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Using energy from space to power in situ resource processing on the Moon

Conceptual illustration of a Lunar Power Station beaming power to facilities on the Moon for energy intensive in situ resource processing . Credit: Astrostrom GMBH

Settlements on the Moon will eventually need to “live off the land” via in situ resource utilization (ISRU). This approach is essential to make settlements economically feasible and self sustaining, obviating the need to expensively import materials up out of Earth’s gravity well. Before we can utilize resources in situ on the Moon we need to understand how to process them there. Researchers at the University of Waterloo in Toronto, Canada are developing technologies for in situ resource processing (ISRP) of lunar soil to produce useful materials, but they will need power. Lots of it.

In a paper presented last October at the 74th International Astronautical Congress in Baku, Azerbaijan, Waterloo Department of Mechanical and Mechatronics Engineering Master of Science Candidate Connor MacRobbie and Team describe how a space-based solar power (SBSP) satellite in lunar orbit could provide the juice for several energy hungry processes that could generate consumables and building materials from lunar regolith.

The study includes a survey of the scientific literature on lunar regolith processing techniques under development, some with experimental results, that would benefit future lunar settlements. Using electrolysis, chemical reduction, pyrolysis and other reactions these methods can be used to extract metals, oxygen, water and other useful commodities from lunar regolith. The techniques have well established pedigrees on Earth, but will need further development for efficient operations on the Moon and will require very elevated temperatures. Thus, the need for an abundant power source like SBSP.

One such promising process is Molten Regolith Electrolysis (MRE). In this method, lunar soil is heated to the melting point in an electrolytic cell. When voltage is applied across the cathode and anode in the cell, the molten regolith decomposes into metal at the cathode and oxygen at the anode, both of which can be collected and stored for use by settlers. No inputs or materials are needed from Earth, only a local power source to melt the untreated regolith.

One of MacRobbie’s supervisors is Dr. John Wen, director of the Laboratory for Emerging Energy Research (LEER) at Waterloo. With the help of Wen and LEER, the Team developed a novel material processing method for MRE. In molten regolith solutions, the constituents and their oxides can be separated by an applied voltage enabling extraction from the solution. Because each individual oxide decomposes at different values, stepping the voltage will facilitate sequential removal and collection of the lunar soil constituents, e.g. iron, titanium, aluminum, silicon, and others; which can be utilized for building and manufacturing. The new method could reduce the cost of processing and provide purer end products. The Team will continue working with LEER on the design of the equipment toward proof of concept with small batches aiming for accurate and repeatable successive extractions of materials using MRE. The only remaining step would be to qualify flight-ready hardware for experiments on the Moon.

In another project LEER is investigating lunar regolith as an input to a power source in space for heating or manufacturing. The embedded metal oxides in lunar soil, when combined with a metal like aluminum, produce thermal energy via a thermite reaction. The aluminum could be sourced from defunct satellites in Earth orbit which has the added benefit of helping to address the orbital debris problem.

Other groups like Swiss-based Astrostom GMBH with their Greater Earth Lunar Power Station are already working on SBSP solutions to provide ample power for lunar surface settlements which could provide sufficient electricity for Waterloo’s ISRP technology. The Astrostom approach would place the power satellite at the L1 Earth-Moon Lagrange point, a location between the Earth and Moon at a distance of 60,000 km above lunar surface. Although not a gravitationally stable location, the station would could maintain a fixed point above a lunar ground station on the Moon’s nearside with minimal station keeping propulsion systems.

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South Korea goes for space-based solar power

Conceptual illustration depicting the design features of a Korean Space Solar Power Satellite (K-SSPS) Credits: Joon-Min Choi, Su-Jin Choi, Sang-Hwa Yi via Creative Commons License CC by 4.0

Researchers from the Korea Aerospace Research Institute (KARI) and the Korea Electrotechnology Research Institute (KERI) describe a concept for a Korean Space Solar Power Satellite in a new publication called the Journal of Space Solar Power and Wireless Transmission. Dubbed K-SSPS, its components would be launched with reusable rockets, robotically assembled and tested in LEO, then boosted to geostationary orbit (GEO) using solar electric thrusters powered by its own solar cell array.

