Introduction

A planetary base is sort of like a space station on the surface of a planet or moon. The base has a focus on supporting some particular endeavour, such as a Mars Exploration mission, a military base, a planetary defense fortress, a military observation post, a military picket along the neutral zone, a trading post or "factory", a mining operation, the interstellar equivalent of a lighthouse hazard beacon, or something along those lines.

For whatever reason it makes more sense to locate the facillity on the surface of a planet instead of a space station.

The presence of a base may encourage other bases to be established in the same location (see Boomtown). This can grow to the point where the establishment becomes a full fledged colony. This can occur with both a military outpost and with a civilian commercial trading post.

The main difference between a base and a colony is that the members of a colony do not expect to ever leave.

A new base is established with rugged cargo spacecraft that can handle landing in a wilderness or otherwise undeveloped area. If the base is planned to be expanded, adding a spaceport will be a big help (even if it is just an area that has been bulldozed flat). Trading posts will put up warehouses, even if it is just a shack to hold the local product responsible for the the existence of a post on such a forlorn planet. Warehouses are also useful to store the glass beads, iron kettles, or whatever cheap junk that the ignorant natives think is valuable enough to trade for in exchange for the beforementioned valuable local product.

Like any other living system, the internal operations of a planetary base can be analyzed with Living Systems Theory, to discover sources of interesting plot complications.

Base Functions

Agriculture
Food-producing station
Exploration
A base to support the exploration of the planet. Commonly encountered as a lunar exploration base or Mars exploration base.
Fuel Depot
Fuel refining and storage facility
Industrial
Factory or smelting plant. To be located near required raw materials, and far from colonies who object to air/water/land pollution.
Mining
Base supporting mining operations, perhaps with an ore refinery.
Pirate Haven
Space pirates need infrastructure (fences for pirated loot, fuel and reaction mass, ship repairs, R&R for the crew). A hidden planetary base can act as a Pirate Haven and cater to these needs.
Planetary Defense
Armed military station defending its planet from outside attack, planetary fortress.
Repair Depot
Emergency cache of critical spacecraft repair tools and replacement parts. Probably under lock and key to restrict access to authorized spacecraft.
Research
Scientific research. The base either studies the planet in general or some interesting local phenomenon. Alternatively it can be for researching dangerous technologies, where the planet can be considered expendable. Though in that case it would make more sense to put the base on a space station.
Staging
Forward base to support spacecraft. May be civilian or military. Generally located in a "remote" location, remote being defined as "a long distance from the home base of the supported spacecraft." (e.g., a military base can be "remote" even if it is near a huge metropolitan planet belonging to a hostile nation).
Tax Haven / Data Haven
These are tax shelters used by the wealthy and by corporations. They are located near the planet a corporation is based on, but are outside territorial limits. More details here.
Transport Nexus
A Transport Nexus is a crossroad spaceport for passengers, a port of entry, warehouses where valuable minerals from asteroid mines are stored and trade goods transshipped, or a "trade-town".
Trading Post
"Trading Post" or "Factory" set up by a merchant to trade their imported goods with the natives in exchange for the native's valuable local goods. The base is run by the merchant, or by a "factor" who is employed by the merchant (which is where the name "factory" comes from). The preferred route between trading posts is called the "trade route", though that does not translate well into orbital trajectories. Trade routes might make sense with certain types of faster-than-light starships.
POWERING A LUNAR BASE

What’s the most practical way to sustain a permanent Moon base through the two-week lunar night? In March of 2014, the Sacramento L5 Society (SL5S), a California chapter of the National Space Society, undertook the task of answering that question, eventually resulting in a detailed analysis of 20 different potential energy delivery systems. This article is a summary of the findings of the SL5S analysis to date. The detailed analysis itself and its accompanying spreadsheet, including a full description of the 20 systems the SL5S has studied to date, can be found on the SL5S website.

History of this analysis

In early 2014, two college students, Akhil Raj Kumar Kalapala and Krishna Bhavana Sivaraju of Rajiv Gandhi University in India, proposed beaming space-based solar energy to the Earth by way of a laser beam located in geosynchronous orbit. On March 14, 2014, an informal “brown bag” Moon Base Working Group (MBWG) started at NASA Ames Research Center in California “to develop a cost-effective plan for establishing and operating the NASA Moon Base that would be within 10% of the total NASA budget.” In March of 2014, Joseph Bland of the SL5S, one of the mentors for Akhil and Krishna, suggested to Michael Abramson, a member of both the SL5S and of the NASA Ames MBWG, that the group examine the possibility of powering a Moon base through the lunar night with a laser either at L1 or in lunar orbit.

Assumptions

Because it takes less energy to put a given mass into low Earth orbit (LEO) than into lunar orbit, and less energy to put a mass into lunar orbit than onto the lunar surface, it is useful to use a given lift capacity to determine relative masses of different systems in different locations. In the SL5S analysis, the lift capacity is defined in SpaceX Falcon Heavy (FH) units. One FH has a liftoff mass of 1,462,836 kilograms. It is assumed that one FH can put 53,000 kilograms into LEO, 17,216 kilograms into either a lunar or Earth-Moon L1 (EML1) orbit, and 5,739 kilograms onto the lunar surface.

Mass doesn’t necessarily have to be lifted directly from Earth to its final destination. For some SL5S calculations, it is assumed that the propellant and electric propulsion (EP) drive used to move a mass from LEO to either lunar orbit or EML1 will equal 30 percent of the transported mass. An EP system can also be used for orbital station keeping, which can be broadly defined as maintaining an object in space in a preferred position or orbit

The SL5S analysis examined energy storage by flywheel, electric battery, chemical, and thermal battery systems. It was concluded that lithium-sulfur (Li-S) batteries presently appeared to have the best specific energy (measured in kilowatt-hours per kilogram), but that other systems would benefit greatly from in situ resource utilization (ISRU) and would become competitive fairly rapidly once manufacturing on the lunar surface began. A specific energy of 0.5 kilowatt-hours per kilogram for Li-S has been used in the SL5S analysis as the basis for energy storage mass calculations for all systems.

As originally suggested by SL5S member Roger Arnold, aggressive collimation of a laser beam with a Fresnel optical lens could be used to dramatically reduce the diameter of a laser beam over a long distance since, for a given light wavelength and distance to target, spot diameter is inversely proportional to aperture diameter. Aggressive laser collimating may be especially practical in a weightless, weather-less environment. Because objects in space are weightlessness, and because space has no atmosphere, a space-based Fresnel laser collimating lens might only be a few mils thick. In this analysis, the mass of a Fresnel lens, including the mounting framework, is assumed to be 0.25 kilograms per square meter, with most of that mass assumed to be in the mounting framework.

Two different different approaches to powering a laser were examined. One uses electricity to power the laser. The system utilizes photovoltaic cells, although the electricity can also be created by a heat engine driven by concentrated solar energy. Another type of system is possible using solar-pumped lasers. In such a system, the solar insolation is concentrated directly on the laser, bypassing the electrical conversion system. Efficiencies for the two systems are expected to eventually be about the same, but the solar-pumped one appears to have a higher specific power even at present efficiencies.

A satellite that is not in sun-synchronous lunar orbit will move regularly into the Moon’s shadow. Adding an energy storage system permits an orbiting laser system to continue beaming energy even when this occurs. This energy storage system can also be used with a sun-synchronous satellite to store energy until the laser system can regain direct contact with the lunar base. Finally, by leaving parts of the energy storage system in orbit rather than moving it to the lunar surface, the overall project mass can be reduced, since rocket motors, fuel, and so on can be scaled back.

