In-situ Resource Utilization Research Articles

Campaign-level dynamic network modelling for spaceflight logistics for the flexible path concept

This paper develops a network optimization formulation for dynamic campaign-level space mission planning. Although many past space missions have been designed mainly from a mission-level perspective, a campaign-level perspective will be important for future space exploration. In order to find the optimal campaign-level space transportation architecture, a mixed-integer linear programming (MILP) formulation with a generalized multi-commodity flow and a time-expanded network is developed. Particularly, a new heuristics-based method, a partially static time-expanded network, is developed to provide a solution quickly. The developed method is applied to a case study containing human exploration of a near-Earth object (NEO) and Mars, related to the concept of the Flexible Path. The numerical results show that using the specific combinations of propulsion technologies, in-situ resource utilization (ISRU), and other space infrastructure elements can reduce the initial mass in low-Earth orbit (IMLEO) significantly. In addition, the case study results also show that we can achieve large IMLEO reduction by designing NEO and Mars missions together as a campaign compared with designing them separately owing to their common space infrastructure pre-deployment. This research will be an important step toward efficient and flexible campaign-level space mission planning.

Lunar Station: The Next Logical Step in Space Development

The International Space Station (ISS) is the product of the efforts of sixteen nations over the course of several decades. It is now complete, operational, and has been continuously occupied since November of 20001. Since then the ISS has been carrying out a wide variety of research and technology development experiments, and starting to produce some pleasantly startling results. The ISS has a mass of 420 metric tons, supports a crew of six with a yearly resupply requirement of around 30 metric tons, within a pressurized volume of 916 cubic meters, and a habitable volume of 388 cubic meters. Its solar arrays produce up to 84 kilowatts of power. In the course of developing the ISS, many lessons were learned and much valuable expertise was gained. Where do we go from here? The ISS offers an existence proof of the feasibility of sustained human occupation and operations in space over decades. It also demonstrates the ability of many countries to work collaboratively on a very complex and expensive project in space over an extended period of time to achieve a common goal. By harvesting best practices and lessons learned, the ISS can also serve as a useful model for exploring architectures for beyond low- earth-orbit (LEO) space development. This paper will explore the concept and feasibility for a Lunar Station. The Station concept can be implemented by either putting the equivalent capability of the ISS down on the surface of the Moon, or by developing the required capabilities through a combination of delivered materials and equipment and in situ resource utilization (ISRU). Scenarios that leverage existing technologies and capabilities as well as capabilities that are under development and are expected to be available within the next 3-5 years, will be examined. This paper will explore how best practices and expertise gained from developing and operating the ISS and other relevant programs can be applied to effectively developing Lunar Station.

Design of a Modular Transportation System for Future Lunar Robotic Missions

A new transportation system for future lunar robotic missions should be designed in the frame of the ROBEX project. This system should be able to adapt to different types of payload and different landing sites. First, three different missions during which a LOFAR (low frequency array), a habitat and an ISRU (in-situ resource utilization) plant should be installed and put into operations robotically on the surface of the Moon are defined. The emphasis has been put on the characteristics which have an influence on the design of the transportation system: the payload mass, the dimensions and when required the frequency of the missions. It is followed by the preliminary design of a reusable lunar resupply vehicle. This vehicle is the first element of the modular transportation system under study. As a first step the results of the trajectory analyses and structure pre-sizing, are presented, for this vehicle which should fly at least twice a year from the Moon surface to a low lunar orbit and back.

An independent assessment of the technical feasibility of the Mars One mission plan – Updated analysis

