Image of ice in a crater on the Martian plain Vastitas Borealis captured by the European Space Agency’s Mars Express orbiter. Credits: ESA/DLR/Freie Universitat Berlin (G. Neukum)
When we establish outposts and eventually, settlements on the Moon or Mars it would be economically beneficial if we did not have to create supply chains from Earth for water, breathable air and the fuel we will need for our rockets. This is why sources of water ice in the permanently shadowed craters at the lunar poles and in glaciers in the equatorial regions on Mars are so attractive as early destinations. Once we get there what equipment will we need to process this valuable resource? The typical way envisioned for cracking water in situ on the Moon or Mars to produce oxygen and hydrogen is through electrolysis. But this method requires a lot of power. There may be a more efficient way. New ESA sponsored research by scientists* in the UK and Europe examines a novel method that mimics photosynthesis in plants using a photoelectrochemical (PEC) device. The findings were published June 6 in Nature Communications.
PEC reactors are currently being studied on Earth for water splitting to produce green hydrogen from sunlight. Since they only rely on solar energy for power they are ideal for space applications. One type of device consists of a semiconductor photocathode immersed in an electrolyte solution that absorbs solar energy for a reaction to split hydrogen from water molecules. Oxygen is produced at the anode of the cell. PEC devices can be fabricated as panels similar to photovoltaic arrays. For use on Mars, the authors analyze another similar PEC technology using a gas-diffusion electrode to reduce atmospheric carbon dioxide in a reaction producing methane for rocket fuel.
The authors modeled the performance of these devices subjected to the expected environmental conditions on the Moon and Mars. Specifically, they looked at attenuation from the accumulation of dust on the PEC cells caused by micrometeorites pulverizing the lunar surface, coupled with the solar wind inducing an electrostatic charge in the resulting dust. And of course dust storms are relatively frequent on Mars which could significantly degrade performance. To address this problem self cleaning coatings are suggested as a solution. Solar irradiance was also considered as it would be reduced at the orbit of Mars. It was concluded that the PEC performance could be significantly boosted with solar concentrators by a factor of 1000 enabling higher production rates and power densities, especially on Mars.
An added advantage for space-based application of this technology is the elements needed to construct PEC devices are readily available on these worlds obviating the need to transport them from Earth and thereby significantly reducing costs.
“…in-situ utilization of elements on both, the Moon and Mars, is feasible for the construction of PEC devices.”
The technology is ideal to augment the production of oxygen in environmentally controlled life support systems of habitats that may not initially be 100% closed and cannot easily be resupplied with consumables from Earth. A competing technology for oxygen production which was recently demonstrated on Mars is the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) which functions via solid oxide electrolysis of carbon dioxide. This process requires high temperatures and therefore, more energy presenting a challenge when increased production of oxygen will be required for large settlements. The author’s analysis show that the PEC devices are more energy efficient and can easily be scaled up.
“Oxygen production via unassisted PEC systems can … be carried out at room temperature … suitable to be housed in temperature controlled space habitats.”
* Authors of the Nature Communications article Assessment of the technological viability of photoelectrochemical devices for oxygen and fuel production on Moon and Mars: Byron Ross at the University of Warwick, UK; Sophia Haussener at Ecole Polytechnique Fédérale de Lausanne, Switerland; Katharina Brinkert, University of Bremen, Germany
Conceptual illustration of the Minerva Space Settlement in orbit around Jupiter’s moon Ganymede. Credits: Minerva Project Team
Space Settlement Progress typically features the latest advancements in technology that are enabling the settlement of space. This post will be a little different. When attending the International Space Development Conference last May I was impressed by a team of students from Highschool Colegiul National Andrei Saguna in Romania, who had conceived of a space settlement in orbit around Jupiter’s satellite Ganymede which they call Minerva. The project was an entry in the National Space Societies’ Space Settlement Contest, and for which they won a second place award for 9th graders. While admiring their poster I was approached by Maria Vasilescu, who proudly described their project and agreed to collaborate with me on this post. She spoke perfect English, shared marketing materials (key chains, buttons and bookmarks with QR codes linking to their website) and explained that the primary purpose of Minerva would be a deep space location for a University of Space Exploration. I was intrigued by the concept and was struck by Maria and her teammates’ enthusiastic vision of humanity’s future in space. I wanted to know more about what motivated this group of teenagers to come together and create such an imaginative project, as youths like them will be future pioneers on the High Frontier. Maria agreed to coordinate with her team on an interview via email about Minerva.
The Minerva Project Team and their poster session at ISDC 2023, a second prize winner for 9th graders of the NSS Space Settlement Contest. Credits: Minerva Project Team: clockwise from lower right: Bodean Mircea-Sorin, Ana Radus, Andrei Ioan Prunea, Alexandra Nica, Alexandra Maria Nemes, Maria Vasilescu
SSP: How did the team come up with this Minerva concept?
Minerva: We took inspiration from our school which gave us a lot of opportunities to which we owe a lot and we wanted to build such a university in the final frontier.
SSP: You mentioned stumbling across some obstacles during your journey but sticking together by motivating each other. Is this an experience you feel comfortable sharing?
Minerva: One of the hardest things was to think about all the aspects that go into making a space settlement as ninth graders, such as the form [Forum on the website], which was decided in the last week, or the economical part. But we managed to meet often and brainstorm to come up with better ideas.
SSP: You said that the project helped you discover your true selves. Can you explain how this came about?
Minerva: We developed ourselves and our passions and we found out what we like because it covers a broad area of subjects beyond science. We managed to see by which area we are drawn to and enjoy actually researching.
SSP: You’ve stated that one of the reasons for building Minerva is to invent new lifestyles different from those that exist on Earth. How do you envision lifestyles changing in space?
Minerva: The university can prepare you for life in space, which will be an important part in the humans’ future, therefore we don’t want to invent new lifestyles, but incorporate space in the ones that already exist.
SSP: You’ve proposed auctioning a Minerva NFT to fund your efforts and future experiments. Would this be the sole source of financing for the project, and will it be sufficient? What about simply charging tuition for the USE?
