musk, Jeff Bezos and Richard Branson spend billions to support a human breakout into space, there is a backlash building that holds these projects as icons of extravagance.” Ironically, these New Space pioneers actually have the opposite goals of lowering the cost of access to space for average citizens and preserving the Earth’s environment by moving “dirty” industries outside it’s biosphere.
Public space agencies and private space companies can help open the high frontier responsibility through cooperation on development of common standards and international agreements in accordance with the Outer Space Treaty. Sercel believes that an urgent need in this area would be establishment of salvage rights for defunct satellites and dormant orbital debris like spent upper stages which under the OST are the responsibility of the nation that launched the payloads.
“That’s a legal impediment for companies developing satellites to clean up orbital debris and firms eager to recycle abandoned antennas and rocket bodies.”
Some work in the area of orbital debris mitigation has already been started by the Space Safety Coalition, an ad hoc coalition of companies, organizations, and other government and industry stakeholders, through establishment of best practices and standardization for space operations. And just last month the Orbital Sustainability Act of 2022 was introduced in the U.S. Senate that will “require the development of uniform orbital debris standard practices in order to support a safe and sustainable orbital environment.”
Good progress on interagency cooperation in space has also been made with the creation of the Artemis Accords, Principles for a Safe, Peaceful, and Prosperous Future. Signed by seven nations thus far, the agreement provides a legal framework in compliance with the OST for humans returning to the Moon and establishing commercial mining rights.
Sercel thinks that before establishing a permanent human presence on Mars we should first thoroughly explore the planet robotically for signs of life to ensure that we do not disrupt any indigenous organisms if a biosphere is found to be present there.
Another example of space ethics, discussed on SSP in previous posts, is determination of the gravity prescription, especially the human gestation component. The answer to this critical factor may drive the decision on where to establish permanent long term settlements so colonists can raise families. It may turn out that having children in less than 1G may not be biologically possible and therefor, for ethical reasons, may change the long term strategy for human expansion in the solar system favoring free space settlements with Earth normal artificial gravity over surface settlements. Sercel believes that determination of the gravity Rx should be a high priority and suggested on The Space Show recently a roadmap of mammalian clinical reproduction studies starting with rodent animal models producing offspring over multiple generations progressing to primates and then, only if these are successful, initiating limited human experiments. Such studies would prevent ethical issues that may arise from birth defects or health problems during pregnancy because we don’t know how lower gravity would effect embryos during gestation.
Dylan Taylor of Voyager Space Holdings has advocated for a sustainable approach to space commercial activities to ensure “…that all humanity can continue to use outer space for peaceful purposes and socioeconomic benefit now and in the long term. This will require international cooperation, discussion, and agreements designed to ensure that outer space is safe, secure and peaceful.”
Sercel is calling for the National Space Council “…to coordinate private organizations to include think tanks, advocacy groups, and the science community to work together to define the field of space ethics…to guide the development of laws and regulations that will ensure the rapid and peaceful exploration, development and settlement of space.”
SSP has addressed the gravity prescription (GRx) in previous posts as being a key human factor affecting where long term space settlements will be established. It’s important to split the GRx into its different components that could effect adult human health, child development and reproduction. We know that microgravity (close to weightlessness) like that experienced on the ISS has detrimental effects on adult human physiology such as osteoporosis from calcium loss, degradation of heart and muscle mass, vision changes due to variable intraocular pressures, immune system anomalies…the list goes on. But many of these issues may be mitigated by exposure to some level of gravity (i.e. the GRx) like what would be experienced on the Moon or Mars. Colonists may also have “health treatments” by brief exposures to doses of 1G in centrifuge facilities built into the settlements if the gravity levels in either location is found to be insufficient. We currently have no data on how human physiology would be impacted in low gravity (other then microgravity).
The most important aspect of the GRx with respect to space settlement relates to reproduction. How would lower gravity effect embryos during gestation? Since humans have evolved in 1G for millions of years, a drastic change in gravity levels during pregnancy could have serious deleterious effects on fetal development. Since fetuses are already suspended in fluid and can be in any orientation during most of their development, it may be that they don’t need anywhere near the number of hours of upright, full gravity that adults need. How lower gravity would affect bone and muscle growth in young children is another unknown. We just don’t know what would happen without a clinical investigation which should obviously be done first on lower mammals such as rodents. Then there are ethical questions that may arise when studying reproduction and growth in higher animal models that could be predictive of human physiology, not to mention what would happen during an accidental human pregnancy under these conditions.
Right now, we only know that 1G works. If space settlements on the Moon or Mars are to be permanent and sustainable, many space settlement advocates believe they need to be biologically self-sustaining. Obviously, most people are going to want to have children where they establish permanent homes. If the gravity of the Moon or Mars prevents healthy pregnancy, long term settlements may not be possible for people who want to raise families. This does not rule out permanent settlements without children (e.g. retirement communities). They just would not be biologically self-sustaining.
SSP has suggested that it might make sense to determine the GRx soon so that if we do determine that 1G is required for having children in space, we begin to shape our strategy for space settlement around free space settlements that produce artificial gravity equivalent to Earth’s. Fortunately, as Joe Carroll has mentioned in recent presentations, the force of gravity on bodies where humanity could establish settlements throughout the solar system seems to be “quantized” to two levels below 1G – about equal to that of the Moon or Mars. All the places where settlements could be built on the surfaces of planets or on the larger moons of the outer planets have gravity roughly at these two levels. So, if we determine that the GRx for these two locations is safe for human health, we will know that we can safely raise families beyond Earth in colonies on the surfaces of any of these worlds. Carroll proposes a Moon/Mars dumbbell gravity research facility be established soon in LEO to nail down the GRx.
