Conceptual illustration of a Habitat Autonomous Locomotive Expandable (HALE) mobile self sustaining habitat under propulsion near a planetary destination. Credits: unknown artist via Thomas Matula
Dr. Thomas Matula, Professor at Sul Ross State University Uvalde, Texas, has developed an economically based strategy for space settlement. His plan addresses the deficiencies in many proposed visions of human expansion beyond earth, namely the missing economic and legal aspects needed for sustainable settlement of the solar system. Matula discussed his approach with David Livingston on The Space Show September 14 and in a paper entitled An Economic Based Strategy for Human Expansion into the Solar System attached to the show blog.
Astrosettlement Development Strategy (ADS) can be boiled down into a four step economically based roadmap for space settlement which could be started with minimal private funding. Each step would achieve economic success before moving on to the next level. The four levels are Earth based research, industrialization of the Moon, developing and settling the solar system and interstellar migration.
In the first step of Earth based research, Matula suggests developing a subscription based online role playing computer game with the purpose of creating a virtual simulation of a space settlement to model the social and economic aspects of communities beyond Earth. SSP has been following similar efforts already underway by Moonwards. Further research in this phase would look into space agriculture to understand the types of plants and dietary needs of space settlers and improving the efficiency of crop growth paving the way for self sustaining habitats. Matula has penned a different paper along these lines called The Role of Space Habitat Research in Providing Solutions to the Multiple Environmental Crises on Earth, also attached to the Space Show Blog, which could have duel use applications in addressing environmental problems on our home planet. There are already efforts underway in this arena with Controlled Environment Agriculture (CEA) utilizing greenhouse automation through the Internet of Things leading to reduction of water needs and an increase in crop yields.
“Developing the technology to green the Solar System will also green the Earth for future generations”
Next on the roadmap is lunar industrialization. The focus of this step is to use robotics and in situ resource utilization to minimize the mass of materials lifted from Earth and to create lunar manufacturing capability in a cislunar economy that can be leveraged to build space based habitats for expansion into deep space.
Developing the solar system comes next. Once an economic foundation of industrialization of the Moon has been established, large mobile habitats can be built at the Earth-Moon Lagrange points L1 and L2. Called HALE, for Habitat Autonomous Locomotive Expandable, these are 1km wide self sustaining habitats with 1G artificial gravity capable of low energy transit throughout the solar system including out to the Kuiper Belt, where they can use the resources there to add to their size or build copies of themselves.
The final phase combines mobile free space settlement with advanced propulsion to develop the capability of expansion into the Oort cloud and on to the stars.
“…propulsion technology could advance to a point that would allow mobile space habitats designed for the Oort Cloud to be transformed into the first generational starships.”
Conceptual rendering of TransAstra Honey Bee Optical Mining Vehicle designed to harvest water from near-Earth asteroids: Credits: TransAstra Corporation
Advocates for mining the Moon and asteroids for resources to support a space based economy are split on where to get started. Should we mine the Moon’s polar regions or would near-Earth asteroids (NEAs) be easier to access?
Joel Sercel, founder and CEO of TransAstra Corporation, is positioning his company to be the provider of gas stations for the coming cislunar economy. In a presentation on asteroid mining to the 2020 Free Market Forum he makes the case (about 10 minutes into the talk) that from an energy perspective in terms of delta V, NEAs located in roughly the same orbital plane as the Earth’s orbit may be easier to access for mining volatiles and rare Earth elements.
Scott Dorrington of the University of New South Wales discusses an architecture of a near-Earth asteroid mining industry in a paper from the proceedings of the 67th International Astronautical Congress. He models a transportation network of various orbits in cislunar space for an economy based on asteroid water-ice as the primary commodity. The network is composed of mining spacecraft, processing plants, and space tugs moving materials between these orbits to service customers in geostationary orbit.
Illustration depicting the layout of a transportation network in an asteroid mining industry in cislunar space. Credits: Scott Dorrington
On the other side of the argument, Kevin Cannon of the Colorado School of Mines in a post on his blog Planetary Intelligence lays out the case for the Moon being the best first choice. All of the useful elements available on asteroids are present on the Moon, and in some cases they are easier to access in terms of concentrated ore deposits. Although delta V requirements are higher to lift materials off the Moon, its much closer to where its needed in a cislunar economy. Trips out to a NEA would take a long time with current propulsion systems. In addition, he thinks mining NEAs would be an “operational nightmare” as most of these bodies are loose rubble piles of rocks and pebbles with irregular surfaces and very low gravity. This makes it hard to “land” on the asteroid, or difficult to capture and manipulate them. In an email I asked him if he was aware of SHEPHERD, a concept for gentle asteroid retrieval with a gas-filled enclosure which SSP covered in a previous post, but he had not heard of it. TransAstra’s Queen Bee asteroid mining spacecraft has a well thought out capture mechanism as well, although this concept like SHEPHERD are currently at very low technology readiness levels.