Minerva: Everything on our settlement is given and made by us for the people so they don’t need to have money to buy material things. And because we have worked to make almost everything renewable and green, the funds MinervaNFT will bring are more than sufficient for everything else. And as for tuition, we feel like putting students through an exam such as the one that defines their attendance to USE is stressful enough as it is. However, the students will need to pay for the transport from Earth to the settlement.
SSP: There does not appear to be any trade or economic activity on Minerva, only academic studies. Students may choose to return to Earth or stay on the space station after they complete their studies. If they stay, have you considered the possibility of graduates developing and marketing other industries such as software development, robotics, mining water from Ganymede as rocket fuel, intellectual property on life support systems, or many other potential industries that could arise from scientific innovation that would take place on a space settlement? Or would this be totally an academic institution?
Minerva: It is not a totally academic institution because we have two thirds of the ship which will be occupied by students that remained on the settlement. But here, you don’t need money, everything being provided by us, so people don’t work for money, they work to occupy time, for enjoyment. If they do develop other industries, it will be fully for the greater good of humanity and the future of our kind, not for money.
SSP: The location chosen for Minerva is very challenging from an engineering perspective. Although Ganymede is not deep in Jupiter’s magnetosphere, and has its own magnetic field which could help mitigate exposure, the location will still have high levels of radiation if unprotected, which complicates the design because much more mass is needed to provide adequate shielding to be safe for humans. In addition, travel times to Jupiter are quite long even with improved propulsion which you’ve indicated would be as high as four years for students wanting to make the journey. Finally, solar energy at Jupiter’s remote distance from the sun requires that photovoltaic arrays be enormous to provide sufficient energy. A good compromise might be the asteroid Ceres, which is believed to be 25% water and does not have a magnetic field generating high radiation like what would be experienced at Jupiter. Others have proposed this asteroid as a good destination for space settlement. Why not locate the settlement in a more accessible and hospitable environment that might reduce costs?
Minerva: The main reason we chose such a far away location is precisely because we want to explore as much as possible of the cosmos. It’s not that we don’t want a closer location, it’s just that we know very little about Jupiter and its surrounding moons and further and this university can offer humanity an opportunity to explore it and send the research back to Earth. At the same time, we have taken the radiation into consideration and just how today’s spaceships have protection against it, so how [sic] our settlement, but ten times more efficient.
SSP: The sources of power for Minerva include solar arrays and nuclear fission, but you excluded fusion energy because it is currently experimental. By the time it will be technologically possible to travel to Jupiter and establish infrastructure that far out in the solar system, we will have developed fusion energy for use on Earth as well as in space. The preliminary design work for a Direct Fusion Drive for rapid transit to the outer planets has been started by Princeton Satellite Systems and the Fusion Industry Association just came out with their third annual report stating that the industry has now attracted over $6 billion in investment. When it is feasible to begin work on Minerva, fusion power sources will likely be available. Will you be updating your project plan as new technologies become available?
Minerva: Of course, we are sure that many aspects of our settlement can be improved by future developments in science, engineering and many other fields. As much as possible, we will incorporate them into our settlement. As mentioned in our paper, when talking about technological advances that may happen, we have to keep up with innovation and incorporate them to help us fulfill every need when travelling to space.
SSP: You raised the concern that Earth is approaching a major crisis with population growth putting a strain on Earth’s vital resources. You also said that the purpose of the space community is to sustain humanity if Earth’s environment became unfavorable for life. In selecting the location of Minerva, when considering Mars and its orbital distance, you said that even though it fulfills most of your requirements “…the disadvantage of Mars its it proximity to Earth…” and it “…is too close to our planet in order for us to choose it as the proper placement for the spacecraft.” Why must Minerva be distant from Earth if the planet is in crisis in the future and why isn’t the orbit of Mars, at 56 million kilometers, considered not far enough away?
Minerva: Mars wasn’t a viable option because, as we have stated before, the purpose of the USE is to gather information and scientific news that can only be found in the farther cosmos. We already know a lot about Mars and planets in close proximity to Earth, we want to venture further, discover and experiment with more than we already have.
SSP: Some surveys say that young people live in fear of the future due to climate change. Many media outlets amplify this doom and gloom. However, some economists point out that using the United Nation’s own data from the Intergovernmental Panel on Climate Change, with the predicted increase in temperature by the year 2100, global GDP will be reduced by only 4% to deal with climate related impacts. Although it is clear that we should eventually reduce our dependance on fossil fuels this is not an existential threat. Plus, technological innovation continues to improve efficiency in resource utilization, energy development and agriculture, enabling higher standards of living notwithstanding increasing population growth.
The viewpoint that the Earth is in “crisis” is closely aligned with Elon Musk’s motivation, who believes it is urgent that we become a multiplanetary species, to have a “Plan B” in case of a planetwide catastrophe. Jeff Bezos has a different perspective, that heavy industrial activity could be moved off world to preserve the Earth’s natural environment and to improve humanities’ standard of living though utilization of unlimited space resources.
Gerard K. O’Neill saw the promise of space settlement as a way to solve Earth’s problems through the humanization of space. He saw it as a way to end poverty for all humans, provide high-quality living space that would continue to grow robustly, to moderate population growth without war, famine, dictatorship or coercion; and to increase individual freedom. Does your team share the same anxiety about the future as other young people: that life on Earth is doomed and therefore, we need to build Minvera as a sanctuary to preserve humanity? Or do you see it as one among many options for space settlement to improve life on Earth and beyond, as outlined in O’Neill’s vision?
Minerva: We see Minerva as a place where people that are smart and passionate about space have a chance to make scientific discoveries that would be impossible to do on Earth. Aligned with Gerald O’Neil’s [sic] view, we believe that humans should expand into space whether it is as a Plan B or by harvesting resources from other planets or celestial objects. With the help of Minerva, the smartest children of their generation will be able to experience these scenarios and be closer to the future. We don’t see Minerva as a Plan B for humanity, students that have finished their 4 years being able to return to earth, but rather as a place where people can enjoy a stress free and enjoyable environment. Therefore Minerva is preparing smart youngsters to be able to take advantage of any of the two cases. If they choose to remain on Earth, the knowledge that they acquired while in the USE will definitely increase humanity’s survivability against the existential threats mentioned.