But is there an argument to be made for skipping the step of determining the GRx and going straight to an O’Neill colony? After all, we know that 1G works just fine. Tom Marotta thinks so. He discussed the GRx with me on The Space Show recently. Marotta, with Al Globus coauthored The High Frontier: An Easier Way. The easier way is to start small in low Earth orbit. O’Neill colonies as originally conceived by Gerard K. O’Neill in The High Frontier would be kilometers long in high orbit (outside the Earth’s protective magnetic field) and weigh millions of tons because of the amount of shielding required to protect occupants from radiation. The sheer enormity of scale makes them extremely expensive and would likely bankrupt most governments, let alone be a challenge for private financing. Marotta and Globus suggest a step-by-step approach starting with a far smaller version of O’Neill’s concept called Kalpana. This rotating space city would be a cylinder roughly 100 meters in diameter and the same in length, spinning at 4 rpm to create 1G of artificial gravity and situated in equatorial low Earth orbit (ELEO) which is protected from radiation by our planet’s magnetic field. If located here the settlement does not require enormous amounts of shielding and would weigh (and therefore cost) far less. Kasper Kubica has proposed using this design for hosting $10M condominiums in space and suggests an ambitious plan for building it with 10 years. Although the move-in cost sounds expensive for the average person, recall that the airline industry started out catering to the ultra-rich to create the initial market which eventually became generally affordable once increasing reliability and economies of scale drove down manufacturing costs.
What about all the orbital debris we’re hearing about in LEO? Wouldn’t this pose a threat of collision with a free space settlement given their larger cross-sections? In an email Marotta responds:
“No, absolutely not, I don’t think orbital debris is a showstopper for Kalpana.
… First, the entire orbital debris problem is very fixable. I’m not concerned about it at all as it won’t take much to clean it up: implement a tax or a carbon-credit style bounty system and in a few years it will be fixed. Another potential historical analogy is the hole in the ozone layer: once the world agreed to limit CFCs the hole started healing itself. Orbital debris is a regulatory and political leadership problem, not a hard technical problem.
Second, even if orbital debris persists, the technology required to build Kalpana…will help protect it. Namely: insurance products to pay companies (e.g. Astroscale, D-Orbit, others) to ‘clear out’ the orbit K-1 will inhabit and/or mobile construction satellites necessary to move pieces of the hull into place can also be used to move large pieces of debris out of the way. In fact, I think having something like Kalpana…in orbit – or even plans for something that large – will actually accelerate the resolution of the orbital debris problem. History has shown that the only time the U.S. government takes orbital debris seriously is when a piece of debris might hit a crewed platform like the ISS. Having more crewed platforms + orbital debris will drastically limit launch opportunities via the launch collision avoidance process. If new satellites can’t be launched efficiently because of a proliferation of crewed stations and orbital debris I suspect the very well-funded and strategically important satellite industry will create a solution very quickly.”
To build a space settlement like the first Kalpana, about 17,000 tons of material will have to be lifted from Earth. Using the current SpaceX Starship payload specifications this would take 170 launches to LEO. By comparison, in 2021 the global launch industry set a record of 134 launches. Starship has not even made it to orbit yet, but assuming it eventually will and the reliability and reusability is demonstrated such that a fleet of them could support a high launch rate, within the next 20 years or so there will be considerable growth in the global launch industry. If larger versions of Kalpana are built the launch rate could approach 10,000 per year for space settlement alone, not to mention that needed for rest of the space industry. This raises the question of where will all these launches take place? Are there enough spaceports in the world to support it? Marotta has an answer for this as well. As CEO of The Spaceport Company, he is laying the groundwork for the global space launch infrastructure that will be needed to support a robust launch industry. His company is building distributed launch infrastructure on mobile offshore platforms. Visit his company website at the link above for more information.
Conceptual illustration of a mobile offshore launch platform. Credits: The Spaceport Company
For quite some time there has been a spirited debate among space settlement advocates on what destination makes the most sense to establish the first outpost and eventual permanent homes beyond Earth. The Moon, Mars or free space O’Neill settlements. Each location has its pros and cons. The Moon being close and having ice deposits in permanently shadowed craters at its poles along with resource rich regolith seems a logical place to start. Mars, although considerably further away has a thin atmosphere and richer resources for in situ utilization. Some believe we should pursue all the above. However, only O’Neill colonies offer 1G of artificial gravity 24/7. With so many unknowns about the gravity prescription for human health and reproduction, free space settlements like Kalpana offer a safe solution if the markets and funding can be found to make them a reality.
Schematic of the Thorium Molten Salt Reactor for space propulsion applications. Credits: Ajay Kothari / The Space Review
President Joe Biden recently signed into law a sweeping climate bill that will have very little (if any) impact on addressing global warming (a reduction of 0.028 degrees F by 2100). While there are tax credits in the bill for construction of new nuclear power plants over the next 10 years, only two are planned to add to the existing 93 facilities operating today which provide 18% of the U.S. energy production. Most of the funding in the bill is targeted at tax credits for EVs and incentives for renewable sources such and wind and solar which are subject to interruption. Nuclear energy holds enormous promise to offset the carbon emissions associated with fossil fuel energy production and can provide reliable base load power, but it is still plagued by negative public perceptions related to safety and the potential for weapons proliferation.
Is it time to reimagine our approach to sourcing clean energy in general, and nuclear power in particular while at the same time addressing climate change? Ajay Kothari thinks so – by research and development and eventual commercialization of nuclear power plants fueled by thorium rather than uranium. Dr. Kothari describes his vision in the August 1, 2022 issue of The Space Review. He believes that this powerful and sustainable power source “…will solve the world’s energy problem a thousand times over with zero carbon dioxide emission during operation, and it may be the cheapest form of energy production for us.”
“One ton of thorium is roughly equivalent to five million barrels of oil”
Thorium is abundant in the Earths crust making it relatively cheap and therefore, more affordable. It is only slightly radioactive, far less so then uranium and does not contain fissile material making it much safer and easier to moderate (i.e. switch off) in the case of an accident. This would prevent meltdowns unlike conventional reactors which have coolants that operate at much higher pressures and need far more complicated engineering safeguards to prevent disasters.
Thorium molten salt reactors are inherently safe. Flibe Energy is designing a Liquid Fluoride Thorium Reactor (LFTR) and according to the company’s website, “…any increase in operating temperature reduces the density of the salt which in turn, causes the reaction to slow and the temperature to fall. LFTR is also designed with a simple frozen salt plug in the bottom of the reactor core vessel. In the event of power loss to the reactor, the frozen salt plug quickly melts and the fuel salt drains down into a storage tank below – causing a termination in the fission process.”