In recent years, the Mars One program has gained significant publicity for its plans to colonize the red planet. Beginning in 2025, the program plans to land four people on Mars every 26 months via a series of one-way missions, using exclusively existing technology. This one-way approach has frequently been cited as a key enabler of accelerating the first crewed landing on Mars. While the Mars One program has received considerable attention, little has been published in the technical literature regarding the formulation of its mission architecture. In light of this, we perform an independent analysis of the technical feasibility of the Mars One mission plan, focusing on the architecture of the life support and in-situ resource utilization (ISRU) systems, and their impact on sparing and space logistics. To perform this analysis, we adopt an iterative analysis approach in which we model and simulate the mission architecture, assess its feasibility, implement any applicable modifications while attempting to remain within the constraints set forth by Mars One, and then resimulate and reanalyze the revised version of the mission architecture. Where required information regarding the Mars One mission architecture is not available, we assume numerical values derived from standard spaceflight design handbooks and documents. Through four iterations of this process, our analysis finds that the Mars One mission plan, as publicly described, is not feasible. This conclusion is obtained from analyses based on mission assumptions derived from and constrained by statements made by Mars One, and is the result of the following findings: (1) several technologies including ISRU, life support, and entry, descent, and landing (EDL) are not currently “existing, validated and available” as claimed by Mars One; (2) the crop growth area described by Mars One is insufficient to feed their crew; (3) increasing the crop growth area to provide sufficient food for the crew leads to atmospheric imbalances that requires a prohibitively large ISRU atmospheric processor or a notably different system architecture to manage; and (4) at least 13 Falcon Heavy launches are needed to deliver a portion of the required equipment to the Martian surface, a value that is at least double that planned by Mars One for the same mission phase. Most importantly, we find that the one-way nature of the Mars One mission, coupled with its plans to increase its crew population every 26 months, causes the operating costs of the program to grow continually over time. This is due to the fact that maintaining a growing colony on the Martian surface incurs increasing equipment and spare parts resupply requirements and hence launch costs over time. Based on published launch vehicle and lander estimates, our analysis finds that by the launch of the fifth crew, the cost associated with launching a portion of all required equipment and spares is approximately equal to half of the total NASA FY2015 budget – and this cost will grow when other critical systems outside the scope of this analysis are included. To mitigate these costs and bring the plan closer towards feasibility, we recommend a number of mission architecture modifications and technology development efforts be implemented before the initiation of any Mars settlement campaign. These include the further development of EDL, life support, and ISRU technologies, as well as additive manufacturing technology that utilizes ISRU-derived Martian feedstock as a potential means to address the growing cost of resupply.

Asteroid Redirect Mission concept: A bold approach for utilizing space resources

The utilization of natural resources from asteroids is an idea that is older than the Space Age. The technologies are now available to transform this endeavor from an idea into reality. The Asteroid Redirect Mission (ARM) is a mission concept which includes the goal of robotically returning a small Near-Earth Asteroid (NEA) or a multi-ton boulder from a large NEA to cislunar space in the mid-2020s using an advanced Solar Electric Propulsion (SEP) vehicle and currently available technologies. The paradigm shift enabled by the ARM concept would allow in-situ resource utilization (ISRU) to be used at the human mission departure location (i.e., cislunar space) versus exclusively at the deep-space mission destination. This approach drastically reduces the barriers associated with utilizing ISRU for human deep-space missions. The successful testing of ISRU techniques and associated equipment could enable large-scale commercial ISRU operations to become a reality and enable a future space-based economy utilizing processed asteroidal materials. This paper provides an overview of the ARM concept and discusses the mission objectives, key technologies, and capabilities associated with the mission, as well as how the ARM and associated operations would benefit humanity׳s quest for the exploration and settlement of space.

Challenges of Solid Oxide Electrolysis for Production of Fuel and Oxygen from Mars Atmospheric CO2

Due to the potential for unmatched efficiency, solid oxide electrolysis has long been considered a leading technology for enabling the hydrogen economy. More recently, the potential of co-electrolysis to “fix” intermittent renewable energy by recycling CO2 to storable, transportable liquid transportation fuels has demonstrated substantial progress. A new field of application for solid oxide electrolysis producing fuels from CO2 is emerging in the area of human exploration of Mars. The Martian atmosphere is 96% CO2, making it a prime resource for extraction of oxygen that will be needed by human explorers and for production of the fuel that will be needed for the ascent vehicle to return them to earth. There are innumerable logistical and programmatic challenges to designing, qualifying, delivering and operating any process for insitu resource utilization (ISRU) on the surface of such a remote and inhospitable place such as Mars. This paper makes no attempt to address any beyond the design of the solid oxide electrolysis device itself. Ceramatec has been active in solid oxide fuel cell R&D for nearly three decades, and solid oxide electrolysis for the later half of that period. The fundamental operating principles and materials of the Mars ISRU application are no different than the hydrogen and synfuel applications of past decades. However there are circumstances of the ISRU application that place challenging constraints on the design and performance that have not been previously encountered in our SOEC development efforts. These issues are outlined and the design, analysis, materials and operational approaches to address them are presented. Ceramatec is designing and building the SOEC (aka SOXE) stack for the MOXIE instrument on the Mars 2020 mission.