SHEPHERD-Fuel variant harvesting ice from a NEA and condensing it into liquid water in storage tanks, then subsequent separation into hydrogen and oxygen (top). These tanks become the fuel source for a self-propelling tanker block (bottom) which can be delivered to a refueling rendezvous point in cislunar space. Credits: Concept depicted by: Bruce Damer and Ryan Norkus with key design partnership from Peter Jenniskens and Julian Nott
Cannon also makes the point that there is very little mass in the accessible NEAs when compared to the abundance of elements on the Moon.
“There’s more than enough material for near-term needs on the Moon too, and it’s far closer and easier to operate on.”
Finally, he believes that the Moon would be a better stepping stone to mining the asteroids then NEAs would be. This is because most of the mass in the asteroid belt is located in the largest bodies Ceres and Vesta. Operations for mining on these worlds would be more akin to activities on the Moon then on near-Earth asteroids.
Image of Vesta taken from the NASA Dawn spacecraft. Credit: NASA/JPL
What about moving a NEA to cislunar space as proposed by NASA under the Obama Administration with the Asteroid Redirect Mission? Paul Sutter, an astrophysicist at SUNY Stony Brook and the Flatiron Institute, investigates this scenario and suggests that at least the argument for these asteroids being too far away might be mitigated by this approach, although it would take a long time to retrieve them using solar electric propulsion, as recommended in the article. The trip time might be reduced with advanced propulsion such as nuclear thermal rockets currently under investigation by NASA.
Conceptual illustration of TransAstra’s Sun Flower™ power towers collecting solar energy above a permanently shadowed region on the Moon to provide power for ice mining operations. Credits: TransAstra Corp.
Update 28 August 2021: Take a deep dive into TransAstra’s future plans with Joel Sercel interviewed by Peter Garretson, Senior Fellow in Defense Studies at the American Foreign Policy Council podcast Space Strategy.
Conceptual depiction of the Pinwheel Magma Reactor on a planetary surface in the foreground and in free space on a tether as shown in the inset. Credits: Kevin Cannon
How can space settlers harness useful resources that have not been concentrated into ore bodies like what takes place via geologic process on Earth over eons of time? Could we artificially speed up the process using synthetic geology? Kevin Cannon, a planetary geologist at the Colorado School of Mines (CSM), thinks it might be possible to unlock the periodic table in space to access a treasure trove of materials with an invention he calls the Pinwheel Magma Reactor. He has submitted a NASA Innovative Advanced Concepts proposal for the concept. The device is a essentially a centrifuge sitting on a planetary surface with a solar furnace reaction chamber spun at the end of its axis. In space, a free flying system could be connected by tether.
PMR chambers are positioned at the end of the axis of a centrifuge. Credits: Kevin Cannon
In a Twitter thread Cannon sets the table with a basic geology lesson explaining why mining on Earth is so different from what we will need in space. The Earth’s dynamic crustal processes, driven by fluid flow and plate tectonics over millions of years, exhibit a very different geology then that under which the Moon, Mars and asteroids evolved. The critical minerals that could be useful to support life and a thriving economy in space settlements are present in far lower concentrations in space then on Earth.
Current plans for ISRU infrastructure on the Moon and asteroids are only targeting a small set of elements like hydrogen, oxygen, carbon, silicon and iron (below, left).
Illustration of the periodic table showing currently targeted elements for ISRU on the left. On the right, the most mined elements on Earth (colored gold) and critical elements (orange) useful for an advanced society. Credits: Kevin Cannon
But an advanced society expanding out into the solar system would benefit from many critical minerals (above, right) that are not easily accessible because of their far lower concentrations. For example, energy production will need uranium and thorium, energy storage systems require lithium and electronics manufacturing is dependent on rare earths. So how to unlock the periodic table for these critical materials?
If we are to live off the land by harvesting useful materials to build and sustain space settlements we’ll need a totally revolutionary mining process. The PMR was designed with this in mind. The procedure begins by loading unprepared rocks or regolith into the chamber followed by heating via a solar furnace. Next, the chamber is spun up in the centrifuge where super gravity concentrates the desired minerals. Cannon believes that the PMR could also be used to extract water from regolith on the moon or asteroids.
“If hydrated asteroid material or icy regolith are put in at low temperatures, they’ll be separated by super-gravity and can be siphoned off.”
