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Lunar Outpost Eagle to fly on Starship – blazing a trail for lunar highways

Artist rendering of the Lunar Outpost Eagle Lunar Terrain Vehicle. Credit: Lunar Outpost

Space News recently reported that Colorado-based Lunar Outpost has signed an agreement with SpaceX to use Starship to deliver their lunar rover, known as the Lunar Outpost Eagle, to the Moon. Announced November 21, the contract supports the Artemis program with surface mobility and infrastructure services. The agreement positions Starship as the delivery vehicle for Lunar Outpost’s Lunar Terrain Vehicle (LTV), which is a contender for NASA’s Lunar Terrain Vehicle Services (LTVS) program. The exact terms of the contract, including the launch schedule, were not disclosed in the announcements. Lunar Outpost has assembled a contractor team under the banner “Lunar Dawn” to execute the company’s LTV solution. The collaborative development program includes in industry leaders Leidos, MDA Space, Goodyear, and General Motors.

Rover Design Features

  • Mobility and Functionality: The Lunar Outpost Eagle is designed to support both crewed and autonomous navigation on the lunar surface. It’s built to operate even during the harsh lunar night, exhibiting resilience against the Moon’s extreme temperature changes.
  • Collaborative Development: The Lunar Dawn team brings expertise in spacecraft design, robotics, automotive technology, and tire manufacturing, ensuring a robust and versatile design.
  • Size and Capacity: Described as truck-sized, the Eagle LTV is intended to be a valuable vehicle for lunar operations, capable of transporting heavy cargo to support NASA’s Artemis astronauts and commercial activities.
  • Testing and Refinement: The design has undergone human factors testing at NASA’s Johnson Space Center, with feedback from astronauts being used to refine the vehicle’s usability and functionality.

Future Plans

  • NASA’s LTV Program: Lunar Outpost is one of three companies selected by NASA for the LTV program to develop rovers to support future Artemis missions. The other two companies are Intuitive Machines and Venturi Astrolab. After a preliminary design review (PDR), NASA will select at least one company for further development and demonstration, with the goal of having a rover operational in time for Artemis 5, currently scheduled for 2030.
  • Commercial Operations: Beyond NASA’s usage, the rovers will be available for commercial operations when not in use by the agency, aiming to support a sustainable lunar economy. This includes plans for infrastructure development and scientific exploration.
  • Series A Funding: Lunar Outpost has recently secured a Series A funding round to accelerate the development of the Lunar Outpost Eagle, ensuring that the rover project moves forward regardless of the outcome of NASA’s selection process.
  • Long-Term Vision: The company’s vision extends to enabling a sustainable human presence in space, with plans to leverage robotics and planetary mobility for development of infrastructure to harness space resources.

This partnership with SpaceX and the development of Eagle under the Lunar Dawn program are pivotal steps in advancing both NASA’s lunar exploration goals and commercial activities on the Moon.

Once delivered to the Moon by Starship, the Eagle rover will drive over harsh regolith terrain which, as discovered by Apollo astronauts when driving the Lunar Roving Vehicle, presents several unique challenges due to the Moon’s distinct environmental conditions. First, lunar dust is highly abrasive and can become electrostatically charged sticking to surfaces and mechanisms resulting in wear and degradation of wheels, bearings, and sensors potentially leading to equipment failure. The Moon’s low gravity can make traction difficult. Rovers might slip or skid becoming less stable when accelerating, braking or turning. Terrain variability and nonuniformity on loose powdery dust or sharp, rocky outcrops could cause stability issues.

These problems can be solved by creating roads with robust, smooth surfaces for safe and reliable mobility on the Moon. Initially, the regolith could be leveled by robots with rollers to compact the regolith to make it less likely to be kicked up by rover wheels. Eventually, technology being developed by companies like Ethos Space for infrastructure on the Moon using their robotic system for melting regolith in place for fabricating lunar landing pads, could be used to build smooth, stable roads.

A network of roads could be constructed to transport water and other resources harvested at the poles to where it would be needed in settlements around the Moon extending from high latitudes down to the equatorial regions. As envisioned by the Space Development Network, this system of roads could be created to provide access to a variety of areas to mine valuable resources as well as thoroughfares to popular exploration and tourism sites. The development of the highway system could start at the poles with telerobots, then eventually be expanded to include equatorial areas and would be fabricated autonomously prior to the arrival of large numbers of settlers.

