With the anticipated manned missions and future long-term habitation of the Martian surface, in-situ resource utilization (ISRU) methods remain critical to provide raw materials and subsequent manufacturing of tools, replacement components, electronics, and more. Due to the overwhelming costs and flight time associated with launching supplies to extraterrestrial bodies, the sustainability of these astronaut colonies will rely on readily available feedstocks and energy-efficient production methods on the surface. The Martian environment contains numerous elements, mostly in the form of compounds within the regolith and local atmosphere, that could be used for producing metallic components. Ionic liquids (ILs) have been demonstrated as a low-temperature regolith and meteorite metal harvesting system by NASA’s Marshall Space Flight Center (MSFC). Additionally, the Bosch process has shown success as an oxygen (O2) generation system possessing theoretical 100 % hydrogen (H2) recovery, producing a solid carbon (C) byproduct. Studies on the use of IL-metals and Bosch C in ferrous castings have been conducted in recent years with immense success. This study further investigates an alloy composition based on IL harvested iron (IL-Fe) and Bosch C to produce a novel IL-steel alloy for additive manufacturing (AM) by combining the products of IL’s and Bosch C into a printable steel composition. The IL-steel powder was produced using commercially available elements and the addition of Bosch C from the rotary kiln C-formation reactor (C-FR) at MSFC’s Environmental Controls and Life Support Systems (ECLSS) branch. Raw materials were alloyed into steel ingots and atomized to a targeted powder size distribution of 15-45 μm. A series of progressively refined build parameters (laser power and exposure time) were used to produce cubic samples that were investigated to determine baseline laser powder bed fusion (PBF-LB) settings for printing with IL-steel. Bulk density was used as the initial filtering mechanisms, with Vickers microhardness and microstructural investigations being conducted on the final matrix of samples. Moving forward, IL and Bosch C production will need further refinement to limit elements that could negatively affect printed products, and production volumes will need to be increased beyond laboratory scales. Future investigations with IL-Steel will require characterization of the powder’s flowability, laser interaction, and printability in reduced gravity and extraterrestrial atmospheric conditions. Additionally, further mechanical characterization, i.e. tension, fatigue, etc., will be required to determine the potential use cases of IL-Steel on Mars and solidify its applicability. The results indicated that the alloying of IL-Fe and Bosch C to create an IL-steel could serve as a viable means of producing a multitude of components and tools, such as rebar for concrete reinforcement, replacement gears, hand tools, and more in-situ for long-term manned missions to Mars.

To ensure the success of surface missions and the eventual habitation of the Lunar and Martian surfaces, construction materials for machine components, tools, plumbing, and more must be considered for the long-term supportability of astronauts. The financial burden of launching these materials from Earth is far too great; therefore, in-situ resource utilization (ISRU) technology will be required. The Martian environment contains numerous elements for producing bulk metal components; however, these elements are almost exclusively found as compounds. The use of ionic liquids (ILs) for elemental metal harvesting is being researched by NASA's Marshall Space Flight Center (MSFC) to extract feedstock materials from local regolith and meteorites. Studied at MSFC as a life support system, the Boschprocess produces a byproduct elemental carbon (C) during oxygen (O2) regeneration from metabolic or environmental carbon dioxide (CO2). This study details the refinement of a ductile iron (DI) designed to simulate the combination of IL-harvested iron (IL-Fe) and Bosch C by investigating the effects of Ni and Mn addition on IL-DI properties. Dilatometry was used to evaluate how the properties of the IL-DI might vary when produced in the Martian environment. DIs were cast using commercial elements with C produced via a C formation reactor (C–Fr) at MSFC with microstructural, hardness, and phase diagram analyses completed. Results suggest that the combination of IL-Fe and Bosch C could be a viable means of producing DI alloys in-situ and, with the quantities used here, the use of Ni could be more beneficial to alloy customization than Mn additions for IL-DI alloys.

