Commercial Lunar Propellant Perspectives - Hydrogen Production - o1 Indroduction

INTRODUCTION o1 - Propellant Production

For decades, humans have fantasized about living on the moon, but we haven't sent anyone there since 1972. So, how close are we to a moon base?

To the Memory of Dr. Spudis

Dr. Spudis earned his master’s degree from Brown University and his Ph.D. from Arizona State University in Geology with a focus on the Moon. His career included work at the US Geological Survey, NASA, John Hopkins University Applied Physics Laboratory, and the Lunar and Planetary Institute advocating for the exploration and the utilization of lunar resources. His work will continue to inspire and guide us all on our journey to the Moon.

“By going to the Moon we can learn how to extract what we need in space from what we find in space. Fundamentally that is a skill that any spacefaring civilization has to master. If you can learn to do that, you’ve got a skill that will allow you to go to Mars and beyond.”

Unified Geologic Map of the Moon

"People have always been fascinated by the moon and when we might return," said current USGS Director and former NASA astronaut Jim Reilly. “So, it’s wonderful to see USGS create a resource that can help NASA with their planning for future missions.”

The lunar map, called the “Unified Geologic Map of the Moon,” will serve as the definitive blueprint of the moon’s surface geology for future human missions and will be invaluable for the international scientific community, educators and the public-at-large. The digital map is available online now and shows the moon’s geology in incredible detail (1:5,000,000 scale).

Orthographic projections of the "Unified Geologic Map of the Moon" showing the geology of the Moon’s near side (left) and far side (right) with shaded topography from the Lunar Orbiter Laser Altimeter (LOLA). This geologic map is a synthesis of six Apollo-era regional geologic maps, updated based on data from recent satellite missions. It will serve as a reference for lunar science and future human missions to the Moon. Credit:

NASA/GSFC/USGS

Background and Need

In the same way that exploration of our planet required mankind to adapt and learn to use local resources varying by continent, region, and climate, so too will mankind learn to find, extract, and use local resources to continue our expansion and exploration of space. The need for this adaptation is driven by the stark contrast between the relatively small amount of material that can be launched from Earth, and the enormous volume and diversity of resources available in space. Commercialization of space resources, enhanced by Public-Private Partnerships (PPP)s, capital investments, and new business models, represents the future of resource extraction industries.

As capabilities in space continue to grow with the advancement of technology, strategic planning and prioritization of resource exploration, it is imperative to guide policy and commercial development of space-based natural resources. In-Situ Resource Utilization (ISRU) represents the near future of the space industry, enabling the efficient use of resources both on Earth and in space, as well as continued expansion and development of human presence outside of our planet.

Technologies developed and refined for ISRU will continue to deliver additional benefits to Earth-bound industries, as demonstrated by the ubiquity of modern technologies first developed for space exploration programs. Thus, ISRU is an important area for investment and rapid development in the near future.

The most pressing need for resources in space is that of fuel; transporting cargo and humans in space requires a vast amount of propellant, and launching the full mass of propellant needed for long-term space missions from the Earth’s surface places severe limitations on missions of all kinds. Thus, developing an architecture for prospecting, mining, processing, storing, and transporting fuel products in space is the first critical step to creating a sustainable space development strategy.

Between the abundance of resources available, relative proximity to the Earth, and decades of scientific study, the Moon presents an ideal objective for early-stage ISRU activities, providing a testing ground for the development of new methods and technologies as well as a platform for continued expansion to other planets and Near-Earth Objects (NEO)s.

Study Methodology

The following study represents the collaborative input from some 40 individuals across 25 organizations to identify the technical and economic feasibility of developing a lunar propellant production plant. Academic, private, and government institutions worked together to identify hardware solutions, quantify near term customers and demand, navigate financial obstacles, and to explore the new industries and scientific findings that would be unlocked by utilizing lunar water ice deposits.