SSP: You’ve created a survey [what was earlier referred to as a “Form” and can be found at the “Forum” link on the Minerva website] for anyone to express their opinion about your project and the prospect of living in space. Will you use this feedback to improve your project?
Minerva: Maybe in the future, yes. We have encouraged people to complete the survey honestly and there’s always place for improvement for anything. And the second reason is to observe humanity’s view on such a settlement. In creating such a complex space settlement, you need to align your view with the society’s beliefs, them being the ones who will eventually populate it.
SSP: Does your team expect to remain engaged with the project as you progress in your education and after you eventually establish your careers here on Earth?
Minerva: It was certainly an experience we will treasure for a long time, but not everything has to be drawn out. I think this project took a lot of work and effort and we want to invest into something new, see this contest from as many angles as possible while we can. This project like no other can incorporate so many aspects of society from which you can discover your biggest passions. Talking to everyone in our group, we found that each one of us enjoyed a different part of the project and we believe that that was the key to our win. We were all doing something we are passionate about and therefore worked even harder for the final result. Now that we’ve learned what topics intrigue us, we can start doing even more work in that domain. We believe that this project is the perfect opportunity and will open numerous doors in any future career path. We strongly recommend this contest to anyone wondering whether they should put their effort into it or not.
AI generated image of an amorous couple embracing in a space tourist destination. Credits: DALL-E
Last April, an international team of researchers published a green paper to solicit public consultation on the urgent need for dialogue concerning uncontrolled human conception which will be problematic for space tourism when it takes off in the near future. A coauthor on the paper, Alex Layendecker of the Florida based Astrosexological Research Institute (ASRI) studied the subject for his PhD thesis. Layendecker gave a talk at ISDC 2023 entitled Sex in Space in the Era of Space Tourism in which he emphasized the huge knowledge gap we have on mammalian conception, gestation and birth in the high radiation and lower gravity environments of outer space. Since humans evolved for millions of years in Earth’s gravity protected from radiation by our planet’s magnetic field and atmosphere, there is a significant risk of developmental abnormalities in offspring which could result in legal liability and potential impacts on commerce if conception occurs in space without consideration of the potential hazards. After his talk, I discussed these matters and the implications for space settlement with Alex who agreed to continue our discussion in an interview by email for this post.
SSP: Alex, it was a pleasure meeting you at ISDC and thank you for taking the time to answer my questions on this important topic. The green paper is attempting to foster discussion from relevant stakeholders on addressing “uncontrolled human conception”. Uncontrolled is defined in the paper as “…without societal approval for human conception – i.e. without regulatory approval from relevant bodies representing a broad societal consensus.” I am not aware of any regulatory authority on these matters at this time and there will likely be considerable challenges to obtain consensus across the space community before tourism becomes mainstream. The intent of the paper appears to be to help develop a framework for regulations (or guidelines) before space tourism takes off. Given how long it takes for regulations to be implemented and the challenges of international consensus, will there be enough time to implement sufficient controls before conception happens in space?
AL: Great question – short answer up front, no, I don’t believe any “controls” will be implemented before the first incidence of human conception in space, given the timelines we’re currently looking at. As you mentioned, regulations can take a long time to come into effect and you need to have a basis for establishing regulations/law – space law itself is still being developed. Our knowledge of reproduction in space is minimal at this stage, certainly not at the level it needs to be at this point of history. We’re also in virtually unexplored territory when it comes to mass space tourism – there have been space tourists in the past, Dennis Tito being the first “official” space tourist in history over 20 years ago – but all previous individuals that went into space for tourism purposes have done so while integrated into the crew, typically with very little privacy and a considerable amount of training. With mass access to space, we’ll soon have groups of individuals going up solely for vacation/leisure purposes, and you can be assured some of them will be engaging in sexual activity. While it would be absurd to try to implement or enforce laws preventing sexual activity in those environments, the dangers associated with potential conception still exist. What is critically needed at this point is a better collective understanding of those dangers, their mitigation, and for space companies to be able to provide those paying customers with enough information that informed consent can be established – space is inherently dangerous already, and people launching into space are briefed on that. They will need to be briefed on the dangers associated with conception in space as well, which could not only potentially threaten the life of the baby but also that of the mother, depending on the times and distances involved.
SSP: Will this be a government effort (since a green paper typically implies government sponsorship) or a self-imposed industry-wide trade association consensus approach like CONFERS? Or a combination?
AL: I think in the immediate sense, there will need to be a self-imposed industry consensus on establishing informed consent among space tourism customers. Sex and potential conception in space is currently a blind spot for would-be space tourism companies, because up to this point many of them haven’t considered the dangers it could pose to their customers, and corporate liability here is also an issue. It’s their responsibility to keep their passengers safe, and to inform them of any dangers to the max extent possible. I don’t necessarily see governments being able to implement or enforce any regulations in this regard, because regulating people doing what they want with their own bodies in the privacy of their own bedrooms typically doesn’t fare well over the long term. Where governments may get involved is if any medical situation develops to the point of needing rapid rescue, but Space Rescue capabilities is another topic.
SSP: Space tourism is likely to attract thrill seekers and risk-takers who are likely to have rebellious personalities with a reluctance to follow rules and regulations, let alone respect for societal norms. If this is the case, will pre-flight consultations on the risks of uncontrolled conception and legal waivers be sufficient to prevent risky behavior? Can the effectiveness of this approach be tested prior to implementation?
AL: Prevent risky behavior? Absolutely not. As you point out, these are folks who are intentionally undertaking an enormously risky endeavor in flying to space already, and at least in the early years, will be primarily comprised of your limits-pushing, boundary-breaking types. So they’re already about risk as individuals. However, legal waivers will of course be part of the whole operation, likely to include waivers around the risks of conception. Waivers or not, people are still going to engage in sex in space, and relatively soon, and if the individuals in question are capable of conception, the act itself brings that risk. Not to mention that there are individuals out there who will be vying for the title of “first couple to officially have sex in space,” despite speculation over the years that it could have occurred in the past. To be part of the first publicly declared coupling in outer space will land their names in history books. Now, there will be individuals who decide that they don’t want to deal with those risks after a thorough briefing on the potential dangers, but not everyone – probably not even a majority, knowing humans – will be deterred.
