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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

SSP: What are the next steps for SHEPHERD?

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

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

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

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

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

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

Links and Resources:

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

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

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

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

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An efficient biological intensive oxygen and sustenance system for life support

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

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

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

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

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

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Self replicating factories for space settlement

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

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

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

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

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

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

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

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

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

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

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Growing fungi for space structural materials

Diagram depicting the mission architecture of a Mars habitat built from mycelia growth. Credits: 2018 Stanford-Brown-RISD iGEM Team / NASA

Lynn Rothschild, a scientist at NASA’s Ames Research Center in California, has just been awarded a NASA Innovative Advanced Concept (NIAC) Phase 2 grant to continue her synthetic biology studies using mycelium, the branching, thread-like structures of fungi, to “grow” space structures such as habitats, furniture and more. Rothchild previously advised a team working on mycelium production, or what she calls Myco-architecture, for habitats on the Moon and Mars. The project took place at NASA Ames as part of the iGEM Competition in the summer of 2018, and was funded by a NIAC Phase 1 award. Called Stanford-Brown-RISD or Myco for Mars as the they called themselves, the team was composed of students from Stanford University and the duel degree program of Brown University and the Rhode Island School of Design.

This new phase of the research will continue development of mycelia production, fabrication, and testing techniques. Rothschild describes the process on the NASA Myco-architecture Project site: “On Earth, a flexible plastic shell produced to the final habitat dimensions would be seeded with mycelia and dried feedstock and the outside sterilized. At destination, the shell could be configured to its final inner dimensions with struts. The mycelial and feedstock material would be moistened with Martian or terrestrial water depending on mass trade-offs, and heated, initiating fungal (and living feedstock) growth. Mycelial growth will cease when feedstock is consumed, heat withdrawn or the mycelia heat-killed. If additions or repairs to the structures are needed, water, heat and feedstock can be added to reactivate growth of the dormant fungi.”

Artist rendering of a habitat grown on Mars from mycelia. Credits: Emilia Mann / 2018 Stanford-Brown-RISD iGEM Team / NASA

This research joins other studies in synthetic biology advancing space settlement such as using fungi to seed asteroids for making soil to be used in space settlement agriculture, microbial lawns for radiation shielding, or cyanobacteria for life support systems.

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Countering the naysayers of space settlement

Space Colonies Torus Interior
Artist concept of a free space settlement. Credits: Don Davis / NASA

Al Globus has just published a set of cogent responses to objections made by those who question why space settlement should be considered as a goal for humanity. A link to the piece is on his website Free Space Settlement. His analysis first defines what space settlement is, then why it should be pursued and finally refutes point by point, arguments against the endeavor.

Globus positions the case for space settlement around surviving and thriving. Surviving centers on dispersing humanity’s eggs outside of Earth’s basket as a hedge against the risk of catastrophic threats such as “…climate change, major asteroid hits, supervolcano eruptions, nuclear war, pandemic, nearby supernova, and technology run amok.” Even if humanity does survive these potential hazards, in about 5 billion years our sun will transition to a red giant making life on Earth uninhabitable. Clearly our future on the home planet is not assured forever. At current population growth rates, we will have exhausted Earths resources long before then.

Thriving recognizes that expanding into space is the next step in human evolution. Globus reminds us that “…living things want to grow and expand, to thrive, not simply exist.” By settling space “…resource wars are unlikely and unnecessary because our Sun provides billions of times the energy used on Earth and the asteroids provide enough material to make new orbital land hundreds of times greater than the surface area of the Earth.”

To the objection that space is too expensive and that funds would be better spent on Earth, there are two talking points. First, it is always prudent to allocate a small percentage of outlays on planning for the future. NASA’s funding in 2020 was less then 1/2 of a percent (0.48%) of total US expenditures. The US spends quite a bit more on social programs so this argument is very weak. Second, the benefits we receive from space activities in our economy pay significant dividends. SSP has covered the return on space investments and the value of space infrastructure previously.

The next general category of objections falls under “It Can’t Be Done” such as farming in space is not feasible, radiation levels are too high and weightless conditions are intolerable for humans. Globus easily addresses each concern with technological solutions well represented on SSP’s ancillary pages.