Longer term, a more efficient method of transportation on the Moon could be magnetic levitation (maglev) trains. Research into this technology has already been proposed by NASA which is actively developing a project named “Flexible Levitation on a Track” (FLOAT), which aims to create a maglev railway system on the lunar surface. This system would use magnetic robots levitating over a flexible film track to transport materials, with the potential to move up to 100 tons of material per day. The FLOAT project has advanced to phase two of NASA’s Innovative Advanced Concepts (NIAC) program.

Artist’s rendering of the Flexible Levitation on a Track (FLOAT) maglev lunar railway system to transport materials on the Moon. Credit: Ethan Schaler / Jet Propulsion Laboratory
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ESA launches the Second Space Resources Challenge

Conceptual illustration of lunar regolith extraction and beneficiation operations creating feedstock for an oxygen production factory on the Moon. Credits: Grok 2

The European Space Agency (ESA) on October 24 initiated their Second Space Resources Challenge. The Space Resources Challenge is an initiative aimed at stimulating innovation in the field of in-situ resource utilization (ISRU) for lunar and potentially other planetary bodies’ development. Launched in partnership with the Luxembourg Space Agency and their joint European Space Resources Innovation Centre (ESRIC), the competition encourages participants from various backgrounds—including students, startups, and established companies—to develop technologies that can collect, process, and utilize resources on the Moon. The challenge focuses on extracting valuable resources like oxygen for human life support and rocket fuel, as well as metals for construction, from lunar regolith. By fostering a competitive environment, ESA seeks to advance technologies that could reduce the dependency on Earth-supplied materials, thereby making long-term lunar missions more economically viable. The competition not only aims to develop new ISRU technologies but also to build a community of innovators interested in the value of space resources, potentially leading to commercial opportunities in the burgeoning space economy.

Launched on October 24, the second Challenge will focus on extraction and beneficiation of lunar regolith, critical steps in establishing a sustainable human presence on the lunar surface. Teams have until February 20th 2025 to submit proposals. Competition winners can claim €500K for the best performing team and will be awarded a development contract for a feasibility study. A second place prize worth €250K will be awarded to the best team in the category of beneficiation.

The first Challenge, which targeted resource prospecting, took place in 2021 and featured a competition between robotic protypes in ESA’s Lunar Utilisation and Navigation Assembly (LUNA) facility, an advanced research and simulation center designed to support Europe’s efforts in lunar exploration. Located within ESA’s European Space Research and Technology Centre (ESTEC) in the Netherlands, LUNA serves as a testing ground for technologies and systems intended for lunar missions. The facility includes a moon-like environment where various aspects of lunar landing, operations, and human habitation can be simulated.

The Second Resource Challenge will focus on:

  • Extraction: The collection, hauling and handling of lunar regolith. In LUNA this will be modeled using lunar simulant, which mimics the Moon’s soil. The problem to be solved in this area of the challenge involves designing robotic systems that can collect and transport material efficiently in the harsh lunar environment.
  • Beneficiation: a term adapted from the terrestrial mining industry, is the process whereby the economic value of an ore is improved by removing the gangue minerals, resulting in a higher-grade product. In the context of ISRU on the Moon, beneficiation will convert regolith into a suitable feedstock through particle sizing and mineral enrichment, preparing it for the next step in the value chain. On the Moon the next process could be extracting valuable resources like oxygen for life support and rocket fuel, and metals for construction or manufacturing, which will be essential for sustaining a long-term human presence on the Moon.

The technology development program will award the teams with the most innovative robotic systems that exhibit autonomy, durability, efficient handling and processing of regolith in the extreme conditions of vacuum, temperature extremes and dust expected in the lunar environment.

Alignment with Strategic Roadmap:

The Second Space Resources Challenge is a pivotal part of ESA’s Space Resources Challenge strategic roadmap to build out the ISRU Value Chain. The next phase of the program will focus on “Watts on the Moon”, i.e. reliable surface power sources for lunar operations. Subsequent phases will develop ISRU applications including extraction of oxygen and water for life support and rocket fuel, with the goal of sustainable in situ factories in the 2030s providing resource supply chains for settlements and the cislunar economy. Integrated systems downstream in the Value Chain, such as Pioneer Astronautics’ (now part of Voyager Space) Moon to Mars Oxygen and Steel Technology (MMOST) application to produce oxygen and metallic iron/steel from lunar regolith, are already under development.