A deflecting system, as the term implies, permits a laser beam to be deflected. In certain circumstances, such a system in lunar orbit may permit nearly uninterrupted laser beaming from an orbiting solar-powered laser system to a given location, thus obviating the need for energy storage either in orbit or on the lunar surface.

A deflecting can also find use in other ways. It is possible to envisage a series of non-orbiting deflection modules placed directly on the lunar surface to transfer beamed energy to other locations. Finally, a surface-based solar powered laser system at the lunar poles may beam solar-powered laser energy to an orbiting deflecting system, distributing lunar pole-generated laser energy to other locations on the Moon (see Lunar Polar Multi-array System below).

The 2009 NASA concept study

In January of 2015, the SL5S analysis was essentially complete when the organization discovered a presentation titled “NASA JSC Lunar Surface Concept Study.” Since January, SL5S conducted an extensive rewrite of its analysis to actively compare the earlier analysis with the 2009 NASA study.

The preferred system recommended in the 2009 NASA study was a photovolatic solar array-powered cryogenic storage regenerating fuel cell system. NASA calculated that a five-kilowatt continuous delivery system would store 2,000 kilowatt-hours with a system energy density of 1.15 kilowatt-hours per kilogram. The study’s alternate preferred system was a fixed orbit laser system, with a 16.1-hour orbit period that required a surface receiver installation with 525 kilowatt-hours of energy storage. The laser was powered and fired when it was both in direct sunlight and in direct line-of-sight with the Moon base.

Other approaches

One concept that was not explored in the 2009 NASA study is the use of several separate solar collectors situated on high lunar mountain peaks, or so-called “peaks of eternal light,” each connected directly to the base via electric cables, lasers, or reflected solar beams. This concept was suggested by SL5S member Michael Abramson in early February of this year. Such a system would approach a continuously-powered polar Moon base. Periods of darkness as long as 36 hours may still be likely, requiring additional energy storage capacity, estimated at 540 kilowatt-hours.

Yet another approach to continuously powering a Moon base was looked at and rejected by NASA as impractical. That approach involved parking a solar-powered laser system at the Earth-Moon L1 or L2 points. However, in making its determination, NASA did not consider the possibility of using aggressive laser collimating.

For any two bodies in space rotating about a common center, there are five points of special interest called Lagrange points. For the Earth-Moon system, they’re called EML1, EML2, and so on.

In the case of EML1, this point is between the Earth and the Moon and along a line between their centers of gravity. In the case of EML2, this point is along the same line but beyond the far side of the Moon. The Lagrange points mark positions where the combined gravitational pull of the two bodies precisely matches the centripetal force required for the points to orbit with those bodies. For example, an object placed at EML1 orbits at the same rate as the Moon even though it is much closer to the Earth.

Lagrange points L1, L2 and L3 are said to be unstable. That is, it requires a force to maintain an object’s position in their vicinity. One type of orbit, called a “halo orbit,” while also unstable, is much more stable than an object placed exactly at one of these Lagrange points. A halo orbit is a three-dimensional somewhat circular orbit approximately perpendicular to the center line connecting the Earth and the Moon at the approximate location of the Lagrange point along that line.

The oscillating Lagrange point orbit

Presently, station keeping in the vicinity of EML1 or EML2 is usually accomplished by a three-dimensional halo orbit. An alternative approach known as the oscillating Lagrange point orbit (OLO), is largely a two-dimensional orbit in the two-body orbital plane. The figure below generally illustrates the theorized course of an OLO over the roughly four weeks of a lunar rotation, as mapped along the approximately 6,400-kilometer line of travel of L1 relative to the Moon between perigee and apogee.

Looked at from above or below the Earth-Moon plane, the OLO approximates a figure eight, orbiting alternatively along the lobe on one side of the line connecting the center of the Earth and the center of the Moon and then along the lobe on the other side of that line. Note that the center line is relative to Earth and Moon and is described by the elliptical movement of the Moon as it orbits around the Earth/Moon barycenter. SL5S member Roger Arnold, originator of this concept, put it this way:

“The metastable neutral point that the station should track is not the L1 point, wherever it happens to be at any given moment. Rather, it’s a point in the 6D phase space for the system (x, x-dot, y, y-dot, and z, z-dot). I.e., both position and velocity vectors must be right. When they are, the station describes an oscillating “orbit” that passes through the L1 point twice per month. Once the station achieves the neutral point, I believe the only station keeping that’s needed is to correct for drift due to measurement errors and unaccounted solar radiation pressure. The neutral point that the station follows will oscillate with the L1 point, but with lesser amplitude and lagging in phase. The proper analogy is to balancing a weight atop a pole whose base is oscillating back and forth. The weight does not precisely track the base and remain positioned exactly above it.”

The OLO appears to be able to operate in much closer proximity to the Lagrangian point with which it is associated than a halo orbit. This is important for beaming energy to the lunar surface from EML1 or EML2. Work is presently being carried out by the SL5S to roughly estimate the extents of a typical OLO at EML1.

Solar sail propulsion and the gravity winch

In certain circumstances, a solar sail arrangement can be used to enhance or even replace an electric propulsion system for OLO station keeping purposes at EML1/EML2. This system has an advantage because of its ability to modify a spacecraft’s position without using fuel. A related idea is the use of reels to pull in or let out either solar sails or “gravity anchors” relative to a space-based platform. This constitutes what might be called the concept of a “gravity winch.” A gravity winch is basically a reeled tether that’s dropped down gravity wells from a “neutral” gravity point, such as a Lagrange point. In the case of a platform at EML1, a tether can be dropped from the platform down the gravity wells of both the Moon and Earth. Shifting the gravity anchors from one side of the platform to the other allows the EML1 platform to “balance” between the two gravity wells, similar to the way a pole helps a tightrope walker balance. This technique may also be useful for putting in place a “lunar elevator” extending from EML1 to the lunar surface.

Results and conclusions

The table below collates the results of our analysis. The Cryogenic-storage Regenerating Fuel Cell (CRFC) and Fixed Orbit Laser System (FOLS) systems are included for reference purposes only. This presumes that any advances in battery technology will be applied across the board to all systems. To aid in comparisons, a CRFC-type system using Li-S energy storage is included as the Lunar Non-polar Surface Mounted System (LNSMS). Also, a FOLS-type system using Li-S energy storage and aggressive laser collimating is included as the Lunar Orbiting Photovoltaic-powered Laser System (LOPVLS).

In the table, the 15-kilowatt continuous systems are shown ranked from low cost to high cost by the column “Tot FH $ without EP” (Total Falcon Heavy cost without electric propulsion). It is assumed that, for an initial Moon base, electric propulsion will not be used to deliver the payloads to their ultimate destinations. FH dollars are calculated based on a price of $1,200 per kilogram in accordance with the statement by SpaceX CEO Elon Musk that, “Ultimately, I believe $500 per pound or less is very achievable.” It’s important to note that FH dollars do not include any costs associated with developing the various systems shown in the table.

The findings of the SL5S analysis are very much first order approximations. In addition, the analysis is still a work in progress. However, in light of the dramatic nature of those findings, it is felt that the systems in question merit a far more in-depth analysis than the S5LS is capable of delivering. It is hoped that this article will inspire the undertaking of such an in-depth analysis by NASA or some other interested party.