It was discovered, that for nearly every major component of the lunar propellant architecture there was already organizations developing the technology and hardware required to meet those function. Figure 1 shows several of the participating organizations and the systems in which they are currently developing hardware solutions. Subsequent sections within this document will outline in detail the hardware solutions that these organizations bring to the table.

Figure 1: Lunar Propellant Architecture Participants

In order to approach the large task of defining a commercial lunar propellant architecture, tools from traditional systems engineering were implemented. As such, the study was initiated by performing a needs analysis. It was determined that several systems being invested in today by private and government organizations would greatly benefit from the utilization of propellant production at the Moon.

Each of these developing customers of a lunar propellant production plant were able to quantify their demand, which can be found in the “Demand” section of this document. Based on input from those customers, it was determined that there will be an early need for nearly 1,640 Metric Tons (MT) of propellant per year on the lunar surface.

With an established need for lunar propellant production, the functional requirements were defined. The functional requirements were captured in the creation of a functional flow diagram. The functional flow diagram identifies the system functions while tracing the flow of ice from its source in Permanently Shadowed Regions (PSR) on the Moon, through processing, and all the way to the end user as propellant.

At the highest level, the systems are outlined by the location in which it exists: the lunar surface, cislunar space, and Earth. In the case of Figure 2, the encompassing grey rectangle represents the lunar surface. The next level down represents the major systems: propellant processing, power, robotic services, communication/navigation, and the lunar mine. At the lowest level are the sub-system functional requirements (indicated by white boxes).

Figure 2: Functional Flow Diagram of Lunar Surface Operations

Similar in the approach to the lunar surface activities shown in Figure 2, the major systems and subsystems for cislunar and Earth operations that support the mine were also defined. Figure 3 shows the cislunar activities in the pale green rectangle and Earth activities in the pale blue rectangle. Included in the cislunar activities are in-space transportation, cryogenic storage, power, and communications/navigation. The extent of activities from the Earth’s surface were communication uplink and downlink.

A key feature to note in both Figure 2 and Figure 3 is that the flow of water into propellant is indicated by a series of bold arrows. In addition, each system begins with a green rounded box and ends with red rounded boxes. In Figure 2 and Figure 3, the red rounded boxes attached to the bolded arrows represent customers: one on the Moon, one in lunar orbit, and one in Low Earth Orbit (LEO).

Figure 3: Functional Flow Diagram of In-Space and Earth Operations

The functional flow diagram described above was collaboratively developed via teleconferences, emails, and discussions over the course of several months with Subject Matter Experts (SME)s. Once completed, the SME’s convened at United Launch Alliance’s (ULA)’s5 headquarters in Colorado on May 1, 2018 for the Commercial Lunar Propellant Architecture Workshop. During the workshop, SMEs reviewed each sub-system box of the functional flow diagram and applied hardware solutions to them.

Within each solution, they identified Technology Readiness Levels (TRL)s, mass, energy inputs and outputs, Recurring Cost (RC), Non-Recurring Cost (NRC), lifespan, power source, communication system, positioning and navigation, and a variety of other critical parameters. This report represents a summary and interpretation of those findings with authors writing sections based on their areas of expertise. The following sections demonstrate the technical and economic feasibility of developing a commercial lunar propellant production plant and the impacts it will have on future space operations and the United States industrial base.

Assumptions and Ground Rules

Although the presence of water ice on the lunar poles has been confirmed, there are still a great number of unknowns about its abundance and physical state. Several science missions have provided compelling details about the craters containing water ice.

Most recently, the Lunar Reconnaissance Orbiter (LRO) detected9 highly reflective patches within the craters indicative of frost concentrations. Other sources of data suggest even wider distribution of water on the Moon. However, there are significant gaps in our understanding of exactly how much, where, and in what condition the water may be found.