SSP: The paper highlights concerns about pregnancy in higher radiation and microgravity environments. From a space settlement perspective, radiation is less of a problem as there are engineering solutions (i.e. provision for adequate shielding) to address that issue. The bigger challenge will be pregnancies in microgravity, or in lower gravity on the Moon and Mars. The physiology of human fetus development in less than 1g is a big unknown. Some space advocates such as Robert Zubrin brush this off with the logic that a fetus in vivo on Earth is developing in essentially neutral buoyancy, and is therefore weightless anyway, so gestation in less than 1g probably won’t matter. Setting aside the issues associated with conception in lower gravity, if a woman can become pregnant in space, do you think this logic may be true for gestation or are there scientific studies and/or physiological arguments on the importance of Earth’s gravity in fetal development that refute this position?
AL: I’ve heard the neutral buoyancy argument before but it doesn’t address all the issues by a long shot. There is more neutral buoyancy during the first trimester of gestation but in the second and third gravity is very important, even just logistically speaking. Gravity helps the baby orient properly for delivery, and helps keep the mother’s uterine muscles strong enough to provide the necessary level of contractions to safely move the baby through the birth canal. On a more cellular level, cytoskeletal development is impacted by gravity, so even proper formation and organization of cells can be affected by microgravity throughout the span of gestation, from conception to birth. Gravity has a huge impact on postnatal development as well – in the small handful of NASA experiments we’ve conducted using mammalian young (baby rat and mouse pups), there were significant fatality rates among younger/less developed pups against ground control groups when exposed to microgravity during key postnatal phases. The youngest pups (5 days old) suffered a 90% mortality rate, and any of the survivors had significant developmental issues. So gravity is crucial not just to fetal development but to newborns and children as well, that much is evident from the data we do have.
SSP: Following up on your response, the Moon/Mars settlement advocates will say partial gravity levels on these worlds may be sufficiently higher than in microgravity to address the issues you mentioned – baby orientation, cytoskeletal development, cellular formation/organization, postnatal development – and a full 1g may not be needed for healthy reproduction. The mammalian studies you mentioned with detrimental postnatal development were in microgravity. We now have a data point at the lunar gravity level from JAXA with their long awaited results of a 2019 study on postnatal mice subjected to 1/6g partial gravity in a paper in Nature that was published last April. The good news is that 1/6g partial gravity prevents muscle atrophy in mice. The downside is that this level of artificial gravity cannot prevent changes in muscle fiber (myofiber) and gene modification induced by microgravity. There appears to be a threshold between 1/6g and Earth-normal gravity, yet to be determined, for skeletal muscle adaptation. Have you seen these results, can you comment on them and do you think they may rule out mammalian postnatal development in lunar gravity?
AL: With regard to the JAXA study, I think I’ve seen a short summary of preliminary results but haven’t gotten to read the full study yet. What I will comment for now is that there’s at least some promise in those results from a thousand foot view. While we still need to determine/set parameters for what we as a society/species consider medically/ethically acceptable for level of impact (obviously there was gene modification in the JAXA mice), there are clearly still some benefits to even lower levels of gravity.
SSP: With respect to risk mitigation and the paper’s recommended area of research: “Consolidation of existing knowledge about the early stages of human (and mammalian) reproduction in space environments and consideration of the ensuing risks to human progeny”, SSP has covered off-Earth reproduction and highlighted the need for ethical clinical studies in LEO to determine the gravity prescription (GRx) for mammalian (and eventually human) procreation. During our personal discussions at ISDC, you mentioned ASRI’splans for such studies in space. Can you elaborate on your vision for mammalian reproduction studies in variable gravity? What would be your experimental design and proposed timeline?
AL: Well, with regard to timelines, humanity as a whole is already behind, so we’ll need to move as quickly as we possibly can while still upholding safe medical and ethical standards. We’re approaching an inflection point where human conception in space is more probable to occur, and we still have vast data gaps that need to be filled on biological reproduction. I’d advocate that the best way to go about filling those gaps would be a systematic approach using mammalian test subjects to determine safe and ethically acceptable gravity parameters for reproduction. We already know a decent amount about the impacts of higher radiation levels on reproduction from data gathered on Earth, but with microgravity we’ve still got a long way to go, and we don’t know what the synergistic effects of microgravity and radiation are together either. With regard to experiments, NASA researchers have actually already designed extensive mammalian reproduction experiments with university partners, but those experiments haven’t been funded by the agency. There was a comprehensive experiment platform called MICEHAB (Multigenerational Independent Colony for Extraterrestrial Habitation, Autonomy and Behavior) that was proposed back in 2015, around the time I was completing my PhD dissertation. It would effectively be a robot-maintained mini space station that would study the microgravity and radiation effects on rodents in spaceflight over multiple generations, which of course requires sexual reproduction. That experiment alone would prove enormously beneficial to data collection efforts. It would be important to study said generations and physiological impacts at variable gravity levels as you mentioned – think the Moon, Mars, 0.5 Earth G, 0.75 Earth G and so on, so we could fine tune what level of impact we as a species are medically and ethically willing to accept in order to settle new worlds. With regard to ASRI’s experiment roadmap, our intent is to start with smaller, simpler experiments that will garner us more data on individual stages of reproduction first using live mice and rats, with the hope of eventually moving on to complex and comprehensive experiments like MICEHAB. Once we have a good plot of data over the course of many experiments, we can hopefully move on to primate relative studies to establish safe parameters for human trials. I anticipate the small mammal experiments alone will take at least five years were we to launch our first mission at this very moment – though speed is often dependent on level of funding, as happens with most science.
SSP: If contraceptives are recommended to prevent conception during space tourism voyages, the paper calls for validation of the efficacy of these methods in off-world environments. Do your plans for variable gravity experiments include such studies and how would you design the protocol?
