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A novel ablative arc mining process for ISRU

Illustration of Ablative Arc Mining Process. Credits: Amelia Greig

A NASA NIAC Phase 1 grant has been awarded to Amelia Greig of the University of Texas, El Paso to study an innovative mining technique called ablative arc mining. The process works by using a pair of electrodes to zap surface regolith with an electrical arc thereby ionizing it into its component constituents. The ablated ions are then sorted and collected by subjecting them to an electromagnetic field which separates the material groups by their respective mass. Such a system, when mounted on a mobile rover, could extract both water and metal ions in the same system.

The goal of the this grant is to identify a feasible ablative arc mining scheme for ISRU on upcoming lunar exploration sorties. The study will define the design of an ablative arc and electromagnetic transport system for extraction and collection of water, silicon, and nickel. The architecture should have an output of 10,000 kg/yr of water for use by lunar outposts or other operations. Finally, a trade study will be performed comparing the efficiency of the proposed concept against other ISRU processes such as microwave or direct solar heating which are designed to only collect a single constituent.

We’ll need ISRU methodologies to enable long-term space settlement on the Moon, Mars, in the Asteroid Belt or to support free space habitats. The ablative arc mining architecture may be an efficient alternative for extraction and collection of multiple volatile constituents in a single system when compared to methods that collect only one material at a time.

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Simpler methane production on Mars

Artist’s depiction of activities at an early Mars base which could include methane production. Credits: NASA

A team of physicists at the University of California, Irvine has found a short cut for efficient propellant production on Mars. The UCI researchers have discovered a way to streamline the conventional two step Sabatier process which first electrolyzes water into hydrogen before reacting with carbon dioxide in the Martian atmosphere to create methane. Both SpaceX and Blue Origin use methane in their rocket engine designs. The novel approach simplifies fuel production by leveraging zinc as a “synthetic enzyme,” which catalyzes carbon dioxide to synthesize methane directly. The improved process will reduce the amount of ISRU equipment (and therefore weight and launch costs) needed for transport to the surface of Mars to facilitate propellent production required for the trip home. The research has only demonstrated proof of concept so follow-on studies are required to improve the TRL for flight-ready hardware.

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Survey of industry experts on challenges of lunar ISRU by 2040

Artist impression of ISRU activities on the Moon. Credits: NASA

What do space experts in industry and academia think will be the technical and policy challenges to overcome for a sustainable lunar outpost leveraging ISRU by 2040 to be realized? A survey using the Delphi method has just been completed to answer this question. The results were just released as a pre-proof in Acta Astronautica. Significant contributors in the fields of ISRU technologies, space architecture, power systems, and space exploration participated in the survey.

There was a group consensus that NASA’s Artemis mission returning humans to the Moon would be delayed by at least 2 years from the previous administration’s target of 2024 due to uncertainty in U.S. policy over the next few years. No surprise here. There was also agreement that ISRU processes could add significant power requirements on the order of 1 MW to a lunar base, and that photovoltaic systems were preferred over nuclear power sources because of a “…political distaste for space nuclear power systems”. Of particular note, the survey participants could not reach agreement on the impact that Covid-19 would have on space exploration.

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UK company aims to turn lunar soil into oxygen

Artist’s depiction of a future lunar base 3D printed from local materials. Credits: ESA/Foster + Partners

A British company called Metalysis as been funded by ESA to study their industrial-scale production of metals and alloys for application in a lunar environment. Metalysis has already demonstrated that they can extract 96% of the total oxygen content from ilmenite, a black iron-titanium oxide with a chemical composition of FeTiO3 found by Apollo astronauts to be abundant in lunar regolith. The process leaves a metallic powder alloy that can be used for in-situ 3D printing on the Moon.

In a press release last month, Metalysis states that “The project will provide an assessment to prepare and de-risk technology developments, focused towards oxygen production for propellants and life support consumables. The ability to extract oxygen on the moon is vital for future exploration and habitation, being essential for sustainable long duration activities in space. In-Situ Resource Utilisation (ISRU) will significantly reduce the payload mass that
would be needed to be launched from Earth.”

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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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NASA’s measurement plan for a lunar water reserve

Diagram depicting NASA’s Lunar Water ISRU Measurement Study (LWIMS). Credits: NASA

NASA just published a Technical Memorandum on its Lunar Water ISRU Measurement Study (LWIMS). The TM describes the establishment of a measurement plan for identification and characterization of a water reserve on the Moon. This program would support the Artemis program to achieve a sustainable lunar presence by 2028.

Three primary data inputs feed information into the system. First, predictive modeling provides a ‘water favorability’ index to map out locations on the Moon with water ice potential. This algorithm is fed data by orbital measurements providing information on a regional scale. It is critical that this orbital data is interpreted properly for water-favorable sites on the Moon. To ensure accuracy, lunar landers will take surface measurements in a series of three phases: mobile reconnaissance for validation of the predictive model, focused exploratory missions to verify water’s presence and final reserve mapping to inform an ISRU ice mining plant by 2028.

