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Why settle space?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Zimmerman continues:

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

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

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

Entrepreneur and inventor Ryan Reynolds had a refreshingly unique perspective:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Conceptual rendering of a Blue Alchemist solar cell fabrication facility on the Moon. Credits: Blue Origin

Jeff Bezos’ new initiative called Blue Alchemist made a splash last month boasting that the team had made photovoltaic cells, cover glass and aluminum wire from lunar regolith simulant. This is an impressive accomplishment if they have defined the end-to-end process which (with refinements for flight readiness) would essentially provide a turnkey system to fabricate solar arrays to generate power on the Moon. The announcement claimed that the approach “…can scale indefinitely, eliminating power as a constraint anywhere on the Moon.” Actually, this may not be possible at first for a single installation as surface based solar arrays can only collect sunlight during the lunar day and would have to charge batteries for use during the 14 day lunar night, unless they were located at the Peaks of Eternal Light near the Moon’s south pole. But if scaling up manufacturing is possible, coupled with production of transmission wire as described, a network of solar power stations in lower latitudes could be connected to distribute power where it is needed during the lunar night.

Very few details were revealed about the design outputs of the end products (not surprisingly) in Blue Origin’s announcement, particularly the “working prototype” solar cell. An image of the component was provided but it was unclear if the process fabricated the cells into a solar array or if the energy conversion efficiency was comparable to current state of the art (around 21%). Nor do we know how massive the manufacturing equipment would be, how much periodic maintenance is needed or if humans are required in the process. Still, if a turnkey manufacturing plant could be placed on the Moon and it’s output was solar arrays sourced from in situ materials, it would significantly reduce the costs of lunar settlements by not having to transport the power generation equipment from Earth. This particular process has the added benefit of producing oxygen as a byproduct, a valuable resource for life support and propulsion.

Research into production of solar cells on the Moon from in situ materials is not new. NASA was looking into it as recently as 2005 and there are studies even dating back to 1989. Blue’s process produces iron, silicon, and aluminum via electrolysis of melted regolith, using an electrical current to separate these useful elements from the oxygen to which they are chemically bound. Solar cells are produced by vapor deposition of the silicon. The older studies referenced above proposed similar processes.

It would be interesting to perform an economic analysis comparing the cost of a solar power system supplied from Earth by a company focusing on reducing launch costs (say, SpaceX) with that of a company like Blue Origin that fabricated the equipment from lunar materials. Peter Hague has done just that in a blog post on Planetocracy using his mass value metric.

Hague runs through the numbers comparing SpaceX’s predicted cost per kilogram delivered to the Moon by Starship with that of Blue Origin’s New Glenn. At current estimates the former is 5 times cheaper than the latter. Thus, to best Starship in mass value, Blue Alchemist would have to produce 5kg of solar panels for every 1kg of equipment delivered to the Moon, after which it would be the economic winner. Siting a recent analysis of lunar in situ resource utilization by Francisco J. Guerrero-Gonzalez and Paul Zabel (Technical University of Munich and German Aerospace Center (DLR), respectively) predicting comparable mass output rates, Hague believes this estimate is reasonable.

Perhaps we should not get ahead of ourselves as Blue Origin’s timeline for development of their New Glenn heavy-lift launch vehicle is moving a glacial pace and one wonders if they have the cart before the horse by siphoning off funds for Blue Alchemist. Jeff Bezos is free to spend his money any way he wishes and definitely seems to be in no hurry.

Conceptual illustration of New Glenn heavy-lift launch vehicle on ascent to orbit. Credits: Blue Origin

But SpaceX’s Starship has not made it to space yet either and after we see the first orbital flight, hopefully as early as next week, the company will have to demonstrate reliable reusability with hundreds of flights to achieve economies of scale commensurate with their predicted launch cost of $2M – $10M. As SpaceX has demonstrated with it’s launch vehicle development process it is not a question of if, it is one of when.

Image of full stack Starship at Starbase in Boco Chica, TX. Credits: SpaceX

As both companies refine their approach to space development, will it be the tortoise or the hare that wins the mass value price race for the cheapest approach to power on the Moon? Or will each company end up complementing each other with energy and transportation infrastructure in cislunar space? Either way, it will be exciting to watch.

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The case for free space settlements if the Gravity Rx = 1G

Cutaway view of interior of Kalpana One, an orbital settlement spinning to produce 1G of artificial gravity. Credits: © Bryan Versteeg, Spacehabs.com / via NSS

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.

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Dennis Wingo’s strategy for development of cislunar space and beyond

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

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Creating a Space Settlement Cambrian Explosion – Interview with Kent Nebergall

Credits: Kent Nebergall

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.

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Highlights from the International Space Development Conference

Conceptual illustration of Mag Mell, a rotating space settlement in the asteroid belt in orbit around Ceres – grand prize winner of the NSS Student Space Settlement Design Contest. Credits: St. Flannan’s College Space Settlement design team*

In this post I summarize a few selected presentations that stood out for me at the National Space Society’s International Space Development Conference 2022 held in Arlington, Virginia May 27-29.