From POWERING A MOON BASE THROUGH THE LUNAR NIGHT
by Joseph Barrett Bland, Michael Abramson, and Roger Arnold (2015)
ORGANIC RANKINE CYCLE

Abstract

We propose using the temperature gradients between the Moon’s surface and the soil at a certain depth to power an Organic Rankine Cycle that could supply a permanent installation, particularly at night, when solar power is not available. Our theoretical and engineering considerations show that, with existing working fluids and quite feasible technical requirements, it is possible to continuously yield 25kW to sustain a 3 member crew.

1. Introduction

     Indeed, the Moon can unravel unique opportunities for science, engineering and resource exploitation. As an example of scientific and engineering goals, we could mention the advantageous opportunities for further lunar laser ranging, astronomy, due to the inexistence of an atmosphere, and radio-astronomy. It is also well know that Moon’s soil is particularly rich in He3, the fuel of the future fusion nuclear reactors. Furthermore, the impact of comets and asteroids on the Moon are important sources of metals, ice and compounds that can supply humankind for many centuries.

     In fact, the colonization of space presents a number of technical challenges, most of which are yet to be overcome. One of which is how to ensure a sustained power supply given the specific conditions of the Moon.

     The power requirements of an initial lunar base camp with 3 crew members have been estimated at 25kW. However an advanced base with an industrial or mining operation could need over 1MW.

     A key feature of the lunar environment when considering long term settlement is the length of the day-night cycles. The moon has a rotation period of approximately 27 days, which is tidally coupled with its orbital period around Earth. This means each day and night on the Moon lasts for approximately 14 Earth days. This poses a problem regarding a continuous power supply.

     The thermal amplitudes on the Moon are extreme, oscillating between day and night mean temperatures of approximately 380K and 120K, respectively.

     Owing to these sharp temperature amplitudes, the lunar soil has significant temperature gradients with depth. Measurements conducted during the Apollo lunar landings show that at depths below 80 cm in the lunar regolith the day-night temperature variations are no longer present. Even below 50 cm the temperature fluctuations are on the order of only ±1 K. The mean soil temperatures in the first few meters where the measurements were taken are on the order of 250 K and there is a temperature gradient of the order of 1 to 3 K/m (ct. Figure 1). The gradient arises from the heat flow from the Moon’s crust.

     The default option for supplying power to a lunar colony has been to use photovoltaic cells in solar panels, similarly to most power systems in space. The use of solar panels as the exclusive power source, requires some kind of energy storage to cover for periods in the shadow. However, current battery technology is far from being able to cover for 14 days without sunlight, unless massive battery farms were to be used.

     There have been proposals to store thermal energy in a heat mass made of processed lunar regolith. In this concept, a solar power concentrator heats a mass of compacted lunar regolith to high temperatures. The stored heat is then used during the night to power a Stirling engine that produces electricity.


     The presence of the aforementioned temperature gradients in the Moon’s soil presents an opportunity to build a thermodynamic power system that can ensure the long-term continuity of power supply on the Moon. Our proposal is to use these temperature gradients to power a thermal engine to supply an installation with uninterrupted power. The main issue when considering classic thermal power systems, usually based on water or air as working fluid, is that they require very high temperatures only achievable either by burning some kind of fuel or through concentration of solar power.


     Recently, however, there has been an increasing number of proposals on the application of what is usually called an Organic Rankine Cycle (ORC), which has been proposed as an alternative for power generation from low-temperature heat sources such as solar heat, waste heat or geothermal energy. This cycle is characterized by the use of an organic working fluid instead of water, allowing for heat conversion in low-temperature sources. The organic working fluids typically have much lower melting and boiling temperatures than water, allowing the engine to work at lower heat source temperatures. Many of the working fluids employed are the ones commonly used in refrigeration cycles. Current applications of ORC on Earth include cogeneration facilities, Ocean Thermal Energy Conversion and low-grade geothermal heat sources.

In this paper, we propose that an ORC can be used effectively as the basis of a thermal power system using the temperature gradients in the Moon’s soil, particularly, during the long lunar night. As we explore a set of possible working fluids, we examine the feasibility of an ORC to power a lunar colony during its long nights and estimate its performance.

Sample Asteroid Base

This is based on a 1981 Boeing report Controlled Ecological Life Support System: Transportation Analysis.

For details about the fusion powered transport ship, go here.

4.5 Asteroid Base

The mission assumes an asteroid mining operation with a 5000 person habitat. The complex transportation scenario for this advanced mission involves four different vehicles and three separate space bases (refs. 86 and 91).


c. The GEO base serves as the final assembly area for the large fusion rocket system used to propel payloads out to the asteroids. Cargo and propellant are unloaded from electric-powered transfer vehicles sent up from the LEO base. The enlarged OTV used to transfer personnel and priority cargo is designed to transport 441,000 lb (200,000 kg) from LEO to GEO. The complex fusion propulsion system is assembled at the base with the fusion power core, propellant tanks, large thermal radiators, and the personnnel and priority cargo modules. The resulting vehicle, shown in figure 4-11, can transport 1250 passengers and 150 metric tons of priority cargo to the asteroids.

The gross start mass for the resupply mission would be 10,000 metric tons, of which power plant comprises 2000 tons; hydrogen propellant, 4000 tons; and payload, 4000 tons (1250-person habitat plus consumables and priority cargo). The power plant consists of two 6 GW fusion reactors utilizing the deuterium-deuterium fusion reaction. The total power plan provides 4.8 GW of thrust power while radiating almost 2.8 GW of waste heat and 4.4 GW of high energy neutrons.

d. There are two methods the fusion rocket will use to propel vehicles to the asteroid base: fast transfer for personnel and priority cargo, and slow transfer for nonpriority cargo. The manned resupply mission is a fast hyperbolic transfer orbit consisting of an 11-day thrust period to achieve hyperbolic velocity, followed by a 226-day coasting, and a 13-day deceleration to match velocity with the asteroid base. The return mission leaves the asteroid approximately 113 days later for a reverse of the ascent mission.

The second method is used to accelerate unmanned cargo pods on a slow elliptical (Hohmann) transfer orbit out to the asteroid base. Figure 4-12 illustrates the different trajectories. The slower trip takes 130 days longer but costs less than half of what the fast, hyperbolic trip costs. All nonpriority cargo is brought to the asteroid facility in this manner. Empty cargo pods are not returned to Earth, they may be discarded or used in a variety of ways as storage modules or Closed Ecological Life Support System (CELSS) modules.

e. A fleet of two fusion rockets is envisioned. They each make one round trip per asteroid orbit (synodic cycle) to the asteroid mining facility and leave a few days apart. Because of the synodic cycle, the fusion rocket vehicles are delayed at the asteroid base for approximately 113 days, at the GEO location they are delayed approximately 288 days. During these delays the fusion rockets are used to decelerate unmanned cargo pods at the asteroid base and to accelerate the pods at GEO. Cargo pod launches are timed to arrive at the asteroid base shortly after the manned resupply vehicles so that the fusion rockets can decelerate the cargo pods. The rendezvous opportunity (synodic cycle) repeats itself every 928 days. This transportation system allows half of the total crew to be rotated each cycle.