Challenges of Solid Oxide Electrolysis for Production of Fuel and Oxygen from Mars Atmospheric CO2

A new field of application for solid oxide electrolysis producing fuels from CO2 is emerging in the area of human exploration of Mars. The Martian atmosphere is 96% CO2, making it a prime resource for extraction of oxygen that will be needed by human explorers and for production of the fuel that will be needed for the ascent vehicle to return them to earth. The fundamental operating principles and materials of the Mars in-situ resource utilization (ISRU) application are no different than the hydrogen and synfuel applications developed in past decades. However there are circumstances of the ISRU application that place challenging constraints on the design and performance that have not been previously encountered in our SOEC development efforts. These issues are outlined and the approaches to address them are presented. Ceramatec is designing and building the SOEC (aka SOXE) stack for the MOXIE instrument on the Mars 2020 mission.

Moonshine: Diurnally varying hydration through natural distillation on the Moon, detected by the Lunar Exploration Neutron Detector (LEND)

The Lunar Exploration Neutron Detector (LEND), on the polar-orbiting Lunar Reconnaissance Orbiter (LRO) spacecraft, has detected suppression in the Moon’s naturally-occurring epithermal neutron leakage flux that is consistent with the presence of diurnally varying quantities of hydrogen in the regolith near the equator. Peak hydrogen concentration (neutron flux suppression) is on the dayside of the dawn terminator and diminishes through the dawn-to-noon sector. The minimum concentration of hydrogen is in the late afternoon and dusk sector. The chemical form of hydrogen is not determinable from these measurements, but other remote sensing methods and anticipated elemental availability suggest water molecules or hydroxyl ions. Signal-to-noise ratio at maximum contrast is 5.6σ in each of two detector systems. Volatiles are deduced to collect in or on the cold nightside surface and distill out of the regolith after dawn as rotation exposes the surface to sunlight. Liberated volatiles migrate away from the warm subsolar region toward the nearby cold nightside surface beyond the terminator, resulting in maximum concentration at the dawn terminator. The peak concentration within the upper ∼1m of regolith is estimated to be 0.0125±0.0022 weight-percent water-equivalent hydrogen (wt% WEH) at dawn, yielding an accumulation of 190±30ml recoverable water per square meter of regolith at each dawn. Volatile transport over the lunar surface in opposition to the Moon’s rotation exposes molecules to solar ultraviolet radiation. The short lifetime against photolysis and permanent loss of hydrogen from the Moon requires a resupply rate that greatly exceeds anticipated delivery of hydrogen by solar wind implantation or by meteoroid impacts, suggesting that the surface inventory must be continually resupplied by release from a deep volatile inventory in the Moon. The natural distillation of water from the regolith by sunlight and its capture on the cold night surface may provide energy-efficient access to volatiles for in situ resource utilization (ISRU) by direct capture before volatiles can enter the surface, eliminating the need to actively mine regolith for volatile resource recovery.