As researchers continue to study methods to facilitate long-term missions beyond low-Earth orbit, the ability to manufacture high-quality mechanical and structural components on the Lunar and Martian surfaces remains a crucial piece to the puzzle for a sustained presence. Due to the immense cost of sending supplies to extraterrestrial bodies, in-situ resource utilization (ISRU) methods are critical for the success and feasibility of these habitation missions. Ionic liquids (ILs) are currently being studied at NASA's Marshall Space Flight Center (MSFC) to harvest elemental metals from meteorites and regolith minerals. Additionally, the Bosch process is being explored as a life support system at MSFC for oxygen (O2) regeneration, rendering a byproduct of elemental carbon (C). In this inves-tigation, the viability of casting ductile iron (DI) using IL-sourced iron (IL-Fe) and Bosch C was studied given the range of applications and performance of DI as an as-cast alloy. Ingots were produced using commercial elements to simulate the use of IL-Fe with C sourced from the byproduct C of the Bosch process. Samples were cast and compared to commercially available 65-45-12 DI with phase trans-formation diagrams, microstructures, and hardness. Results showed that IL-sourced elements are a viable source of elemental alloying materials for a range of DI alloys, with some limitations.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

As the race to colonize Mars continues, the need for energy efficient, low waste manufacturing techniques remains as a major hurdle. Launching building materials from Earth is not feasible logistically or financially; therefore, in-situ resource utilization (ISRU) methods are required to ensure the success and longevity of these Martian colonies. Ionic liquids (ILs) are currently studied at NASA’s Marshall Space Flight Center (MSFC) as a means to harvest metallic elements from regolith oxides and meteorites. IL technology provides an energy efficient method to extracting critical manufacturing materials, such as iron (Fe), that can be used for structures, plumbing, and tools. In this study, IL-sourced Fe (IL-Fe) was used as feedstock for laser-based powder bed fusion (PBF-LB) to obtain a baseline of material characteristics for additive manufacturing. Samples were then investigated to determine microstructure, hardness, and chemical composition. IL-Fe showed potential as a feedstock for the production of metallic materials via laser-based additive manufacturing techniques.

Ionic liquids (ILs) have been considered as suitable media for the extraction of metals and other elements from the Martian regolith. The complex mineralogy of the Martian regolith and the innumerable possible combinations of cation/anion pairs in available ILs pose challenges to the selection of most effective ILs to extract desired regolith elements. In this work, we utilized molecular dynamics simulations to fundamentally investigate the interactions between three major element oxides in the composition of the Martian regolith simulants, represented as alumina, hematite, and silica, and one basic and one acidic IL, i.e., 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) and 1-ethyl-3-methylimidazolium hydrogen sulfate ([emim][HSO4]), respectively. We used potential of mean force (PMF) calculations to generate the free energy profiles of the cations and anions of both ILs on the oxide surfaces. Additionally, we generated their number density profiles on these surfaces to examine the structural features, including ion layering, at the IL-oxide interfaces. Our results indicate that both ILs have less favorable interactions with the silica surface and, hence, are less stable on it than on the metal oxide surfaces. Between the two ILs, [emim][Ac] shows more favorable energetics than [emim][HSO4] with the hematite surface. However, clear distinction cannot be made between the two ILs regarding their interactions with the alumina surface. Our calculated net interfacial energies of the IL-oxide systems further confirm our findings. The current work provides a general methodology to perform an initial screening of different ILs with respect to their potentials to selectively extract metals and other elements from the Martian regolith.

Element recovery from the Martian regolith using ionic liquids (ILs) is an active area of research within the field of in-situ resource utilization. In this work, we performed a classical molecular dynamics (MD) simulation study to better understand the solvation thermodynamics and structures of potential cationic and anionic species originating from the Martian regolith in two select ILs, i.e., 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) and 1-ethyl-3-methylimidazolium hydrogen sulfate ([emim][HSO4]), at two temperatures of 298.15 and 473.15 K. The studied cationic and anionic species represent the stable ions, i.e., a series of tetra-, tri-, di-, and monovalent cations, as well as several silicate, phosphate, chromate, titanate, and select halide anions, based on the mineral composition of the Martian regolith. We calculated the solvation free energies (SFEs) of these ionic species in the ILs using the free energy perturbation method. Moreover, we investigated the solvation environment of these ionic solutes by generating the relevant radial distribution functions and calculating the running coordination numbers of ILs' anions and cations surrounding the solutes. Overall, the average absolute values of the SFEs for cationic solutes increase with increasing ion valency (charge) and size of the solute at both temperatures. For anionic solutes, a more complex effect of anion molecular size and charge is responsible for the trends observed in the absolute values of the SFEs. For example, we found orthosilicate to be the most soluble anionic species in both ILs. On the other hand, the dichromate anion was found to be essentially insoluble in both ILs. Comparing between the solvation efficiencies of the ILs, [emim][Ac] shows larger negative SFE values than [emim][HSO4] for all cationic solutes at both temperatures. While the temperature effect on the solvation of cationic solutes is mixed, higher temperatures generally favor the dissolution of the anionic solutes in both ILs. Our results provide molecular insights into the solvation thermodynamics of various potential ionic species that may be extracted from the Martian regolith using suitable ILs. (C) 2020 Elsevier B.V. All rights reserved.