86. Advanced Propulsion Systems Concept for Orbital Transfer. 1981. NAS8-33935.

91. Technology Requirements for Future Earth-to-Geosynchronous Orbit Transportation Systems. June 1980. NAS1-15301.

William Black:

This is still a work in progress, and more or less I’m attempting Winchell’s stone soup method. I’ve previously come up with a model for an asteroid mining base, I haven’t plugged in numbers for every item yet, I’m looking up references and doing research, this is what I have so far. This is all preliminary, so feel free to make suggestions.

In this case the report suggests these 1,250 persons are passengers en route an asteroid mining base.

With extensive automation (at the base) crew size would be determined by maintenance and servicing needs. Total crew size depends on the scale of the operation. In my experience many people suffer from a lack of perspective when it comes to industrial scale commercial operations. It’s very easy to think; “well this will all be automated, so there hardly need be any personnel.” Well, the equipment has to run 24/7 and when its down the operation is not making money. So even if your mining equipment is largely automated or robotic, it has to be monitored, maintained, and repaired in the field, or even recovered and brought into the shop situated at the main base for repair.

I’ve prepared a rough breakdown based partly on my own work for my own future history setting but adapted to this scenario.

The report specifies an asteroid mining base, specifically a commercial operation, with a base population of 5000. The report is not specific on what is being mined, but the example given is Ceres. We might speculate this is an ice mining operation recovering water ice to feed electrolysis plants separating hydrogen and oxygen on an industrial scale, perhaps in support of other large scale mining operations spread across the asteroid belt. Perhaps providing material for transit to propellant depots located elsewhere. There are similar operations in my future history setting and I’ve done some research on this previously.

Fusion powered Transport

The fusion powered transport might need as few as 3 to 4 flight crew I would think. Pilot, co pilot, navigation/communications officer, power-systems specialist. 4 crew per watch, 4 watches per 24 hours in-flight. So a flight crew of 16.

In regards the asteroid mining base:

Assume commercial operations running four shifts 24/7.

Operations management follows a mission control model managing one hundred remote mining sites scattered over a relatively large area, each with autonomous robotic mining/excavating vehicles and/or drilling rigs. Autonomous loaders, conveyors, for feeding material into separators for processing. Autonomous vehicles to remove and cart away waste material for disposal. Electrolysis plants for separating water ice to hydrogen/oxygen and a ice-melt and filtration plant producing fresh water for base consumption.

Mission Control

Mission control is situated at the main base. Operators remotely monitor operations at each site and assign a trouble shooting tickets for breakdowns and malfunctions.

Each mission control operator handles two remote operations sites, so mission control needs 50 men per shift x 4 shifts: 200 mission control operators.

Trouble shooting maintenance/repair teams for each operational site:

Software/hardware computer team

2 technicians each shift for each site. 200 technicians per shift x 4 shifts: 800 technicians.

Responsible for remote autonomous vehicles primary control systems including sensors and switches, data uplinks, and other operational mining site-to-mission control communications systems, remote cameras and the like.

Mechanical team 1

Stationed at central maintenance hub.

Eight crew for each operational site, per shift, x 4 shifts. 3200 crew

Responsible for

Hardware: remote manipulator systems
Hardware: conveyor systems
Hardware: motors/drive systems
Hardware: pneumatics/hydraulics
Hardware: thermal management, heaters and heat rejection systems
Hardware: electronics

Mechanical team 2, Surface EVA

Four recovery/maintenance teams for each shift, with a five man crew for each. 20 men per shift x 4 shifts: 80 man surface recovery/on-site maintenance crew.

Manages remote autonomous vehicle recovery and/or maintenance in-field and transportation of units back to central maintenance hub.

Cryogenics team.

Manages handling, storage, and transfer of cryogenic materials.
Maintains refueling station for cargo and personnel surface to orbit transfer vehicles and surface-to-surface suborbital transports.
Manages maintenance and repair of cryogenic systems.

Base Hospital

Staff 200
Emergency trauma team on duty 24/7.
Surgical suite staffed 24/7
General care services staffed daily, say 9-5.
Hospital/recovery services, nursing staff, on duty 24/7.

EMT EVA Team

Two five man teams per shift x 4 shifts: 40 crew.

This might just be a meat wagon. A suit failure on the surface of Ceres say fifty kilometers from the base, or a vehicle crash wouldn’t be likely to leave survivors, but it is possible crew may survive such incidents and require rescue.

Base Stores

Warehouse/supplies management & cargo/freight handling crew, warehousing would likely be largely automated such as large scale commercial systems commonly used in the air freight industry today, still a certain number of human operators are required and inventory control needs a certain level of human intervention.

Base Police Force

Staff on duty 24/7.

I took a look at personnel per population studies and most specify 1.8 to 2.3 police officers per 1,000 residents. So, ten officers per shift x 4 shifts: 40 officers. Call center/dispatch staff of 2 per shift x 4 shifts: 8 dispatch staff.

Base Systems

Life support systems, plumbing, air circulation, electrical, computer network, power systems management crew, staff on duty 24/7. 50 man crew on duty each shift x 4 shifts: 200 man crew.

Base Command

Watch officers, office staff, manages book keeping and accounting, documentation of all issues, and maintains base database and records. Watch officer staff on duty 24/7.

Communications Center staff

?

Flight Team

48 dedicated pilots

Flight Operations Control Center

For my theoretical commercial operation I’ve assumed all propulsive vehicles rather than surface crawlers.

Pilots control all suborbital point-to-point vehicles, equipment retrieval vehicles, cargo tugs, EMT EVA transports. Base flight crew is supplemented by crew from fusion transport flight crew who are stationed on the base for 113 days between arrival and departure. The fusion powered transport is used to decelerate unmanned cargo pod shots between arrival and departure. Since the fusion drive system cannot be fired in close proximity to the base there need be a number of cargo tugs to load and off-load cargo pods and transfer personnel between base and the fusion powered transport.

Number of and types of vehicles:

Equipment recovery and on-site maintenance vehicles: 4
EMT EVA Rescue vehicles: 2
Cargo Tugs: 4
Fleet Size: 10 vehicles.

These might be differently equipped vehicles of a single common type. For example the Equipment recovery and on-site maintenance vehicle might carry a tool crib and spare parts storage bay with an on-board work station where the EMT EVA Rescue vehicle would carry a medical pod with an on-board trauma suite. Personnel transfer craft might be cargo tugs with a passenger module rather than a cargo pod.

Flight Center Vehicle Maintenance Crew

100 vehicle specialists, 25 on duty per shift.

Additional Base Personnel

Cafeteria
Food Preparation & service staff

With a base of this scale there are likely to be attached concessions, a convenience store, fast food outlets, or even an upscale restaurant or two, a bar/night club, a theater perhaps. Likely the base has its own on-site local internet, television and movie channels playing recorded material.


In my model I’ve assigned duty stations/shifts to 4,676 Base personnel leaving 324 base personnel split among the various positions with uncounted crew.

Comment by William Black in a thread on Google Plus (2015)

Sample Lunar Base

2.4.6.1 Elements and Systems Description

Figure 2.4.6-1 summarizes the surface elements identified to support Case Study 4. In addition to those identified in the previous case studies (EMU's, Phobos EVA systems, construction equipment, regolith baggers, unpressurized rovers), the list includes many new elements. The surface habitats involve three major life-enabling components: structure, environmental control and life support system (ECLSS), and thermal control system (TCS). The ECLSS is substantially closed to reduce the logistics strain of continuous occupation. A pressurized rover permits extended traverses. Plants use local resources to produce substantial amounts of rocket propellants. Increased power needs are provided by a megawatt-class nuclear power plant.