Once developed for energy production on Earth, the same technology has applications in space. While it would not be used in a booster during launch, a molten salt thorium reactor upper stage, like that shown in the illustration above, could provide an efficient 700 second specific impulse by heating hydrogen as fuel for advanced propulsion for the next few decades until fusion energy comes on line. An added benefit would be that the upper stage reactor could also be used to provide energy at the destination, for example on the Moon or Mars.
“One kilogram of thorium taken from Earth [to the Moon] … can support a 2.6 thermal megawatt plant for a year.”
A thorium reactor was developed at Oak Ridge National Laboratory (ORNL) back in the 1960s but was never commercialized after the then Atomic Energy Commission favored plutonium fast-breeder reactors.
Diagram of the thorium fuel cycle in molten salt reactors. Credits: Flibe Energy
There are challenges to overcome. For example, the thorium fuel cycle is complicated and still produces some radioactive waste, but far less and with much shorter half life when compared to conventional uranium nuclear reactors. But the benefits of this clean, abundant and affordable energy source could make investment by the public and private sector worth the effort.
“With US reserves at 595,000 tons of thorium, we have enough to last us 600 years at current rates.”
Kothari has been a long time proponent of Thorium reactors. He recently gave a talk on the molten salt thorium reactor via Zoom for the University of Maryland now available on YouTube. You can also hear an in-depth discussion of the technology on The Space Show when he was a guest back in October 2021 and when he returns to the show September 13, 2022.
Dr. Kothari agreed to take a deeper dive with SSP into what he calls “Thor – The Life-Saver” through an email interview. If you have questions I didn’t cover about thorium molten salt reactors please leave a comment.
SSP: Dr. Kothari, thank you for taking the time to answer my questions. With respect to the public’s fear of nuclear power in general, the safety of thorium molten salt reactors is certainly an argument in favor to the technology. But aren’t there still risks of nuclear proliferation?
AK: We have more than 400 reactors in more than 40 countries worldwide. We found ways to have countries develop their reactors but have proliferation controls. This idea, the TMSR, creates no Plutonium, and would be easier to monitor. Besides, whether we want [to] or not, other countries WILL do it. Many are. Also we can develop the technology for ourselves and [for] friendly countries OR at the very least, USE IT FOR OURSELVES! How can we deny this incredible opportunity for our (US) populace? Is that fair?
SSP: Flibe Energy appears to be the only U.S. company pursuing LFTR technology. Chicago based Clean Core is focusing on thorium-based fuels to be used in existing pressurized heavy-water reactor designs. What do you think of these two company’s approaches and are you aware of any other thorium reactor development efforts in the U.S, either in private industry or academia?
AK: MIT is developing tech to resolve some of the TMSR issues that would be quite helpful [SSP found this story from MIT Nuclear Reactor Laboratory on deployment of its “…nuclear reactor (MITR) and related testing apparatus as a proving ground for the materials and processes critical to molten-salt-cooled reactors.”]. Others are shown in the chart below with some of them being US based (bottom right).
Color coded map showing global molten salt reactor technology development activities and the sponsoring country/entities. FHR= Fluoride salt-cooled high-temperature reactor. LEU = Low Enriched Uranium. HEU= Highly Enriched Uranium. TRU=Transuranic wastes, i.e. heavier elements than Uranium. Credits: Oak Ridge National Laboratory
SSP: How difficult would it be to adapt this technology for space propulsion and power applications and is it so far off that fusion energy may be available by the time development efforts come to fruition?
AK: In my opinion, …. controlled fusion may be 100, 200 or 50 years away. We have a valley of death … between now and then. This TMSR can fill the gap but can also be used for space propulsion as my diagram above shows. Sure, the TRL of it needs to be brought up, but that’s what we are here for. It would be less heavy than [the] NERVA idea, especially if the chemical processing plant is separated and U233 is used for space propulsion rather than Th232. This would be the idea. The rate of fission is then controlled by the graphite rod moderators/controllers.
SSP: China has been working on a LFTR since 2011 and was recently cleared to start operating the reactor which is a direct descendent of the original experimental design that ORNL studied in the 1960s. It would appear that the Chinese have a significant head start. Is this concerning?
AK; Absolutely. All I can say is that we are idiots.
SSP: One of the disadvantages of thorium reactors is that large upfront costs are needed due to the significant amount of testing and licensing work for qualification of commercial reactors. The reactors also involve high fuel fabrication and reprocessing costs. How would you address these issues to attract investors?
AK: This idea really is a golden nugget, so to speak. The way to attract investors is to bring the TRL up with government (DoE, NASA and DoD) funds. When the light at the end of the tunnel is seen by investors, they will jump in with both feet. It may still be 5-10 years away but if we do not do it soon, (1) it will always remain so, and (2) some other country (China) or many other countries will DEFINITELY move ahead of us!
SSP: Another disadvantage is the presence of a significant level of gamma ray emissions due to Uranium-232 in the fuel cycle. How will this be dealt with safely?
AK: The Gamma ray radiation occurs from Protactinium 233 absorbing another neutron (before it Beta decays) to become Pa234 If it is separated in a chemical processing plant, it would remain easier to handle. From Wiki[pedia]: “The contamination could also be avoided by using a molten-salt breeder reactor and separating the 233Pa before it decays into 233U)”.
SSP: What regulatory and policy changes are needed to realize this technology in the U.S.?
AK: [The] NRC and DoE should allow smaller (~2 MW) size experimental reactors at Universities and research institutions right now.
SSP: On a related note, what efforts can leaders in private industry, academia and government undertake to begin the research and technology needed to commercialize thorium molten salt reactors.
AK: There are a few uncertain items in this nuclear process that Universities, small businesses and government research institutions can resolve. Government agencies need to fund SBIR/STTR type of initiatives to address the following technical issues:
The sustainability of the heat exchangers whether they are to be made of Hastelloy-N or some other composite. This characterization is needed w.r.t. neutron flux intensity, temperature reached and time exposed (in months to years)
The same as above for reactor containment vessels and pipes carrying the hot molten salt.