Space Resources Challenge strategic roadmap depicting gradual progression of ISRU development activities. Challenges are planned to be solicited every three years. Credits: ESA

The Second Space Resources Challenge competition is a critical forward-thinking step in ESA’s plans for space development. By concentrating on the extraction and beneficiation of lunar regolith, ESA is not only preparing for the logistics of long-term lunar habitation but also setting a precedent for how future space missions might operate autonomously and sustainably. This challenge underscores ESA’s commitment to innovation, sustainability, and the strategic use of space resources, paving the way for humanity’s next steps in the settlement of the Moon and other worlds in the Solar System.

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Ethos Space has ambitious plans for the Moon and beyond

Conceptual illustration of a SpaceX Starship on a lunar landing pad made from in situ materials by Ethos Space, which plans to use lunar resources for space development. Credits: Starship image: SpaceX; Lunar landing pad and landscape: Grok 2

Kevin Cannon, one of our favorite researchers on ISRU here on SSP, recently appeared on The Space Show to discuss his new position as Senior Lunar Geologist for Ethos Space, a Los Angeles based lunar infrastructure startup that just emerged from stealth last June. Near term (by 2028), the company plans to support the Artemis program by attempting to robotically building landing pads for Starship using lunar regolith, an application SSP covered last year in a ground breaking trade study. Ethos also hopes to extract oxygen from lunar regolith which makes up 80% of rocket propellant and could be a major market segment in a cislunar economy. Incidentally, a few years ago Cannon looked into where on the Moon is the best place to source oxygen.

Long term (20 – 30 years from now) Ethos hopes to use lunar materials to manufacture a sunshade commissioned by world governments that would be placed at the L1 Sun-Earth Lagrange point to combat global warming by blocking 2% of sunlight that reaches our planet. Ethos Space CEO, Ross Centers, is founder of the nonprofit Planetary Sunshade Foundation which issued a report on the state of space based radiation modification about a year ago.

Conceptual illustration of planetary sunshade fabricated from materials sourced on the Moon. Credits: Ethos Space
Diagram depicting the proposed location for a sunshade located at the L1 Sun-Earth Lagrange point (not to scale). Credits: Planetary Sunshade Foundation
Ray trace showing that the more acute umbra shadow of a sunshade would not reach Earth while the diffuse penumbra is what would cover our planet (not to scale). Credits: Planetary Sunshade Foundation

Cannon believes that a sunshade is a better geoengineering solution to cool the climate then cloud seeding with sulfur dioxide aerosols as at least one startup company, Make Sunsets, is proposing. Cannon believes this approach, which he says amounts to “using pollution to fight pollution”, will not be very popular with the general public. Make Sunsets counters this argument with an analysis available on their website showing that sulfur dioxide released high in the stratosphere is highly effective in counteracting the warming effect of carbon dioxide while dispersing to negligible levels globally reducing the chance of producing acid rain, the primary concern of sulfur releases in the lower atmosphere. In fact, a paper in Geophysical Research Letters published last August documents evidence that recent regulations on cargo ship emissions limiting sulfur pollutants may have actually contributed to global warming. In 2020 the International Maritime Organization (IMO) instituted new regulations reducing the maximum allowed sulfur emission per kg of fuel in ships by 80%. As a result, artificial clouds created by ship emissions decreased causing northern hemisphere surface temperatures to rise. This example reinforces the need to study geoengineering projects carefully to prevent unforeseen consequences. With respect to the sunshade, Cannon anticipates that international coordination will definitely be required as some countries may have farm land that would actually benefit from anticipated warming so may not want these regions shaded.

Back to the Moon: On The Space Show podcast Cannon mentioned that Ethos will be partnering with Astrolab, a Hawthorne, California based company which has already been awarded a NASA contract to develop a Lunar Terrain Vehicle for the Artemis program. Astrolab’s current concept, dubbed FLEX, is designed to carry two suited astronauts, has a robotic arm for science excavations, and can survive the extreme temperatures at the Lunar South Pole. The rover can be teleoperated remotely from Earth or driven by suited astronauts. The Ethos robotic system for fabricating lunar landing pads would be towed behind this rover while melting the regolith in place forming molten stripes over multiple passes that cool into igneous rock that would be very robust. The mechanism for how the regolith will be melted was not disclosed but if they are guided by the trade study mentioned above, microwave sintering makes the most sense.

