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NASA In-Situ Resource Utilization (ISRU) Project – Development & Implementation

Gerald B. Sanders1 NASA/Johnson Space Center, Houston, TX, 77058, USA

William E. Larson2 NASA/Kennedy Space Center, Cape Canaveral, FL, 32899, USA

Kurt R. Sacksteder3 NASA/Glenn Research Center, Cleveland, OH, 44135, USA

and

Carole A. Mclemore4 NASA/Marshall Space Flight Center, Huntsville, AL, 35812, USA

Abstract The establishment of sustained human presence on the Moon for science and exploration combines the design,

integration, and operation challenges experienced from both the short Apollo lunar missions and the build-up and sustained crew operations of the International Space Station (ISS). With the goal of establishing a lunar Outpost on the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth’s economic sphere, a change in how both the Apollo and ISS Programs were planned and executed is required for this new international lunar exploration program. Since the Vision for Space Exploration (VSE) was released in 2004, NASA, in conjunction with international space agencies, industry, and academia, has continued to define and refine plans for sustained and affordable robotic and human exploration of the Moon and beyond. One area NASA is developing that can significantly change how systems required for sustained human presence are designed and integrated, as well as potentially break our reliance on Earth supplied logistics, is In-Situ Resource Utilization (ISRU). ISRU, also known “living off the land”, involves the extraction and processing of local resources into useful products. In particular, the ability to make propellants, life support consumables, fuel cell reagents, and radiation shielding can significantly reduce the cost, mass, and risk of sustained human activities beyond Earth. The ability to modify the lunar landscape for safer landing, transfer of payloads from the lander to an outpost, dust generation mitigation, and infrastructure placement and buildup are also extremely important for long-term lunar operations. Because ISRU hardware and systems have never been demonstrated before, NASA is examining how these capabilities can be added into mission designs and plans such that lunar mission success is currently not relying on these capabilities, but that the systems developed are flexible enough to incorporate the capabilities once they have been demonstrated. With this in mind, the ISRU Project within the Exploration Technology Development Program (ETDP) has initiated development and testing of hardware and systems in three main focus areas: (1) Regolith Excavation, Handling and Material Transportation; (2) Oxygen Extraction from Regolith; and (3) ISRU Precursor Activities. To minimize cost and ensure that ISRU technologies, systems, and functions are integrated properly into the Outpost, technology development efforts are being coordinated with other ETDP development areas such as Surface Mobility, Surface Power, Life Support, EVA, and Propulsion, as well as outside government agencies, industry, academia, and International Partners to the maximum extent possible to leverage funding and increase commonality of hardware at the Outpost. Lastly, laboratory and field system-level tests and demonstrations will be performed as often as possible to demonstrate improvements in: Capabilities (ex.

1 ISRU Project Manager for ETDP, EP, and AIAA Member 2 Chief, Applied Science Division, KT-D-2, and AIAA Member 3 ISRU Lead for Excavation, MS 77-5, and AIAA Member 4 Deputy for ISRU Development Support, VP33, and AIAA Member

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Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc.The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes.All other rights are reserved by the copyright owner.

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digging deeper); Performance (ex. lower power); and Duration (ex. more autonomy or more robustness), as well as form the partnerships with industry and International Partners that will be needed once actual Outpost flight hardware development and deployment begins. This paper will provide the status of work performed to date within the NASA ISRU Project with respect to technology and system development and field demonstration activities, as well as the current strategy to implement ISRU in future robotic and human lunar exploration missions.

I. Introduction The Vision for Space Exploration (VSE) and the US Space Exploration Policy calls for humans to return to the

Moon by 2020, eventual human exploration of Mars, development of innovative technologies and infrastructure, and promotion of international and commercial participation in space exploration. This space exploration program must be both affordable and sustainable to meet near and long-term objectives. With the goal of establishing a lunar Outpost on the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth’s economic sphere, a change in how technology is developed and space exploration is performed is required. Shortly after the VSE was released, the President’s Commission on Implementation of US Space Exploration Policy, also known as the Aldridge Report, recommended that NASA immediately begin work on 17 technology areas the Commission identified as enabling. One technology area identified that opens up the possibility for the first time of breaking our reliance on Earth supplied consumables and learn to “live off the land” is In-Situ Resource Utilization (ISRU). ISRU involves the extraction and processing of space resources (both natural and man-made) into useful products, and can have a substantial impact on mission and architecture concepts. In particular, the ability to make propellants, life support consumables, fuel cell reagents, and propellants can significantly reduce the cost, mass, and risk of sustained human activities beyond Earth. The ability to produce water or use lunar regolith for radiation shielding can also significantly reduce the payload mass and risk of sustained human activities beyond Earth. Lastly, the ability to modify the lunar landscape and regolith for safer landing, transfer of payloads from the lander to an outpost, dust generation mitigation, and infrastructure placement and buildup is also extremely important for long-term lunar operations.

Based on results from the NASA Lunar Architecture Team (LAT) Phase I study, a lunar architecture was presented at the 2nd Space Exploration Conference that established the following top level requirements and attributes:

Return to the Moon with crew by 2020 Establish a single Outpost at a polar location Minimum crew of 4 staying for 7 days on the lunar surface Provide extensive surface mobility Develop infrastructure to lead to sustained human presence on the Moon Prepare for human missions to Mars

A single lunar Outpost at a polar location was chosen over Sorties to multiple locations on the Moon by the LAT

for numerous reasons, including: it met the two top ‘Themes’ for returning to the Moon - Exploration Preparation and Human Civilization; it enables global participation; it provides moderate thermal environments and greatly enhanced solar power capabilities; and it allows development and maturation of learning to extract and use lunar resources, including potential water/ice in the permanently shadowed craters. Even though ISRU was deemed a critical capability and key to implementing the VSE and sustained human exploration, the LAT Phase I study recommended that while ISRU can not be in the ‘critical path’ to successful implementation of a lunar Outpost since it had not yet been demonstrated, that the lunar architecture be designed to be open and flexible enough to take advantage of ISRU when it was demonstrated and available. Besides establishing an Outpost on the Moon, NASA also proposed that an ‘open architecture’ approach for human lunar exploration be utilized. While NASA stated that it was the intent of the US to develop the launch and space vehicles necessary to transport crew and cargo to the lunar surface and return them to Earth when the mission is complete, initial communication and navigation, and initial Extra Vehicular Activity (EVA) suits, it also stated that all other elements and future upgrades to sustain and grow this Outpost were open for international or commercial cooperation (Ref. 1).

Since the incorporation of ISRU into a lunar surface and transportation architecture can not only reduce the mass and cost of lunar exploration, but can also significantly change the technologies selected and operations performed, a three pronged approach has been utilized to develop and incorporate ISRU into the human lunar architecture: (1) Identify and evaluate ISRU capabilities with mission planners and lunar architecture study teams to insert ISRU into the architecture; (2) Development ISRU technologies and systems in conjunction with other lunar surface

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system elements, technology projects, and commercial and international partners; and (3) build confidence in ISRU early and often through testing and potentially on robotic precursor missions.