Chemical separation for in-line or off-line work for Protactinium and U233.
Tritium mitigation ideas (probably using CO2 in closed loop for electricity generation) or sequestration of it for later use in fusion when and if available. Designing and demonstrating tritium separators are key elements of DOE’s solid fuel MSR program at both universities and national laboratories
Gamma ray mitigation or reduction
Thorium doesn’t spontaneously undergo fission – when an atom’s nucleus splits and releases energy that can generate electricity. Left to its own devices it decays very slowly, giving off alpha radiation that can’t even penetrate human skin, so holidaymakers don’t need to worry about sunbathing on thorium-rich beaches.
We don’t have as much experience with Thorium. The nuclear industry is quite conservative, and the biggest problem with Thorium is that we are lacking in operational experience with it. When money is at stake, it’s difficult to get people to change from the norm.
Irradiated Thorium is more dangerously radioactive in the short term. The Th-U cycle invariably produces some U-232, which decays to Tl-208, which has a 2.6 MeV gamma ray decay mode. Bi-212 also causes problems. These gamma rays are very hard to shield, requiring more expensive spent fuel handling and/or reprocessing.
Thorium doesn’t work as well as U-Pu in a fast reactor. While U-233 an excellent fuel in the slow-neutron regime, it is between U-235 and Pu-239 in the fast spectrum. So for reactors that require excellent neutron economy (such as breed-and-burn concepts), Thorium is not ideal.
Proliferation Issues
Thorium is generally accepted as proliferation resistant compared to U-Pu cycles. The problem with plutonium is that it can be chemically separated from the waste and perhaps used in bombs. It is publicly known that even reactor-grade plutonium can be made into a bomb if done carefully. By avoiding plutonium altogether, thorium cycles are superior in this regard.
Besides avoiding plutonium, Thorium has additional self-protection from the hard gamma rays emitted due to U-232 as discussed above. This makes stealing Thorium based fuels more challenging. Also, the heat from these gammas makes weapon fabrication difficult, as it is hard to keep the weapon pit from melting due to its own heat. Note, however, that the gammas come from the decay chain of U-232, not from U-232 itself. This means that the contaminants could be chemically separated and the material would be much easier to work with. U-232 has a 70 year half-life so it takes a long time for these gammas to come back.
The one hypothetical proliferation concern with Thorium fuel though, is that the Protactinium can be chemically separated shortly after it is produced and removed from the neutron flux (the path to U-233 is Th-232 -> Th-233 -> Pa-233 -> U-233). Then, it will decay directly to pure U-233. By this challenging route, one could obtain weapons material. But Pa-233 has a 27 day half-life, so once the waste is safe for a few times this, weapons are out of the question. So concerns over people stealing spent fuel are largely reduced by Th, but the possibility of the owner of a Th-U reactor obtaining bomb material is not.
One especially cool possibility suitable for the slow-neutron breeding capability of the Th-U fuel cycle is the molten salt reactor (MSR), or as one particular MSR is commonly known on the internet, the Liquid Fluoride Thorium Reactors (LFTR). In these, fuel is not cast into pellets, but is rather dissolved in a vat of liquid salt. The chain reaction heats the salt, which naturally convects through a heat exchanger to bring the heat out to a turbine and make electricity. Online chemical processing removes fission product neutron poisons and allows online refueling (eliminating the need to shut down for fuel management, etc.). None of these reactors operate today, but Oak Ridge had a test reactor of this type in the 1960s called the Molten Salt Reactor Experiment [Wikipedia] (MSRE). The MSRE successfully proved that the concept has merit and can be operated for extended amounts of time. It competed with the liquid metal cooled fast breeder reactors (LMFBRs) for federal funding and lost out. Alvin Weinberg discusses the history of this project in much detail in his autobiography, The First Nuclear Era [amazon.com], and there is more info available all over the internet. These reactors could be extremely safe, proliferation resistant, resource efficient, environmentally superior (to traditional nukes, as well as to fossil fuel obviously), and maybe even cheap. Exotic, but successfully tested. Who’s going to start the startup on these? (Just kidding, there are already like 4 startups working on them, and China is developing them as well).
Loss of coolant accident consequences are significantly different than for Light Water Reactors
– Low driving pressure and lack of phase change fluids
– Guard vessels employed on some designs
– Planned vessel drain down to cooled, criticality-safe drain tanks on some designs
Image credit: NASA/Goddard/Arizona State University
The Cislunar Science and Technology Subcommittee of the White House Office Science and Technology Policy Office (OSTP) recently issued a Request for Information to inform development of a national science and technology strategy on U.S. activities in cislunar space.
Dennis Wingo provided a response to question #1 of this RFI, namely what research and development should the U.S. government prioritize to help advance a robust, cooperative, and sustainable ecosystem in cislunar space in the next 10 to 50 years?
In a prolog to his response Wingo reminds us that historically, NASA’s mission has focused narrowly on science and technology. What is needed is a sense of purpose that will capture the imagination and support of the American people. In today’s world there seems to be more dystopian predictions of the future than positive visions for humanity. We seem to be dominated by fear of “…doom and gloom scenarios of the climate catastrophe, the degrowth movement, and many of the most negative aspects of our current societal trajectory.” This fear is manifested by what Wingo defines as a “geocentric” mindset focused primarily within the material limitations of the Earth and its environs.
“The question is, is there an alternative to change this narrative of gloom and doom?”
He recommends that policy makers foster a cognitive shift to a “solarcentric” worldview: the promise of an economic future of abundance through utilization of the virtually limitless resources of the Moon, Asteroids, and of the entire solar system. An example provided is to harvest the resources of the asteroid Psyche which holds a billion times the minable metal on Earth, and to which NASA had planned on launching an exploratory mission this year but had to delay it due to late delivery of the spacecraft’s flight software and testing equipment.
Artist rendering of NASA’s Psyche Mission spacecraft. Credits: NASA/JPL-Caltech/Arizona State Univ./Space Systems Loral/Peter Rubin
Back to the RFI, Wingo has four recommendations that will open up the solar system to economic development and address many of the problems that cause the geocentrists despair.