Image of Astrolab’s FLEX rover which may tow the Ethos Space robotic system for melting lunar regolith to fabricate landing pads on the Moon. Credits: Astolab

In a post a few years ago on his blog Planetary Intelligence, Cannon makes the case that mining Luna for platinum group metals (PGM) would be more economically feasible than from near-Earth objects (NEO) because of transit times and operational difficulties due the typical NEO being an “…irregular shaped rubble pile–or basically a space sandcastle of loose dust and boulders–held weakly together by cohesion and microgravity, and spinning rapidly.” In addition, terrestrial ore grades are higher than in NEOs potentially making the economics challenging to compete with mines on Earth. The CEO of asteroid mining company Astroforge, Matt Gialich, begs to differ. He thinks there is a business case for mining NEOs and has venture capital backers that agree. Cannon actually collaborated with Gialich on a paper making the case for mining PGMs from main belt asteroids which SSP covered last year. However, the distances involved make near term profits difficult, and Astroforge is now focusing on NEO’s relatively close to Earth. Gailich also appeared on The Space Show this year and addressed the terrestrial ore grade question when I posed it to him, essentially saying that extraction of PGMs from NEOs could be economically competitive with terrestrial mines because they are so deep and have slim profit margins.

Both Ethos and Astroforge will have mission results in the next decade, although they are targeting completely different markets. Hopefully, both will succeed.

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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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JAXA’s Lunar Farming Concept Study

Cutaway illustration depicting a sublunar farm covered by regolith, providing food and augmenting life support for a settlement on the Moon. Credits: Microsoft Image Creator

The Japan Aerospace Exploration Agency (JAXA) published a report last November summarizing the findings of its Lunar Farming Concept Study Working Group. JAXA’s team, composed of professionals in universities and private experts, assumes that humans will eventually establish permanent communities on the Moon and conducted the study using cutting-edge agriculture science and biotechnology to design a plant factory that would provide nutritional sustenance and oxygen in a life support system for a lunar settlement.

The working group was composed of four subgroups: cultivation, unmanned technology, recycling, and overall system design. The cultivation subgroup focused on the farm’s environmental controls including light levels (provided by LEDs), irrigation and atmospheric conditions tailored to each crop type. The unmanned technology team dealt with robotic maintenance of the plant factory environment including autonomous monitoring, sowing, cultivating and harvesting. The recycling group ensured soil improvement and reuse of limited resources, inedible scraps and waste material. Finally, the overall system subgroup studied the farm as a whole taking into account each plant species.

The scale of the lunar colony in the study was spit into two scenarios. An initial settlement in the near future with a 6 person crew followed by a larger scale permanent community at a later date with 100 people. The objective was to define a scalable cultivation system that would provide energy and nutritional requirements for settlers without resupply from Earth. The design would leverage recycling to fullest extent possible, minimize the use of materials sourced on the Moon such as water and oxygen from the polar regions, and reduce supplies imported from Earth, realizing that the system would not be 100% closed. LED lighting was utilized to optimize wavelength for chlorophyll absorption as well as diurnal growth cycles during the 14 day lunar night, being necessary for crop illumination in an underground farming community protected from radiation by thick layers of regolith. Nuclear power was considered as a power source.

An important finding of the study leveraged a metric called the Equivalent Systems Mass (ESM), to evaluate the life support systems of the different lunar farm designs explored by the team. ESM is a mathematical formula used to perform trade studies to determine which options have the lowest launch cost and is calculated from the system variables mass, volume, power, cooling, and crew working hours. When comparing the ESM of several biomass production systems it was found that the mass of the system could be minimized by appropriate sizing of crop cultivation shelves and increased space utilization efficiency. It was shown that over a 10 year period an optimized design for a lunar farm would not have to be replenished with food from the Earth when building materials, water and oxygen were supplemented by sources on the Moon and nuclear power was assumed as a power source.

The JAXA study adds to the space farming body of knowledge needed for establishing life support systems for space settlement.

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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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Artificial photosynthesis for production of oxygen and fuel on the Moon and Mars

Image of ice in a crater on the Martian plain Vastitas Borealis captured by the European Space Agency’s Mars Express orbiter. Credits: ESA/DLR/Freie Universitat Berlin (G. Neukum)

When we establish outposts and eventually, settlements on the Moon or Mars it would be economically beneficial if we did not have to create supply chains from Earth for water, breathable air and the fuel we will need for our rockets. This is why sources of water ice in the permanently shadowed craters at the lunar poles and in glaciers in the equatorial regions on Mars are so attractive as early destinations. Once we get there what equipment will we need to process this valuable resource? The typical way envisioned for cracking water in situ on the Moon or Mars to produce oxygen and hydrogen is through electrolysis. But this method requires a lot of power. There may be a more efficient way. New ESA sponsored research by scientists* in the UK and Europe examines a novel method that mimics photosynthesis in plants using a photoelectrochemical (PEC) device. The findings were published June 6 in Nature Communications.