Simulated real-time lunar volatiles prospecting with a rover-borne neutron spectrometer

In situ resource utilization (ISRU) may one day enable long duration lunar missions. But the efficacy of such an approach greatly depends on (1) physical and chemical makeup of the resource, and (2) the logistical cost of exploiting the resource. Establishing these key strategic factors requires prospecting: the capability of locating and characterizing potential resources. There is already considerable evidence from orbital and impact missions that the lunar poles harbor plausibly rich reservoirs of volatiles. The next step is to land on the Moon and assess the nature, “ore-grade”, and extractability of water ice and other materials. In support of this next step, a mission simulation was carried out on the island of Hawai’i in July of 2012. A robotic rover, provided by the Canadian Space Agency, carried several NASA ISRU-supporting instruments in a field test to address how such a mission might be carried out. This exercise was meant to test the ability to (a) locate and characterize volatiles, (b) acquire subsurface samples in a volatile-rich location, and (c) analyze the form and composition of the volatiles to determine their utility. This paper describes the successful demonstration of neutron spectroscopy as a prospecting and decision support system to locate and evaluate potential ISRU targets in the field exercise.

Dynamic modeling and optimization for space logistics using time-expanded networks

This research develops a dynamic logistics network formulation for lifecycle optimization of mission sequences as a system-level integrated method to find an optimal combination of technologies to be used at each stage of the campaign. This formulation can find the optimal transportation architecture considering its technology trades over time. The proposed methodologies are inspired by the ground logistics analysis techniques based on linear programming network optimization. Particularly, the time-expanded network and its extension are developed for dynamic space logistics network optimization trading the quality of the solution with the computational load. In this paper, the methodologies are applied to a human Mars exploration architecture design problem. The results reveal multiple dynamic system-level trades over time and give recommendation of the optimal strategy for the human Mars exploration architecture. The considered trades include those between In-Situ Resource Utilization (ISRU) and propulsion technologies as well as the orbit and depot location selections over time. This research serves as a precursor for eventual permanent settlement and colonization of other planets by humans and us becoming a multi-planet species.

Biological system development for GraviSat: A new platform for studying photosynthesis and microalgae in space

Microalgae have great potential to be used as part of a regenerative life support system and to facilitate in-situ resource utilization (ISRU) on long-duration human space missions. Little is currently known, however, about microalgal responses to the space environment over long (months) or even short (hours to days) time scales. We describe here the development of biological support subsystems for a prototype “3U” (i.e., three conjoined 10-cm cubes) nanosatellite, called GraviSat, designed to experimentally elucidate the effects of space microgravity and the radiation environment on microalgae and other microorganisms. The GraviSat project comprises the co-development of biological handling-and-support technologies with implementation of integrated measurement hardware for photosynthetic efficiency and physiological activity in support of long-duration (3–12 months) space missions. It supports sample replication in a fully autonomous system that will grow and analyze microalgal cultures in 120 μL wells around the circumference of a microfluidic polymer disc; the cultures will be launched while in stasis, then grown in orbit. The disc spins at different rotational velocities to generate a range of artificial gravity levels in space, from microgravity to multiples of Earth gravity. Development of the biological support technologies for GraviSat comprised the screening of more than twenty microalgal strains for various physical, metabolic and biochemical attributes that support prolonged growth in a microfluidic disc, as well as the capacity for reversible metabolic stasis. Hardware development included that necessary to facilitate accurate and precise measurements of physical parameters by optical methods (pulse amplitude modulated fluorometry) and electrochemical sensors (ion-sensitive microelectrodes). Nearly all microalgal strains were biocompatible with nanosatellite materials; however, microalgal growth was rapidly inhibited (∼1 week) within sealed microwells that did not include dissolved bicarbonate due to CO2 starvation. Additionally, oxygen production by some microalgae resulted in bubble formation within the wells, which interfered with sensor measurements. Our research achieved prolonged growth periods (>10 months) without excess oxygen production using two microalgal strains, Chlorella vulgaris UTEX 29 and Dunaliella bardawil 30 861, by lowering light intensities (2–10 μmol photons m−2 s−1) and temperature (4–12 °C). Although the experiments described here were performed to develop the GraviSat platform, the results of this study should be useful for the incorporation of microalgae in other satellite payloads with low-volume microfluidic systems.

In Situ Resource Utilization (ISRU) field expedition 2012: Near-Infrared Volatile Spectrometer System (NIRVSS) science measurements compared to site knowledge

The scientific information collected and evaluated using the Near-Infrared Volatile Spectrometer System (NIRVSS) during the 2012 In Situ Resource Utilization (ISRU) field campaign, exhibits variations related to differing surface materials and presence of volatiles during both rover traverses and auger activities demonstrating the promise of using NIRVSS for volatile prospecting on the lunar surface.