The weight of evidence is that the lunar polar craters would be excellent locations for extracting commercially important amounts of water. This paper has been prepared by a group of experts working with a common model of how that water could be extracted, processed, and distributed for use. The common assumptions were:

• Six major infrastructure elements are required: mining/processing, propellant storage, power, robotic systems, communication/navigation, and transportation (in-space and on lunar surface)
• All construction and operation will be done by robotic systems
• A solar power plant and/or power beaming facility will rely on sunlight, so it must be located outside the PSR in a sunlit area
• Nuclear power plants can function within PSR but require mechanisms for heat rejection
• Extraction of the water will be by direct sublimation, so moving large amounts of regolith can be avoided
• Water will be broken down into hydrogen and oxygen, which will be liquefied for storage
• Low temperatures within the crater will be a challenge for robotic design, but will reduce power needs for storage by keeping the Liquid Hydrogen (LH2) and oxygen cold
• Only considered technology currently in development or already developed
• Operations must be economically viable for commercial sustainability

To make the facility economically viable, the value of resources it produces must exceed its cost, including the costs of development, launch, installation and operation.

Document Organization

This work is organized into sections detailing an architecture for lunar ISRU that leverages current technologies and economic trends into a comprehensive plan for near-term space development. Following this introduction, are several sections describing hardware solutions for mining, processing, storage, powering, robotically supporting, and transporting lunar derived propellant. Several of these sections are further broken down to categorize the specific type or location of their operations.

Following these technical sections, is an in depth look at the business case for lunar propellant including demand, pricing, an economic analysis of various scenarios, and costs. This is followed by a detailed look at lunar mining from a legal and regulatory perspective. The Benefits section explores the industries that will be stimulated by this effort and forecasts both the near and long-term ramifications to the global economy, quality of life on Earth, and evolution of humankind.

Finally, in the recommendations, a path to technology development and implementation is identified as well as strategic investment opportunities. Credit is given to authors with a footnote attached to the title of their sections. It is through their collaborative work that the complete story of the lunar propellant production can be told.

Prospecting

Lunar Volatile Deposits - Solar Wind Implanted Volatiles

As the Moon is continually affected by the solar wind and other space radiation, the regolith contains elevated levels of volatile elements with the amount dependent upon length of exposure on the lunar surface. The most dominant solar wind volatile is hydrogen that can reduce FeO in minerals to metallic Fe and form OH- or H2O when impact energy facilitates the reduction reaction.

Many regolith agglutinates (impact glass-welded mineral fragments) contain vesicles attesting to the volatile release on impact melt generation. Therefore, the longer regolith is exposed to the solar wind, the more implanted volatiles will build up in that regolith. The ferromagnetic resonance (IS) normalized to total iron content (represented as FeO) has been used to measure the relative exposure age of regolith. In the returned regolith samples there are positive correlations with solar wind-implanted species (e.g., H, He, C, N, Ar).

Endogenous Lunar Volatiles

Ever since the Apollo samples were returned, it was evident that the lunar interior did contain volatile species, but it was unclear exactly what those were. For example, vesicular basalts were returned (e.g., Apollo 15 samples 15556 and seat-belt rock 15016) and glass beads that were interpreted to be the result of gas-charged fire-fountain eruptions (e.g., Apollo 15 green glass 15426, Apollo 17 orange glass 74220). This gas was originally suggested to be rich in carbon monoxide (CO).

Figure 4: Locations of Pyroclastic Glasses with ≥300 ppm (0.27 wt.%) H2O Signatures

It wasn’t until 37 years after the Apollo 15 green glass and 36 years after the Apollo 17 orange glass were collected that volatiles of S, F, Cl, and H2O were shown to be diffusing out of the glass beads during eruption and that significant reservoirs of these volatiles were present in at least parts of the lunar interior.

Hauri et al. also showed that the source of the Apollo 15 and 17 pyroclastic glasses was as volatile-rich as the Earth’s upper mantle. These results from Apollo samples led to a re-evaluation of orbital data from the Moon Mineralogy Mapper (M3) instrument on the Indian Chandrayaan-1 mission and showed that many pyroclastic glass deposits on the lunar near side exhibited a hydration signature exceeding 300 ppm (0.27 wt.%) (Figure 4).