AL: Well, the first important thing to remember is that contraceptives are known to fail occasionally on Earth – condoms can break (especially if used incorrectly), and even orally-taken birth control pills aren’t considered 100% effective. Currently ASRI doesn’t have plans for contraception studies because that’s further forward than we can reasonably forecast at this point. Frankly we need to establish medical parameters first regarding conception in space and know where the risk lines are before we implement birth control studies using humans. We have to take many small steps before we get there. Once we do have established limits for safe reproduction in space environments, we would look to operate any birth control studies within those parameters to determine efficacy. That way if the contraceptives do fail, we at least know the resulting pregnancy has a reasonable chance of success.
SSP: Should experiments on mammalian reproduction in variable gravity determine that fetal developmental or health issues arise after conception and gestation in less than 1g, do you think this may lead to a significant shift in the long-term strategy for space settlement (e.g. toward O’Neill type artificial gravity space settlements) if children are to be born and raised in space?
AL: I certainly think so. There’s a lot at stake here. If we can’t safely birth and grow new generations of humans at a Martian gravity level (0.38 Earth G), then we’ve largely lost Mars as a destination for permanent multigenerational settlement. Fully grown adults can live and work down on the planet itself, but we’d need to come up with an alternate nearby solution for pregnant mothers and children growing up to certain age. From an engineering perspective, artificial gravity space settlements like an O’Neill cylinder make the most sense to me personally, so long as there’s Earth-level radiation shielding and gravity, and you can recreate Earth-like environments within those structures. During our conversation at ISDC I referred to it as an “Orbital Incubator” concept, though I’m of course not the first person to ever discuss something like that.
SSP: I appreciate you sharing your PhD Thesis with me. In that work you developed the Reproduction and Development in Off-Earth Environments (RADIO-EE) Scale to provide a metric that could help future researchers identify potential issues/threats to human reproduction in space environments, i.e. microgravity and radiation. Respecting your request that the images of the metric not be published at this time, qualitatively, the scale plots the different phases of reproduction, fetal development, live birth and beyond against levels of gravity or radiation in outer space environments encompassing the range from microgravity all the way up to 1g (and even higher). The scale displays green, amber, and red areas mapping safe, cautionary, and forbidden zones, respectively, dependent on location (e.g. Moon, Mars, free space, etc.). When I originally read your thesis I thought you included both gravity and radiation on the same chart but after our discussions I understand that they would have to be separated out. I also acknowledge that we have no data at this time and the metric is a work in process to be filled in as experiments are performed in space. Have you consideredusing three dimensions (gravity on x-axis, radiation on the y-axis, viability on the z-axis) and create a surface function for viability. Does that make sense?
AL: I’m totally with you on the 3D model scale (I’ve always thought of it like navigating a “tunnel” made up of green data points to reach the end of the reproductive cycle safely). The scale was originally envisioned as separate graphs for Microgravity/Hypergravity and Radiation, but obviously we couldn’t combine those in 2D because those two different factors can vary wildly depending on where you’re physically located in the solar system/outer space in general. So the best answer is to effectively plot green, amber, and red “zones” on each chart (again based on location), then make sure that wherever we’re trying to grow/raise offspring (of any Earth species) we’re keeping our expectant mothers and children in double-green zones (for both gravity, and radiation). Now the third axis would actually be time (i.e. what point are you at in the reproductive cycle), with viability being determined by where all three axes meet in a green/amber/red zone.
I’d like to thank Alex for this informative discussion and look forward to further updates as his research progresses. We urgently need his insights to inform ethical policies and practices regarding reproduction for the space tourism industry in the short term, and eventually for having and raising healthy children wherever we decide to establish space settlements. Readers can listen to Alex describe his research live and talk to him in person when he appears on The Space Show currently scheduled for August 27.
Artist impression of an asteroid smelting operation. Credits: Bryan Versteeg / spacehabs.com
When humanity migrates out into the solar system we’ll need a variety of elements on the periodic table to build settlements and the infrastructure needed to support them such as solar power satellites. But before that future becomes a reality, there may be a near term market on Earth for precious metals sourced in space as transportation costs come down. There is also the added benefit of moving the mining industry off planet to preserve the environment. Could the asteroid belt provide these materials? Kevin Cannon, assistant professor at the Space Resources Program at the Colorado School of Mines describes the prospects for mining precious metals and building materials for space infrastructure asteroids in a recent paper in Planetary and Space Science. Coauthors on the paper Matt Gialich and Jose Acain, are CEO and CTO, respectively, at the asteroid mining company AstroForge which just came out of stealth mode last year.
The asteroids have accessible mining volume that exceeds that available on the Moon or Mars. This is because only the thin outer crust of these bodies is reachable by excavation, whereas the asteroids are small enough to be totally consumed resulting in higher accessible mining volume.
To-scale accessible mining volume of terrestrial bodies, calculated as the total volume for the asteroids (main belt mass of 2.39 x 1023 kg, mean bulk density of 2000 kg/m3), and as the volume for an outer shell 1.2 km in thickness for the Moon, Mercury, and Mars, equivalent to the deepest open pit mine on Earth. Note the combined volume of the near-Earth asteroids (~5 x 1012 m3) is too small to be visible at this scale. Figure 1 in paper. Credits K.M. Cannon et al.
The authors take a fresh look at available data from meteorite fragments of asteroids. Their analysis found that for Platinum Group Metals (PGMs), the accessible concentrations are higher in asteroids than ores here on Earth making them potentially profitable to transport back for use in commodity markets.
“Asteroids are a promising source of metals in space, and this promise will mostly be unlocked in the main belt where the Accessible Mining Volume of bodies greatly exceeds that of the terrestrial planets and moons”
PGMs are indispensable in a wide range of industrial, medical, and electronic applications. Some examples of end-use applications include catalysts for the petroleum and auto industries (palladium and platinum), in pacemakers and other medical implants (iridium and platinum), as a stain for fingerprints and DNA (osmium), in the production of nitric acid (rhodium), and in chemicals, such as cleaning liquids, adhesives, and paints (ruthenium).