The Carbon Dioxide Removal by Ionic Liquid Sorbent (CDRILS) system is designed for efficient, safe and reliable carbon dioxide (CO2) removal from cabin air on long-duration missions to the Moon, deep space, and Mars. CDRILS integrates an ionic liquid sorbent with hollow fiber membrane contactors for rapid CO2 removal and recovery. The liquid-based system provides continuous CO2 delivery, which avoids complicated valve networks to switch between absorbing and desorbing beds and enables simpler integration to the Sabatier without the need for the CO2 Management System (CMS). Ionic liquids are particularly desirable as liquid absorbents for space applications since they are non-volatile, non-odorous, and have high oxidative stability. The hollow fiber membrane contactors offer both high contact area and rigorous containment between the gas and liquid phases in a microgravity environment. Scale-up of the CDRILS technology has presented a series of fascinating challenges, since the interaction between hollow fiber properties, ionic liquid properties and performance is complex. Properties measured with lab-scale hollow fiber contactors are used to estimate the performance of contactors that are similar in scale to flight-scale demonstrations. To accomplish this, component and system models have been built to relate the key scrubber and stripper design and operating variables with performance, and experiments directed to validate the models have been performed. System size, weight and power are determined by component selection, arrangement, and operating conditions. Reliability will be extremely important for any long-range mission and depends on the stability of the ionic liquids and hollow fiber contactors. We report on our continuing long term stability experiments for the ionic liquid and contactor materials and our investigation of the physical properties of additional ionic liquids.

In this study, we evaluated the molar conductivity and dynamic viscosity of 1-ethyl-3-methylimidazolium acetate based solvent systems containing dissolved cellulose (cotton or microcrystalline cellulose), cellobiose, or glucose. Matrix variables included solute concentration, as well as concentration of acetonitrile or water (typical molecular species present in IL-based biopolymer solutions). Ion conductivity, dynamic viscosity, and density were measured for each solution, and the data was correlated graphically on Walden plots. When this approach is used, the systems containing dissolved cellulose appear superionic. This apparent superionicity results from large (up to 140-fold) increases in solution viscosity due to dissolved biopolymer, and correspondingly small (ca. 0.7-fold) decreases in solution conductivity. Differences in solution hydroxyl content as well as cellulose content and degree of polymerization are proposed as the physical explanation behind the apparent superionic behavior. (C) The Author(s) 2019. Published by ECS.

This study evaluated the ion transport properties of 1-ethyl-3-methylimidazolium acetate (EMIAc)-based solutions containing additional acetonitrile (AN), H2O, and up to 3.0 wt-% carbohydrate solutes. Solution ion conductivitywas directly measured via frequency response, and ion self-diffusivity coefficients determined via pulsed-field gradient spin-echo (PGSE) NMR. These data combined to determine solution ionicity. Multiple linear regression analysis shows ionicity is primarily impacted by the added neutral solvent, and weakly impacted by temperature. Addition of equimolar AN or H2O increases both cation and anion self-diffusivity (D+ and D-, respectively), and each of these solvent systems decreases the D+/D- quotient. Addition of carbohydrate solutes decreases cation and anion self-diffusivity, but solute additions slightly increase the D+/D- quotient. Our observation that carbohydrate solutes reduce Ac self-diffusivity by a greater fraction than EMI supports the general assertion that acetate anions are more heavily involved in solvating cellulose than EMI cations. Finally, EMIAc solutions containingmicrocrystalline cellulose (MCC) were evaluated by NMR spin-lattice relaxation (T-1) measurements. These T-1 data reveal the microviscosity of EMIAc:MCC solutions is virtually unchanged with addition of up to 3.0 wt-% solute, in agreement with the ion transport properties measured at the same scale. (C) The Author(s) 2019. Published by ECS.