Polar Volatile Deposits

There are regions on the Moon that contain elevated volatile abundances that have become increasingly highlighted as more orbital missions have visited the Moon. Concentrations of water at the lunar south pole was hinted at by the bistatic radar experiment conducted by the Clementine mission and Earth-based radar.

Lunar Prospector measured significant hydrogen deposits at both lunar poles using neutron spectrometer data and although spatial resolution was poor, it was inferred that the hydrogen deposits were in Permanently Shadowed Regions (PSR).

The first ground truth regarding these polar volatile deposits came from the Lunar CRater Observation and Sensing Satellite (LCROSS) mission that measured the material composition of the plume created as its companion Centaur upper stage impacted Cabeus crater, a PSR at the south pole.

It was estimated that the Centaur created a crater that was 28 m (92 feet) in diameter and 5 m (16 feet) deep14 . The plume of material was shown to contain 5.6 ± 2.9% H2O by mass, along with NH3, H2S, SO2, C2H4, CO2, CH3OH, CH4, and OH.

While LCROSS definitively showed that water ice was present in Cabeus, the mini- Radio Frequency (RF) radar data did not find evidence for water ice in this crater. The interpretation is that Cabeus contains ice intimately mixed with regolith, whereas for radar to detect such deposits discrete layers or large blocks of water ice are needed.

However, Patterson et al. reported bi-static radar data from Cabeus that was consistent with the presence of water ice at depth within the regolith. However, this detection was at a location distinct from that of the LCROSS impactor and the PSR reported by Spudis et al. Significantly, it was from the portion of the crater not in permanent shadow.

The Lunar Exploration Neutron Detector (LEND) has been collecting neutron data since the beginning of the LRO mission and indicates that neutron suppression regions (equivalent to hydrogen enrichment) not only occur within PSR, but also around them.

The Lunar Exploration Analysis Group (LEAG) undertook a specific action team analysis to integrate multiple datasets to map out potential exploration areas for lunar volatiles [19]. This showed there are areas that could be explored for lunar volatiles without entering the PSR – a very hostile environment that would be challenging to work in.

Parameters used included >150 ppm hydrogen, average temperatures of <110 K, slopes of <10 degrees (to be navigable by current rovers), and areas outside and adjacent to PSR. The intersection of these different datasets are shown in Figure 5. For the South Pole (Figure 5a), the Cabeus and Shoemaker-Nobile vicinities meet the criteria and have the advantage of some Earth visibility. For the north pole (Figure 5b), the Peary vicinity meets the criteria and have Earth visibility, but there is a substantial area on the far side that is also promising.

The one point of ground truth we have for volatiles within a PSR is the LCROSS impact site into the PSR of Cabeus crater. The parameters of the Cabeus PSR are documented by the LRO instruments and have been compared to other PSR in the south (Figure 5c) and north (Figure 5d) poles. For the South Pole, the remainder of Cabeus crater and the Nobile-Shoemaker craters are locations similar to the LCROSS site in H abundance and temperature (Figure 5c).

For the North Pole, Peary and the north rim of Hermite are most similar to the LCROSS site and have Earth visibility. There are several regions on the far side that extend from the North Pole towards the crater Hevesy that also show similarities to the LCROSS impact site (Figure 5d).

Figure 5: Representation of the South [(a) and (c)] and North [(b) and (d)] Poles of the Moon The intersection of the following criteria are represented in (a) and (b): >150 ppm hydrogen, <110 K average temperature, <10 degree slopes, and areas outside and adjacent to PSR. In (c) and (d), the blue highlighted areas represent those areas that are like Cabeus as defined by the LCROSS mission. The definition of “likeness” is explained in LEAG .

Quantitative estimates of water ice in and around PSR have been published using data from LRO. The Lunar Orbiter Laser Altimeter (LOLA) used an infrared spectrometer (IR @ 1064 nm) to measure topography and slopes, but enhanced reflections were observed in several PSR at both poles, with Shackleton crater at the south pole giving the highest reflection.