The baseline conceptual design for K-SSPS provides 2GW of delivered power to the ground collected by a 4km diameter rectenna located in the Demilitarized Zone. There is sufficient space in this region for 60 rectennas of this size for a total collected power of 120 GW. In terms of electricity generation, such a system would provide a terawatt-hour of electricity per year which exceeds South Korea’s electricity consumption in 2021.

This study also addresses disposal of the system after its useful life estimated to be about three decades, Since such massive systems spanning an area measuring several square kilometers would present a rather large cross section increasing the risk of collision with other decommissioned satellites in the usual graveyard orbit located 235 km above GEO, the authors propose a novel but controversial approach: controlled crash landing the spent satellite in a safe zone on the far side of the Moon. This would enable future colonies on the Moon to harvest these valuable Earth-sourced materials from the impact zone, recycling them into useful commodities to help sustain lunar operations. Care would have to be taken to ensure that the structure is guided to a designated area far from established infrastructure, most of which (if not all) would be located on the near side facing Earth. Not considered in the study was recycling and/or repurposing the K-SSPS materials in space using material processing technology like Cislunar Industries’ Modular Space Foundry (previously Microspace Foundry).

South Korea’s space agency, the Korea Aerospace Research Institute (KARI), has set a goal of a test system deployment in LEO by 2040, with a full scale system in GEO by 2050. Since this effort will take considerable development time and significant financial investment, KARI plans a small-scale two-satellite pilot system demonstration in LEO within the next decade to validate the wireless power transmission technology and the deployment mechanisms. The pilot system, which was described in a paper presented at the 73rd International Astronautical Congress in September 2022, will be placed in a sun synchronous orbit and features a solar panel equipped antenna array beaming power to a receiver satellite 100m away, in a sun synchronous orbit.

Diagram depicting the operational concepts planned over the mission life of the KARI pilot space solar power demonstration. Credits: Joon-Min Choi, Su-Jin Choi, Sang-Hwa Yi via Creative Commons License CC by 4.0

KARI and KIRI have described their case studies on a space solar power program as a renewable energy option for Korea to help address global efforts to achieve net zero greenhouse gas emissions by 2050. This paper summarizes their concept design for a 2GW space solar satellite highlighting gaps in the economic and technological knowledge needed for success, proposed a responsible and sustainable disposal method, and outlined an achievable architecture for a near term pilot demonstration within a decade. Korea joins other global development efforts that SSP has been following with their own unique approach to space-based solar power (SBSP).

However, doubters have been surfacing recently highlighting the significant engineering and economic challenges that need to be addressed for SBSP to be competitive with ground-based renewable energy sources and backup storage systems, the technology of which are rapidly developing and improving. One skeptic, former European Space Agency engineer Henri Barde, published an article in IEEE Spectrum arguing that among other things, designers will have a significant challenge shaping and aiming the microwave beam of a kilometer-scale phased array antennae. In his opinion, this and other engineering obstacles will not be solved until fusion energy will be commercially available. In a rebuttal on LinkedIn, CEO of SBSP startup Virtus Solis John Bucknell responded that his company has proprietary software that can simulate greater than 2km transmission apertures and that SBSP is in the engineering phase while fusion is still in R&D, the complexity of which makes capital and operating costs a big unknown for commercialization.

NASA has yet again kicked the can down the road, claiming in their most recent study that expected greenhouse gas emissions and the cost of space hardware for current design options will be on a par with existing renewable electricity technologies and therefore recommends further study to close several technology gaps for SBSP to make economic sense. The next few years will be critical for engineering testing, not only for Korea’s pilot satellite, but Virtus Solis‘s in-space plans and Northrup Grumman’s end-to-end test in 2025 of their Space Solar Power Incremental Demonstrations and Research prototype system. Once in-space prototype testing demonstrates sufficient feasibility to retire technical risks, venture capital investors may feel comfortable funding subsequent operational phases toward profitable commercialization.