First up is Mag Mel, the grand prize winner of the NSS Student Space Settlement design contest, awarded to a team* of students from St. Flannan’s College in Ireland. This concept caught my eye because it was in part inspired by Pekka Janhunen’s Ceres Megasatellite Space Settlement and leverages Bruce Damer’s SHEPHERD asteroid capture and retrieval system for harvesting building materials.

The title Mag Mell comes from Irish mythology translating to “A delightful or pleasant plain.” These young, bright space enthusiasts designed their space settlement as a pleasant place to live for up to 10,000 people. Each took turns presenting a different aspect of their design to ISDC attendees during the dinner talks on Saturday. I was struck by their optimism for the future and hopeful that they will be representing the next generation of space settlers.

Robotically 3D printed in-situ, Mag Mell would be placed in Ceres equatorial orbit and built using materials mined from that world and other bodies in the Asteroid Belt. The settlement was designed as a rotating half-cut torus with different angular rotation rates for the central hub and outer rim, featuring artificial 1G gravity and an Earth-like atmosphere. Access to the surface of the asteroid would be provided by a space elevator over 1000 km in length.

* St. Flannan’s College Space Settlement design team: Cian Pyne, Jack O’Connor, Adam Downes, Garbhán Monahan, and Naem Haq

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

Daniel Tompkins, an agricultural scientist and founder of GrowMars, presented his Expanding Loop concept of self replicating greenhouses which would be 3D printed in situ on the Moon or Mars (or in LEO). The process works by utilizing sunlight and local resources like water and waste CO2 from human respiration to grow algae for food with byproducts of bio-polymers as binders for 3D printing blocks from composite concretes. Tompkins has a plan for a LEO demonstration next year and envisions a facility eventually attached to the International Space Station. He calculates that a 4000kg greenhouse could be fabricated from 1 year of waste CO2 generated by four astronauts. An added bonus is that as the greenhouse expands, an excess of bioplastic output would be produced, enabling additional in-space manufacturing.

Diagram depicting GrowMars Expanding Loop algae growing process to create greenhouse blocks and byproducts such as proteins and fertilizer. Credits: GrowMars / Daniel Tompkins.
Illustration of a portion of the Spacescraper tethered ring from the Atlantis Project. Credits: Phil Swan

Phil Swan introduced the Atlantis Project, an effort to create a permanent tethered ring habitat at the limit of the Earth’s atmosphere, which he calls a Spacescraper.  The structure would be placed on a stayed bearing consisting of two concentric rings magnetically attached and levitated up to 80 km in the air.  In a white paper available on the project’s website, details of the force vectors for levitation of the device, the value proposition and the economic feasibility are described. As discussed during the talk at ISDC, potential applications include:

  • Electromagnetic launch to space
  • Carbon neutral international travel
  • Evacuated tube transit system
  • Astronomical observatories
  • Communication and internet
  • Solar energy collection for electrical power
  • Space tourism
  • High rise real estate

Phil Swan will be coming on The Space Show June 21 to provide more details.

Conceptual illustration of a Mars city design with dual centrifuges for artificial gravity. Credits: Kent Nebergall

Finally, the Chair of the Mars Society Steering committee and founder of MacroInvent Kent Nebergall, gave a presentation on Creating a Space Settlement Cambrian Explosion. That period, 540 million years ago when fossil evidence goes from just multicellular organisms to most of the phyla that exist today in only 10 million years, could be a metaphor for space settlement in our times going from extremely slow progress to a quick expansion via every possible solution. Nebergall suggests that we may be on the verge of a similar growth spurt in space settlement and proposes a roadmap to make it happen this century.

He envisions three settlement eras beginning with development of SpaceX Starship transportation infrastructure transitioning to robust cities on Mars with eventual para-terraforming of that planet. He also has plans for how to overcome some of the most challenging barriers – momentum and money. Stay tuned for more as Kent has agreed to an exclusive interview on this topic in a subsequent post on SSP as well as an appearance on The Space Show July 10th.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

SSP: You state in several of your papers that:

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

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

‘ “A space settlement” refers to a habitation in space or on a celestial body where families live on a permanent basis, and that engages in commercial activity which enables the settlement to grow over time, with the goal of becoming economically and biologically self-sustaining as a part of a larger network of space settlements. “Space settlement” refers to the creation of that larger network of space settlements. ‘

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

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

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

The NERVA solid core nuclear rocket engine. Credits: NASA

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

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

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

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

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

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

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

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

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

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

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

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A lunar space elevator achievable with today’s technology

Conceptual depiction of a lunar space elevator. Credits: Cool Worlds Lab via YouTube.com

As SSP posted previously, a space elevator serving Earth holds great promise for reducing the cost of access to space but remains out of reach at least for a couple of decades as there are no existing materials strong enough to support their own weight in Earth’s gravity well. But a lunar space elevator (LSE) is possible with commercial polymers available today and could be built for about $2 billion according to Charles Radley, a Systems Engineer and AIAA Associate Fellow. In a paper available on Academia.edu he shows how a “… lunar elevator is both feasible and affordable, and indeed profitable.”