Figure 2.4.6-2 depicts a concept for the lunar base layout. Primary power is provided by a nuclear plant whose reactor core is shielded by burying it in regolith allowing some freedom to place it near habitat and laboratory areas. Oxygen plants are located some distance away for safety and to isolate dust and contaminants. The liquid oxygen product is stored in buried tanks to facilitate cooling. A permanent landing/launch pad area lies some kilometers from the base to isolate debris lofted by rocket exhaust. Various navigation aids lie along the lander flight path. Support equipment provides services such as refueling and auxiliary power to landers while at the base. Improved roadways ease access between the major areas.

Inflatable/erectable habitat structures are chosen over modules since they provide more volume for a given mass. The inflatable, depicted in figure 2.4.6-3, consists of a spherical pneumatic envelope around a structural cage that supports floors, walls, and equipment. The cage also supports the envelope if pressure is lost. The design assumes that the habitat is inflated to standard sea-level pressure. A 2-m diameter vertical shaft provides access for crew and equipment. The habitat includes two airlocks, one of which is provided by a construction shack module that is connected to the inflatable by a flexible tunnel. The airlocks have front porches to facilitate cleaning and dusting off extravehicular mobility units (EMU's). The lower half of the habitat is buried below the surface and the top half is covered with bagged regolith for shielding from radiation and micrometeoroids. Burying substantially reduces hazards from external radiation. The envelope is a high-strength multi-ply fabric with an impermeable inner layer and a thermal coating outside. The structural frame is a cage of longitudinal and latitudinal curved beams that surround a combination of radial and concentric beams that support the flooring. A 16-m-diameter configuration has four floors and can house 12 crewmembers with total floorspace of 594 m2. If made of a material similar to Kevlar-29, the envelope would be about 5 mm thick and would weigh about 3.3 t. The remaining mass totals about 16.3t and includes the structural frame (9 t), floor (6 t) and walls (1.3t).

Inflatables require more time to set up than pre-outfitted modules. In the current concept, a construction shack module lands near a hole that has been excavated with explosives. After shaping the hole, the inflatable is laid out, anchored, and erected. Covering with regolith is the most time-consuming task and is a prime candidate for automation.

A regenerative ECLSS is necessary for extended-duration missions to avoid prohibitive resupply logistics. The initial lunar ECLSS uses physical and chemical methods to regenerate oxygen and obtain 97 percent closure of the water cycle. ECLSS technology is assumed to evolve so that the Mars ECLSS is bioregenerative with partial closure of the food loop. The martian system uses local resources to make up water, oxygen, and nitrogen losses.

Total ECLSS closure is not feasible. Even the most optimistic estimates for a lunar base envision a bioregenerative system that recycles about 97 percent of the total mass with resupply of gasses lost through leaks and airlocks. The most important material loops are water, gasses, and food. Water is especially important because of its weight: resupply needs are about 0.93 t/yr per person with 90 percent closure and 0.28 t/yr per person with 97 percent closure. To achieve 97 percent closure involves recycling humidity condensates, wash and hygiene water, and urine. A major trade in designing an ECLSS is the cost of closure versus resupply. It is generally more economical to resupply trace substances than to recycle or reproduce them. With this in mind, the basic goals of regenerative ECLSS can be summarized as follows:

a. Keep material losses to a minimum.
b. Recover useful material from waste.
c. Reduce resupply logistics to a minimum.

The first two goals can be accomplished with physical and chemical means. Achieving the third goal requires post-Space Station Freedom ECLSS and/or biological systems.

The TCS provides for passive protection, acquisition, transport, and rejection of latent and sensible heat. Inside the habitat the major heat sources are metabolism and equipment. Since regolith provides good insulation from the surface environment, the major problem is heat rejection. To handle the drastic temperature variations in a lunar day, a cascaded vapor cycle system is envisioned. Two loops provide adequate heat rejection during the day when temperatures can reach 130°C and a bypass is provided to prevent over rejection at night when temperatures can fall below -150°C The system provides final rejection temperatures of 43°C and 67°C to reject both the metabolic and equipment heat-loads during the day and provides a final rejection temperature of-11 °C to reject the heat loads during the lunar night.

Radiation protection is a major concern for long-term habitation of extraterrestrial surfaces. The major hazards are from solar flares and lengthened exposure to galactic cosmic radiation (GCR). Solar flares occur sporadically and are roughly correlated with the sunspot cycle. GCR contains many more energetic particles man solar flares but at substantially lower fluxes. Solar flares can be lethal over short time periods whereas GCR presents a more long-term hazard. Shields of bagged regolith about 50-100 cm thick have been estimated to achieve a tolerable radiation environment for solar events. The shields also suffice for protection from micrometeoroids which generally penetrate only a few centimeters. Current GCR models are not yet adequate for predicting long-term shielding needs. With such coverings the habitats provide an adequate haven during a solar storm. EVA crew are at risk unless they can retreat to the habitat or some temporary haven. A regolith bagger provides for constructing temporary radiation shelters for crew when far from the base shelter such as during an extended traverse in the pressurized rover. Since the regolith bagging and stacking process can take a significant amount of time, it must be started somewhat before a solar storm.

Currently the ability to predict solar flares is somewhat limited, and warnings are best provided by surveillance of the sun. Warnings of solar storms may be as short as half an hour. Earth-based support can also be limited or nonexistent; for example, when Mars is on the opposite side of the Sun from the Earth. Improved ability to predict solar storms can reduce risks to crew since operations can be restricted during high alert periods. Radiation protection garments provide emergency partial protection when the crew does not have enough time to return to the habitat or construct a haven. The period of maximum flux of a solar storm is often on the order of a few hours. In such situations these garments give enough protection to limit exposure to tolerable levels for short periods of time. Such garments could consist of about 3 inches of multilayered carbon fiber and provide about 8 grams per square centimeter of shielding. This would reduce the dose rate of a solar flare by a factor of five to seven times that of an unshielded suit. During an event like the 6-hour peak of the August 1972 storm, one of the largest on record, they would allow for an emergency dose of about 10-15 rem as compared to 72 rem. However, they could not support an entire flare period but would give crew added time for more appropriate measures.

Including one propellant plant (150 t LOX/yr), base power needs are estimated to be in the 700-900 kWe range. Nuclear plants are favored at higher power levels because of their reduced mass. The lunar design envisions an SP-100-type reactor deployed in a cylindrical excavation with an aluminum bulkhead for protection from dust. This allows freer placement of the reactor relative to habitats and permits crew maintenance of radiator panels. Six high efficiency free piston Stirling engines running at 91.7 percent of capacity and two reserve engines ensure dependable power generation. Vertical spoke-wheel radiator panels and mercury heat pipes provide waste heat rejection. A PV/RFC power systemprovidesfortheearly base and emergency backup. A nuclear power plant concept for Mars will be determined in FY1989 studies.

The pad area is located several kilometers away to minimize blast effects. Analyses indicate that within 400 m, metal objects will experience significant pitting and glass surfaces will experience damage within 2 km. Permanent pads require surface stabilization such as gravel, paving tiles, or compaction. Gravel created as a byproduct of propellant production is a promising option. Pad markings and navigation aids help pilots and automated landers to find the pads and make precision landings. The devices envisioned are lightweight and contain a transponder, a visual marker, and a light. A retroreflec-tor aids the use of a laser rangefinder. Since operation is infrequent and for short duration, power requirements are minimal. A number of specialized vehicles support pad operations. The construction crane is used to load and offload cargo to the truck. A propellant refill vehicle and power carts service the lander with fuel and auxiliary power.