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Greater Earth (GE⊕) Lunar Power Station

Conceptual illustration showing the first iteration of the proposed design of a GE⊕ Lunar Power Station beaming power to facilities on the Moon. Credit: Astrostrom

In response to ESA’s Open Space Innovation Platform Campaign on Clean Energy – New Ideas for Solar Power from Space, the Swiss company Astrostrom laid out a comprehensive plan last June for a solar power satellite built using resources from the Moon. Called the Greater Earth Lunar Power Station (GE⊕-LPS, using the Greek astronomical symbol for Earth, ⊕ ), the ambitious initiative would construct a solar power satellite located at the Earth-Moon L1 Lagrange point to beam power via microwaves to a lunar base. Greater Earth and the GE⊕ designation are terms coined by the leader of the study, Arthur Woods, and are “…based on Earth’s true cosmic dimensions as defined by the laws of physics and celestial mechanics.” From his website of the same name, Woods provides this description of the GE⊕ region: “Earth’s gravitational influence extends 1.5 million kilometers in all directions from its center where it meets the gravitational influence of the Sun. This larger sphere, has a diameter of 3 million kilometers which encompasses the Moon, has 13 million times the volume of the physical Earth and through it, passes some more than 55,000 times the amount of solar energy which is available on the surface of the planet.”

GE⊕-LPS would demonstrate feasibility for several key technologies needed for a cislunar economy and is envisioned to provide a hub of operations in the Greater Earth environment. Eventually, the system could be scaled up to provide clean energy for the Earth as humanity transitions away from fossil fuel consumption later this century.

One emerging technology proposed to aid in construction of the system is a lunar space elevator (LSE) which could efficiently transport materials sourced on the lunar surface to L1. SSP explored this concept in a paper by Charles Radley, a contributor to the Astrostrom report, in a previous post showing that a LSE will be feasible for the Moon in the next few decades (an Earth space elevator won’t be technologically possible in the near future).

Another intriguing aspect of the station is that it would provide artificial gravity in a tourist destination habitat shielded by water and lunar regolith. This facility could be a prototype for future free space settlements in cislunar environs and beyond.

Fabrication of the GE⊕-LPS would depend heavily on automated operations on the Moon such as robotic road construction, mining and manufacturing using in situ resources. Technology readiness levels in these areas are maturing both in terrestrial mining operations, which could be utilized in space, as well as fabrication of solar cells using lunar regolith demonstrated recently by Blue Origin. That company’s Blue Alchemist’s process for autonomously fabricating photovoltaic cells from lunar soil was considered by Astrostrom in the report as a potential source for components of the GE⊕-LPS, if further research can close the business case.

Most of the engineering challenges needed to realize the GE⊕-LPS require no major technological breakthroughs when compared to, for example (given in the report), those needed to commercialize fusion energy. These include further development in the technologies of the lunar space elevator, in situ lunar solar cell manufacturing, lunar material process engineering, thin-film fabrication, lunar propellent production, and a European heavy lift reusable launch system. The latter assumes the system would be solely commissioned by the EU, the target market for the study. Of course, cooperation with the U.S. could leverage SpaceX or Blue Origin reusable launchers expected to mature later this decade. With respect to fusion energy development, technological advances and venture funding have been accelerating over the last few years. Helion, a startup in Everett, Washington is claiming that it will have grid-ready fusion power by 2028 and already has Microsoft lined up as a customer.

Astrostrom estimates that an initial investment of around €10 billion / year over a decade for a total of €100 billion ($110 billion US) would be required to fund the program. They suggest the finances be managed by a consortium of European countries called the Greater Earth Energy Organization (GEEO) to supply power initially to that continent, but eventually expanding globally. Although the budget dwarfs the European Space Agency’s annual expenditures ( €6.5 billion ), the cost does not seem unreasonable when compared to the U.S. allocation of $369 billion in incentives for energy and climate-related programs in the recently passed Inflation Reduction Act. The GE⊕-LPS should eventually provide a return on investment through increasing profits from a cislunar economy, peaceful international cooperation and benefits from clean energy security.