First, we should make the Artemis moon landings permanent outposts with year long stays as opposed to 6 day “camping trips”. This should be possible with resupply missions by SpaceX as they ramp up Starship launch rates (assuming the launch vehicle and lander are validated in the same timeframe, which seems reasonable). Next, we need power and lots of it – on the order of megawatts. This should be infrastructure put in place by the government to support commerce on the Moon. By leveraging existing electrical power standards and production techniques, large scale solar power facilities could be mass produced at low cost on Earth and shipped to the moon before the capability of in situ utilization of lunar resources is established. Some companies such as TransAstra already have preliminary designs for solar power facilities on the Moon.
Which brings us to ISRU. The next recommendation is to JUST DO IT. This technology is fairly straightforward and could be used to split oxygen from metal oxides abundant in lunar regolith to source air and steel. Pioneer Astronautics is already developing what they call Moon to Mars Oxygen and Steel Technology (MMOST) for just this application.
Conceptual illustration of the Lunar OXygen In-situ Experiment (LOXIE) Production Prototype. Credits: Mark Berggren / Pioneer Astronautics
And lets not forget the wealth of in situ resources that could be unlocked via synthetic geology made possible by Kevin Cannon’s Pinwheel Magma Reactor.
Conceptual depiction of the Pinwheel Magma Reactor on a planetary surface in the foreground and in free space on a tether as shown in the inset. Credits: Kevin Cannon
Of course there is water everywhere in the solar system just waiting to be harvested for fuel and life support in a water-based economy.
Illustration of an ice extraction concept for collection of water on the Moon. Credits: George Sowers / Colorado School of Mines
Wingo’s final recommendation is industrialization of the Moon in preparation for the settlement of Mars followed by the exploration of the vast resources of the Asteroid Belt. He makes it clear that this is more important than just a goal for NASA, which has historically focused on scientific objectives, and should therefore be a national initiative.
“…for the preservation and extension of our society and to preclude the global fight for our limited resources here.”
With the right vision afforded by this approach and strong leadership leading to its implementation, Wingo lays out a prediction of how the next fifty years could unfold. By 2030 over ten megawatts of power generation could be emplaced on the Moon which would enable propellant production from the pyrolysis of metal oxides and hydrogen production from lunar water. This capability allows refueling of Starship obviating the need to loft propellent from Earth and thereby lowering the costs of a human landing system to service lunar facilities. From there the cislunar economy would begin to skyrocket.
The 2040s see a sustainable 25% annual growth in the lunar economy with a burgeoning Aldrin Cycler business to support asteroid mining and over 1000 people living on the Moon.
By the 2050s, fusion reactors provide power and propulsion while the first Ceres settlement has been established providing minerals to support the Martian colonies.
“The sky is no longer the limit”
By sowing these first seeds of infrastructure a vibrant cislunar economy will enable sustainable settlement across the solar system. A solarcentric development mythology may be just what is needed to become a spacefaring civilization.
Artist’s concept of an O’Neill space colony. Credits: Rachel Silverman / Blue Origin
I met Kent Nebergall during a cocktail reception at ISDC which took place May 27-29. He chairs the Steering Committee for the Mars Society (MS) and gave a fascinating talk Sunday afternoon on Creating a Space Settlement Cambrian Explosion. We had a wide-ranging discussion on some of his visions for space settlement and he agreed to collaborate on this post. We’ll do a deep dive into some of the topics he covered in his talk, which is available on his website at MacroInvent.
In summary, he breaks down some of the key challenges of space settlement and proposes economic models for sustainable growth. His roadmap lays out a series of space settlement architectures starting with a variant of SpaceX Starship used as a building block for large rotating habitats and surface bases for the moon, Mars, and asteroids. Next, he presents his Eureka Mars Settlement design which was entered in the MS 2019 Mars Colony Design Contest addressing every technical challenge. Finally, an elegant system for para-terraforming Martian canyons in multi-layered habitats is proposed, “…with the goal of maximizing species diversity and migration beyond our finite world. We not only preserve and diversify species across biomes, but engineer new species for both artificial and exoplanetary habitats. This is an engine for creating technology and biological revolutions in sequence so that as each matures, a new generation is in place to keep driving expansion across the solar system and beyond.”
Here’s my interview with Kent conducted via email. I hope you enjoy it!
SSP: You created a checklist of the required technologies needed to enable space settlement where each row is sorted by increasing necessity while the columns are sorted by greater isolation from Earth.
Credits: Kent Nebergall
Musk has started to crack the cheap access to space nut and large vehicle launch at upper left with Starship but we’re not there yet. Given that Musk’s timelines always should be taken with a grain of salt, and the challenge of planetary protection (bottom of column 3) could potentially prevent Musk from obtaining a launch license for a crewed mission before scientists have a chance to robotically search for signs of life, what is your estimation of the probability that Humans will land on Mars by 2029, in accordance with your proposed timeline (see below)?
KN: Elon time is real, definitely. My outside analysis implies that SpaceX is using Agile development systems borrowed from the software industry. The benefit of Agile is that technological progress is as fast as humanly possible. The bad news is that it largely ignores things that traditional management styles value, such as being able to predict the date something is really finished. At any rate, my general conclusion is that anything Elon predicts will be off by 43 percent as a baseline, assuming no outside factors are involved. Starship has slid more because the specifications kept changing, much as they did with Falcon Heavy.
We seem to be locked in on the early orbital design, which seems to be purely for getting Starlink 2 satellites in place and providing return on investment while getting the core flight systems refined. It doesn’t need solar panels, crew space, or the ability to stay on orbit more than a day. Crewed Starship may take another few years and use a smaller than expected cabin with a large payload bay. 2029 is the most recent year of a crewed Mars landing from Elon (as of March, 2022). If we allow for Elon Time, we could expect cargo in that launch window. I suspect one vehicle may try to return to prove out that flight range, like return to Earth from deep space. The first mission would largely be watching Optimus Prime robots setting up a farm of solar panels to make fuel for the return trip.