II. Incorporation of ISRU into the Lunar Surface System Architecture Before the Lunar Architecture Team effort, previous lunar and space exploration studies that involved ISRU

included grand concepts such as reusable space transportation systems supplied with ISRU derived propellants, large space colonies from ISRU derived materials and building techniques, and extensive power generation and power beaming from ISRU produced solar arrays and rectennas. However, these studies provided no guidance on how to reach this desired ‘end-state’ with technologies and systems that had never been built, let alone demonstrated in a previous space mission. Also, because of the grand concepts evaluated, ISRU systems were large and required extensive infrastructure and power to accomplish their objects. For the LAT, a new approach to integrating ISRU into the lunar surface system architecture was required. This approach had to have the following attributes:

Provided immediate benefits to subsequent missions Required the minimum of infrastructure and power to achieve initial capabilities Was not in the immediate critical path of mission success, but enhanced or enabled capabilities above non-ISRU architectures

Evolved with growth in capabilities, criticality, Mars Forward, and commercialization of space

To design, develop, and implement ISRU systems that achieved these attributes, ISRU developers worked with architecture planners and surface system element leads to understand development trade studies, issues, and risks of concern to success of the individual elements and the lunar architecture as a whole. At the same time, ISRU developers had to develop designs, models, and concepts of operation that could mitigate these development issues and risks. From this understanding, a phased approach to ISRU incorporation was proposed and has been the basis for subsequent ISRU technology and system development. The approach is time phased to meet the desired ISRU integration attributes:

Pre-Outpost/Pre-Sustained Human Presence: Determine type, amount, and location of possible resources of interest (including water/ice) and perform proof-of-concept and risk reduction demonstrations that can provide early benefits if successful

Initial Outpost: Produce oxygen and water to close life support, Extra-Vehicular Activity (EVA), and pressurized rover consumable needs, supplement and enhance crew radiation shielding, and provide site preparation and Outpost emplacement capabilities to mitigate dust and landing hazards

Outpost Growth: Produce oxygen and fuel propellants for robotic and human vehicles, provide feedstock for in-situ manufacturing, fabricate structures that utilize in-situ materials, and initiate in-situ energy generation and storage capabilities.

Table 1 depicts preliminary requirements for ISRU excavation, material transport, and mission consumable

production and processing based on Lunar Architecture Team Phase II investigations for Initial Outpost (Ref. 2). For NASA, there are three major milestones that will strongly influence and define the final LSS architecture;

LSS Lunar Capability Concept Review (LCCR) in June 2010, LSS System Requirements Review (SRR) in July 2012, and the LSS Preliminary Design Review (PDR) in August 2014. By the LSS LCCR, the feasibility of critical surface system and element designs and operations must be demonstrated. By LSS SRR, critical surface systems and elements must be adequately demonstrated such that mass, power, volume, and operational requirements can be baselined for inclusion into the lunar surface system architecture within acceptable risk to cost and schedule. Lastly, by LSS PDR, lunar surface systems and elements must be developed and demonstrated to Technology Readiness Level (TRL) 6, which refers to system demonstration under relevant lunar and operational environments. These milestone dates drive the element and integration development activities required to successfully meet the objective of human lunar exploration by 2020.

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Table 1. ISRU Consumable and Excavation Requirements from LAT Phase II ISRU Consumable Processing Requirements MT/yr (min.)Oxygen Production

For ECLSS & EVA 1.0For Water Production 0.8For Altair Ascent Propulsion 0.76

Water ProductionFor ECLSS & EVA (from in-situ O2 + Scavenged H2) 0.9Required H2 Scavenged from LSAM Descent Stage 0.1For radiation shielding in habitat module (3 modules)* 1.0 for 3 yrsFor radiation and thermal system on pressurized rover (2 modules)* 0.45

Methane ProductionFor LSAM Ascent Propulsion (max) 2160

Excavation and Regolith Transport Requirements MT/yr (max.)For oxygen production from regolith*** 106Landing area clearing (50 m diameter) 589Berm preparation 283Road/pathway clearing 90

*One time production need** 28 excursions per year with at least 1 MPU***Worst case for 1 MT/yr

III. Impact of ISRU on the Lunar Surface System Architecture The lunar exploration architecture and specifically the Lunar Surface System (LSS) needs, goals, and objectives

have evolved and changed with each architecture study performed since the completion of the LAT Phase I, and lunar surface systems and elements have evolved and changed with them. However, whether the lunar Outpost stays in one location, or moves over time to other locations on the lunar surface the main basic elements required are the same as those identified in the LAT Phase I study and include: Power Systems, Communications/Navigation, EVA, Habitation, Surface Mobility, ISRU, Robotic Systems, and Science Capabilities.

Typically critical systems, such as power, propulsion, thermal, and life support, for each major lunar surface element are designed and optimized based on their own requirements instead of from a more integrated element or surface architecture perspective. While this may minimize the mass and volume for each individual system or element when considered alone, the total mass, volume, and development costs associated with all these systems can be much higher when considered from an integrated vehicle aspect. The incorporation of ISRU into lunar architecture planning can significantly change the design and implementation of habitat, lander, life support, surface and mobile power, and EVA suits by changing the focus from minimizing mass and cost of individual elements or relying on all resupply from Earth, to developing an integrated surface development and deployment strategy. ISRU implementation impacts are based on understanding and identifying common consumable needs and requirements as well as understanding and identifying common technologies and systems. Figure 1 denotes interfaces and interactions between surface elements and ISRU that can significantly influence other surface element designs and technology selections.

For Surface Mobility, ISRU requirements and capabilities can influence the size, operation, and duration of mobility platforms required as well as navigation and control software for performing both long-term simplistic operations such as excavation for oxygen production from regolith as well as short-term complex operations such as clearing an area or burial of a nuclear reactor. For Power Systems, high-cycle life, high-power density power systems and fuel cell reagent regeneration for mobility platforms such as the Small Pressurized Rover (SPR) need to be balanced with long-term night-time power generation and fuel cell reactant storage and regeneration for the Outpost and ISRU water processing and oxygen generation and storage capabilities. Since ISRU requires power for regolith processing to extract and store oxygen, both solar concentrator and solar array energy generation needs for ISRU and other applications need to be coordinated. For Life Support and EVA, oxygen, water, buffer gas, and cleaning gas consumption, transfer, and regeneration need to be coordinated between Environmental Control and Life Support System (ECLSS) and ISRU. For the Lander, the ability to provide oxygen and methane for ascent propulsion and scavenge residual hydrogen from the lander stage can significantly change the payload capability of

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the Altair lander as well as risks associated with propellant leakage leading to eventual reuse of transportation assets. Lastly, since ISRU, fuel cell power, life support, EVA, and lander propulsion all utilize common consumables (oxygen, hydrogen, and water) that need to be transferred and stored, common processing, storage, and transfer technologies, systems, and operations are possible. While a surface system-level development approach with ISRU that crosses multiple system ‘control volumes’ will require greater coordination at the start and may require more and integrated testing than individual system/element development, it can lead to reduced total development and operational risk, mass, power, and cost, while potentially minimizing logistical needs and increase flexibility in recovering from hardware failure.