PEC reactors are currently being studied on Earth for water splitting to produce green hydrogen from sunlight. Since they only rely on solar energy for power they are ideal for space applications. One type of device consists of a semiconductor photocathode immersed in an electrolyte solution that absorbs solar energy for a reaction to split hydrogen from water molecules. Oxygen is produced at the anode of the cell. PEC devices can be fabricated as panels similar to photovoltaic arrays. For use on Mars, the authors analyze another similar PEC technology using a gas-diffusion electrode to reduce atmospheric carbon dioxide in a reaction producing methane for rocket fuel.

The authors modeled the performance of these devices subjected to the expected environmental conditions on the Moon and Mars. Specifically, they looked at attenuation from the accumulation of dust on the PEC cells caused by micrometeorites pulverizing the lunar surface, coupled with the solar wind inducing an electrostatic charge in the resulting dust. And of course dust storms are relatively frequent on Mars which could significantly degrade performance. To address this problem self cleaning coatings are suggested as a solution. Solar irradiance was also considered as it would be reduced at the orbit of Mars. It was concluded that the PEC performance could be significantly boosted with solar concentrators by a factor of 1000 enabling higher production rates and power densities, especially on Mars.

An added advantage for space-based application of this technology is the elements needed to construct PEC devices are readily available on these worlds obviating the need to transport them from Earth and thereby significantly reducing costs.

“…in-situ utilization of elements on both, the Moon and Mars, is feasible for the construction of PEC devices.”

The technology is ideal to augment the production of oxygen in environmentally controlled life support systems of habitats that may not initially be 100% closed and cannot easily be resupplied with consumables from Earth. A competing technology for oxygen production which was recently demonstrated on Mars is the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) which functions via solid oxide electrolysis of carbon dioxide. This process requires high temperatures and therefore, more energy presenting a challenge when increased production of oxygen will be required for large settlements. The author’s analysis show that the PEC devices are more energy efficient and can easily be scaled up.

“Oxygen production via unassisted PEC systems can … be carried out at room temperature … suitable to be housed in temperature controlled space habitats.”

* Authors of the Nature Communications article Assessment of the technological viability of photoelectrochemical devices for oxygen and fuel production on Moon and Mars: Byron Ross at the University of Warwick, UK; Sophia Haussener at Ecole Polytechnique Fédérale de Lausanne, Switerland; Katharina Brinkert, University of Bremen, Germany

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Lunar-derived propellant fueling a cislunar economy may be competitive with Earth

AI generated image depicting a propellant factory on the Moon. Credits: DALL-E

The economics of an in-space industry based on lunar-derived rocket propellant was examined by Florida Space Institute planetary physicist Philip Metzger in a prepublication paper submitted to arXiv on March 16 . The study will be published in the June issue of Acta Astronautica. Many skeptics of this approach believe that with launch costs plummeting, driven down primarily due to reusability pioneered by SpaceX, it will be cheaper to power the nascent cislunar economy with propellant launched from Earth rather then fuel derived from lunar ice mining.

In his analysis, Metzger examines a cislunar economy of companies that operate geostationary satellites which need to purchase boost services using orbital transfer vehicles fueled by cryogenic hydrogen and oxygen. The question is, would sourcing H2/O2 from ice mined on the Moon be competitive with launching propellant from Earth. He notes that previous studies that favored Earth to solve this problem were flawed because they compared the different technologies for mining water on the Moon (e.g. strip mining, borehole sublimation, tent sublimation, or excavation with beneficiation) rather than analyzing the economics of the cis-lunar economy as a sector.

With that approach in mind, Metzger develops an economic model with figures of merit to assess how various technologies for ice mining compare to Earth sourced propellant. One such parameter is the “gear ratio” G, which in the parlance of orbital dynamics, is the ratio of the mass of hardware and propellant before versus after moving between two locations in accordance with the rocket equation. The other key metric is the production mass ratio Ø, which is the mass of propellant delivered to a specific location divided by the mass of the capital equipment needed to produce the fuel.