Regolith, being largely composed of metal oxides, has the potential to be an excellent in situ source of metals, such as iron, nickel and aluminum, as well as oxygen. There is, however, no current technology that is suited for the in space separation of metal oxides into their constituent elements. Terrestrial methods require large volumes/masses of hazardous reagents. Alternative methods, such as molten oxide electrolysis, have been investigated, but these processes generally require high temperatures to operate. Such a requirement imposes significant material compatibility restraints, necessitates high energy inputs, and may pose a threat to the health and safety of the crew. This paper discusses a novel process that uses ionic liquids (ILs) to recover high purity metals and oxygen from regolith and meteorite materials. ILs are organic salts that are molten at or near room temperature, and can have a number of attractive properties including wide liquidus ranges and high thermal and electrochemical stability. The structure of an IL can be readily modified to tune these properties, allowing the synthesis of task specific ILs. Together, these attributes give ILs great utility in a number of space related areas, such environmental control and life support, in space repair and manufacture, and in situ resource utilization.

Selected ionic liquids have been shown to be effective solvents for biopolymers. This aspect of ILs has been leveraged in a process called Natural Fiber Welding (NFW) which enables the reconfiguration of biopolymer materials while retaining much of their native structure. Biopolymer dissolution in ionic liquids is largely driven by the interaction of a chaotropic anion and the hydrogen bonds present in biopolymers. This suggests that increasing the concentration of an IL should lead to a greater degree of biopolymer mobilization. However, previous work in our lab has shown that the addition of large mole fractions of polar, aprotic solvents, up to 75 mole-%, can actually increase the degree to which NFW modifies a biopolymer substrate. We have speculated this improvement in the NFW ability of an IL solvent could be the result of the impact of the solvent and/or biopolymer on the anion availability. Ions present in an ionic liquid usually have a high degree of ion aggregation between cations and anions, with 20 to 50% of ions being aggregated. Any anions that are present in such aggregates are less available to interact with biopolymer chains and thus will contribute less to biopolymer mobilization. Ion aggregation can be adjusted through a number of approaches, including changing temperature or introducing a co-solvent to solvate ions. Therefore, the addition of aprotic solvents may, in reality, result in an increase in the availability of anions to disrupt hydrogen bonding, even if the overall concentration of anions actually decreases. The ionic character of a solvent mixture can be characterized by determination of its ionicity. Ionicity is the ratio of diffusion-based estimated ion conductivity to measured ion conductivity, where ionicity values less than unity indicate the presence of ion-aggregation. For highly aggregated ionic liquids, ionicity values less than 0.5 are typical. By monitoring changes in ionicity, the impact of co-solvents and solution on the ionic character of an ionic liquid can be assessed. Changes in ionicity were evaluated for dissolved cellulose, cellobiose, and glucose in 1-ethyl-3-methylimidazolium acetate (EMIAc) and 1:1-mole-ratio mixtures of EMIAc with acetonitrile (1:1 EMIAc:AN) and water (1:1 EMIAc:H 2 O). Test solutions were made with these three solvent types by dissolving 0.1, 0.5, 1.0, and 3.0 wt.-% of either cotton, microcrystalline cellulose (MCC), cellobiose, or glucose. EMIAc’s ionicity decreased with the 1:1 addition of AN by 27 and 19 % at 20 and 60°C, respectively, and EMIAc’s ionicity increased with the 1:1 addition of H 2 O by 13 and 22 % at 20 and 60°C, respectively. No significant changes in ionicity were observed with the addition of the carbohydrate solutes. Solutes’ negligible changes to ionicity are consistent with how these solutes produce almost indistinguishable decreases in molar conductivity at given solute content for a given solvent type, suggesting the ion aggregation and conductivity behavior remain unchanged with solute up to 3.0 wt.-%.