Figure 1. Lunar surface system element connectivity

IV. ISRU Technology and System Development Unlike the United States Apollo Program, the goal and purpose of the next human missions to the Moon will not

be brief science and exploration visits to the lunar surface by a single nation, but missions involving multiple nations/space agencies with crews exploring wide regions of the lunar surface and staying for increasingly longer periods of time until a permanent presence is achieved. Apollo experience reminds developers and mission planners that hardware must operate under extremely harsh environmental and abrasive conditions and every kilogram of mass and payload must be critical to achieve the mission’s objectives due to the difficulty and cost of reaching the lunar surface. Experience from the ISS reminds developers and mission planners that integration of all hardware must be designed and planned from the start of the program, operations and evolution of capabilities on a continuous basis are important, and long-term life-cycle costs and logistical needs are equally or more important than minimizing early development and test costs.

In 2005, NASA initiated the Exploration Technology Development Program (ETDP) to develop technologies and systems in 23 project areas critical for enabling a sustained human exploration program beyond low Earth orbit based on recommendations from the Aldridge Report, critical areas identified by the Exploration Systems Architecture Study (ESAS), and by external panels. These 23 Technology project areas were divided between three main categories: crewed systems, vehicle systems, and surface systems. The 23 project areas have changed slightly over time through combining areas, deleting areas, and adding new project areas as the lunar architecture has matured such that today there are now 22 Technology project areas. In-Situ Resource Utilization (ISRU) is one of the 22 Technology project areas in ETDP.

The ISRU Project involves multiple NASA centers, each contributing their unique expertise to the development of this new technology area. The work is broken down into distinct elements, shown in Figure 2, that meet both the desired ISRU lunar architecture integration attributes as well as the time phased needs for the future human lunar Outpost. Technology and subsystem development is performed under four (4) primary technology areas: Regolith Excavation, Handling, & Transport, Oxygen Extraction from Regolith, In-Situ Water/Fuel Production, and In-Situ Construction. Because ISRU has never been demonstrated before and there is tremendous uncertainty in whether water/ice exists in the permanently shadowed craters at the lunar poles, the ISRU Project also initiated development of potential precursor hardware and experiments under ISRU Precursor Activities. For ISRU technologies and systems to be implemented in a lunar surface system architecture, subsystems must be integrated and tested in end-to-end operations within the ISRU project as well as with other technology and system development areas. This integration and testing is performed under ISRU Integrated System Demonstration. Lastly, the ISRU Development Support area is placed in between the technology and demonstration elements because this area supports both the technology development and the field demonstrations.

Explosives

Thermal Energy

Surface & Fuel Cell

Power Generation

Altair Propulsion

Environmental Control & Life

Support System (ECLSS)

Residual PropellantsPurge gas/tank pressurant

Propellant (O2 or O2/fuel)

Fuel cell reagents (O2 and fuel)

InIn--SituSituResourceResourceUtilizationUtilization

(ISRU)(ISRU)

Fuel cell, water processing, &

CFM technologies common with

ISRU

ECLSS technologycommon with ISRU

Gas for pneumatic systems

Explosives

Materials for concrete & metal structures

Hydrocarbons for plastics

O2, H2O and N2/Ar for Habitat & EVA suits

Science Activities

Water from fuel cell

Gas for drills & hardware

N2 and/or Ar for science instruments

CFM technology common

with ISRU

Defines propellant options & propulsion capabilities

Defines level of closed-loop ECLSS required

Defines surface power needs and fuel cell reagents

Defines resource excavation & transportation

capabilities

Surface Mobility

Construction & Manufacturing

Extra Vehicular Activity (EVA)

O2, H2O and N2/Ar for Rover & EVA suits

Defines surface exploration capabilities

CO2 for dust cleaningWater and carbon waste from ECLSS

Explosives

Thermal Energy

Surface & Fuel Cell

Power Generation

Altair Propulsion

Environmental Control & Life

Support System (ECLSS)

Residual PropellantsPurge gas/tank pressurant

Propellant (O2 or O2/fuel)

Fuel cell reagents (O2 and fuel)

InIn--SituSituResourceResourceUtilizationUtilization

(ISRU)(ISRU)

InIn--SituSituResourceResourceUtilizationUtilization

(ISRU)(ISRU)

Fuel cell, water processing, &

CFM technologies common with

ISRU

ECLSS technologycommon with ISRU

Gas for pneumatic systems

Explosives

Materials for concrete & metal structures

Hydrocarbons for plastics

O2, H2O and N2/Ar for Habitat & EVA suits

Science Activities

Water from fuel cell

Gas for drills & hardware

N2 and/or Ar for science instruments

CFM technology common

with ISRU

Defines propellant options & propulsion capabilities

Defines level of closed-loop ECLSS required

Defines surface power needs and fuel cell reagents

Defines resource excavation & transportation

capabilities

Surface Mobility

Construction & Manufacturing

Extra Vehicular Activity (EVA)

O2, H2O and N2/Ar for Rover & EVA suits

Defines surface exploration capabilities

CO2 for dust cleaningWater and carbon waste from ECLSS

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Figure 2. ISRU Project Work Breakdown Structure

A. Regolith Excavation, Handling, and Transport Based on lunar architecture studies performed to date, there are five (5) possible regolith excavation, material

handling, and regolith transport needs that have been identified for a human lunar Outpost: (i) Excavation for oxygen production, (ii) Excavation and material handling for landing pad and berm fabrication, (iii) Excavation for Outpost habitat protection (ex. radiation and micrometeoroids), (iv) Excavation for Outpost element emplacement (ex. Nuclear reactor burial), and (v) Excavation for Science (ex. Trenching for stratigraphy evaluation). The most important identified to date is regolith excavation and transport for oxygen production, since this is the first step in making oxygen on the Moon. While the term ‘excavation’ brings to mind large and heavy machines and large mining sites, this is not the case for what is required to support early ISRU oxygen production rates for the Outpost of 1 to 2 metric tons of oxygen per year. However, when you consider the density of regolith and the fact that a polar location will allow you to operate for at least 70% of the year (estimated 80% availability per year not including Sep. and Oct. at rim of Shackleton crater, Ref 3), the lowest yield extraction process would only need to excavate a soccer field to a depth of less than 1 cm per year of operation. With higher yield extraction processes, the excavation area could be reduced to the size of a basketball court!