“The irony is that Elon could just pack the ship with Tesla humanoid robots for the first few missions…”
The planetary protection regulatory barrier is quite possible, yes. We just saw the regulatory findings for Bocca Chica. That requires several frivolous preconditions for flight, like writing an essay on historic monuments and accommodating ocelots, which haven’t been seen in the area in forty years. I doubt the capacity of political Simon Says playground games like has been exhausted yet.
What we’ve seen historically is that those who cannot compete will throw up regulatory and legal barriers. However, we’ve also seen that these efforts eventually burn out after a few years. This has been true with paddle wheel river ships, steam ships, railroads, and airlines. It’s playing out with Tesla and the big three domestic automakers now as well. Most of those tricks were already pulled with Falcon 9, so I think that path is largely burned through. I’m nearly certain they will try the planetary protection argument later. We have already seen with the ocelots that they are willing to protect absent species.
The irony is that Elon could just pack the ship with Tesla humanoid robots for the first few missions and build a base while running life searches in the area. The base could be built with nearly the same productivity as a human crew, and the cultural pressure to move humans into it would be quite high if no life is found in the meantime. It would be great marketing for the Tesla robots as well.
SSP: The table seems comprehensive and covers just about everything. Has it changed or been updated in 18 years? I noticed “Spacesuit Lifespan”. Why is this a challenge for space settlement?
KN: The table is fairly solid in terms of subject matter, but I’ve started a project to rebuild it. I only found out recently that NASA’s term for this is RIDGE (Radiation, Isolation, Distance, Gravity and Environment). My slicing into 26 categories is more precise – literally an alphabet of categories.
First, if it were a true “periodic table” analog, it would transpose the columns. But it’s much easier to fit in PowerPoint this way. Second, I have used this principle for other challenge sets and found interesting implications, so I may make a more advanced version in the future with far more depth. I’ll still use this for PowerPoint, though, because it can be read from the back row in under a minute. Third, each “challenge” is actually a family of challenges. There are multiple health problems with microgravity, for example, but one root cause – the absence of gravity. So, while each challenge in the table has many sub-factors, there is a single root cause and a solution that eliminates that cause also eliminates all sub-sets of problems. If a solution cannot fix the root cause, than separate solutions are needed for each child challenge like bone loss.
Spacesuit lifespan for the ISS is an issue because the suits are often older than the station itself. On the moon, the spacesuits picked up abrasive moon dust in the joints and could have eventually lost flexibility or pressure integrity if they’d been used much longer. A Mars suit is in some ways easier because the soil is more weathered and therefore less abrasive. Space settlement hits a standstill if you can’t go outside. Unfortunately, efforts to replace them have cost a billion dollars so far and have just been restarted for an even higher price tag. It seems to be the classic example of doing as little progress as possible while spending as much money as possible. There have been some great technologies developed but there has been no pressure to finish a completed suit. As the old saying goes, “One day, you just have to just shoot the engineer and cut metal”.
At one point, SpaceX outright said, “We can do it.” But NASA showed no interest, and SpaceX apparently didn’t bid on the moon suit designs this time. They have been converting the ascent suit from Dragon to one able to do spacewalks in the 1960’s Gemini sense for launch this year. I wouldn’t be surprised if they develop a moon suit just because they can, and on their own dime. It would be quite embarrassing for all involved, including SpaceX, if we had a 100 tonne payload moon lander capable of holding dozens of people, and not have a single suit capable of letting them leave the ship.
SSP: You mentioned orbital debris being a potential barrier for your plan’s LEO operations and you’ve come up with methods for shielding early orbital habitats, but they may not be effective against larger debris fragments. The X-prize Foundation is considering an award for ideas to solve this problem and there are numerous startups on the verge of addressing the issue. Such a solution would have to be implemented quickly and on a massive scale for your timeline to be achieved. If orbital debris looks like it may still be a problem for larger orbital settlements until they can be established in higher orbits, could your plan be modified to perhaps include debris removal as an economic driver? [SpaceX president and COO Gwynne Shotwell has suggested that Starship could be leveraged to help clean up LEO]
The problem must be sliced up, just as the other grand challenges are sliced up. We need several approaches at once. First, refueling starship is a bit risky, and the risk rises with prolonged exposure to the debris hazard. SpaceX originally wanted to launch the Mars vehicle, then refuel it on orbit over several tanker flights. More recently, they are implying they would fly a tanker up, fill it with several other tankers, then refuel the Mars or Lunar vehicle in one go. This makes a lot more sense. A tanker or depot hit by debris would be a space junk hazard, but it wouldn’t cost lives or science hardware.
We need to de-orbit the largest items, many of which are spent rocket stages. SpaceX has offered to gobble them up with Starship, but that means a lot of delta V in terms of altitude, inclination, elliptical elements, and so on. I could see a sort of penny jar approach where they drop off a satellite, then pick up an old one or two (the satellite and old rocket stage) before returning. Realistically, though, old rocket stages and satellites that haven’t vented every single tank (main and RCS [reaction control system]) will be hazardous to approach.
It seems the best solution would be mass-produced mini-satellites with ion drive and electrodynamic tethers. Each mini-sat would find a spent rocket stage or defunct satellite and add an electrodynamic tether to drag it down using Earth’s magnetic field while also powering an ion engine to assist in de-orbiting. You would have to do a few at a time because the tethers themselves would become a hazard if we had thousands of them cutting through space like razor ribbons.
I could also see a spider robot that would grab larger satellites with propellant still on board, wrap them up like a spider wrapping a bug in silk, and then puncturing the tanks carefully to both refill itself and render the satellite inert. It would then be safe to grab with a Starship or de-orbit with a drag or propellant system [Another concept for debris removal could be Bruce Damer’s SHEPHERD which we covered a year ago. Although originally conceived for asteroid capture, a pathfinder application could be satellite servicing/decommissioning].
We didn’t create the problem in a day, and we can’t solve it quickly either. But we can take an approach of de-orbiting two tons for every ton launched once we have mass produced systems for doing so. Maybe other launch providers can grab defunct satellites with their orbital launch stages before dragging them both into the Pacific.