Of course the technology needs to be validated and flight hardware developed to determine if the PMR can be a tool to speed up the geological processes to concentrate useful materials for humans, who can then use them to synthetically propagate life in space. Cannon sums it up:
“Obviously a lot of work to be done to prove out the concept. But I think that a process flow of synthetic geology -> synthetic biology is the way to solve the concentration problem in space and enrich any element we want from the periodic table.”
Conceptual illustration of a Virtus Solis satellite array beaming power to central California (not to scale). Credits: Virtus Solis Technologies. NOTE: all images in this post are credited to Virtus Solis Technologies
Ever since I was in high school space solar power has been the holy grail of space advocates. I even wrote a report on the topic based on Peter Glaser’s vision in my high school physics class before Gerard K. O’Neill popularized the concept in The High Frontier leveraging it as the economic engine behind orbiting space settlements. But the technology was far from mature back then, and O’Neill knew back in 1976 the other main reason why after all these years space solar power has not been realized:
“If satellite solar power is an alternative as attractive as this discussion indicates, the question is, why is it not being supported and pushed in vigorous way? The answer can be summarized in one phrase: lift costs.” – Gerard K. O’Neill, The High Frontier
John Bucknell, CEO and Founder of Virtus Solis, the company behind the first design to cost space solar power system (SSPS), believes that recent technological advances, not the least of which are plummeting launch costs, will change all that. He claims that his approach will be able to undercut fossil fuel power plants on price. He recently appeared on The Space Show (TSS) with Dr. David Livingston discussing his new venture. SSP reached out to him for an exclusive interview and a deep dive on his approach, the market for space solar power and its impact on space development.
SSP: Technological advancements of all the elements of a space solar power system have gradually matured over the last few decades such that size, mass and costs have been reduced to the point where there are now experiments in space to demonstrate feasibility. For example, SSP has been following the first test of the Naval Research Laboratory’s Photovoltaic Radio-frequency Antenna Module (PRAM) aboard the Air Force’s X37 Orbital test vehicle. Caltech’s Space-based Solar Power Project (SSPP) has been working on a tile configuration that combines the photovoltaic (PV) solar power collection, conversion to radio frequency power, and transmission through antennas in a compact module. According to your write-up in Next Big Future on a talk given to the Power Satellite Economics Group by the SSPP project manager Dr. Rich Madonna, they plan a flight demonstration of the tile configuration this December. The Air Force Research Laboratory’s Space Solar Power Incremental Demonstrations and Research (SSPIDR) project also plans a flight demonstration later this year with an as yet unannounced configuration. Which configuration of this critical element (PRAM or tile) do you think is the most cost effective and can you say if your system will be using one of these two configurations or some other alternative?
Bucknell: There is a lot of merit to the tile configuration as it shares much of it’s manufacturing process with existing printed circuit board (PCB) construction techniques. The PRAM itself is a version of the tile, but as it was Dr. Paul Jaffe’s doctoral dissertation prototype (from 2013) it did not use PCB techniques and should not be considered an intended SSPS architecture. Details of Caltech’s latest design aren’t released, but it appears they intend to deploy a flexible membrane version of the tile to allow automated deployment. Similar story with SSPIDR. As space solar power is a manufacturing play as much as anything, you would choose known large scale manufacturing techniques as your basis for scaling if you intend earth-based manufacturing – which we do. So yes, we are planning a version of the tile configuration.
SSP: You’ve said that the TRL levels of most of the elements of an SSPS are fairly mature but that the wireless power transmission of a full up phased array antenna from space to Earth is at TRL 5-6. The Air Force Research Laboratory (AFRL) plans a prototype flight as the next phase of the SSPIDR project with demonstration of wireless power transmission from LEO to Earth in 2023. What is your timeline for launching a demo and will it beat the Air Force?
Bucknell: Our timescales are similar for a demonstrator, but I suspect the objectives of a military-focused solution would be different than ours. We would plan a LEO technology demonstrator meeting most of the performance metrics required for a MEO commercial deployment.
SSP: Your solution is composed of mass produced, factory-built components including satellites that will be launched repeatedly as needed to build out orbital arrays. Will multiple satellites be launched in one payload or will each module be launched on its own? What is the mass upper limit of each payload and how many launches are needed for the entire system?
Bucknell: We intend a modular solution, such that very few variants are required for all missions. A good performance metric for a SSP satellite would be W/kg – and we believe we can approach 500 W/kg for our satellites (Caltech has demonstrated over 1000 W/kg for their solution). With known launchers and their payloads a 100MW system would take three launches of a Starship, with less capable launchers requiring many more. Since launch cost is inversely related to payload mass, we expect Starship to be the least expensive option although having a competitive launch landscape will help that aspect of the economics with forthcoming launchers from Relativity Space, Astra and Rocket Lab being possibilities.