The relatively small surface area combined with the fact that the top several centimeters of lunar regolith are loosely consolidated means that large dedicated excavators will not be required for this task alone. However, even if the excavators are not large or require a lot of power to support oxygen extraction from regolith, there are other more difficult excavation tasks to consider and significant environment and design challenges that must be overcome to successfully operate for years on the lunar surface. These challenges include abrasion and wear from lunar regolith, excavation force prediction for granular and highly compacted material, regolith granular flow under vacuum and 1/6-gravity conditions, and long-duration autonomous operations with little or no maintenance under lunar conditions. In order to understand how to design and build excavators for the Moon, a multifaceted approach is utilized which includes regolith behavior and excavation simulant modeling, environment simulation and controlled laboratory testing, design and fabrication, and field testing.

Excavating the loose upper few centimeters of the lunar surface is essentially a granular media flow problem, both for digging and dumping. So one challenge for lunar design and operations is to minimize the flow resistance forces and the resulting reaction forces on the vehicle. Minimizing these forces is important in 1/6-g as the rover’s wheels are not held as tightly to the surface as they would be on Earth, and rover mass still needs to be minimized to keep launch mass down. Current terrestrial engineering practices for granular flow process design utilizes particle property and bulk-material property measurements (Ref. 4). The ISRU Project uses these practices as a starting point, but because the lunar regolith has very different particle properties from terrestrial soil and vacuum can change particle flow behavior compared to flow in air, the differences must be accounted for. Lunar simulants developed and produced in the past mostly mimicked chemical/mineral composition but poorly mimicked the abrasive, irregular shape physical particle characteristics due to the manufacturing technique. The particle differences between actual and simulated lunar regolith lead to very different flow characteristics. Therefore work is

Regolith Excavation &

Transport

Regolith Char. & Modeling

Soil Prep. & Controlled Testing

Excavation Hardware – O2

Production

Excavation Hardware – Site

Preparation

Oxygen Extraction

from Regolith

ROxygen (H2 Reduction)

PILOT (H2 & CH4Reduction -

LMA/Orbitec)

Electrowinning

ISRU Precursor Activities

RESOLVE (Resource & O2

Demo)

Resource Prospecting & Site Characterization

ISRU Development

Support

System & Element Modeling

Regolith Simulant Eval., Dev., & Production

ISRU Integrated System

Demonstration

ISRU Facility & Analog Site

Development

OPTIMA (end-to-end O2

Production)

Landing Site Prep. (LANCE-

Chariot)

Develop Full Scale Hardware to Outpost Requirements

Develop Hardware/Software for Preparation of ISRU

Deployment

Focused Support for Hardware Development

Integrate Hardware to Demonstrate

Capabilities

Hardware Flow

Design & Operation

Coordination

Evaluate Competing

Technologies, Standardize Feedstock,

& Ensure Test Capabilities

Exist

Solar Concentrators

Rover-based ISRU Precursor(RESOLVE-CMU)

In-Situ Fuel/Water Production

Trash/Waste Processing for

H2O & CH4

H2 Scavenging & Conversion to H2O

Surface Stabilization

SILO (Beneficiation-Pneumatic Lift)

= Work performed in FY06 to FY08

= Work proposed for FY09+

Key

OVEN – Subscale O2 Demo

Precursor Lander Demo

Vacuum & 1/6g Applicability Tests

In-Situ Construction

In-situ Energy Construction

In-Situ Structure Construction

Hdwr Scavenging & Feedstock Production

Other O2Extraction Concepts

Regolith Excavation &

Transport

Regolith Char. & Modeling

Soil Prep. & Controlled Testing

Excavation Hardware – O2

Production

Excavation Hardware – Site

Preparation

Oxygen Extraction

from Regolith

ROxygen (H2 Reduction)

PILOT (H2 & CH4Reduction -

LMA/Orbitec)

Electrowinning

ISRU Precursor Activities

RESOLVE (Resource & O2

Demo)

Resource Prospecting & Site Characterization

ISRU Development

Support

System & Element Modeling

Regolith Simulant Eval., Dev., & Production

ISRU Integrated System

Demonstration

ISRU Facility & Analog Site

Development

OPTIMA (end-to-end O2

Production)

Landing Site Prep. (LANCE-

Chariot)

Develop Full Scale Hardware to Outpost Requirements

Develop Hardware/Software for Preparation of ISRU

Deployment

Focused Support for Hardware Development

Integrate Hardware to Demonstrate

Capabilities

Hardware Flow

Design & Operation

Coordination

Evaluate Competing

Technologies, Standardize Feedstock,

& Ensure Test Capabilities

Exist

Solar Concentrators

Rover-based ISRU Precursor(RESOLVE-CMU)

In-Situ Fuel/Water Production

Trash/Waste Processing for

H2O & CH4

H2 Scavenging & Conversion to H2O

Surface Stabilization

SILO (Beneficiation-Pneumatic Lift)

= Work performed in FY06 to FY08

= Work proposed for FY09+

Key

OVEN – Subscale O2 Demo

Precursor Lander Demo

Vacuum & 1/6g Applicability Tests

In-Situ Construction

In-situ Energy Construction

In-Situ Structure Construction

Hdwr Scavenging & Feedstock Production

Other O2Extraction Concepts

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underway led by the Marshall Space Flight Center (MSFC) to develop better simulants (under ISRU Development Support) and to perform laboratory testing to characterize the difference in the behavior of different simulants so that models can be developed that will better predict lunar regolith flow and excavation behavior. The methods being used include both Discrete Element Modeling and the Mesh Free Method. Both efforts are making progress, but much work remains to adapt them to the lunar environment.

Modeling granular behavior and flow of irregular-shaped, varied-size, and multiple mineral and glass particles under vacuum and 1/6 gravity is extremely complex. Therefore, the models themselves have limited value if there is no way to validate their predictions. As such, controlled laboratory test capabilities utilizing prepared soil bins are being developed and utilized (Ref. 5). These tests allow designers to test model predictions and in an iterative process allow both the computer models and the excavation implements being tested to be improved. The laboratory tests range in size from benchtop soil bins (see Figure 3a) to large bins that can accommodate full scale implement testing. Before testing, the soil bins need to be prepared such that the density and compaction are as representative of the lunar surface as possible. At this time, there is not a facility that will allow this type of implement testing to be performed under vacuum and/or 1/6 g conditions. However, to begin to correlate lunar excavation performance with terrestrial testing, data from lunar excavation performed during the Surveyor program of the 1960’s is being used and recreated. Two Surveyor spacecraft included a simple arm/scoop payload, and the data for one of the soil scoop experiments was reported in the literature. While motor torque data of lunar operations was obtained, actual drawings of the scoop were not available. Therefore, personnel at the Glenn Research Center (GRC) borrowed the Surveyor 3 scoop returned to Earth by the Apollo 12 astronauts from the Kansas Cosmosphere and Space Center and made dimensional measurements to build a replica, Then the Apollo experiment was repeated using a prepared soil bin with lunar simulant (see Figure 3b). While not performed in either vacuum or 1/6-g, the tests still provided confidence that our laboratory tests and modeling efforts are anchored by actual lunar measurements.