The “tent sublimation technology” mentioned in the paper was invented by George Sowers and is featured in his 2019 NIAC Phase I Final Report on ice mining from cold bodies in the solar system covered by SSP previously.

Although G is constrained by the laws of physics, reasonable values are possible and a value of Ø ≥ 35 is the threshold above which lunar propellant wins out. The tent sublimation technology is estimated to have Ø over 400, an order of magnitude higher than the minimum to gain an advantage. Metzger’s new approach took into account that launch costs will eventually come down as far as possible but even then, found that lunar propellant can be produced at a competitive advantage. The only caveat is validation of the TRL and reliability of ice mining technologies.

“Lunar-derived rocket propellant can outcompete rocket propellant launched from Earth, no matter how low launch costs go.”

Although not included in Metzger’s study, a method for extraction of water from lunar regolith is heating by low power microwaves. A recent study found that this technology is effective for extracting water from simulated lunar soil laced with ice. It would be interesting to see if Ø for this technique exceeds the advantage threshold.

Developing the business case for lunar water is the first step in rapidly bootstrapping an off-Earth economy.  Metzger has written about this previously where he sees robotics, 3D printing and in situ resource utilization being leveraged to accelerate growth of a solar system civilization.

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Solar cell manufacturing using lunar resources

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

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

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

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

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

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

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

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

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

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

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

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Lunar landing pad trade study

Artist’s impression of a lunar landing pad. Credits: SEArch+

When humanity returns to the Moon and begins to build infrastructure for permanent settlements, propulsive landings will present considerable risk because rocket plumes can accelerate lunar dust particles in the bare regolith to high velocities which could result in considerable damage to nearby structures. Obviously, nothing can be done about the first spacecraft that will return to the moon later this decade unless they use their own rocket plume to create a landing pad like the concept proposed in a NIAC Grant by Masten Space Systems (now part of Astrobotic).

Flight Alumina Spray Technique (FAST) instant landing pad deployment during lunar landing. Source: Matthew Kuhns, Masten Space Systems Inc (now Astrobotic)

Therefore, before significant operations can begin on the Moon that require lots of rockets, a high priority will be construction of landing pads to prevent sandblasting by rocket plume ejecta of planned structures such as habitats, science experiments and other equipment. Several methods are currently being studied. Some require high energy consumption. Others could take a long time to implement. Still others are technologically immature. Which technique makes the most economic sense? Phil Metzger and Greg Autry examine options for the best approach to this urgent need in a November 2022 paper in New Space.

A lunar landing pad should have an inner and outer zone. The inner zone will have to withstand the intense heat of a rocket plume during decent and ascent. The outer zone can be less robust as the expanding gases will cool rapidly and decrease in pressure but will still be expanding rapidly, so erosion will have to be mitigated over a wider area.

Landing pad layout showing inner and outer zone measurements proposed in this study (Figure 1 in paper). Credits: Philip Metzger and Greg Autry / New Space – Lunar surface image credit: NASA.

Several processes of fabricating landing pads were examined by the authors. Sintering of regolith is one such technique, where dust grains are heated and fused by a variety of methods including microwave heating or focused solar energy. SSP has reported on the latter previously, but in this study it was noted that that technology needs further development work. Fabricating pavers by baking in ovens in situ was also examined in a addition to infusion of a polymer into the regolith to promote particle adhesion.

An economic model was developed to support construction of landing pads for NASA’s Artemis Program based on experimental data and the physics for predicting critical features of construction methods. Factors such as the equipment energy consumption, the mass of microwave generators compared to the power output needed to sinter the soil to specified thickness, and the mass of polymer needed to infuse the regolith to fabricate the pads were included in the model. Other factors were considered including the costs associated with program delays, hardware development, transportation of equipment to the lunar surface, and reliability.

When varying these parameters and comparing different combinations of manufacturing techniques, the trade study optimized the mass of construction equipment to balance the costs of transportation with program delays. The authors found that from a cost perspective, microwave sintering makes the most sense for both the inner and outer regions of the landing pad, at least initially. When transportation costs come down to below a threshold of $110K/kg then a hybrid combination of microwave sintering in the inner zone and polymer infusion of regolith in the outer zone makes the most sense.

Once astronauts land safely and begin EVAs on the lunar surface, they can keep from tracking dust into their habitat by taking an electron beam shower.

Other lunar dust problems and their risks can be mitigated with solutions covered previously on SSP.