It has been pointed out by some analysts that flooding markets here on Earth with abundant supplies of PGMs from space will cause prices to plummet, but the advantage of reducing carbon emissions and environmental damage associated with mining activities may make it worth it. The authors also point out that there are probably various uses where PGMs offer advantages in material properties over other metals but are not being used because they are currently too expensive.
Asteroids are rich in other materials such as silicon and aluminum which would be economically more useful for in-space applications. As the authors point out, some companies are already planning for use of metals and manufacturing in space such as Redwire Corporation with their On-Orbit Servicing, Assembly and Manufacturing (OSAM) and Archinaut One, which will attempt to build structural beams in LEO. Another example mentioned in the paper has been covered by SSP: the DARPA NOM4D program with aspirations to develop technologies for manufacturing megawatt-class solar arrays and radio frequency antennas using space materials. Finally, another potential market for aluminum sourced in space is fuel for Neumann Thrusters (although spent upper stage orbital debris may provide nearer term supplies). And of course, silicon will be needed to fabricate photovoltaic cell arrays for space-based solar power.
AstroForge will test their asteroid mining technology on two missions this year. Brokkr-1, a 6U CubeSat just launched on the SpaceX Transporter 7 mission last April, will validate the company’s refinery technology for extracting metals by vaporizing simulated asteroid materials and separating out the constituent components. Brokkr-2 will launch a second spacecraft on a rideshare mission chartered by Intuitive Machines attempting their second Moon landing later this year. Brokkr-2 will hitch a ride and then fly on to a target asteroid located over 35 million km from Earth. The journey is expected to take about 11 months and will fly by the body and continue testing for two years to simulate a roundtrip mission.
AI generated image depicting a propellant factory on the Moon. Credits: DALL-E
The economics of an in-space industry based on lunar-derived rocket propellant was examined by Florida Space Institute planetary physicist Philip Metzger in a prepublication paper submitted to arXiv on March 16 . The study will be published in the June issue of Acta Astronautica. Many skeptics of this approach believe that with launch costs plummeting, driven down primarily due to reusability pioneered by SpaceX, it will be cheaper to power the nascent cislunar economy with propellant launched from Earth rather then fuel derived from lunar ice mining.
In his analysis, Metzger examines a cislunar economy of companies that operate geostationary satellites which need to purchase boost services using orbital transfer vehicles fueled by cryogenic hydrogen and oxygen. The question is, would sourcing H2/O2 from ice mined on the Moon be competitive with launching propellant from Earth. He notes that previous studies that favored Earth to solve this problem were flawed because they compared the different technologies for mining water on the Moon (e.g. strip mining, borehole sublimation, tent sublimation, or excavation with beneficiation) rather than analyzing the economics of the cis-lunar economy as a sector.
With that approach in mind, Metzger develops an economic model with figures of merit to assess how various technologies for ice mining compare to Earth sourced propellant. One such parameter is the “gear ratio” G, which in the parlance of orbital dynamics, is the ratio of the mass of hardware and propellant before versus after moving between two locations in accordance with the rocket equation. The other key metric is the production mass ratio Ø, which is the mass of propellant delivered to a specific location divided by the mass of the capital equipment needed to produce the fuel.
The “tent sublimation technology” mentioned in the paper was invented by George Sowers and is featured in his 2019 NIAC Phase I Final Report on ice mining from cold bodies in the solar system covered by SSP previously.
Although G is constrained by the laws of physics, reasonable values are possible and a value of Ø ≥ 35 is the threshold above which lunar propellant wins out. The tent sublimation technology is estimated to have Ø over 400, an order of magnitude higher than the minimum to gain an advantage. Metzger’s new approach took into account that launch costs will eventually come down as far as possible but even then, found that lunar propellant can be produced at a competitive advantage. The only caveat is validation of the TRL and reliability of ice mining technologies.
“Lunar-derived rocket propellant can outcompete rocket propellant launched from Earth, no matter how low launch costs go.”
Although not included in Metzger’s study, a method for extraction of water from lunar regolith is heating by low power microwaves. A recent study found that this technology is effective for extracting water from simulated lunar soil laced with ice. It would be interesting to see if Ø for this technique exceeds the advantage threshold.
Developing the business case for lunar water is the first step in rapidly bootstrapping an off-Earth economy. Metzger has written about this previously where he sees robotics, 3D printing and in situ resource utilization being leveraged to accelerate growth of a solar system civilization.
Artist’s impression of the interior of an O’Neill Cylinder space settlement near the endcap. Credits: Don Davis courtesy of NASA
Its a given that space travel and settlement are difficult. The forces of nature conspire against humans outside their comfortable biosphere and normal gravity conditions. To ascertain just how difficult human expansion off Earth will be, a new quantitative method of human sustainability called the Panscosmorio Theory has been developed by Lee Irons and his daughter Morgan in a paper in Frontiers of Astronomy and Space Sciences. The pair use the laws of thermal dynamics and the effects of gravity upon ecosystems to analyze the evolution of human life in Earth’s biosphere and gravity well. Their theory sheds light on the challenges and conditions required for self restoring ecosystems to sustain a healthy growing human population in extraterrestrial environments.
“Stated simply, sustainable development of a human settlement requires a basal ecosystem to be present on location with self-restoring order, capacity, and organization equivalent to Earth.”
The theory describes the limits of space settlement ecosystems necessary to sustain life based on sufficient area and availability of resources (e.g. sources of energy) defining four levels of sustainability, each with increasing supply chain requirements.
Level 1 sustainability is essentially duplicating Earth’s basal ecosystem. Under these conditions a space settlement would be self-sustaining requiring no inputs of resources from outside. This is the holy grail – not easily achieved. Think terraforming Mars or finding an Earth-like planet around another star.
Level 2 is a bit less stable with insufficient vitality and capacity resulting in a brittle ecosystem that is subject to blight and loss of diversity when subjected to disturbances. Humans could adapt in a settlement under these conditions but would required augmentation by “…a minimal supply chain to replace depleted resources and specialized technology.”