While the excavation needs to support 1 MT of oxygen per year are not extensive, the actual size of the mobility system available will be determined by other numerous factors such as how often can it be used to perform excavation tasks, what other excavation or regolith movement tasks need to be performed that are more difficult, how far is the excavation site from the regolith processing unit, and are multiple platforms required to ensure reliability. At present NASA’s lunar exploration architecture includes two fairly large mobility platforms, one for crew mobility called ‘Chariot’ and the other for payload off-loading and transportation tasks called ‘ATHLETE’. However, smaller dedicated vehicles may be more appropriate for the excavation for oxygen task to due the relatively small payload needed and the potential for limited availability of the larger mobility units. Also, because there are numerous terrestrial excavation methods to consider, an extensive trade study was performed evaluating different excavation concepts to help focus future design efforts (Ref. 6). Until a final decision is made, the ISRU Project is evaluating both large and small mobility platform design and operation performance with the ETDP Human Robotic Systems (HRS) Project.

As a start, a small excavation concept vehicle called ‘Cratos’ was built and has been put through a set of controlled laboratory tests at GRC (see Figure 4a) (Ref. 7). Cratos weighs about 80 kg and is a little under a meter square and can deliver an average load of 23 kg of regolith per trip to the oxygen production system’s regolith hopper. Assuming the lowest yield oxygen extraction process (hydrogen reduction which is ~1% by mass), it will take 100,000 kg of regolith to produce the 1000 kg of oxygen require by the architecture per year. Based on Cratos’ average load of 23 kg, it would only have to make twelve excavation runs per day to harvest the necessary regolith. This can easily be accomplished by a vehicle like Cratos in just a few hours per day.

Besides modeling, and performing soil bin and laboratory testing on concepts for excavation and regolith delivery for oxygen extraction, work is also underway in the area of understanding and developing site preparation hardware and techniques. As depicted in Table 1, substantially more lunar regolith must be moved and handled to clear areas for landing pads and roads and build berms for landing plume mitigation than is required for supporting

Figure 3a. BenchtopSoil Bin with Blade Figure 3b. Surveyor Scoop Replica

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oxygen extraction from regolith. Also, these tasks may require excavation below the loosely consolidated top material and the removal and handling of rocks. ISRU Project personnel at the Kennedy Space Center (KSC) in collaboration with the HRS Project developed a “bulldozer” blade, called LANCE (Lunar Attachement Node for Construction and Excavation) that could be used to move large amounts of soil and be attached to the HRS ‘Chariot’ crew rover. This proof of concept project is not intended to be a final design for the architecture, but rather an opportunity for two ETDP projects to begin to work together and understand the integration and operation issues for excavation implements attached to a mobility platform. Tests with this device have been performed with varying degrees of success at different locations and soil conditions. As with any terrestrial bulldozer, the operator’s skill has an impact on the performance of the vehicle. So while early tests had some problems with the wheel slippage and the vehicle bogging down, later tests at Moses Lake, Washington had great success using LANCE to build a berm (Figure 4b).

Figure 4a. Cratos vehicle delivering sand Figure 4b. LANCE on Chariot building a berm at Moses Lake Future work in the area of Regolith Excavation, Handling, and Material Transport involves continuation in all

main areas identified. Work on modeling and laboratory testing will continue with emphasis on performing further blade/excavation performance measurements and regolith flow behavior under 1/6-g parabolic flight conditions. Work on regolith excavation and transportation for oxygen extraction of regolith will continue with the design and fabrication of hardware for both a new small rover from the HRS project as well as for the crew Chariot mobility platform. Lastly, work on site preparation will continue with enhancements to the LANCE blade and attachment mechanism.

B. Oxygen Extraction from Regolith Oxygen production from lunar regolith has been studied for over 40 years and numerous processes have been

proposed and evaluated (Ref. 8). In fact, oxygen extraction from lunar regolith was proposed even before humans landed on the Moon; Sanders Rosenberg published an article in 1966 describing the use of the Carbothermal reduction method to produce lunar oxygen (Ref. 9). In 1988 a NASA sponsored report from Eagle Engineering Inc. detailed thirteen different processes that could be used to extract oxygen from regolith. Based on past oxygen extraction process evaluation studies and small scale laboratory experiments performed over the last 40 years, the ISRU Project chose three processes for detailed development: Hydrogen (H2) Reduction, Carbothermal Reduction, and Molten Oxide Electrolysis (MOE). Each of these processes have strengths and weaknesses with respect to extraction efficiency, complexity, and development risk.

Of the three processes, H2 Reduction is the simplest and least efficient. When regolith is heated between 800 and 1000 °C and mixed with hydrogen gas, iron oxide-bearing minerals and glasses in the lunar regolith, such as ilmenite (FeTiO3) are reduced to produce water vapor. The water is condensed and electrolyzed to produce oxygen and to regenerate the reactant hydrogen for subsequent processing. While this is not the most efficient process because the amount of iron-oxide in lunar regolith is fairly low (5 to 15%), it does have the advantage of lower temperatures that keep the lunar regolith in granular form, which greatly simplifies material handling. The ISRU Project initiated development of two Outpost-scale H2 Reduction systems to allow comparison of different approaches for regolith feed and removal, regolith mixing and heating with H2, water vapor removal and collection, water electrolysis, and oxygen storage. One concept being developed by Lockheed Martin Astronautics (LMA) under a contract, called ‘PILOT’ for Precursor ISRU Lunar Oxygen Testbed, uses a “cement mixer” approach with a tumbling reactor to mix and heat the regolith. The second concept, under development led by NASA Johnson Space Center (JSC) called ‘ROxygen’, uses a vertical reactor with both fluidization and an internal auger to stir and heat the regolith. The purpose of this ‘1st generation’ hardware is not to build a system that meets flight mass or power requirements, but rather this is intended to be the first end-to-end integration and test of excavation, oxygen

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production, and product storage in an automated system configuration. The results of these tests will guide the down selection of technical approaches and move towards ever increasing flight-like designs and capabilities. Computer Aided Design (CAD) drawings of each end-to-end system are shown in Figure 5a and 5b.