Exploratory Review of Sintered Lunar Soil Based on the Results of the Thermal Analysis of a Lunar Soil Simulant

AbstractThe exploration and development of space will require energy that is reliable, ubiquitous, and economical to produce. The international space station relies on photovoltaics to generate electricity stored in nickel-hydrogen batteries for powering the station during the “night”. This paper investigates an alternative technology designed to take advantage of in-situ resource utilization (ISRU) available on the moon or other celestial bodies. Rather than depending on chemical batteries to store energy the envisioned method would “stock” solar thermal energy in sintered regolith, serving as a thermal battery that provides heat and power during the long night. It discusses the sintering process and the temperatures required to achieve agglomeration of the Australian Lunar Regolith Simulant-1 (ALRS-1). The main aim of the presented work was to determine the specific heat capacity of a sintered simulant, across a temperature range of 25°C to 700°C. Discussed are the concept of a closed cycle power storag...

Real-time science operations to support a lunar polar volatiles rover mission

Future human exploration of the Moon will likely rely on in situ resource utilization (ISRU) to enable long duration lunar missions. Prior to utilizing ISRU on the Moon, the natural resources (in this case lunar volatiles) must be identified and characterized, and ISRU demonstrated on the lunar surface. To enable future uses of ISRU, NASA and the CSA are developing a lunar rover payload that can (1) locate near subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith, and (3) demonstrate the form, extractability and usefulness of the materials. Such investigations are important both for ISRU purposes and for understanding the scientific nature of these intriguing lunar volatile deposits.Temperature models and orbital data suggest near surface volatile concentrations may exist at briefly lit lunar polar locations outside persistently shadowed regions. A lunar rover could be remotely operated at some of these locations for the ∼2–14days of expected sunlight at relatively low cost. Due to the limited operational time available, both science and rover operations decisions must be made in real time, requiring immediate situational awareness, data analysis, and decision support tools. Given these constraints, such a mission requires a new concept of operations.In this paper we outline the results and lessons learned from an analog field campaign in July 2012 which tested operations for a lunar polar rover concept. A rover was operated in the analog environment of Hawaii by an off-site Flight Control Center, a rover navigation center in Canada, a Science Backroom at NASA Ames Research Center in California, and support teams at NASA Johnson Space Center in Texas and NASA Kennedy Space Center in Florida. We find that this type of mission requires highly efficient, real time, remotely operated rover operations to enable low cost, scientifically relevant exploration of the distribution and nature of lunar polar volatiles. The field demonstration illustrated the need for science operations personnel in constant communications with the flight mission operators and the Science Backroom to provide immediate and continual science support and validation throughout the mission. Specific data analysis tools are also required to enable immediate data monitoring, visualization, and decision making. The field campaign demonstrated that this novel methodology of real-time science operations is possible and applicable to providing important new insights regarding lunar polar volatiles for both science and exploration.

Flowability of lunar regolith simulants under reduced gravity and vacuum in hopper-based conveying devices

This paper reports on a series of experiments that were conducted on a partial-g parabolic flight campaign to determine key parameters of hoppers, designed for regolith sampling, science experiments, or in situ resource utilization (ISRU) processes on Moon or Mars. A major problem related to these applications is the clogging of feeding and conveying devices due to the physical properties of the regolith. In the experiments the flow rate of two representative lunar regolith simulants (JSC-1A and NU-LHT-2M) through hoppers was investigated under low vacuum conditions and reduced gravity. The effect of gravity, hopper outlet width, and hopper inclination angle on the sample flow was determined. It was found that both gravity and outlet width influence the flow rate of the investigated regolith simulants linearly. The effect of the inclination angle was visible, but no general relation to the flow rate could be determined. No specific difference in flow rate was observed between the two investigated sample types. Furthermore we observed lower sample compaction under reduced gravity, occurrence of abrupt dust release during sample flow under higher ambient pressures, and random arching and related flow rate restrictions.