Level 3 sustainability has insufficient area and power capacity to be resilient against cascade failure following disturbances. In this case the settlement would only be an early stage outpost working toward higher levels of sustainability, and would require robust supplemental supply chains to augment the ecosystem to support human life.
Level 4 sustainability is the least stable necessitating close proximity to Earth with limited stays by humans and would require an umbilical supply chain supplementing resources for human life support, and would essentially be under the umbrella of Earth’s basal ecosystem. The International Space Station and the planned Artemis Base Camp would fall into this category.
Understanding the complex web of interactions between biological, physical and chemical processes in an ecosystem and predicting early signs of instability before catastrophic failure occurs is key. Curt Holmer has modeled the stability of environmental control and life support systems for smaller space habitats. Scaling these up and making them robust against disturbances transitioning from Level 2 to 1 is the challenge.
How does gravity fit in? The role of gravity in the biochemical and physiological functions of humans and other lifeforms on Earth has been a key driver of evolution for billions of years. This cannot be easily changed, especially for human reproduction. But even if we were able to provide artificial gravity in a rotating space settlement, the authors point out that reproducing the atmospheric pressure gradients that exist on Earth as well as providing sufficient area, capacity and stability to achieve Level 1 ecosystem sustainability will be very difficult.
Peter Hague agrees that living outside the Earth’s gravity well will be a significant challenge in a recent post on Planetocracy. He has the view, held by many in the space settlement community, that O’Neill colonies are a long way off because they would require significant development on the Moon (or asteroids) and vast construction efforts to build the enormous structures as originally envisioned by O’Neill. Plus, we may not be able to easily replicate the complexity of Earth’s ecosystem within them, as intimated by the Panscosmorio Theory. In Hague’s view Mars settlement may be easier.
Should we determine the Gravity Rx? Some space advocates believe that knowledge of this important parameter, especially for mammalian reproduction, will inform the long term strategy for permanent space settlements. If we discover, through ethical clinical studies starting with rodents and progressing to higher mammalian animal models, that humans cannot reproduce in less than 1G, we would want to know this soon so that plans for the extensive infrastructure to produce O’Neill colonies providing Earth-normal artificial gravity can be integrated into our space development strategy.
Others believe why bother? We know that 1G works. Is there a shortcut to realizing these massive rotating settlements without the enormous efforts as originally envisioned by Gerard K. O’Neill? Tom Marotta and Al Globus believe there is an easier way by starting small and Kasper Kubica’s strategy may provide a funding mechanism for this approach. Given the limits of sustainability of the ecosystems in these smaller capacity rotating settlements, it definitely makes sense to initially locate them close to Earth with reliable supply chains anticipated to be available when Starship is fully developed over the next few years.
Companies like Gravitics, Vast and Above: Space Development Corporation (formally Orbital Assembly Corporation) are paving the way with businesses developing artificial gravity facilities in LEO. And last week, Airbus entered the fray with plans for Loop, their LEO multi-purpose orbital module with a centrifuge for “doses” of artificial gravity scheduled to begin operations in the early 2030s. Panscosmorio Theory not withstanding, we will definitely test the limits of space settlement sustainability and improve over time.
Listen to Lee and Morgan Irons discuss their theory with David Livingston on The Space Show.
AI generated image of crops growing in sealed enclosure within a radiation protected lava tube on Mars. Credits: Microsoft DALL-E Image Creator
Agriculture on Mars is problematic. Even if radiation exposure could be solved (perhaps by locating greenhouses in lava tubes) and sufficient sources of water secured, there is that pesky perchlorate in the soil. Not to worry. The Interstellar Research Group has us covered. IRG, who’s mission is to assist in building a technological, philosophical, and economic infrastructure that advances the goal of establishing outposts throughout the Solar System and, finally, achieving a pathway to the stars, has initiated MaRMIE – the Martian Regolith Microbiome Inoculation Experiment. An informative summary of the project is provided by Alex Tolley over on Centauri Dreams.
SSP has addressed the biological remediation of perchlorates in Martian regolith previously. The research paper linked in that article examined phytoremediation which uses aquatic plants for perchlorate removal and microbial remediation processes utilizing microorganisms and extremophiles. IRG focused on the latter but noted that since the contaminants are water soluble, simply rinsing of the Martian regolith may be a potential solution for removal of the contaminants if sufficient sources of water can be found.
Perchlorates are only one piece of the puzzle to create fertile soil on Mars. So IRG expanded the scope of this initiative to design an experiment to simulate crop growth under the extreme conditions we can expect on Mars, taking into account the composition and pressure of the atmosphere, temperature extremes and high levels of ionizing radiation. The group envisioned a framework of research that would include five phases. The first phase would address the perchlorate issue experimenting with a variety of bacterial and microfungal agents applied to simulated Martian regolith mixed with perchlorates.
In the next phase, the simulated regolith would be conditioned by creating a microbiome to inoculate the regolith. This would include evaluation of pioneer plant species under Martian environmental conditions to transition the regolith into fertile soil.
The third phase would then attempt to grow crops in the mock soil under Martian lighting and atmospheric conditions with increasing ambient pressures until plant growth is satisfactory.
In the fourth phase, the experiment would be repeated with the same settings as in the third phase but decreasing the temperature to find when plant grow tapered off to unacceptable levels. This approach would home in on the optimum conditions for crop growth in the prepared Martian soil.
Finally, the infrastructure to create a farm implementing these conditions on the surface of Mars with appropriate protection from radiation would be defined.
It is not the intention of IRG to actually run these experiments. The output of the effort would be a published paper documenting the known issues and providing an outline of the required studies. Tolley explains that “IRG hopes that this framework will be seen and used as a structure for designing experiments and building on the results of previous experiments, by any researchers interested in the ultimate goal of viable large-scale agriculture on Mars.”
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.