The Carbothermal Reduction process is a more efficient oxygen production technique compared to H2 Reduction because not only will it reduce the iron oxide but also some of the silicates found abundantly in the lunar regolith. However, the process requires much high temperatures (1800 °C) with the regolith becoming molten. When methane is introduced into the melt chamber the methane reacts with the molten regolith and carbon monoxide is produced. The carbon monoxide is fed with hydrogen into a methanation reactor where the methane is regenerated and water is produced. The water is electrolyzed to recover the hydrogen and produce oxygen. This process can achieve efficiencies of 14% extraction of oxygen by mass or greater, but the main challenges of this approach are delivering the energy needed to form the melt and developing techniques to deal with molten materials. Orbital Technologies Incorporated (Orbitec) is currently developing a Carbothermal Reduction system under contract to NASA, and significant process has been made toward tackling these challenges (Ref. 10). The Orbitec Carbothermal Reduction system design utilizes concentrated solar light channeled through fiber optic cables (under development by Physical Science Inc through Phase II and Phase III Small Business Innovative Research contracts) to melt the regolith and uses an ingenious concept using the regolith’s inherent insulation properties to contain the localized melt crucibles (see Figure 6a and 6b). Once the reduction reaction is complete, the melts are allowed to cool, and once solid can be removed from the regolith bed with an automatic rake mechanism, thereby avoiding reactor wall material and molten material handling issues. The rake is then used to smooth the bed and prepare it for the next batch of oxygen production. The combined PSI solar concentrator system with Orbitec Carbothermal Reactor and NASA water electrolysis and oxygen storage system will be integrated and test in 2009.

The final oxygen production technology under development, Molten Oxide Electrolysis (MOE ), is at the lower

end of the technology readiness scale, but holds sufficient promise to warrant investment. It is extremely attractive

Gas Handling System

Regolith Loading System to Fill Regolith Hopper

Regolith Hopper

Carbothermal ReductionChamber and Regolith

Handling System

Processed Regolith Exit Valve Assembly

Figure 6a. Orbitec CarbothermalReduction System

Figure 6b. PSI Solar Concentrator Breadboard

Figure 5a. NASA ROxygen H2Reduction System

Figure 5b. LMA PILOT H2 Reduction System

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because it allows both high oxygen yield and pure metals will precipitate out of the melt as the oxygen is released which can be separated and used for future fabrication and construction tasks. This process may also allow continuous processing instead of batch processing with constant thermal cycling for the hydrogen reduction and carbothermal processes. Many challenges remain, but significant progress has been made by the Massachusetts Institute of Technology (MIT) towards one of the most significant challenges, developing an inert anode. The test cell at MIT, shown in operation in Figure 7a, has lead to clear progress in anode materials and the direct measurement of pure oxygen being produced at the anode. Detailed discussion of this work is not possible at this time to protect the innovator’s intellectual property rights, but full details will be disclosed when patent protection is in place. The other big challenge of MOE, molten materials handling and continuous feed/removal, is under design and development at Ohio State University. The concept under development will use the evolved pressure of the oxygen gas to force molten material out of the bottom of the reactor and into molds where ingots of metal will be formed (see Figure 7b). This concept will be built and tested during the coming year. If successful, a breadboard of an end-to-end MOE system may be within reach by 2010.

C. ISRU Precursor Hardware As mentioned previously, since ISRU has not yet been demonstrated, the LAT Phase I study recommended that

ISRU should not be in the ‘critical path’ to successful implementation of a lunar Outpost. To that end, the ISRU Project initiated a phased technology and system development approach that included development of precursor hardware development to determine the type, amount, and location of possible resources of interest (including water/ice) and to perform proof-of-concept and risk reduction demonstrations if a robotic mission opportunity became available. To meet this objective, the Regolith & Environment Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) prototype experiment was initiated in 2005. RESOLVE is a flexible package that can be used to look at lunar volatiles in the regolith, look for water/ice in the permanently shadowed crater, and perform a subscale proof-of-concept H2 reduction of regolith oxygen production demonstration (Ref. 11). It consists of a one meter coring drill that acquires subsurface regolith. The core sample is transferred, divided into 4 individual segments, and each segment is crushed and examined for volatiles with a gas chromatograph (GC). After crushing, the regolith is transferred and heated in an oven in a step-wise manner to once again monitor for the evolution of volatiles with the GC (Ref. 12). The GC was designed to sense both solar wind volatiles like, hydrogen, carbon, nitrogen, etc. as well as detect compounds like water or ammonia that might have been trapped in the permanently shadowed craters from comets (Ref. 13). Once the volatile characterization portion of the experiment is complete, the oven’s temperature is raised to over 800 °C and H2 gas is introduced to perform the H2 Reduction reaction described previously. The water produced in this reaction is captured in water beds so that the water can first be quantified, and then electrolyzed. A 1st generation engineering breadboard unit (EBU) was built and laboratory tests were performed in 2007 to demonstrate the feasibility and design features of the hardware required to perform these tasks (see Figure 8a). Once this was completed, it was determined that a 2nd generation EBU was needed to evaluate and demonstrate both the end-to-end operations required for a robotic mission as well as the packaging required to fit the hardware onto a rover (see Figure 8b). Discussions were held with the ETDP HRS project on how best to begin integration and coordination of ISRU and HRS hardware and systems to meet future lunar robotic and human exploration needs. It was decided that the HRS project would provide a rover specifically designed to carry RESOLVE and its drill through a contract with Carnegie Mellon University (CMU) as the first step in linking the ISRU and HRS ETDP projects. In December, 2007, the RESOLVE drill was successfully integrated and operated

Figure 7a. MIT MOE Reactor Figure 7b. OSU Feed/Removal Subsystem

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on the CMU “Scarab” rover, and the entire RESOLVE package is schedule to be integrated onto the Scarab rover tested at a lunar analog site on Hawaii in November of 2008.

D. ISRU Development Support Even though ISRU, and particularly oxygen extraction from lunar regolith, has been studied for over 40 years,

very little work beyond laboratory experiments had been performed before the ISRU Project was established. It became quickly apparent that to support lunar architecture studies and initiate the development of large scale ISRU systems, three support efforts were required: One, develop new analytical tools and models to estimate the mass, volume, and power of ISRU components and systems; Two, develop new simulants that better represented the physical and mineral/chemical attributes of actual lunar regolith, particularly for the lunar polar region; and Three, define and begin to address the need for lunar environment simulation capabilities that would support ISRU hardware testing under lunar vacuum, thermal, solar, and most importantly dust/regolith conditions. While work has progressed in all three areas, the design, development, and manufacturing of new lunar simulants will have the greatest impact on not only ISRU development but all lunar surface system technology and element system development as well.