Development of an Electrostatic Precipitator to Remove Martian Atmospheric Dust From ISRU Gas Intakes During Planetary Exploration Missions

Manned exploration missions to Mars will need dependable in situ resource utilization (ISRU) for oxygen production. The Martian atmosphere is composed of 95.3% CO2, other gases, and 0.13% O2 at ~ 9 mbar (1% of the Earth's pressure). However, it also contains 2-10- μm dust uploaded by dust devils and high winds. Oxygen extraction requires removal of the dust with little pressure drop (Δp). An electrostatic precipitator (ESP) has lower Δp than a filter, but the low pressure causes an electrical breakdown at electric fields ( ~ 1 kV/cm) ~ 30× lower than on Earth, making implementation challenging. Molecular mean free paths (λ = 4 μm) and ion mobility values (b = 0.008 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V·s) are ~ 100× larger than at Earth's pressure (λ = 44 nm) and (b = 8.4 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> ). The large λ lowers Stokes drag, particularly for smaller particles. Pauthenier field charging dominates for particles with and diffusion charging for d<;2 μm. The low E proportionally decreases both Pauthenier particle charging and the F = qE collection force. This greatly reduces the particle migration velocities (w), e.g., for d = 10 μm, w = 0.01 m/s compared with 0.4 m/s on Earth. However, for small particles (d = 1 μm), this is compensated by diffusion charging and reduced drag ( w = 0.04 m/s on Mars, 0.05 m/s on Earth). The Martian atmosphere was simulated with 95% CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /5% humid air at 9 mbar. Paschen curves were measured, and I- V curves ( I ~ 5 - 300 μA for V ~ 1.3 - 2.3 kV) were obtained for 5-10-cm-diameter wire/rod-cylinder ESPs. Only positive polarity yielded stable uniform corona. Charging of 0.5-1.3-cm-diameter spheres agreed with the Pauthenier theory. A Martian dust simulant collection efficiency test is in progress.

Initial design of laboratories for sustainable habitation

An effective and self-sustainable artificial habitat design is essential for human spaceflight and expansion of mankind into orbit or towards other celestial bodies. There are two approaches that need to be implemented in future sustainable habitats: the use of re-cycling technologies in order to gain experience in closed-loop processes and the primary production of resource materials using In Situ Resource Utilisation (ISRU) principles. Various products will be provided and, where applicable, recycled in such a system taking into account basic human factors requirements such as crew work load capacity, safety and well-being, namely:•higher plants (e.g. vegetables, fruits, crops),•animal husbandry (e.g. fishery, insects),•fuel gases (e.g. hydrogen, oxygen),•building materials (e.g. structural and insulation materials),•consumables (e.g. clothes),•base maintenance services (e.g. water or waste recycling) and power supply.Although the theory of closed-loop habitats has been the subject of many research campaigns, the practical implementation and realisation within a real habitat still needs to be established.The paper deals with the interdisciplinary DLR study of a terrestrial Facility of Laboratories for Sustainable Habitation (FLaSH). The first habitat design workshop has been held in DLR's Concurrent Engineering Facility (CEF) of the Institute of Space Systems. The study objectives such as a scenario set-up of selected habitat modules or input–output relationships were fulfilled with the support of experts from the domains of air, water, waste, greenhouse, animal, food processing, human factors, living, sickbay, ISRU, workshop, design and configuration.

A Systematic Investigation to Obtain Physical Assets on the Moon through Self-propagating High-temperature Reactions