An interesting set of protestations are described as “Power Plays” raising the specter of space wars, settlements attacking Earth or cult factions taking over space settlements. And there is the ominous possibility of “Deudney threats” as described in Daniel Deudney’s negative prediction of our space future in his book Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity”. Globus handled these objections quite well and links to his critique of the book in the The Space Review.

Other miscellaneous complaints by doubters are addressed easily by Globus. His talking points are valuable tools to be used in persuasive dialogs with those who may be uninformed on the promise of space development. They should help in building consensus toward moving peacefully out into the solar system and establishing prosperous settlements throughout the galaxy.

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Evolutionary computational design of closed ecosystems using artificial gravity

Orbiting Modular Artificial-Gravity Spacecraft (OMAGS) concept for testing ecosystems in space – Exterior and cutaway views. Credits: Gregory Dorais / NASA

One of the most important technologies to realize permanent space settlements is the development of self-sustaining controlled ecological life support systems (CELSS). This will require replication of independent self-contained subsets of Earth’s biosphere containing select flora and fauna under controlled conditions for eventual human life support. But are 100% closed ecosystems (with the exception of the exchange of radiation and information) beyond Earth possible? Could a series of controlled evolutionary experiments using machine learning be carried out on controlled ecosystems in space under variable gravity conditions to rapidly optimize the key variables needed to identify the smallest possible CELSS for long term human survival? Gregory Dorais, a research scientist at NASA Ames Research Center, thinks so and describes the strategy in a paper called An Evolutionary Computation System Design Concept for Developing Controlled Closed Ecosystems.

Dorais introduces his concept with a brief description of Closed EcoSystems (CESs) and early efforts by NASA to develop a CELSS for space settlement. Of particular concern are the challenges of putting humans in the equation. There are consequences related to the ratio between human biomass and non-human biomass in ecosystems. On Earth this ratio is low so the ecosystem can self-regulate compensating for imbalances. But in a space biosphere, this ratio in the life support system is comparatively huge leading to significant challenges in maintaining equilibrium. For example, the ISS needs frequent resupply of consumables by spacecraft to replenish losses in the life support system. Wastes that cannot be recycled are either incinerated in the Earth’s atmosphere or exhausted into space. A completely closed system that is self-sustaining has not yet been developed.

Dorais’ design concept for an experimental testbed can be used to explore the viability of different biomass ratios of various combinations of larger animal species and eventually humans. The system consists of a collection of independent CESs controlled and interconnected to generate data for machine learning toward optimizing long term viability. Gradually, the size of the animals in the CES can be increased evolving over time with the ultimate goal of human life support. To kick things off, an Orbiting Modular Artificial-Gravity Spacecraft (OMAGS) is proposed, with room for 24 CESs housed in a 150cm radius centrifuge with appropriate radiation shielding capable of testing the ecosystems under different fractional gravity conditions. The spacecraft is envisioned to be placed in an elliptical orbit in cis-lunar space.

To scale illustration of the OMAGS proposed mission orbit in cislunar space. Credits: Gregory Dorais / NASA

The OMAGS spacecraft has been sized to fit in a SpaceX Falcon Heavy payload fairing.

Illustration of a OMAGS payload sized for a SpaceX Falcon Heavy launch vehicle. Credits: Gregory Dorais / NASA

A NASA patent and tech transfer fact sheet entitled Closed Ecological System Network Data Collection, Analysis, Control, and Optimization System has been issued for this innovation under the NASA Technology Transfer Program.

In a related presentation delivered in November 2018, Dorais says “Once CESs are demonstrated to reliably persist in space, within specified gravity and radiation limits, it is a small step for similar CESs to persist just about anywhere in space (Earth orbit, Moon, Mars, Earth-Mars cycler orbit, asteroids, …) enabling life to permanently extend beyond Earth and grow exponentially.”