That said, we can’t get every paint chip and bolt out of orbit this way. We will hit a law of diminishing returns. Anything below that line will require a technology to survive impacts. The pykrete ice shield I proposed could be much smaller, such as just one hexagonal hangar big enough for 2-3 starships in LEO at a time. Once refueled, the craft would go to the much safer L5 point or directly to the moon if that is the destination. Keeping a ring at L5 would not require a massive ice shield or centrifuge habitat to be a useful waystation. But those would be designed into it up front to give room for expansion.
If we decided that a Mars mission had to wait for all the infrastructure I proposed, we’d be in the same trap that Von Braun would have fell into of wanting massive infrastructure before the first crewed lunar mission. You need a balance of infrastructure and exploration to give both meaning.
“We can democratize early if we give some participation method in the initial investments in time, technology, and financing.”
SSP: Musk says he needs 100s of starships to deliver millions of tons of materials to support large cities on Mars by mid-century (his timeline). You’ve created a somewhat more reasonable timeline for Starship round trip logistics for this effort based on Hohmann transfer orbits and Mars orbital launch windows (i.e. every 2 years).
Credits: Kent Nebergall
What will be the economic driver for such an ambitious project besides Musk just “making it so”? I saw later in your presentation that you proposed an initial sponsorship and collectables market followed by MarsSpec competitions. How will these initiatives kickstart sufficient market enthusiasm to support such an enormous fleet of Starships?
KN: It’s a complex topic, and easily a book in itself. To cut to the core of it, any major discovery or invention that is not democratized becomes historic or esoteric rather than revolutionary. Technology revolutions do not take place in particle accelerators any more than music revolutions take place in symphony orchestra pits. Things that don’t impact people constantly are simply curiosities. Even many things taken for granted like GPS and running water are ignored, but they remain transformative. When the furnace filter factory worker sends part of his month’s labor to Mars, we have space settlement. We can democratize early if we give some participation method in the initial investments in time, technology, and financing. But these waves will go from new and novel to basic and ignored rather quickly, and this is especially true if they succeed.
Imagine being a medieval merchant and getting an opportunity to send a bag of grain on a voyage to Cabot or some other explorer. In return you get a rock from the opposite side of the world, a certificate saying what you gave and authenticating what you got back, and a tiny bit of participation in the history of your era that you can share with your children. A decade later, your son is working in a smelting plant in a port city and making hardware for houses in the new world. In another decade your grandchildren are growing crops in Maryland. It’s a bit like that. Each wave will fund and create the industrial and skill base for the next wave before becoming culturally ubiquitous. The last child has no interest in a rock from his Maryland backyard. But to the grandfather living a generation or two beforehand, it may as well be from the moon. The wave of sponsorship, followed by specifications for space-rated products, followed by biological engineering in lower gravity worlds will each create benefits and enthusiasm back on Earth. After that last wave, the economic ecosystem becomes permanently multi-planetary.
Everything else about space is a simple engineering problem. Minds, trends, budgets, and so on are not so well behaved as atoms or heat, but they have a lot of history that we can use to model workable solutions. This is the one I came up with.
“The problem with any grand engineering venture is that every design looks good until it comes in contact with reality.”
SSP: The Eureka Space Settlement concept features dual centrifuges providing artificial gravity equivalent to the Moon and Mars.
Eureka settlement duel centrifuge facility providing lunar gravity on the inner ring and Mars gravity on the outer one. Credits: Kent Nebergall
I like the idea of using variable gravity to study biological effects on plant and mammalian physiology, adapting species to be multi-planetary and prepping for settlements that will need gravity as we move out into the outer solar system, but this can be done more cheaply in LEO or in cislunar space as outlined earlier in your architecture. Why not simplify the Eureka settlement by eliminating the centrifuge and going with normal Mars gravity?
KN: The problem with any grand engineering venture is that every design looks good until it comes in contact with reality. You can’t model every issue up front, and one of the hardest to work out without experience are multi-generational ecosystems. If we build a $100 billion Mars city and the kids have birth defects, we have a huge liability issue and a city that will be turned over to robots or dust.
The advocates assume all will be fine, but they tend to downplay issues. The critics assume all will go poorly, but they never want to venture past the status quo. Reality will be a mixed bag of data points on a bell curve between the two with both unknown threats and opportunities waiting for discovery. This unknown is a big reason for the enthusiasm to try in the first place.
I came up with the steelman methodology by taking all the criticisms and range of danger possibilities and cranking the bell curve values up a few sigma to the nasty side. The idea is that if you can STILL make an affordable design that pays for itself when the universe is coming after you with a hammer, you probably will be fine when the bell curve is realized. You should always have a back-down plan to have surface domes with no centrifuges, or simply use the centrifuges for pregnant mammals and trees that need to fight gravity to have enough limb strength to bear fruit. That said, another beauty of this design is that a Pluto colony or asteroid colony will almost certainly need centrifuges for multigenerational life. Prototyping it on Mars may be overkill for Mars, but perfect for Pluto or Enceladus. This makes it much easier for Mars settlers to think about colonizing the outer solar system. Even the children of our dreams need dreams, after all.
“A space outpost must bring materials to itself, so a system like that without surface outposts or asteroid mining is a dead end.”
SSP: In the proposed first wave of the architecture, rotating settlements are created from Starship building blocks in high orbit to create “…deep space industrial outposts in the O’Neill tradition with a thousand inhabitants each. On the lunar and Martian surface, we simply take a slice of the ring architecture with starships inside as an outpost.” With the amount of investment needed to build the infrastructure to transport materials and people for large settlements on Mars, and given that the biggest grand challenge on your chart is reproduction (which may not be possible in less than Earth’s gravity), why wouldn’t it make more sense to focus efforts on building larger 1G rotating free space settlements where we know having children is possible?
KN: It’s not so much a roadmap of first this structure here, then that one there. It’s a draft set of compatible building standards for everywhere. Think about the standard sizes for bricks, pipes, and wiring and how entire continents use them interchangeably over a hundred years or more. My goal was to lay out what the maximum amount of infrastructure would look like with the minimum number of parts.