The use of in situ resources offers great potential for bootstrapping and leveraging growth. FY 1988 activities focused on propellant plants for the surfaces of the Moon, Mars, and Phobos. Each is designed as a self-contained unit that includes its own power supply.

The lunar plant is baselined to use the hydrogen reduction of ilmenite process to produce oxygen from lunar regolith. Ilmenite is an iron titanium oxide whose two chief sources are high titanium basalts and mare soils. The ilmenite content of soils varies: about 7 percent by weight represents a typical value for rich deposits. Basalts can contain substantial ilmenite (the richest Apollo mare basalt samples contained about 33 percent by weight). Since the basalts require substantial crushing and grinding to release the ilmenite particles, the mare soil is preferred. Ilmenite reacts endothermically with hydrogen to produce water, iron, and titanium dioxide. Sufficient reaction rates require elevated temperatures. It has been reported that about 70 percent of the oxygen is removed after one hour at 1000°C. In the envisioned design, automated excavator vehicles mine the ore and deposit it into grizzly scalpers. A continuous conveyor carries the feedstock to the beneficiation process where the slightly magnetic ilmenite particles are removed with high intensity magnetic fields. If basalt feedstock is used, it is crushed, ground, and sorted before separation. Soil feedstock requires additional sorting and larger magnetic separators. Processing is done by feeding the ilmenite through low and high pressure hoppers into a three-stage fluidized-bed reactor. Most of the reaction takes place in the middle bed. Residual solids from the last bed are discarded through a solid gas separator after being used to preheat the material in the first bed. A solid state electrolytic cell dissociates the water into oxygen and hydrogen. The oxygen is liquefied for use as rocket propellant and the hydrogen is recycled. A pilot plant producing about 2 t/mo and powered by PV/RFC with a 35 percent duty cycle (daytime operations and hot standby at night) is estimated to weigh about 22.5 t. A 12.5 t/mo plant using nuclear power on a 90 percent duty cycle is estimated to weigh about 47.5 t.


5.1 POWER SYSTEMS

5.1.1 SP-100 Nuclear Power System Conceptual Design for Lunar Base Applications

The objective of this study was to provide a conceptual design of a nuclear power system using an SP-100 reactor and Stirling engine conversion for use on the lunar surface. System configurations were selected for their ability to enable and/or enhance a lunar base mission. Numerous system components and coupling options were examined and recommended options were chosen for safety implications, high performance, low mass, and ease of assembly.

Background. This conceptual design study was performed as a result of a request from the Propulsion, Power, and Energy Division in the Office of Aeronautics and Space Technology (OAST). The design includes system performance and sizing data, as well as layout rationale. An artisf s rendering of the nuclear power system as it applies to a typical mature lunar base was included as part of the study (figure 5.1.1-1). Because of obvious implications to the Office of Exploration (OEXP) case studies, the conceptual design study was extended to provide an evaluation of nuclear power system impacts on an advanced lunar base.

Key Assumptions.

a. Mature lunar base with power requirements in the 700-900 kWe range
b. Presence of rovers for construction and maintenance
c. Advanced technologies, including the SP-100 reactor, free-piston Stirling engines, and mercury heat-pipe radiators
d. Nuclear power system supplies electrical power only; the use of thermal energy from the power system will be examined in future studies
e. Use of lunar-soil shielding designed to meet human safety requirements

Approach.

This conceptual design was developed using Lewis Research Center (LeRC) experience with the SP-100 reactor and Stirling engines. A critical aspect of the study was to gain an understanding of the lunar environmental conditions and to identify their impacts on the design of the power system. To more fully understand the interactions of a reactor power system with a lunar base, a possible mature lunar base concept was defined with the assistance of the OEXP Surface Systems Integration Agent. The study was a 3-month in-house effort of LeRC's Advanced Space Analysis Office (ASAO) and Power Technology Division (PTD).

Findings.

Lunar Base Assumptions. The lunar base concept is derived from studies performed at the Johnson Space Center. The central core of the base is comprised of two inflatable, spherical modules for habitation and scientific research. These modules are partially buried and shielded from cosmic radiation. Adjacent to the inflatable structures is a rover storage and recharging facility. The inflatable modules and rover facility can be seen in figure 5.1.1-1 in the upper right corner.

A lunar soil processing plant producing oxygen is located approximately 5 kilometers from this habitation area. Lunar soil is transported to this plant after it has been collected from a nearby mining site. A launch and landing facility is located within a kilometer of the oxygen plant. The proximity of the launch pad to the processing plant enables oxygen for propellant to be delivered quickly to orbit for use in chemically propelled transfer vehicles. The processing plant and landing pad are located in the upper left corner of the figure.

Power Requirements. A solar photovoltaic (PV) power system with regenerative fuel cells is assumed to meet the power requirements of the initial habitat module (25 to 100 kWe). As the base expands to include scientific experimentation, rover recharging, and soil processing, a nuclear power system becomes the most viable means of meeting the higher power requirements.

The processing plant will be the predominant power load. For the purpose of this study, that requirement takes the form of electrical power for electrolysis of water, following a hydrogen reduction of lunar ilmenite. The thermal energy requirements of the processing plant would also be provided by the nuclear power system through electrical resistance heating. For an oxygen production capability of 25 t/m, the plant would require 740 kWe, or 90 percent of the nuclear system output.

The remainder of the electrical power generated by the nuclear system would be distributed to the habitat and science modules for life support, to the science laboratory for experimentation, and to the rover storage and recharging facility.

Nuclear Power System Design. The nuclear power system is designed with an emphasis on safety and reliability. It is shown in the foreground of figure 5.1.1-1. This conceptual design consists of a 2500 kWe SP-100 reactor coupled to eight free-piston Stirling engines. The reactor is identical to the design currently baselined in the SP-100 program, whereas the Stirling engines replace the thermoelectric power conversion system of the present SP-100 design. Two of the Stirling engines are held in reserve to provide engine backup for dependable power generation. The remaining six engines operate at 91.7 percent of their rated capacity of 150 kWe. The design power level for this system is 825 kWe. The system is modular and can be replicated in increments of 825 kWe to meet higher power requirements.

It would also be possible, and perhaps desirable, to replicate this system design and operate the two systems at reduced power levels to meet the 825 kWe power requirement. If one reactor power system needs to be shut down, the other system could compensate for the loss in power. As power requirements increase, the capacity of the systems could be gradually increased to meet the higher power levels.

The Stirling engines are arranged in a spoked-wheel configuration and share a common heat transport manifold with the reactor. Each engine is equipped with a pumped heat-rejection loop connected to a mercury heat-pipe radiator. The radiator panels are arranged in a vertical configuration and extend radially from the Stirling engines. A thermal apron is placed between the panels to reduce the lunar surface temperature and thus reduce the required radiator area. The total mass of the system, including power conditioning and transmission lines, is 20t.

The reactor is located in an excavated cylindrical hole which provides shielding from gamma and neutron radiation. The use of lunar soil eliminates the need to transport heavy terrestrial shielding materials to the lunar surface. A boral bulkhead with a domed cap maintains a dust-free environment for the reactor.