SSP: The way you have described the Virtus Solis system, it sounds like once your elements are in orbit, additional steps are needed to coordinate them into a functional collector/phased array. Presumably, this requires some sort of on-orbit assembly or automated in-space maneuvering of the modules into the final configuration. I know you are in stealth mode at this point, but can you reveal any details about how the system all comes together?
Bucknell: An on-orbit robotic assembly step is necessary, although the robotic sophistication required is intentionally very low.
SSP: Your system is composed of a constellation of collection/transmitter units placed in multiple elliptical Molniya sun-synchronous orbits with perigee 800-km, apogee 35,000-km and high inclination (e.g. > 60 degrees). I understand this allows the PV collectors to always face the sun while the microwave array can transmit to the target area without the need for physical steering, which simplifies the design of the spacecraft. Upon launch, will the elements be placed in this orbit right away or will they be “assembled” in LEO and then moved to the destination orbit. Do the individual elements or each system assembly as a whole have on-board propulsion?
Bucknell: The concept of operations is array assembly in final orbit, mostly to avoid debris raising from lower orbits.
Schematic illustration of a three-array Virtus Solis constellation in Molniya orbits serving Earth’s Northern Hemisphere and a two-array constellation serving the Southern Hemisphere of Luna
SSP: The primary objective of the AFRL SSPIDR project is delivery of power to forward deployed expeditionary forces on Earth which would assure energy supply with reduced risk and lower logistical costs. It sounds like your system would not work for this application given the need for 2-km diameter rectenna. Could this potential market be a point of entry for your system if it were scaled down or reconfigured in some way?
Bucknell: Wireless Power Transmission (WPT) at orbital to surface distances suffer from diffraction limits, which is true for optics of all kinds. It is not physically possible to place all the power on a small receiver, and therefore the military will likely accept that constraint. As a commercial enterprise, we could not afford to not collect the expensively-acquired and transmitted energy to the ground station. There are also health and safety considerations for higher intensity WPT systems – ours cannot exceed the intensity of sunlight for example, and therefore is not weaponizable.
SSP: You said on TSS that your strategy would, at least initially, bypass utilities in favor of independent power producers. What criteria is required to qualify your system for adoption by these organizations? You mentioned you have already started discussions with one such group. Can you provide any further details about how they would incorporate an SSPS into their existing assets?
Bucknell: One of the key features of space solar power is on-demand dispatchability. Grid-tied space solar power generation has the benefit of being able to bid into existing grids when generation is needed and task the asset to other sites when demand is low. This all assumes that penetration will be gradual, but some potential customers might desire baseload capacity in which case there is not as much need for dispatchability. Each customer’s optimal generation profile is likely to be unique so it is preferable to attempt to match that with a flexible system.
Conceptual illustration of a 1GW Virtus Solis rectenna array next to Topaz Solar Farm of 550MW capacity in San Luis Obispo County, California
SSP: Other companies have alternative SSPS designs planned for this market. For example, SPS – ALPHA by Solar Space Technologies in Australia and CASSIOPeiA by International Electric Company in theUK. How does Virtus Solis differentiate itself from the competition?
Bucknell: From a product perspective, we are able to provide baseload capacity at far lower cost. Also, we intentionally selected orbits to not only reduce costs but to induce sharing of the orbital assets across the globe such that this is not a solution just for one country or region.
SSP: How big is the likely commercial market for your product/services going to be by the time you are ready to start commercial operations? Can you share some of your assumptions and how they are derived?
Bucknell: Recent data indicates that electrical generation infrastructure worldwide is about $1.5T annually. If you add fossil fuel prospecting, it is $3.5T. Total worldwide generation market size is about $8T. All of this is derived from BP’s “Statistical Review of World Energy – June 2018” and the report from the International Energy Agency “World Energy Investment 2018”
SSP: For your company to start operations, what total funding will be required, and will it come from a combination of government and private sources, or will you be securing funding only from private investors?
Bucknell: As a startup, especially in hardware, funding comes from where you can get it. To date no governmental funding opportunities have matched our technology, but that might change. Our early raise has been from angel investors and venture capital firms. Over the course of the research and development efforts, we expect demand for capital will be below $100M over the next several years but accurately forecasting the future is challenging. We would note this level of required investment is far below our competition.
SSP: For hiring your management team, since this business is not mature, what analogous industries would you be looking at to recruit top talent?