Models suggest 3-14% water ice by mass would be needed to give such reflectance observed in the PSR. The Lyman Alpha Mapping Project (LAMP) ultraviolet spectrometer (110-190 nm) also detected a strong change in spectral behavior at locations with maximum surface temperatures <110 K consistent with cold-trapped surface ice.

The results showed that the regolith in most PSR have much larger porosities than non-PSR regions, but the enhanced albedo was heterogeneously distributed and not observed in all PSR. Modeling indicates the enhanced albedo can be achieved by layers of >100 nm, or 1-2% of water frost at the surface. The LEND neutron data have also been used to estimate amounts of water-equivalent hydrogen (WEH) in and around PSR (Figure 6).

The richest deposits are within PSR at the South Pole (up to 0.55 wt.% WEH), but this could be due to the fact that the LRO orbit has consistently had a lower altitude over the south pole than the north for much of the mission. The data from the North Pole may have been diluted due to a larger footprint for the data.

Figure 6: WEH Estimates from the LRO-LEND Neutron Data15 - Shown in and around PSR at the (a) lunar South Pole, and (b) lunar North Pole.

Recently, the M3 data has been used to examine PSRs and have detected water ice at the surface of some of them. Most ice locations thus detected also exhibit LOLA reflectance and LAMP UV ratio values consistent with the presence of water ice at the surface, coupled with annual maximum temperatures below 110 K (Figure 7).

However, only ～3.5% of Cold Traps (CT)s exhibit ice exposures, probably due to lunar polar wander and impact gardening. In terms of ISRU potential, spectral modeling shows that some ice-bearing pixels may contain ～30wt% ice that is intimately mixed with dry regolith.

Figure 7: Presence of Surface Water Ice in PSRs at the North and South Polar Regions of the Moon Data points show the coincidence of positive results for surface water ice using M3 and LOLA data for the North Pole, and M3, LOLA, and LAMP data for the South Pole. Data points also have maximum annual temperatures of <110 K) from Diviner data. Adapted from Li et al.

Based on the data gathered by missions in the last 25 years, we have well defined targets to get to the lunar surface and start prospecting for water ice and other volatiles on the surface of the Moon.

Although PSR may contain highly concentrated water deposits, they are extremely inhospitable and will be challenging for preliminary prospecting missions. Exploration outside of the PSR is also critical to understanding the H-rich deposits that extend beyond them including the pyroclastic deposits that show promise as volatile resources.

The major next step is to undertake geologic prospecting in promising regions to determine the distribution, form, composition, abundance, and extent of the deposits, as well as the geomechanical properties of the deposits.

Such extensive ground truth data are needed to close business cases; understand the origin and evolution of such deposits; and to allow the lunar economy to be further developed.

Exploring in Permanent Darkness

Eventually, however, exploration within the Permanently Shadowed Regions (PSR) must be undertaken with all the technical challenges that it would bring. It is critical that we survey and prospect “appropriate ground” – we cannot do extensive wide area surveys on the ground. Thus, the question is, “What constitutes such ground?”

As a start, consider the following criteria:

1. Locate areas of permanent darkness (PD) within PSRs for highest concentrations of volatiles.
2. Locate water ice deposits within 10 km of a Permanently Lit Area (PLA)so that power transmission from sunlit locations is possible (nuclear power option may mitigate this criteria)
3. Remote data indicates general presence of H2/water enrichment at location.
4. Accessible terrain and slopes for whatever mobility solution is chosen.

These are not too stringent and offer several possible sites to focus on. We have no real preference for which pole we choose, but in general, the North Pole has many smaller PSRs that are within 10 km of a PLA (Figure 8).

The North Pole is on the northern rim of Peary crater, indicating substantial real estate with PLAs; though, the craters containing ice are substantially far away from this location.

The small craters on the southern floor of Peary, in Hermite A, and in the rough terrain to the south and west of Hinshelwood however, do contain ice and are within proximity to PLAs. The south offers larger PSRs (and more water), but terrain is very rugged, with up to 40? slopes (!).