Safe radiation levels are maintained in all directions around the power system. This allows for flexibility in choosing a reactor site. The excavated shield design also allows for periodic maintenance on the system's radiator panels. For this conceptual design, the nuclear power system has been placed 1 km from the habitation area and approximately 4 km from the processing plant.

A FALL OF MOONDUST

     It was at least two years since Lawrence had been inside an igloo. There was a time, when he had been a junior engineer out on construction projects, when he had lived in one for weeks on end, and had forgotten what it was like to be surrounded by rigid walls. Since those days, of course, there had been many improvements in design; it was now no particular hardship to live in a home that would fold up into a small trunk.
     This was one of the latest models—a Goodyear Mark XX—and it could sustain six men for an indefinite period, as long as they were supplied with power, water, food, and oxygen. The igloo could provide everything else-even entertainment, for it had a built-in microlibrary of books, music, and video. This was no extravagant luxury, though the auditors queried it with great regularity. In space, boredom could be a killer. It might take longer than, say, a leak in an air line, but it could be just as effective, and was sometimes much messier.
     Lawrence stooped slightly to enter the air lock. In some of the old models, he remembered, you practically had to go down on hands and knees. He waited for the “pressure equalized” signal, then stepped into the hemispherical main chamber.
     It was like being inside a balloon; indeed, that was exactly where he was. He could see only part of the interior, for it had been divided into several compartments by movable screens. (Another modern refinement; in his day, the only privacy was that given by the curtain across the toilet.) Overhead, three meters above the floor, were the lights and the air-conditioning grille, suspended from the ceiling by elastic webbing. Against the curved wall stood collapsible metal racks, only partly erected. From the other side of the nearest screen came the sound of a voice reading from an inventory, while every few seconds another interjected, “Check.”
     Lawrence stepped around the screen and found himself in the dormitory section of the igloo. Like the wall racks, the double bunks had not been fully erected; it was merely necessary to see that all the bits and pieces were in their place, for as soon as the inventory was completed everything would be packed and rushed to the site.
     Lawrence did not interrupt the two storemen as they continued their careful stock-taking. This was one of those unexciting but vital jobs—of which there were so many on the Moon—upon which lives could depend. A mistake here could be a sentence of death for someone, sometime in the future.
     When the checkers had come to the end of a sheet, Lawrence said, “Is this the largest model you have in stock?”
     “The largest that’s serviceable” was the answer. “We have a twelve-man Mark Nineteen, but there’s a slow leak in the outer envelope that has to be fixed.”
     “How long will that take?”
     “Only a few minutes. But then there’s a twelve-hour inflation test before we’re allowed to check it out.
     This was one of those times when the man who made the rules had to break them.
     “We can’t wait to make the full test. Put on a double patch and take a leak reading; if it’s inside the standard tolerance, get the igloo checked out right away. I’ll authorize the clearance.”

From A FALL OF MOONDUST by Arthur C. Clarke (1961)

Sample Lunar Base 2

This is from the US Army's report (1959) on Project Horizon about establishing an Army base on Luna by the end of 1966. Apparently the project was not pursued because the US Army could not explain what exactly were the military applications of such a base.

Sample Lunar Base 3

This is from Lunar base synthesis study. Volume 3 - Shelter design Final report, North American Rockwell's study on constructing a lunar base.


Base is composed of eight modules arranged in a closed-loop circular floor plan. Base has 736 cubic meters of space and 232 square meters of floor area. The modules are designed to operate autonomously, but in pairs to improve efficiency. For instance, the three crew modules provide atomospheric and crew services to the lab module, the assembly-recreation module, and the base maintenance module.

The base has an estimated mass of 27,000 kilograms, without supplies.

There are three crew modules. Each houses four crew plus one other major function. Each of the four crew has an individual stateroom with 3.7 square meters of floor. Staterooms have a bunk, desk, chair, and storage closets. The major functions shared in the crew modules are: Command and Control center, Medical facility, Backup galley and backup control center.

The garage module accomodates the prime mover for repair or maintenance. It is also used by the space tug as a shipping container to transport the prime mover (or other mobile unit) to the lunar surface.

The warehouse module is used as a shipping container by the space tug to transport cargo to the base. Then it becomes a general storage module for the base.

The maintenance module provides facilities for the repair and maintenance of all base systems. It has an electronic area, a mechanical area, and a suit area. It also has an EVA port with an airlock large enough to accomodate six spacesuited crew at a time. This inclueds an air shower and multifiltration system to cope with lunar dust. The airlock can connect to the airlock on a prime mover, for shirt-sleeve transfer of crew.

The assembly / recreation module includes the main galley with food preperation and preservation facilities. It also contains a four crew airlock, with dust control. It also can dock to a prime mover for shirt-sleeve transfer.


The base is constructed of lunar base modules. The modules are 9.2 meters long, 4.6 meters in diameter, and have a dry mass of 4,500 kilograms. They have docking ports on each end. Modules are delivered by space tugs and assembled by prime movers.

Sample Lunar Base 4

This is from a Johnson Space Center study focusing on the "wet workshop" concept, re-using the spent fuel tanks as habitat modules. I mean, after all the fuel has been used up, the tanks are not doing anything. Except reducing the payload mass.

Remember that every gram counts, so try to make each gram do double-duty. Every gram you save is an extra gram of payload.

Lunar Lander “HabiTank” Concept

“The Challenge” given to the JSC team was to further explore and refine the concept of the “wet” habitat, namely using the spent propellant tanks as habitable volume after landing on the surface. The Lunar Lander Preparatory Study Team was formed to explore the HabiTank, as it came to be called, its design, its features, capabilities, derived requirements, and interface requirements, and how it might affect the design of the CEV.

“The Vision” was to develop a multifunctional and well-integrated lunar lander system that allowed sustainability and flexibility for landing crew and cargo to explore and establish a human presence on the Moon circa 2020.

The HabiTank Vehicle Concept

During the lunar Apollo missions, living spaces were small, there was no privacy, and the lunar surface stays were very brief.

The novel feature of the HabiTank Lander concept was the ability to dual-use the lander’s two large hydrogen tanks as habitable volumes for a lunar outpost. The use of these tanks offered the capability for long-term human presence to be developed very quickly, and they also offered flexibility to build alternate outpost sites compared to deployment of an entirely new habitat and infrastructure. They also provided easy expansion of the habitable space of the outpost, and maximum utilization of all lander elements.

The team worked out many of the outfitting details of converting the tank components from cryogenic propellant tanks to fully outfitted living and working habitation spaces.

The team first decided that the HabiTanks should be designed and built with their end-state in mind. Rather than optimize the tanks for hydrogen storage, which represented only a small portion of their operational lifetime, they were optimized for their use as habitable elements. This was reflected first in their dimensions. Instead of an optimized cylindrical cross-section, the HabiTanks had a rounded rectangular cross-section, with a width of 2.6 m by a height of 2.9 m by 4.6 m long – each tank providing ~ 25 m3 of volume. For the design to work, an airlock was required to be pre-connected and nestled in between the two large hydrogen tanks. Due to the time required to retrofit a tank into a habitable unit, it was deemed necessary to provide a “Sortie” Hab for missions of 3 to 7 surface days (meaning that the Sortie hab gives the crew a place to live in while they convert the HabiTanks into something habitable).