Current oxygen recovery technology onboard the International Space Station only recovers approximately 50% of the oxygen from metabolic carbon dioxide, thus requiring resupply mass in order to sustain life onboard. Future long duration manned missions will require maximum oxygen recovery in order to reduce resupply mass. Complete recovery of oxygen can be achieved through Bosch technology. The challenge with this technology is that the solid carbon produced during the process results in undesired catalyst resupply mass. Although there have been several approaches to solve this challenge, in order to totally eliminate the need for resupply only one potential process has been identified. This process is a fully-regenerable Ionic Liquid (IL)-based Bosch system that employs in situ resources. In 2016, efforts were made that proved the feasibility of an IL-based Bosch system. ILs were used to electroplate iron onto a copper substrate and to regenerate the iron by extracting the iron from the copper substrate and product carbon. In 2017, efforts were initiated to scale the proposed technology. Here we report the results of those efforts as well as an IL-based Bosch system concept and basic reactor design.

Changes in ionicity were evaluated for dissolved cellulose, cellobiose, and glucose in 1-ethyl-3-methylimidazolium acetate (EMIAc) and 1:1-mole-ratio mixtures of EMIAc with acetonitrile (1:1 EMIAc:AN) and water (1:1 EMIAc:H2O). Test solutions were made with these three solvent types by dissolving 0.1, 0.5, 1.0, and 3.0 wt.-% of either cotton, microcrystalline cellulose (MCC), cellobiose, or glucose. EMIAc's ionicity decreased with the 1:1 addition of AN by 27 and 19 % at 20 and 60 degrees C, respectively, and EMIAc's ionicity increased with the 1:1 addition of H2O by 13 and 22 % at 20 and 60 degrees C, respectively. No significant changes in ionicity were observed with the addition of the carbohydrate solutes. Solutes' negligible changes to ionicity are consistent with how these low-concentrations of solutes produce similar decreases in molar conductivity at given solute content for a given solvent type, suggesting the ion aggregation and conductivity behavior remain unchanged with solute up to 3.0 wt.-%.

The effect of dissolved cellulose, cellobiose, and glucose on ionic conductivity, density, and viscosity were evaluated for 1-ethyl-3-methylimidazolium acetate (EMIAc) and 1:1-mole-ratio mixtures of EMIAc with acetonitrile (1:1 EMIAc:AN) and water (1:1 EMIAc:H2O). Test solutions were made with these three solvents by dissolving 0.1, 0.5, 1.0, and 3.0 wt.-% of either cotton, microcrystalline cellulose (MCC), cellobiose, or glucose. Each solute caused slight decreases in ion conductivity at higher solute contents, decreasing to factors only as low as 0.7 of their corresponding solvent-type's conductivity. The solutes' effects upon viscosity differed: cellulose solutes caused increases in viscosity upon reaching higher solute contents, where the solvents' viscosities increased to factors between 10 and 20 at 3.0 wt.-% MCC and to factors between 40 and 140 at 1.0 wt.-% cotton. This difference in impact on viscosity between MCC and cotton is possibly due to cotton's higher degree of polymerization. Meanwhile cellobiose and glucose only increased viscosity to factors as high as 1.1 and 1.3, respectively, upon reaching 3.0 wt.-% solute contents. The large increases in viscosity and corresponding small decreases in conductivity make the solutions of 3.0 wt.-% MCC and 0.5 and 1.0 wt.-% cotton appear superionic.