Future space missions on the Moon, Mars and near Earth asteroids, etc., are expected to be strongly facilitated and time extended by the possibility of “In-Situ Fabrication and Repair” (ISFR) the required equipments and infrastructures. In addition, the combination of the latter approach with the “In-Situ Resources Utilization” (ISRU) paradigm contributes to overcome drawbacks related to the transportation of the needed material from the Earth. In this regard, various technologies have been recently proposed with the aim of developing suitable structures to be placed on the Moon surface for the protection against cosmic rays, solar wind, meteoroids, etc. Specifically, the possibility of exploiting combustion synthesistype reactions using Lunar resources for the fabrication of ceramic-based products was considered. Along these lines, by taking advantage of the fact that Lunar soil contains up to 20 wt.% of ilmenite (FeTiO3), the highly exothermic thermite reduction of the latter oxide with Al is systematically investigated in this work. A self-propagating (SHS) behavior is displayed only above a certain Al/FeTiO3 molar ratio (0.9). In addition, as the amount of Al in the mixture is increased, the reactive process proceeds faster and the combustion temperature becomes higher, due to the increased system exothermicity. Correspondingly, the maximum amount of Lunar regolith to be possibly reacted with additional FeTiO3 and Al is identified. The obtained products (a mixture of Al-, Ti-, Mg-, and Ca-oxides, and metallic phases) exhibit satisfactory compressive strength properties (≥ 25.8 MPa) that make them promising as construction materials. Parabolic flight experiments evidenced that SHS process dynamics and product characteristics are barely affected by gravity. The obtained findings allow us to conclude that the optimal conditions identified during terrestrial experiments are still valid for in-situ applications in Lunar environment.

Physical Assets by SHS in the Framework of ISRU and ISFR Paradigms for Human Space Missions on the Moon

&lt;p&gt;In this work a brief overview of the most important technologies for space exploration, with particular emphasis on the Moon missions, is presented. It is shown that the focus has been on the technologies to extract consumables (O&lt;sub&gt;2&lt;/sub&gt;, H&lt;sub&gt;2&lt;/sub&gt;O, N&lt;sub&gt;2&lt;/sub&gt;) for human life-support replenishment. The fact that the exploitation of extraterrestrial resources to obtain the desired materials during each ongoing mission, which has been the subject of several investigations since the sixties of the last century, is discussed. The paradigms ISRU (In Situ Resources Utilization) and ISFR (In Situ Fabrication and Repair) are then introduced. In particular, one of the most important process for the production of oxygen, i.e. the reduction of ilmenite by hydrogen is analyzed. In addition, the current iteration of the roadmap which identifies two feasible pathways for human missions after ISS (International Space Station) is addressed. Next, the fabrication of Lunar physical assets is taken into account, while focusing particularly on those processes where combustion-like reactions are exploited. The main results recently obtained in the literature in this regards are also summarized. In particular, the choice of the reducing agent and the influence of the most important processing parameters (composition of the starting mixture, gas pressure level, and gravity conditions) are examined in a systematic manner.&lt;/p&gt;

Prototype Development of an Integrated Mars Atmosphere and Soil-Processing System

The concept of living off the land by using the indigenous resources of the Moon, Mars, or other potential sites of robotic and human exploration has been termed in situ resource utilization (ISRU) and will be an enabling technology to open up the solar system. Although the most recent National Aeronautics and Space Administration (NASA) human Mars mission study (Design Reference Architecture 5.0) showed that production of propellants and life support consumables was a mission-enabling capability, mission planners were hesitant to select the newly proposed water extraction from Mars soil option because of the perceived high risk associated with this approach. To overcome resistance in putting ISRU capabilities in the critical path of mission success, NASA ISRU developers have adopted the approach of designing and building hardware into end-to-end systems at representative mission scales and testing these systems under mission-relevant conditions at analog field test sites. Previous ISRU field demonstrations have been standalone lunar ISRU modules running on alternating current power with nonoptimal integration. The primary goal of the Mars atmosphere and regolith collector/processor for lander operations (MARCO POLO) project is to design, build, and test an end-to-end first-generation Mars ISRU atmospheric and soil-processing system powered by mission-relevant direct current power while also demonstrating closed-loop power production via the combination of a fuel cell and electrolyzer. A secondary goal is to perform remote and autonomous operations with this integrated system on a 3×3-m(∼9×9-ft) octagon lander and transfer oxygen and methane produced to a cryocart for use with a thruster to demonstrate an end-to-end Mars resource-to-thrust concept. This paper will outline the overall design, technologies used, and concept of operations for the MARCO POLO project and its upcoming field demonstration.