Bucknell: Everything in our systems exist today elsewhere. The wireless data industry (5G for example) has the tools and experience for developing radio frequency antennas and associated broadcast hardware. The automotive industry has extensive experience with manufacturing electronics at low cost in high volumes, including power and control electronics. Controls software engineering is a large field in aerospace and automotive, but in a large distributed system like ours the controls software will extend far beyond guidance, navigation and control (GNC).
SSP: O’Neill envisioned the production of SSPSs as the market driver for space settlements, in addition to replication of more space colonies. This approach seems to have gathered less steam over the years as economics, technological improvements, and safety concerns have taken people out of the equation to build SSPSs in space. In a recent article in the German online publication 1E9 Magazine you talked about SSPSs being useful for settlements on the Moon and Mars. What role do you see them playing in free space settlements and could they still help realize O’Neill’s vision?
Bucknell: We stand at a cross-roads for in-space infrastructure. For the first time access to space costs look to be low enough to make viable commercial reasons to deploy large amounts of infrastructure into cislunar space and beyond. To date the infrastructure beyond earth observation and telecom has been deployed to mostly satisfy nation-state needs for science unable to be performed anywhere else as well as exploration missions (also a form of science). However, there has to be a strong pull/demand to spur the construction of access to space hardware (heavy lift rockets) that consequently lowers the cost further through economies of scale. As I described in my Space Show interview there are only a few commercial in-space businesses that are viable with today’s launch costs. We have had telecom for a long time, followed closely by military and then commercial earth observation. Now we have a large constellation of “internet of space”. Even with those applications, there is not a large pull to scale reusable launch vehicle production – as reusability is counter-productive for economies of scale. A large, self-supporting in-space infrastructure would be needed to bootstrap launch production sufficiently to self-fulfil low cost access to space – Space Solar Power is that infrastructure. Space tourism, asteroid mining and others do not have scale nor potential lofted mass to scale the launch market adequately. In that way, O’Neill’s vision is right – and the follow-on markets can leverage the largely paid-for launch infrastructure to make themselves viable. Space solar power will be the enabler for humanity to live and work off-Earth, and Virtus Solis is leading the way.
Illustration of photonic laser thruster infrastructure for in-space transportation in cislunar space. Credits: Young K. Bae
Y.K. Bae Corp is on the verge of testing a revolutionary photonic laser thruster (PLT) that could be a game changer for in space propulsion and interplanetary travel. Founder and Chief Scientist Young K. Bae Ph.D described the technology in a recent Future In-Space Operations (FISO) Telecon presentation. The secret is generating thrust through photon pressure of a recycled laser beam enabling high energy to thrust efficiency without onboard propellant. Y.K. Bae Corp’s Continuous-Operation laser thruster or PLT-C is capable of delivering continuous thrust for long periods of time (e.g. days – years). The crew/payload section of the craft contains no power supplies, fuel or rocket engines. A power source is needed at the destination to generate a velocity reversal and stopping beam.
Dr. Bae believes an in-space “photonic railway” using this technology could open the solar system to commercialization and laid out a timeline for development of the photonic laser thruster. He believes that a 1 Newton (N) thrust PLT demonstration on the ISS could be accomplished within 3 years, a 50-N thrust PLT suborbital lunar launch is possible within 10 years, transits to the Moon can be done within 20 years and trips to Mars/Asteroids are projected to be in the 30 – 40 year timeframe.
When scaled up, super high ∆v can be achieved using the PLT. With a total electric laser power of 1000MW, travel times from the Earth to Mars could be achieved in less then 20 days for a 1-ton ship with 50% payload. From Mars out to Jupiter, a trip would take about 45 days for a craft with the same mass. The PLT spacecraft could be the main mode of rapid in-space transportation for humans and high price or lighter commodities after conventional thrusters (e.g. chemical rockets) establish the initial infrastructure and continue as the transportation choice for low cost or heavier payloads.
Illustration of a photonic railway using PLT infrastructure for in-space propulsion established at (from right to left, not to scale) Earth, Mars, Jupiter, Pluto and beyond. Credits: Young K. Bae.
Y.K. Bae Corp has demonstrated the photonic laser thruster technology in the lab. Check out their cubesat demo video.
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 orbitSHEPHERD-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 constructionSHEPHERD-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 coloniesSHEPHERD-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 regolithVision 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 vehicleInflation of bag enclosure using controlling gas, introduced target object (perhaps a meteorite returned to space)Management of target object position with gas jetsLit 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 separatedSHEPHERD Bio with image of Earth overlain on its 500m diameter terrarium worldMitosis 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
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
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
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
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.