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ISRU technology gap assessment

Diagram depicting the three main areas of in-situ resource utilization and their connections to surface systems. Credits: ISECG

The International Space Exploration Coordination Group (ISECG), a forum of 14 space agencies which aims to implement a global space exploration strategy through coordination of their mutual efforts, established a Gap Assessment Team (GAT) in 2019 to examine the technology readiness of in-situ resource utilization (ISRU). The purpose of the ISRU GAT effort was to evaluate and identify technology needs and inform the ISECG on gaps that must be closed to realize future missions. The assessment was intended to initiate an international dialogue among experts and drive policy decisions on investment in exploration technologies, while identifying potential areas for stakeholder collaboration. A report has just been released summarizing these efforts.

ISRU systems that can collect and utilize resources available at the site of exploration, instead of transporting them from Earth with considerable expense, cover three broad areas depicted in the diagram above; In-Situ Propellant & Consumable Production, In-Situ Construction, and In-Space Manufacturing with ISRU-Derived Feedstock.

To help understand how each function interacts and influences other areas of ISRU and how they integrate with life support systems, a functional flow diagram shown below was created to help visualize the flow of resources step by step to final product realization.

Integrated ISRU functional flow diagram (Including ties to life support). Credits: ISECG

The GAT reached consensus on key findings and recommendations (listed below) to stakeholders and decision-makers for implementing ISRU capabilities deemed essential for future human space exploration and settlement activities.

Key Findings
* ISRU is a disruptive capability and requires an architecture-level integrated system design approach from the start.
* The most significant impact ISRU has on missions and architectures is the ability to reduce launch mass, thereby reducing the size and/or number of the launch vehicles needed, or use the mass savings to allow other science and exploration hardware to be flown on the same launch vehicle. The next significant impact is the ability to extend the life of assets or reuse assets multiple times.
* The highest impact ISRU products that can be used early in human lunar operations are mission consumables including propellants, fuel cell reactants, life support commodities (such as water, oxygen, and buffer gases) from polar resources (highland regolith and water/volatiles in PSRs).
* While not in the original scope, evaluation of human Mars architecture studies suggest that there is synergy between Moon and Mars ISRU with respect to water and mineral resources of interest, products and usage, and phasing into mission architectures.
* A significant amount of work is underway or planned for ISRU development across all the countries/agencies involved in the study, particularly in the areas of resource assessment, robotics/mobility, and oxygen extraction from regolith.
* While it appears each country/space agency has access to research and component/subsystem size facilities that can accommodate regolith/dust and lunar vacuum/temperatures, there are a limited number of large system-level facilities that exist or are planned.
* The assessment performed on the type and availability of lunar and Mars simulants for development and flight testing shows that 1) while simulants are available for development and testing, greater quantities and higher fidelity simulants will be needed soon, especially for polar/highland-type regolith, and 2) selection and use of proper simulants is critical for minimizing risks in development and flight operations.
* Examination of resource assessment development and activities identified new efforts in refocusing technologies and instrumentation for lunar and Mars operations, and several missions to begin surface and deep assessment of resources are in development, especially to obtain maps of minerals on the lunar surface, surface topography, and terrain features, or to understand the depth profile of water and volatiles.
* While there is significant interest in terrestrial additive manufacturing/construction development, development for space applications has been limited and primarily under Earth-ambient conditions.
* Further research, analysis, and engagement are required to identify synergies between terrestrial mining and in-situ resource utilization (ISRU). Throughout the mining cycle and ISRU architecture, key areas for investigation include; dependence on remote, autonomous, and robotic operations; position, navigation, and timing systems; and energy technologies (e.g., small modular reactors and hydrogen technology).
* Stakeholder engagement is required between the terrestrial mining and space sectors to drive collaboration to identify and benefit from lessons learned from terrestrial innovations for harsh or remote operations.
* Long-term (months/years) radiation exposure limits for crew currently do not exist to properly evaluate radiation shielding requirements. These are needed to properly evaluate Earth-based and ISRU-based shielding options.