Because supplies of the previous lunar mare simulant JSC-1 were almost depleted and the ISRU project needed simulants right away to begin development tests, a new supply of JSC-1 was created as a bridge until new polar highland simulants were available. Because actual lunar regolith contain glasses, agglutinates, nano-phase iron, solar wind volatiles, and minerals and mineral phases that could impact surface system operations, careful consideration of how ‘realistic’ the new simulants need to be verses the cost of producing them was required. It was also recognized that other simulants have been developed or could be developed by other organizations or industry, so a process to evaluate and standardize simulant characterization was deemed necessary. Led by NASA MSFC, the approach taken to begin development of the new simulants was to: (i) Assess and understand users’ needs, applications, quantities, and schedule, (ii) Define and develop simulant standards based on Apollo core samples, (iii) Define methods of measure for simulants (past, present, future), (iv) Evaluate simulant constituent production methods, and (v) Produce ‘base’ simulants and ‘tailored’ simulant blends at required quantities based on customer needs. Accomplishments to date in simulant development include defining and developing Figures of Merit (FoMs) to be used in quantitatively comparing all lunar simulants to reference Apollo lunar regolith samples for highland and mare soils, acquiring large amounts of Apollo lunar regolith property data for use in FoMs, and development of a new series of Lunar Highland Type Prototype Simulants (NU-LHT - NASA/USGS Lunar Highland Type Simulant) in collaboration with the U.S. Geological Survey (USGS) and distributed to users.

V. ISRU and Lunar Surface System Integration and Testing The inclusion of ISRU in the lunar surface system architecture opens up possibilities for interaction and

integration that would not otherwise exist. In particular the ability to produce and regenerate mission critical consumables such as oxygen, water, and fuel for crew, power, and propulsion can change surface element designs, technologies, and operations. Because ISRU is only beneficial for exploration if other elements utilize the products and capabilities available from ISRU, early design and operation interaction between ISRU and other surface elements is required. Also, because other ETDP project areas are responsible for development of critical ISRU subsystems, ISRU development must be highly coordinated with other ETDP development areas to ensure capabilities and operations can be demonstrated at the architecture-level before critical decision milestones occur. The other ETDP projects that the ISRU Project must interact and integrate requirements and hardware to be successful are:

Exploration Life Support (ECLSS)

Figure 8a. 1st Generation RESOLVE EBU Figure 8b. 2nd Gen. RESOLVE EBU

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Extravehicular Activity (EVA) Human Robotic Systems - surface mobility (HRS) Energy Storage and Power Systems - batteries and fuel cells (EPS) Cryogenic Fluid Management Systems (CFM) Thermal Control for Surface Systems (TCS) Other Technology project areas in ETDP, such as Dust Mitigation, Structures, Materials, & Mechanisms

(SMM), Autonomy for Operations (AO), and Advanced Environmental Monitoring & Control are also important since they provide cross-cutting support for many surface system technology development areas.

To ensure that surface elements understand and can quantify the benefits of ISRU products and capabilities, and to ensure that ISRU development is aligned with other ETDP surface system development areas, the ETDP ISRU project has initiated lunar analog field tests with other ETDP surface project areas using requirements and capabilities identified and defined in human lunar architecture studies. Why initiate and perform lunar analog field tests? For one, it matures technologies and systems in a timely and structured manner by requiring decisions to be made on design options and interfaces so that schedules can be maintained. Performing a series of field tests over time, allows systems and capabilities to evolve and become more optimized by applying lessons learned and new technologies with each successive test. Also, by using requirements and capabilities defined from human lunar architecture studies, the technologies and systems developed and demonstrated are at a scale relevant to future Outpost missions. Secondly, by performing demonstrations with other ETDP development areas and external participants, development requirements, schedules, priorities, and funding can be coordinated to ensure hardware is integrated and tested before critical LSS decision milestones occur. A surface architecture level design-build-test cycle is now possible. Thirdly, lunar surface system concepts can be evaluated under applicable conditions, and important open architecture attributes such as modularity, commonality, interconnection, maintainability, and growth can be demonstrated and evolved. The impact of life-cycle, mean-time-between-failure, and logistics and replacement considerations can be assessed at a lunar surface architecture level. Lastly, operations and procedures associated with integrated surface system capabilities such as end-to-end oxygen extraction from regolith, or surface consumable regeneration and transfer for mobile fuel cell power systems can be evaluated and different techniques and technologies, such as gas vs liquid oxygen storage and transfer, can be assessed under similar conditions to provide a fair apples-to-apples comparison of strengths and weaknesses.

Besides the concrete reasons already stated for performing lunar analog field tests with multiple surface system and element development areas, there are several intrinsic benefits that should also be recognized. The greatest intrinsic value is that it provides opportunities for partnerships to be initiated to provide critical systems or elements can be integrated and demonstrated when available. This in turn promotes early establishment of data and design exchange and interaction and communication protocols well before flight hardware development is initiated so that International Traffic in Arms Regulations (ITAR) concerns can be addressed and alleviated for international partners. Lastly, performing analog field tests and demonstrations provide excellent opportunities for education and public outreach. They provide early and visual efforts to the public of NASA, international, and commercial interest in human lunar exploration.

As a first step, the ISRU and HRS Projects planned two joint field demonstrations efforts in 2008. The first was completed in June at Moses Lake in Washington State with the purpose of demonstrating site preparation capabilities of possible interest to future Outpost missions. The second field demonstration is currently scheduled to occur in November at a lunar analog site on Mauna Kea in Hawaii with three main objectives: (i) Demonstrate Outpost-scale end-to-end production and storage of oxygen from lunar regolith, (ii) Demonstrate mobile resource characterization and subscale oxygen production, and (iii) Evaluate the partnership with the Pacific International Space Center for Exploration Systems (PISCES).

A. Outpost Site Preparation Because establishing and operating a lunar Outpost will require multiple missions to the same location, the

terrain and long-term operation in the lunar dust environment raises several concerns that may need to be mitigated. For example, Apollo 12 landing near the Surveyor 3 spacecraft showed that dust projected by the Apollo Lunar Module rocket exhaust plume while landing caused abrasion and damage to the Surveyor 3 surface (Ref. 14). It is not inconceivable that the higher landing thrust of the proposed NASA Altair lander would cause even more damage to Outpost habitat and power systems exposed to this dusty plume. To mitigate this hazard, fabrication of regolith berms or surface stabilization may be required. Also, because multiple landings will need to be performed, areas near the Outpost may need to be cleared of rock hazards so that landings can be performed with the minimum of risk. As a first step in demonstrating capabilities that may be needed to perform these tasks, the ETDP ISRU project

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built a composite blade for attachment on the crew surface rover called “Chariot” designed and build by the Human-Robotic System (HRS) project. Area clearing, leveling, and small berm fabrication was demonstrated in June, 2008 at Moses Lake under crewed and remote operation conditions (see Figure 4b).

B. Outpost-Scale end-to-end production of Oxygen from lunar Regolith The ability to demonstrate the extraction and utilization of space resources for future human exploration is a

major objective and rationale for NASA’s human exploration of the Moon. To begin to build confidence in ISRU capabilities, the ISRU Project initiated the Outpost Precursor Testbed for ISRU and Modular Architecture (OPTIMA) effort. OPTIMA involves first demonstrating the feasibility of end-to-end oxygen extraction from regolith as well as initiating work on creating a modular architecture to support future development efforts. With this in mind, development of two complete systems utilizing different technologies or techniques were initiated but with common requirements and common interfaces between the main units/modules for excavation, regolith processing, gas/water cleanup, water electrolysis, and oxygen storage. Each system is designed such that modules and excavators could be exchanged if desired as a start for creating a modular and expandable surface architecture. Hardware for both end-to-end systems is shown in Figures 5a and 5b will be tested in Hawaii in November, 2008. Besides the hardware, the OPTIMA field test activities will help better understand operations associated with ISRU oxygen production.