This study determined the effect of dissolved cellulose on the ion conductivity, dynamic viscosity, and density of 1-ethyl-3-methylimidazolium acetate (EMIAc). Cellulose solutions were prepared with three different solvents and two different sources of cellulose. The solvents were pure EMIAc, EMIAc combined in a 1:1 mole ratio with water, and EMIAc combined in a 1:1 mole ratio with acetonitrile. The cellulose sources were microcrystalline cellulose (MCC) and cotton. MCC was tested at 0, 0.001, 0.005, 0.01, and 0.03 g (g solution)-1 and cotton was tested at 0, 0.001, 0.005, and 0.01 g (g solution)-1. Each solution was evaluated over the range of 20 to 60°C. Both MCC and cotton increased the dynamic viscosity and decreased molar conductivity (with several small exceptions) for all three solvent types. The fractional changes (from zero cellulose content) for dynamic viscosity were large compared to the fractional changes in molar conductivity. The source of cellulose had a large impact on the resulting change in dynamic viscosity, as cotton increased dynamic viscosity drastically more than MCC for a given cellulose mass fraction for all solvents. For comparison, solutions were also made with glucose and cellobiose instead of cellulose in order to remove the inherent movement constraints on anhydroglucopyranose moieties within the cellulose chain. These comparisons help to understand why the addition of cellulose polymer affects dynamic viscosity more than molar conductivity by one or more orders of magnitude. Knowledge of the ion transport phenomena will allow a more thorough understanding of why ionic liquids like EMIAc are capable of dissolving biopolymers like cellulose.

Natural fiber welding (NFW) is a process that uses controlled amounts of ionic liquid and molecular co-solvent(s) to swell and mobilize portions of a natural polymer substrate. By carefully selecting factors controlling NFW such as time, temperature and solvent system composition, partial dissolution occurs, mobilizing and redistributing only a small portion of the natural polymer and leaving much of the underlying substrate intact. The NFW process results in fibers with a shell of dissolved/mobilized polymer, permanently adhered to both the outer diameter of the fiber and (depending on the extent of welding) to the surface of adjacent fibers. When polymeric and/or particulate materials are added during the NFW process, these substances can be integrated into the natural polymer matrix and modify its properties to include novel functionalities. In the present work we have applied the NFW process to the modification of natural polymer yarns. We have studied the processing conditions that impact the NFW of natural polymer yarns and the accompanied incorporation of functional materials (e.g., magnetic, conductive, and capacitive). We will discuss the preparation these functionalized yarns, and we will show data for their analysis using tensile testing, infrared spectroscopy, and scanning electron and con-focal fluorescence microscopies.

The physical and transport properties (density, viscosity, ionic conductivity, and ion diffusion coefficients) are reported for solutions containing 1-ethyl-3-methylimidazolium acetate (EMIAc) and cellulose, either with no molecular solvent, with water, or with acetonitrile (AN). Ionicity values, or the fraction of ions present in the ionic liquid (IL) that are "free" were calculated for each solution. The addition of molecular solvents to IL-cellulose solutions significantly changes the association behavior of the ions, with the presence of acetonitrile increasing aggregation while water decreases aggregation. Adding cellulose to all solutions results in more ideal behavior from the IL, with the increase in ideality being a function of the type of solvent present. The observed behavior suggests that water and AN have fundamentally different interactions with EMIAc and these differences in interaction may explain the varying cellulose solvation behavior of solutions containing these solvents.

Throughout history humankind has exploited the remarkable properties of natural polymers such as silk and cellulose. In modern times, these natural materials still possess properties that rival the most advanced synthetic polymers. Recent work has shown ionic liquids (IL) to be effective solvents for the dissolution of a wide variety of natural polymers, and new materials can be created from these natural feedstocks by processes that involve their full dissolution and subsequent reconstitution. However, many reports show that the dissolution and reconstitution processes eliminate the native polymer structure, often with negative consequences to the physical properties of the resulting materials. Alternatively, if only the surface layers of these natural materials are mobilized through an ionic liquid facilitated process called Natural Fiber Welding (NFW), the underlying material retains its native character and mechanical properties while still allowing for significant material modification. Furthermore, the addition of functional materials (e.g. magnetic, conductive, antimicrobial) into the IL welding solution, allows for these substances to be entrained in and on the surface of the substrate imparting unique properties to the natural materials. Our group has endeavored to utilize NFW to modify natural materials to introduce novel functionalities. This work has encompassed the incorporation of a wide variety of polymeric, organic and inorganic materials into natural fiber matrices. Through the introduction of the appropriate materials we have been able to impart capacitive, conductive, catalytic, magnetic, optical, antimicrobial, and/or fire retardant functionalites into natural polymeric materials. In this presentation we will show our most recent efforts utilizing NFW to prepare novel functional natural materials.