Recommendations
* To help advance ISRU development and use in future human exploration, it is recommended that countries/agencies focus on the defined Strategic Knowledge Gaps (SKGs) that have been identified as high priority for each of the 3 human lunar exploration phases described. Early emphasis should be placed on geotechnical properties and resource prospecting for regolith near and inside permanently shadowed regions.
* Since the access and use of in-situ resources is a major objective for human lunar and Mars exploration and the commercialization of space, locating, characterizing, and mapping potential resources are critical to achieving this objective. While work on resource assessment physical, mineral, and water/volatile measurement instruments are underway, and new orbital and lunar surface missions are in development or planned, a focused and coordinated lunar resource assessment effort is needed. It is recommended that Science, ISRU, Human Exploration, and Commercial Space coordinate and work closely on Geodetic Grid and Navigation, Surface Trafficability, and Dust and Blast Ejecta to ensure surface activities and data collection are performed efficiently and safely.
* While short-duration lunar surface crewed missions can be completed with acceptable radiation exposure risk, it is recommended that long-term exposure limits be established and radiation shielding options (Earth and ISRU-based) be analyzed as soon as possible to mitigate risks for sustained operations by the end of the decade.
* Long-term sustained operations will require a continuous flow of missions to the same location. While distance and placing of landers can be initially used to mitigate damage to already delivered equipment and infrastructure, an approach for sustained landing/ascent (in particular for reusable vehicles and hoppers) is needed. Dedicated plume-surface interaction analysis and mitigation technique development are recommended. It is also recommended that development of capabilities and establishment of landing/ascent pads be incorporated into human lunar architectures early to support sustained operations
* Experience from Apollo missions indicates that wear, sealing, and thermal issues associated with lunar regolith/dust may be a significant risk to long-term surface operations. Coordination and collaboration on dust properties/fundamentals, and mitigation techniques and lessons learned are highly recommended. This effort should also involve coordination and collaboration on the development, characterization, and use of
appropriate lunar regolith simulants and thermal-vacuum facility test capabilities and operations for ground development and flight certification.
* To maximize the use of limited financial resources, it is recommended that the ISECG space agencies leverage the information presented in the report, in particular, the content of the “Technology Capture by WBS and Country/Space Agency portfolio” as a starting basis for further discussions on collaborations and partnerships related to resource assessment and ISRU development/operations.
* Collaboration and public-private partnerships with terrestrial industry, especially mining, resource processing, and robotics/autonomy are recommended to reduce the cost/risk of ISRU development and use.
* This includes establishment of an international regulatory framework for resource assessment, extraction, and operations, which are necessary to promote private capital investment and commercial space activities.
* The sustainable development aspects of the ISRU activity are recommended to be taken into account from the start of activity planning for the surface exploration of Moon and Mars.
* Aspects of reusing and recycling hardware are recommended to be taken into account from the design and architecture phase of mission planning. This will contribute to minimizing the exploration footprint (e.g. abandoned hardware) and therefore is key towards sustainability.
* To accelerate the development of key technologies, close knowledge gaps, and expedite testing/readiness, it has been seen that the use of unconventional models, such as government-sponsored prize challenges can be effective innovation catalysts operationalizing the above recommendations, and ultimately, bringing ISRU to the Moon and onwards to Mars.

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Artificial gravity space settlement ground-analog

Cross sectional diagram of hypergravity vehicle with tilted cabin on track in max G orientation. Credits: Gregory Dorais / American Institute of Aeronautics and Astronautics

Gregory Dorais, a research scientist at NASA Ames Research Center, has combined several existing technologies including centrifuges, tilted trains and roller coasters to devise a novel hypergravity space settlement ground-analog that could be used to study the effects of artificial gravity on humans, animals and plants for extended periods. He introduced the concept in a paper presented at the American Institute of Aeronautics and Astronautics Space 2016 Conference in Long Beach, California. Experimental results using such a facility could inform designs for orbital rotating habitats providing up to 1G of artificial gravity or even surface-based outposts on the Moon, Mars or anywhere. The facility could also study higher levels of gravity (thus the name “hypergravity”) which could be beneficial in mitigating deleterious effects of microgravity on human physiology.

Dorais’ Extended-Stay HyperGravity Facility (ESHGF) would merge technologies of centrifuges and trains, creating a 150 meter circular track with a series of connected tilting cars. The tracks could use tubular rails similar to today’s rollercoasters or eventually use magnetic levitation. An optional transfer vehicle placed on an outer concentric track is proposed where people and cargo can be moved between a depot and the hypergravity vehicles while they are in motion so that a constant velocity can be maintained without disruptive force changes during operations.