Artist impression of a rotating space settlement constructed from an asteroid. Credits: Bryan Versteeg, spacehabs.com
When Gerard K. O’Neill first proposed building enormous rotating space settlements at the Earth-Moon Lagrange points back in the 1970s he envisioned many space shuttle flights to launch the initial equipment and people into space. He thought that mass drivers placed on the Moon would be an efficient and cost effective mechanism for lofting copious amounts of lunar regolith needed for radiation shielding to protect colonists aboard the settlements. Alas, the economics of the shuttle did not work out back then, as reusability (among other things) was not ready for prime time, making launch costs a show stopper. Also, O’Neill thought that hundreds of people would be working under weightless conditions in space to fabricate the settlements. This was problematic because of the health hazards of exposure to radiation and microgravity.
All three problems can be solved according to David W. Jensen in an article posted on the ArXiv server. He envisions restructuring an asteroid into a spin gravity space settlement using self replicating robots to process asteroid materials in situ. High launch costs would be solved with a single modest-size probe containing a small number of seed robots that fashion more robots, tools and equipment. This approach bootstraps the colony fabrication through self replicating machines and in situ resource utilization.
“The restructuring process improves the productivity using self-replication parallelism and tool specialization.”
By removing humans from the initial asteroid processing activities, health risks from radiation and the deleterious effects of microgravity would be eliminated. Restructuring of the asteroid would take about a decade, after which colonists would have a rotating space settlement the size of a Stanford Torus providing Earth normal gravity and a safe living space shielded from radiation, ready for buildout and eventual occupation.
Cutaway view of a Stanford Torus space settlement. Credits: Rick Guidice / NASA
The key to this approach is self replication of robots delivered in the initial seed payload which significantly reduces costs by launching only one rocket to the target asteroid. The first machines sent are called replicators, or spiders for short. Four of these spiders with a minimum of supplies use the raw materials of the asteroid to make thousands of copies of themselves plus additional helper machines (tools and equipment). The spiders and helpers cooperate to produce end products of construction materials and the colony structures.
Jensen does not assume total self-replication, meaning that the robots do not need to make complete copies of themselves. A small percentage of more complex mechanisms such as microprocessors are provided in the initial payload as supplemental “vitamins” to finish out the machines. The intent is to minimize the need for humans in the initial construction phase. The objective is to fabricate a basic scaffolding for a rotating space settlement with access to an abundant storehouse of volatiles and metals. The final enclosed structure would then support migration of colonists who would complete construction and add more advanced manufacturing technologies such as solar cell production and microelectronics. As SSP has explained previously, complete closure of self-replicating machines is very challenging, but is not needed in this case.
The technology has wide applications and could be applied to Earth’s desserts, on the surface of the Moon or Mars, or even on the satellites of Jupiter and Saturn.
“We plan to apply and study these concepts for use in lunar, Titan, and Martian environments.”
Jensen’s restructuring process could complement or be combined with other asteroid mining architectures such as the University of Rochester’s approach which builds spin gravity cities starting with a carbon fiber collapsible scaffolding completely encapsulating the target asteroid. As the process matures it could be applied to even larger bodies such as the asteroid Ceres eventually combining settlements into a mega satellite community as envisioned by Pekka Janhunen.
“The equipment and process are scalable and … create a space station structure that can support a population of nearly one million people.”
Artist’s impression of a lunar landing pad. Credits: SEArch+
When humanity returns to the Moon and begins to build infrastructure for permanent settlements, propulsive landings will present considerable risk because rocket plumes can accelerate lunar dust particles in the bare regolith to high velocities which could result in considerable damage to nearby structures. Obviously, nothing can be done about the first spacecraft that will return to the moon later this decade unless they use their own rocket plume to create a landing pad like the concept proposed in a NIAC Grant by Masten Space Systems (now part of Astrobotic).
Flight Alumina Spray Technique (FAST) instant landing pad deployment during lunar landing. Source: Matthew Kuhns, Masten Space Systems Inc (now Astrobotic)
Therefore, before significant operations can begin on the Moon that require lots of rockets, a high priority will be construction of landing pads to prevent sandblasting by rocket plume ejecta of planned structures such as habitats, science experiments and other equipment. Several methods are currently being studied. Some require high energy consumption. Others could take a long time to implement. Still others are technologically immature. Which technique makes the most economic sense? Phil Metzger and Greg Autry examine options for the best approach to this urgent need in a November 2022 paper in New Space.
A lunar landing pad should have an inner and outer zone. The inner zone will have to withstand the intense heat of a rocket plume during decent and ascent. The outer zone can be less robust as the expanding gases will cool rapidly and decrease in pressure but will still be expanding rapidly, so erosion will have to be mitigated over a wider area.
Landing pad layout showing inner and outer zone measurements proposed in this study (Figure 1 in paper). Credits: Philip Metzger and Greg Autry / New Space – Lunar surface image credit: NASA.
Several processes of fabricating landing pads were examined by the authors. Sintering of regolith is one such technique, where dust grains are heated and fused by a variety of methods including microwave heating or focused solar energy. SSP has reported on the latter previously, but in this study it was noted that that technology needs further development work. Fabricating pavers by baking in ovens in situ was also examined in a addition to infusion of a polymer into the regolith to promote particle adhesion.
An economic model was developed to support construction of landing pads for NASA’s Artemis Program based on experimental data and the physics for predicting critical features of construction methods. Factors such as the equipment energy consumption, the mass of microwave generators compared to the power output needed to sinter the soil to specified thickness, and the mass of polymer needed to infuse the regolith to fabricate the pads were included in the model. Other factors were considered including the costs associated with program delays, hardware development, transportation of equipment to the lunar surface, and reliability.
When varying these parameters and comparing different combinations of manufacturing techniques, the trade study optimized the mass of construction equipment to balance the costs of transportation with program delays. The authors found that from a cost perspective, microwave sintering makes the most sense for both the inner and outer regions of the landing pad, at least initially. When transportation costs come down to below a threshold of $110K/kg then a hybrid combination of microwave sintering in the inner zone and polymer infusion of regolith in the outer zone makes the most sense.
Once astronauts land safely and begin EVAs on the lunar surface, they can keep from tracking dust into their habitat by taking an electron beam shower.
Other lunar dust problems and their risks can be mitigated with solutions covered previously on SSP.