The GE⊕-LPS adds to a growing list of space-based solar power concepts being studied by several nations to provide clean, reliable baseload energy alternatives for an expanding economy that most experts agree needs to eventually migrate away from dependence on fossil fuels to reduce carbon emissions. Competition will produce the most cost effective system which, coupled with an array of other carbon-free energy sources including nuclear fission and fusion, can provide “always on” power during a gradual, carefully planned transition away from fossil fuels. The GE⊕-LPS is particularly attractive as it would leverage resources from the Moon and develop lunar manufacturing infrastructure while serving a potential tourist market that could pave the way for space settlement.

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The prospects for mining precious metals and structural materials from asteroids

Artist impression of an asteroid smelting operation. Credits: Bryan Versteeg / spacehabs.com

When humanity migrates out into the solar system we’ll need a variety of elements on the periodic table to build settlements and the infrastructure needed to support them such as solar power satellites. But before that future becomes a reality, there may be a near term market on Earth for precious metals sourced in space as transportation costs come down. There is also the added benefit of moving the mining industry off planet to preserve the environment. Could the asteroid belt provide these materials? Kevin Cannon, assistant professor at the Space Resources Program at the Colorado School of Mines describes the prospects for mining precious metals and building materials for space infrastructure asteroids in a recent paper in Planetary and Space Science. Coauthors on the paper Matt Gialich and Jose Acain, are CEO and CTO, respectively, at the asteroid mining company AstroForge which just came out of stealth mode last year.

The asteroids have accessible mining volume that exceeds that available on the Moon or Mars. This is because only the thin outer crust of these bodies is reachable by excavation, whereas the asteroids are small enough to be totally consumed resulting in higher accessible mining volume.

To-scale accessible mining volume of terrestrial bodies, calculated as the total volume for the asteroids (main belt mass of 2.39 x 1023 kg, mean bulk density of 2000 kg/m3), and as the volume for an outer shell 1.2 km in thickness for the Moon, Mercury, and Mars, equivalent to the deepest open pit mine on Earth. Note the combined volume of the near-Earth asteroids (~5 x 1012 m3) is too small to be visible at this scale. Figure 1 in paper. Credits K.M. Cannon et al.

The authors take a fresh look at available data from meteorite fragments of asteroids. Their analysis found that for Platinum Group Metals (PGMs), the accessible concentrations are higher in asteroids than ores here on Earth making them potentially profitable to transport back for use in commodity markets.

“Asteroids are a promising source of metals in space, and this promise will mostly be unlocked in the main belt where the Accessible Mining Volume of bodies greatly exceeds that of the terrestrial planets and
moons”

PGMs are indispensable in a wide range of industrial, medical, and electronic applications. Some examples of end-use applications include catalysts for the petroleum and auto industries (palladium and platinum), in pacemakers and other medical implants (iridium and platinum), as a stain for fingerprints and DNA (osmium), in the production of nitric acid (rhodium), and in chemicals, such as cleaning liquids, adhesives, and paints (ruthenium).

It has been pointed out by some analysts that flooding markets here on Earth with abundant supplies of PGMs from space will cause prices to plummet, but the advantage of reducing carbon emissions and environmental damage associated with mining activities may make it worth it. The authors also point out that there are probably various uses where PGMs offer advantages in material properties over other metals but are not being used because they are currently too expensive.

Asteroids are rich in other materials such as silicon and aluminum which would be economically more useful for in-space applications. As the authors point out, some companies are already planning for use of metals and manufacturing in space such as Redwire Corporation with their On-Orbit Servicing, Assembly and Manufacturing (OSAM) and Archinaut One, which will attempt to build structural beams in LEO. Another example mentioned in the paper has been covered by SSP: the DARPA NOM4D program with aspirations to develop technologies for manufacturing megawatt-class solar arrays and radio frequency antennas using space materials. Finally, another potential market for aluminum sourced in space is fuel for Neumann Thrusters (although spent upper stage orbital debris may provide nearer term supplies). And of course, silicon will be needed to fabricate photovoltaic cell arrays for space-based solar power.