C. Mobile Resource Characterization and Subscale Oxygen Production One reason for establishing a lunar Outpost at the lunar poles is the potential for water/ice or hydrogen-bearing

volatiles that may be present in or near the permanently shadowed craters at the lunar poles. While the RESOLVE experiment allowed the ISRU Project to develop capabilities and hardware of interest for potential future lunar missions, on its own, it does not provide all the resource characterization instruments needed nor a method of delivery to multiple sites of interest. Discussions were held with the ETDP HRS project on how best to begin integration and coordination of ISRU and HRS hardware and systems to meet future lunar robotic and human exploration needs. It was decided that the HRS project would provide a rover specifically designed to carry RESOLVE and its drill through a contract with Carnegie Mellon University (CMU) as the first step in linking the ISRU and HRS ETDP projects. In December, 2007, the RESOLVE drill was successfully integrated and operated on the CMU “Scarab” rover (see Figure 9a), and the entire RESOLVE package is schedule to be integrated onto the Scarab rover tested at a lunar analog site on Hawaii in November of 2008 (see Figure 9b).

D. Future Activities and Partnership Opportunities Now that the NASA ETDP ISRU and HRS projects have initiated joint development and field test activities,

plans are being formulated to evolve these efforts and include other ETDP development areas and external partners in future field tests. Items of interest for future development and demonstration include, but are not limited to, the following:

Carbothermal-reduction for regolith reactor and solar concentrator unit High pressure water electrolysis module for fuel cell reactant regeneration, EVA tank refill, and ISRU

Figure 9a. RESOLVE Drill on Scarab Rover Figure 9b. RESOLVE on Scarab Rover

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Standardized fluid/electrical interfaces, and high pressure oxygen and liquid oxygen storage and transfer for fuel cell and ISRU applications.

Integrated thermal management and solar power for ISRU oxygen production from regolith operations Human-rover (“Chariot”) based excavation and regolith delivery Enhanced small rover based excavation and regolith delivery with size and mineral beneficiation and

autonomous operation Enhanced site preparation and Outpost emplacement implements

VI. CONCLUSIONS In-Situ Resource Utilization is a concept that will revolutionize human space exploration. NASA studies have

shown that ISRU can provide significant mass, cost, and risk reduction benefits for human lunar exploration and Outpost development through production of mission critical consumables, enhanced radiation protection, and site preparation and dust-landing hazard mitigation. To achieve these benefits, NASA’s ISRU project has a technology development program underway has already demonstrated excavation and material transportation, the production of oxygen from regolith using three different methods, and the ability to characterize local resources and perform subscale ISRU demonstrations. The ISRU Project has also begun a series of integrated system demonstrations that will lead to a complete ISRU system in time for the 2014 Preliminary Design Review for Lunar Surface Systems as well as reduce the risk and costs of integrating multiple lunar surface system technologies and elements.

References

1. Lavoie, Tony, “Lunar Architecture Overview”, Implementing the Vision, 2nd Space Exploration Conference, Houston, TX., Dec. 6, 2006

2. Sanders, Gerald, and Larson, William, “In-Situ Resource Utilization (ISRU) & Integration Into Outpost Surface Systems”, Final ISRU Focus Element Report, Lunar Architecture Team Phase II, August 24, 2007

3. Linne, Diane, Freeh, Josh, and Abercrombie, Andrew, “Commonality of Electrolysis Sub-Systems for ISRU, Power, and Life Support for a Lunar Outpost”, presented at Space Technology & Applications International Forum - STAIF 2008, Albuquerque, NM, February 11 - 14, 2007

4. Wilkinson, Allen, & Degennaro, Alfred, “Digging and pushing lunar regolith: Classical soil mechanics and the forces needed for excavation and traction”. Journal of Terramechanics 44.2. pgs.133-152. . 2007

5. Bucek, M., Agui, J.H., Zeng, X., Wilkinson, R.A. "Experimental Measurements of Excavation Forces in Lunar Soil Test Beds," Earth and Space 2008 - 11th International Conference on Engineering, Science, Construction, and Operations in Challenging Environments, Long Beach, CA. March 2008.

6. Mueller, Robert P. & King, Robert H., "Trade Study of Excavation Tools and Equipment for Lunar Outpost Development and ISRU ", presented at Space Technology & Applications International Forum - STAIF 2008, Albuquerque, NM, February, 2008

7. Caruso J. J. , Greer L. C., John W. T., Spina D. C., Krasowski M. J., Abel P. B., Prokop N. F., Flatico J. M., Dr. Sacksteder K. R., Cratos: A Simple Low Power Excavation and Hauling System for Lunar Oxygen Production and General Excavation Tasks, 2007

8. Taylor, L.A., Carrier, W. D., “Oxygen Production On The Moon”, Resources of Near-Earth Space, Lewis, Mathews, & Guerrieri, Editors, Univ. Ariz. Press, Pg 69-108, 1993

9. Rosenberg, S.D., Guter, G.A., and Miller, F.E. “The On-Site Manufacture of Propellant Oxygen from Lunar Resources.” Aerospace Chemical Engineering, AiChE, Volume 62, Number 61, pp 228-234, 1966

10. Gustafson, R. and White, B., “Oxygen Production via Carbothermal Reduction of Lunar Regolith”, presented at Space Technology and Applications International Forum - STAIF 2008, Albuquerque, NM, February 11 - 14, 2007

11. Sanders, Gerald, et. al., “Regolith & Environment Science, and Oxygen & Lunar Volatile Extraction (RESOLVE) for Robotic Lunar Polar Lander Mission”, International Lunar Conference, Toronto, Canada, Sept., 2005.

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12. Kleinhenz, Julie E., Sacksteder, Kurt R., and Nayagam, Vedha, ” Lunar Resource Utilization: Development of a Reactor for Volatile Extraction from Regolith”, Aerospace Sciences Conference, Reno, NV. 2007

13. Lueck, Dale E., Captain, Janine E., Gibson, Tracy L, Peterson, Barbara V., and Berger Cristina M., “Selection, Development and Results for The RESOLVE Regolith Volatiles Characterization Analytical System”, Space Technology & Applications International Forum - STAIF 2008, Albuquerque, NM, February, 2008

14. Metzger, Philip, et. al, “Prediction and Mitigation of Plume-Induced Spray of Soil during Lunar Landings”, Lunar Architecture Team Phase I, Oct., 2006.