There is a false dichotomy between structures like space stations made entirely from material from Earth, and local materials formed with 3D printers that can do everything with complete reliability. Both are impractical extremes, and to some degree strawman designs. Importing everything is prohibitively expensive even with Starship. Conversely, creating structures from random conglomerates of whatever material is at the landing site will be too brittle. By proposing bags that can be made of basalt cloth but that will initially come from Earth, I’m bridging the two extremes. They can be filled with dust, water, sand, or whatever is fine grained enough and can be either sintered or cemented in place. Such structures don’t have to be aligned with absolute precision and can follow soft contours or whatever is needed. You also don’t need four meters of shielding for cosmic rays if you augment it with magnets. They can be scaled in layers or levels as needed, just like bricks or two by four boards are in homes.
A space outpost must bring materials to itself, so a system like that without surface outposts or asteroid mining is a dead end.
Centrifuges for surface settlements are a bit awkward, to be sure. A train system that keeps the floor below you when spinning or de-spinning is a better system at first. Eureka was mainly done with fixed pitch decks just to show that the scale of a centrifuge for a large torus L5 ring could be done on a surface with some clever engineering. My original design goal was to make the cars, car beds, rails, and buildings swappable without stopping the ring rotation. In the same way, the pressure shell has inner and outer walls that can in theory be replaced while the other keeps pressure. It’s probably not necessary, but the goal is to remove all design barriers early in the thought process so that future engineers aren’t painted into corners.
SSP: After the first settlements are established on Mars, you suggest starting to adapt the Mars environment to Earth-like conditions through “para-terraforming” small parts of the planet such as the Hebes Chasma, a canyon the size of Lake Erie just north of Valles Marineris. This feature has the advantage of being right on the equator and closed at both ends so that kilometer sized arch structures could enclose the valley to warm the local environment with many Eureka settlements below.
Top: Artist concept of kilometer scale arches built above space settlements and enclosing a Martian canyon to provide a para-terraformed environment. Bottom: Magnificent view from below depicting these domes at cloud level on a typical summer day. Credits: Kent Nebergall / Aarya Singh
Planetary protection was mentioned as one of the grand challenges to be overcome. Some space scientists are advocating for robotic missions to answer the question of whether life existed (or still exists) on Mars before humans reach Mars. No such missions are planned prior to Musk’s timeline for putting humans on Mars at the end of this decade. Are you assuming that by the time humans are ready for para-terraforming that the question of life on Mars will be answered?
KN: We would certainly know if active, widespread, indigenous life was an issue by the time of building canyon settlements the size of Lake Erie. Even isolated pockets would leave fossil traces in broader zones.
The bigger question is that of whether or not it is possible to settle Mars if there is a risk of crossing into a local biome accidently. Eureka is built entirely on the surface, so it doesn’t cross the sterilized surface soils if it doesn’t have to. We should be able to mine from Mars with sterile equipment and be able to sterilize further after robotic extraction. We can extract water ice, volcanic rock, and surface dust and build the entire settlement from those basic materials. We can avoid sedimentary materials until we are confident they are not biologically active.
I suspect any life on Mars is from Earth, and brought by meteors. The cross-traffic of meteors throughout the solar system may mean bacterial and possibly slightly more complex life all over the solar system from the late bombardments of Earth. We should consider this no more exotic than breathing in Australia or swimming in the ocean. Microbes adapted for those environments would not be adapted to be pathogenic because why spend billions of generations preparing for a food source that may never arrive? We would have a bigger problem with random toxins that hadn’t leached out or reacted to life billions of years ago than with life itself. I respect the work of those who want sterile capsules of pristine soil captured by the current Mars rover prior to human arrival. That certainly makes sense. I like Carol Stoker’s Icebreaker mission concept. I think NASA and universities would be smart to work with SpaceX on simple rack-mount instrumentation that could be flown to planetary destinations en masse and serviced by Optimus Prime Tesla robots.
“My goal is to build the next generation of the quiet heroes of the dinner table. And certainly a few of those will be leaders too.”
SSP: You’re writing a book about creating an inventor mindset to enable a million “mini-Musks” – people who are not necessarily rich, but who shake up the world in constructive and innovative ways. Tell us more about this philosophy.
KN: The core concept is that if you could get a thousand people to do a hundredth of what Elon has accomplished, it would be a tenfold increase in what we’ve seen in terms of his contribution to technology. That’s not a very big ask individually, even if it’s more garage labs than factories for now. I looked deeply into what Elon Musk does and what other inventors like him have done. I’ve looked at technology revolutions and what key things spark the massive growth waves of innovation. Obviously, there are intersections between the two.
I’m writing a short book this summer to document Elon’s methodologies in an approachable and comprehensive reference. If it attracts enough interest, I can take that core module into different directions. One is digging more into how the mind invents. Another is breaking down how technology revolutions work. A third is all this work on space settlement. I’ve also come up with intellectual property around the root of these concepts that would be valuable software and services. I guess we’ll see what reaction the Elon book gets and see where that goes. It’s a bit heartbreaking to see millions spent on NFTs and other random “stupid money” projects when I’m coming up with concepts for trillion-dollar companies as a hobby.
While we talk a lot about Musk, there are thousands of people who work just behind the spotlight. My father was a production test pilot who put his life on the line to ensure that bombers were flyable for national security, and that the technology that became the commercial jet airliner a decade later would be safe for billions of travelers. He worked with some historic figures of aviation, and his dinner stories were amazing. The Mars Society gave me a way to repeat a little of this history for myself in this dawn of the Mars Age.
Technology revolutions may celebrate a few leaders. But without thousands of talented people several feet behind these inventors, they are little more than curiosities – Di Vinci notebooks or Antikythera mechanisms. My goal is to build the next generation of the quiet heroes of the dinner table. And certainly a few of those will be leaders too. That is my hope. To fill the diaries of pioneers that give permanent cultural bedrock to the accomplishments of people like Elon. Otherwise, even a moon landing is a short story written in water.
Don’t miss Kent’s appearance on The Space Show coming up on Sunday July 10 where you can call in and ask him in person your own questions about these and other visions for space settlement.