AstroForge will test their asteroid mining technology on two missions this year. Brokkr-1, a 6U CubeSat just launched on the SpaceX Transporter 7 mission last April, will validate the company’s refinery technology for extracting metals by vaporizing simulated asteroid materials and separating out the constituent components. Brokkr-2 will launch a second spacecraft on a rideshare mission chartered by Intuitive Machines attempting their second Moon landing later this year. Brokkr-2 will hitch a ride and then fly on to a target asteroid located over 35 million km from Earth. The journey is expected to take about 11 months and will fly by the body and continue testing for two years to simulate a roundtrip mission.

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UK to fund study of solar power satellites for wireless power generation from space

Solar Power Satellite delivering wireless power to the UK during daylight hours. (NOTE: power would be delivered 24/7). Credits: Frazer-Nash Consultancy

The United Kingdom’s Department of Business, Energy and Industrial Strategy (BEIS) is commissioning a study by the engineering consultancy Frazer-Nash on the feasibility of space-based solar power for delivery of clean, emission free energy to the country’s electrical power grid 24 hours a day. The study, announced on the Frazer-Nash website, will provide an impartial assessment for the government of the engineering viability, budget and economic benefits of space-based solar power for the UK. Frazer-Nash will partner with Oxford Economics, a global forecasting and quantitative analysis company.

Some key challenges expected from the investigation include: a realistic analysis of the scale of the engineering undertaking to build a satellite of such magnitude in space; can the economics justify the effort to be competitive with other sources of power generation; and finally, what are the international regulatory implications of radio frequency spectrum allocation?

Solar Power Satellite delivering wireless power to the UK at night. (NOTE: power would be delivered 24/7). Credits: Frazer-Nash Consultancy


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The Aerospace Corporation calls for a near term investment decision on Space-based Solar Power

Artist’s concept of a rectenna, a ground site that receives the microwave power transmission from a solar power satellite and converts it into electricity for a utility grid or other users. Credits: James A. Vedda and Karen L. Jones, The Aerospace Corporation

Space enthusiasts have been dreaming of the promise of space-based solar power ever since Peter Glaser first conceived of the idea in the 1960s and Gerald K. O’Neill leveraged the concept to popularize space settlements in his ground breaking book The High Frontier. But the costs have been preventatively high for many years and the technology has been stubbornly out of reach. Recent events and scientific advances have begun to change this situation. For example, launch providers are becoming more widely available and costs are coming down. Photovoltaic cell efficiency has dramatically improved since solar power satellites (SPS) were first conceived. On orbit robotic assembly, additive manufacturing and mass production is within reach. Finally, ISRU on the moon could provide access to materials outside the Earth’s gravity well dramatically reducing the cost of materials needed to build SPSs in space.

In a position paper released last month by The Aerospace Corporation’s Center for Space Policy and Strategy, recommendations are made for policy decisions by the U.S. government to make strategic investments in development of this space infrastructure, lest other countries beat us to the punch.

The authors of the paper, James A. Vedda and Karen L. Jones, say that “U.S. decisionmakers will have an opportunity during the next presidential term to establish the role of the United States in this potentially disruptive technology. If SPS can develop into a major component of orbital infrastructure, and someday contribute an additional source of renewable energy to users on Earth, the United States will want to be at the forefront of high-capacity power beaming in all its applications rather than become dependent on others for the technology and services they provide.”

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ESA seeks innovative ideas on space solar power

Artist’s concept of solar power satellite. Credits: John Mankins / Forbes

The European Space Agency is soliciting submission of abstracts on ideas for development of space-based solar power that would address some of the technological bottlenecks preventing feasible realization. In a campaign for new ideas under its Open Space Innovation Platform, the Agency is seeking novel proposals for space-based solar power systems for applications on the Earth, Moon or Mars. They also are seeking methods of scaling and integrating space-based solar power into energy grids, in-space construction techniques and early in-space demonstration concepts.

Awards of 90,000€, 100,000€ or 175,000€ are being offered for ideas that would be implemented as co-funded research, system studies or early technology demonstrations, respectively.