None of these sites is in Earth Line of Site (LOS) view for communications. RF and/or laser communications relay will be needed, either on surface or (more probably) in orbit.

How do we get this information? After due consideration, the best way is to slog it out overland, with a long-lived, capable rover that can explore multiple dark areas. Challenging.

A lower cost solution might be to build multiple, small, hard-landing probes, but you will probably only get hints at what’s really there (e.g., a neutron spectrometer is very small and could work on a hard lander, but only senses bulk H2, and then, only the upper meter of the surface.)

You need a soft-lander. Anything that can deliver between 500-1000 kg to the surface can be made to work. The rover needs power, including lighting for work within PD. A rechargeable battery with a Radioisotope Thermoelectric Generator (RTG) is one possible solution to this challenge. If not possible under budget restrictions, rechargeable fuel cells/batteries could also be considered.

A hydrogen/oxygen lander using residual propellants in a fuel cell or ULA’s Integrated Vehicle Fluids (IVF) Auxiliary Power Unit (APU) is a non-nuclear alternative that would offer days or weeks for a rechargeable crater rover.

I would consider a prospect complete if it were able to investigate and characterize all PSRs within the 10 km circle. Water is heterogeneously distributed on the Moon – some large areas seem to have none, while some small ones have excess. Water deposition appears to be a non-equilibrium, stochastic process.

Strawman prospecting rover instrument package:

• Drill or mole (obtain subsurface samples) such as the Trident system described in the next section
• Sample handler and packaging for analysis (prepare samples for analysis)
• Gas chromatograph/mass spectrometer (complete major, minor, trace elements)
• Oven (bake soil and watch evolved gas release)
• Neutron spectrometer (bulk H2 over traverse and in prospects)
• Imaging Light Detection and Radar (LIDAR) (make detailed topo maps of good prospects; navigation)
• Multi-spectral imager with artificial illumination (map 3 micron water band)

Figure 8: Lunar Polar Lighting Studies Terrain within 2 of latitude (60 km) of the lunar north and south poles. Black areas are PDs; white areas receive sunlight for >50% of lunar day (PLAs).

Top crater PSR candidates for exploration:

North Pole prime candidates: Hermite A, the region to the south and west of Hinshelwood, and the small (~5-10 km diameter) craters on the southern floor of Peary. Prime power site – rim of Hermite

A, Peary, Hinshelwood, and Whipple.

South Pole prime candidates: Shackleton, de Gerlache, small-unnamed PSRs around Shackleton. Prime power site: rim of Shackleton (about 9:00 o’clock position)

Methodology

The most basic element needed for a new endeavor is information. This is especially true where large investments hinge on undertakings that carry elevated levels of difficulty and extended timeframes.

In order to determine an effective location for resource extraction or outpost placement on the Moon, information about the regolith composition and terrain of potential sites will have to be known beforehand.

The purpose of a prospector mission is to build upon previous knowledge gained and provide critical data about key characteristics of the lunar surface. Early Prospector missions are not only essential for gathering data for scientific purposes, but also for maximizing the effectiveness of subsequent missions.

Composition of the lunar regolith can vary widely between regions and will dictate the products that are most appropriate for extraction in that location. To know the composition at a desired location, prospecting missions will consist of a rover-like vehicle with a specially tailored payload, similar to that of the National Aeronautics and Space Administration’s (NASA)’s cancelled Resource Prospector (RP).

A trowel or scooping mechanism should be employed to gather surface samples, but more likely, a core drill will be used for excavating and collecting subsurface samples, giving a better indication of local resources.

An onboard oven will heat up the collected samples in order to release volatiles, which then are characterized by a neutron spectrometer or an infrared spectrometer. All this instrumentation will sit upon a rover body capable of traversing the surface and imaging its surroundings. Images and location will be overlaid with regolith analysis to provide a resource map for the area of interest.

Another prospecting architecture will employ a satellite mission orbiting the Moon, like NASA’s recent LCROSS and LRO that remotely senses regolith composition. This vehicle will cover more area, but will not be able to gather as detailed information as the rover will.