A functional LSE would require a tether of low mass material that is also strong enough to support its own weight in the Moon’s gravitational field. In addition, it needs to be robust enough to transport payloads reliably and repeatedly over the entire working distance in cislunar space. The LSE would be a very long tether extending from the Moon’s surface up to a station at the system’s center of mass (COM) located at either of two Earth-Moon Lagrange points, L1 or L2. The physics of the system requires that the tether extend beyond the COM terminating at a counterweight several thousand kilometers higher. For the L1 system, the tether extends about 58,000 km up from the Moon to the station at the COM and then extends another 220,000 km up (toward the Earth) to the counterweight.

Several high tensile strength, low mass polymers developed in the 1990s that fulfill the system requirements are commercially available in large quantities today (e.g. T1000TM, DyneemaTM and ZylonTM * ). A 48 ton system composed of the tether, the L1 COM station, a lunar surface attachment fixture (SAF), counterweight and payload climbers could be launched on a single Falcon Heavy vehicle.

Starting at L1, the deployment would begin with the counterweight and SAF simultaneously played out in opposite directions (up and down in relation to the Moon, respectively) unspooling the tethers at rates that maintains the COM station at the L1 position. Upon the SAF reaching the desired location on the Moon, it would be affixed to the surface by drilling down to a sufficient depth to anchor the structure such that it could adequately withstand tension and lateral forces.

When compared to chemical rocket operations on the moon, there is a significant cost reduction in lifting materials off the surface if multiple climbers are used and the frequency of their trips up and down the LSE is maximized. The cost reduction is on the order of 9X, enabling the system to pay for itself in one month. Radley concludes that:

“These large cost reductions are game changing and will enable major expansion of human activities beyond Earth orbit, and establish profitable lunar based industries.”

The Liftport Group, a collaborator on the paper, is administering The Alexandria Project, a database repository collecting and organizing questions about the infrastructure needed for development of an LSE toward creation of a requirements document.

* T1000G is a trademark of Toray Composite Materials America, Inc.; Dyneema is a trademark of Royal DSM NV; Zylon is a trademark of Toyobo Corporation

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Are we close to a tipping point for human spaceflight?

Artist depiction of Starship on the lunar surface returning astronauts to the Moon as part of NASA’s Artemis Program. Credits: SpaceX

What will be the impact on the direction of U.S. space policy should SpaceX successfully demonstrate an orbital flight of Starship? Doug Plata, President and Founder of the Space Development Network believes that when Starship achieves orbit, policy makers should “…place Starship at the center of the country’s human spaceflight program…”. In an article in The Space Review he makes the case that if successful in its efforts, SpaceX may be edging us closer to a tipping point on deciding which path to take for the country’s human rated launch vehicle: Space Launch System (SLS) or Starship? This question is accentuated by recent news reports of yet another delay in the Artemis 1 uncrewed test flight of SLS which Ars Technica reports may not launch until the summer of 2022…assuming everything goes perfectly. Meanwhile, SpaceX continues its development of Starship at a breakneck pace, while simultaneously building the manufacturing infrastructure to “…crank them out by the hundreds”, says Plata. With the delay of Artemis 1, it is possible that SpaceX will demonstrate the first orbital launch of Starship before NASA’s first launch of SLS.

NASA has already selected SpaceX to return astronauts to the Moon via Starship as the Human Landing System for the Artemis program, although work has stalled on the contract due to Blue Origin’s lawsuit. But with a reusable Starship at a fraction of the cost, comparable heavy lift capability and a much higher flight rate, how long can SLS last? A case could be made for keeping SLS until SpaceX’s Super Heavy booster is human rated and Starship can be reliably shown to reenter the Earth’s atmosphere and land safely. But this won’t be long given Elon Musk’s aggressive timelines. Will it continue to make sense to launch astronauts on SLS/Orion, transfer them to Starship in lunar orbit and descend to the surface of the Moon when the the whole mission could be accomplished without SLS at a fraction of the cost?

“At some point, it will be obvious that SLS is an unnecessarily expensive alternative to Starship”

With Starship’s anticipated payload capabilities of delivery of 100s of tons and large crews to the lunar surface, and recent advances in inflatable technology, a habitat with a footprint of about 21,000 sq. ft. is within reach. Plata believes that the billions of dollars slated for SLS would be better spent contracting with SpaceX for delivery of inflatables and their supporting infrastructure to the lunar surface. This could lead to a large international lunar base which may eventually become a permanent settlement.

Instabase
Conceptual illustration of InstaBase – a fully inflatable lunar base capable of supporting an initial crew of eight. Credits: The Space Development Network via The Space Review

“But there is an important historic significance to Starship as well…the real historic prize to be seized is the establishment of humanity’s first foothold off Earth.”