ESHGF system depicted in a complete ring configuration (not to scale). Credits: Gregory Dorais / American Institute of Aeronautics and Astronautics
Hypergravity vehicle single cabin side and perspective views. Credits: Gregory Dorais / American Institute of Aeronautics and Astronautics

The interior of each car could be customized to meet the needs of its inhabitants, but would likely include all the expected functions of a thriving space colony including living quarters, agricultural facilities, marketplaces, recreational centers and much more.

The system is modular and extendable allowing the facility to start small and then expand into a variety of configurations to investigate multiple gravity level environments as sanctioned by budgets. Dorais says that the facility “… will permit research on the long-term health and behavioral effects of various artificial-gravity levels and rotation rates on humans and other life, among other things, to establish the design requirements for long-term space settlements.”

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Sustainable space commerce and settlement

Artist impression of a sustainable settlement on the Moon. Credits: ESA – CC BY-SA IGO 3.0

Dylan Taylor of Voyager Space Holdings recently wrote an article in The Space Review on sustainable space manufacturing. He makes a convincing case that long-duration space missions and eventual human expansion throughout the solar system will require radical changes in the way we design, manufacture, repair and maintain space assets to ensure longevity. In addition, the cost of lifting materials out of Earth’s deep gravity well will drive sustainable technologies such as additive manufacturing in space and in situ resource utilization to reduce the mass of materials needed to be launched off our planet to support space infrastructure. In-space recycling and reuse technologies will also be needed along with robotic manufacturing, self-reparability and eventually, self-replicating machines.

But there is more to the philosophy of sustainability and its impact on the future of space activities. According to the Secure World Foundation (SWF), sustainability is essential for “Ensuring that all humanity can continue to use outer space for peaceful purposes and socioeconomic benefit now and in the long term. This will require international cooperation, discussion, and agreements designed to ensure that outer space is safe, secure and peaceful.” Much of the discussion centers around the problem of orbital debris, radio frequency interference, and accidental or irresponsible actions by space actors. SWF is active in facilitating dialog among stakeholders and international cooperation.

The National Science and Technology Council released a report in January called the National Orbital Debris Research and Development Plan. To address the issue, there are several companies about to start operations in LEO to deal with the orbital debris or in-orbit servicing. Japan based Astroscale just launched a demonstration mission of their End-of-Life Services by Astroscale (ELSA) platform to prove the technology of capturing and deorbiting satellites that have reached their end of life or other inert orbital debris.

Image of the Astroscales ELSA-d mission showing the larger servicer spacecraft releasing and preparing to dock with a “client” in a series of technical demonstrations, proving the capability to find and dock with defunct satellites and other debris. Credits Astroscale.

Even financial services and investment houses like Morgan Stanley are pushing for sustainability to reduce the risks to potential benefits emerging from the Newspace economy such as remote sensing to support food security, greenhouse gas monitoring, and renewable energy not to mention internet access for billions of people.

Sustainable operations on the Moon are being studied by several groups as the impact of exploration and development of Earth’s natural satellite is considered. Lunar dust when kicked up by rocket exhaust plumes could create hazards to space actor’s assets as well as Apollo heritage sites. SWF, along with For All Moonkind, the Open Lunar Foundation, the MIT Space Exploration Initiative and Arizona State University have teamed up on a project called the Moon Dialogs to advance interdisciplinary lunar policy directions on the mitigation of the lunar dust problem and to shape governance and coordination mechanisms among stakeholders on the lunar surface. SSP’s take on lunar dust mitigation was covered last July.

These few examples just scratch the surface. NASA, ESA and the UN Office for Outer Space Affairs have initiatives to foster sustainability in space. Humanity will need a collaborative approach where public and private stakeholders work together to ensure that the infrastructure to support near term commercial activities in space and eventual space settlement is both durable and self-sustaining.

The long-term sustainability of space. Credits: ESA / UNOOSA