In order to get a better understanding of a location, a method that was used in LCROSS was to use an impactor to strike the surface, creating a cloud of material for a satellite to analyze.

Prospecting missions will have several different architectural schemes that depend upon the number of vehicles used. At one end of the spectrum, a single, highly capable vehicle with a longer lifetime will be deployed. At the other end, a swarm of smaller units will be used to collect samples.

These would most likely not be able to dig as deep or have the lifespan of a larger version, but will be able to gather more information quickly and decrease risk by providing redundancy.

Ultimately, it will depend on the mission goal and the associated economics; however, a hybrid approach will be a good compromise that better supports subsequent mining operations.

A suggested prospecting architecture will begin with remote sensing to gain a general understanding in areas not previously mapped by LCROSS or LRO. The next step will be to deploy a swarm of cheaper prospecting autonomous robotics to gain detailed information on a large area of the lunar surface.

The last step in this suggested architecture will then be to use a single or pair of more capable prospectors to gather detailed resource information at the most promising sites.

Surface and Subsurface Sampling

For approximately two decades, Honeybee Robotics20 has been developing one-meter-class drills for the acquisition of volatile-rich samples from planetary surfaces. The latest drill system, referred to as TRIDENT (The Regolith Drill for Exploration of New Terrains), is a 16-kg rotary-percussive drill and deployment system that was designed to be deployed from a roving platform to support missions requiring acquisition of samples from up to a depth of 2 m (the design is scalable to length). It is capable of drilling into ice-cemented regolith and rock at high rates of penetration (> 1 m/hour) with very modest requirements for power (100-200 W) and weight on bit (< 100 N). The system is shown in Figure 9.

Figure 9: TRIDENT Drill and Deployment System

CAD model of TRIDENT drill and deployment system (Left); photograph of TRIDENT drill and deployment system mounted to a support structure.

To support the Lunar RP mission, TRIDENT was qualified to operate in the South Pole’s Aitken Basin, where it would experience hard vacuum, radiation, reduced gravity, and cryogenic temperatures down to 40 K. Lunar RP’s purpose was to ground truth the presence of water within a PSR of the Moon.

A photograph of the RP15 rover under development for the mission is shown in Figure 10. It includes a suite of instruments designed to identify and analyze volatile content within lunar regolith. Operational concepts for sampling within the mission were as follows:

1. The Neutron Spectrometer Subsystem (NSS) monitors the lunar surface for high concentrations of hydrogen that would indicate a high likelihood of water present in the regolith. When a hydrogen-rich site is located, the rover parks above the site and deploys TRIDENT.
2. TRIDENT drills 10 cm into the regolith and then retracts, emptying cuttings onto the lunar surface or into a sample container, as instructed. TRIDENT continues to take 10-cm “bites” until it has reached its maximum depth of 1 m. During this time, TRIDENT monitors its bit temperature using an embedded Resistance Temperature Detector (RTD) to provide information about the regolith thermal profile and to verify that the bit remains sufficiently cold to prevent volatile loss from the sample.
3. The samples deposited onto the ground during drilling are first analyzed by the Near InfraRed Volatiles Spectrometer Subsystem (NIRVSS). NIRVSS characterizes the hydrocarbons, mineralogical context for the site, and the nature of any water ice present to determine whether a given sample is appropriate for further analysis.

Figure 10: Lunar Resource Prospector RP15 - Photograph of RP15 rover for Lunar Resource Prospector mission with annotations for NSS, NIRVSS, OVEN, LAVA systems for volatile recognition; drill shown is an earlier version of TRIDENT.

If the sample is expected to be of high scientific value, TRIDENT places it into the Oxygen and Volatile Extraction Node (OVEN). The OVEN heats up the captured sample and transfers evolved volatiles into the Lunar Advanced Volatiles Analysis (LAVA) subsystem which quantifies and characterizes volatile species. The OVEN can also be used to demonstrate hydrogen reduction, while LAVA can perform a Water Droplet Demonstration (WDD)