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Making oxygen from moondust with ROXY (and improving life on Earth)

Artist’s rendition of Airbus lunar lander with ROXY on board. Credits: Airbus

In a breakthrough experiment last month, a team led by Airbus Defence and Space (Friedrichshafen, Germany) has for the first time produced oxygen and other metals from simulated lunar soil with a proprietary process called Regolith to OXYgen and Metals Conversion, or ROXY. The revolutionary new process could be the core of an ISRU value chain on the moon, providing oxygen for habitats or rocket fuel, with added byproducts of metals and alloys as feedstock for additive manufacturing of building materials. This would significantly reduce the cost of settlements on the Moon as the construction materials could be fabricated in situ, without the need to be brought from Earth. Check out Airbus’ animation of ROXY here.

Airbus thinks that the ROXY reactor could have beneficial environmentally friendly applications on Earth as well:

“On Earth, ROXY opens a new pathway to drastically reduce the emissions of greenhouse gases that result from production of metals.” Since the process is essentially free of emissions “…these environmental impacts could be reduced, providing a significant contribution to the UN sustainability goals – another example of how space technologies can improve life on Earth”

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Lunar regolith beneficiation: a review of the latest research

Artist impression of a moon base. Credits: ESA

In the July Issue of Planetary and Space Science there is a summary of research on beneficiation, the process used for separation of minerals from waste in lunar regolith to prepare feedstock for chemical reactions to produce oxygen. One of the most commonly studied processes is hydrogen reduction of ilmenite (FeTiO3), a mineral abundant in the lunar maria. This type of research is critical to prepare for situ resource utilization (ISRU) needed for lunar settlements.

Benefication processes use differences in physical properties (e.g., density, electromagnetic characteristics) to manipulate materials, most commonly (especially on Earth) with water to facilitate separation. This is not practical in space environments where large scale water use will be more challenging then on Earth. On the Moon, dry techniques such as magnetic or electrostatic process are better suited to this application. The authors describe the physics behind the beneficiation process for ISRU in the lunar environment and survey the research performed thus far on these methods with interesting recommendations for further studies.

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Lava Hive: ISRU Mars habitat

Stepwise illustration of the casting process to produce the Lava Hive; (1) deposition of foundation base, (2) regolith is gathered and sintered into a flow channel, (3) molten basalt from the sand/regolith is poured into the channel and allowed to solidify, (4) the next layer of regolith is spread across, and another channel sintered, (5) layer by layer the structure is constructed, (6) loose, un-sintered regolith is excavated from the structure, revealing the completed dome. Credits Aidan Cowley, et al.*

In a paper posted on Academia.edu, the 3rd prize winner for the 2015 NASA 3D Printed Mars Habitat Centennial Challenge called Lava Hive is described by a team* of European researchers. The habitat is produced by additive manufacturing via a ‘lava-casting’ construction technique and utilizing recycled spacecraft structures. Innovations include ‘re-use’ of discarded landing vehicles as part of the central habitat, 3D printed adjacent structures connected to the central habitat and use of a novel ‘LavaCast’ process to fabricate solid structures resistant to radiation and thermal cycling.

Illustration of the Lava Hive. The central habitat core is shown with the smaller 3D printed satellite structures clustered around it. Credits: René Waclavicek, LIQUIFER Systems Group, 2015

The Lava Hive Mars settlement has a number of advantages including a modular design with the ability to expand or adapt to changing mission requirements while “living off the land” with a simple ISRU process utilizing Martian soil, thereby reducing the amount of mass that would need to be launched from Earth.

* Authors of this paper are: Aidan Cowley, Barbara Imhof, Leo Teeney, René Waclavicek, Francesco Spina, Alberto Canals, Juergen Schleppi, Pablo Lopez Soriano

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Mass value: metric for space settlement

Image credit: Richard Bizley, bizelyart.com / National Space Society

In a paper published in New Space last March, Peter Hague describes a figure of merit he developed to drive policy decisions to help accelerate space exploration and space settlement. The aim of the paper was to generate a single metric for every potential space mission on a common scale for comparison purposes. This ‘mass value’ is the amount of mass that would need to be placed in low Earth orbit (LEO) to perform the same mission using a baseline method. That method would use only storable propellants and Hohmann transfer orbits – no gravity assists, aerocapture, high energy propellants or ISRU.

This approach puts a price on all the add-ons which expand the mission beyond the baseline. One can then use a single normalized scale to calculate how much mass to LEO you would save by making propellant on Mars for example, or by taking advantage of a certain launch window to get a gravity assist.

A hands-off government entity could subsidize space expenditures at a flat rate per kg of mass value, confident they are promoting space development without having legislators involved in engineering decisions.

Aggregating all the missions by a nation, company, or other entity could be used to calculate an analogue of GDP for a space civilization. While this does not measure everything we care about – scientific merit, human occupation, etc – neither does GDP. It does capture the overall capability to move around the solar system; and as such, is as useful for charting our journey to becoming a Type II civilization on the Kardashev Scale as it is for analyzing individual missions.

Thanks to Peter Hague for the material in this post. We’ve heard a rumor that there may be a book forthcoming on the subject. Looking forward to it!