Each tank had a closed hatch on its aft face that was later used to interconnect the tanks together. They were also hard mated to an airlock with hatchways that were sealed while the tanks contained propellant. The Sortie Habitat that contained much of the equipment was later used to outfit the HabiTanks. The ascent stage of the vehicle was a minimalist design and provided crew access to the Sortie Habitat through a hatchway that had a pyrotechnic separation capability that was activated when the ascent stage departed at end of mission. Up to four crew members could be carried to the surface of the Moon in this lander. Power was provided by fuel cells and solar collection.

Preparing the HabiTank for Human Entry

The design team studied the process required for the conversion of these vessels from cryogenic propellant tanks to fully outfitted living and working quarters. These steps included removing any residual propellant from the tanks, warming up the tanks, pressurizing the tanks with breathable atmosphere, verifying the pressure seal in the airlock/crew quarters vestibule, installing lighting, power and air circulation, disassembling the vertical baffles, installing the environmental monitoring system, alarm system, and communications systems, and activating airflow to the HabiTank.

This process was repeated for each HabiTank with minor variations, driven by the specific items to be outfitted in each one. The concept was to convert each HabiTank into crew quarters, a galley and wardroom area, or other surface support areas such as extravehicular activity and mission operations.

Once the lander had reached the lunar surface, crew or Mission Control personnel could begin to initiate the following steps to make the HabiTanks safe for human entry. First, the propellant tanks were closed off (deadfaced) and sealed from the propellant feed-lines, tank quantity sensors, repress lines, etc. Then the ground initiated pump-out of residual propellant. Next, the ground or crew was to initiate purge of residual propellant vapor. There was to be a time delay of ~13 hours for tanks to thermally condition, after which the internal atmosphere was sampled. Then, N2 was bled into the HabiTanks to establish the correct PPN2. Once this step was complete, O2 was to be introduced into the HabiTanks to establish the proper O2/N2 mix. Once the HabiTank was thermally stabilized and contained a breathable atmosphere, it was possible to begin the transformation from tank structure to outpost Habitation Module. The Pressurized Logistics Module (PLM) was mated to the HabiTanks with extendable inflatable tunnels. (the PLMs were delivered previously to the Lunar surface by an uncrewed cargo flight)

The crew would perform several steps to prepare the HabiTank for habitation beginning with Crew Quarters Module 1. First, the crew would verify the pressure seal in airlock/crew quarters vestibule. Then they would open the equalization valve to equalize pressure between HabiTank and vestibule. When complete, they could open the hatch in the lander airlock, giving access to the airlock/crew quarters vestibule. The crew would then remove the thermal insulation from the vestibule, followed by the HabiTank cover plate. The passageway from lander airlock to HabiTank was then opened.

The crew members then were to install temporary lighting, power, and air circulation fans in the HabiTank so they could work intravehicular activity inside the tank to complete its transformation. The next step was to disassemble the removable sections of vertical baffle 1 and store the baffle plates temporarily in the airlock. They likewise disassembled removable sections of vertical baffles 2 and 3, and also temporarily stored those baffle plates in the airlock. Once the baffles had been removed, the crew needed to verify the pressure seal in the crew quarters to PLM vestibule, after which the crew could open the equalization valve to equalize pressure between the HabiTank and the vestibule. Next, the crew members were to remove the HabiTank cover plate and open the equalization valve to equalize pressure between the HabiTank and the PLM tunnel so that the hatch to the PLM could be opened.

Once the passageway tunnel from the HabiTank to PLM was open, the crew could begin to install the permanent utilities trunk (i.e., power, data, communications, air) in the HabiTank ceiling. Then, they could install the environmental monitoring, alarm, and communications systems, and the PLM airflow could be activated to the HabiTank. Any temporary air circulation fans could be removed. They would then configure the internal power and data cabling, and remove and stow any temporary power.

Next, the crew was to install Ortho-grid outfitting connectors and the wall liners (if applicable – some functional areas may have left the exposed aluminum skin). They could install and activate the permanent ambient lightemitting diode (LED) lighting. Any temporary lighting was removed and set up as task lighting. Next, the crew was to assemble the HabiTank furniture (chair, bed, desk, stowage, counter, table, etc., as appropriate) from the baffle plates temporarily stored in the airlock and fabric and padding stored in the PLM. The crew could position the furniture in designated locations in the HabiTank. Support cables and additional fabric partitions could be installed, and the remaining crew accommodations equipment (e.g., laptops, displays, crew personal items, etc.) were to be unpacked from the PLM and stowed in the HabiTank.

All the system utilities were then checked and verified operational prior to connection of electronic equipment. Upon a successful systems check, the HabiTank crew quarters were ready for occupation. This process was repeated for each HabiTank with minor variations driven by the specific items to be outfitted in each one. The Galley, EVA Maintenance, Geo Lab, Life Science, and Medical HabiTanks would have all also included a water line in their utilities trunks.

To refine the concepts and designs, and the outfitting process, the team built a full-scale mock-up of the HabiTank. By evaluating the mock-up, the team had a better understanding of the various issues that would impact the conversion process from a hydrogen tank to a habitable volume.

Working Through All the Mission Phases

The team also investigated the features of the ascent and descent stages. Using a full-scale mock-up of the ascent vehicle, the team was able to identify requirements and issues relating to crew accommodations, flight communications, ground communications, and mission operations.

The ascent stage avionics hardware and software provided Guidance, Navigation & Control (GN&C) information to enable the crew to land the combined ascent and descent stages on the Moon and support the later rendezvous of the ascent stage with the CEV. Displays and Controls provided the data necessary to control and manage the vehicle through all mission phases. Communications and Tracking equipment allowed the crew to talk to each other and to the ground mission control center.

Strategizing the Outpost Development and Lander Design

The HabiTanks from the spent lander descent stages formed Habitation Modules that could be connected together with the PLM to form a larger lunar outpost. The PLM was pre-integrated with inflatable tunnels and portals to allow connections to the opposite ends for the HabiTank/airlock system. The PLM or utility module served as a logistics module to transport the HabiTank outfitting and was also where the habitation subsystems were integrated and operated. This strategy allowed the outpost to be quickly assembled and become operational earlier. The HabiTanks and airlocks were planned to remain intact on the lander super structure to ensure structural integrity while transporting the entire lander stage to the final outpost location. Four descent stages and two PLMs were to be used to create the required functionality and volume for the outpost to support four crew members during their 180- to 210-day surface operations stay.

The Lander HabiTank concept offered a number of advantages for lunar outpost development and lander design. These advantages included the following:

  • Capability for long-term human presence developed very quickly.
  • If the HabiTank failed on one flight (e.g., could not relocate, or could not be accessed), subsequent flights could provide it with little overall manifest impact.
  • More useful volume (e.g., tanks, airlock, Sortie Habitat, etc.) came with every flight.
  • The HabiTank was not locked into one outpost location – Sortie Landers with keep-alive capability could be deployed at different sites on the lunar surface to support an extended sortie strategy of exploration (“Cabin in the Woods”).

Additional advantages of this lander configuration were:

  • Single descent engine configuration met reliability and redundancy requirements.
  • Spent descent stages did not create a field of impacted debris.
  • Packaging brought the airlock porch close to surface.
  • Good visibility for crew during landing.
  • Propellant feed problems of large tanks mitigated by use of sump tank.
  • Used a minimal ascent stage.
  • Airlock was not thrown away with each flight.
  • Only one common descent style was needed to perform a variety of missions:
    • Crew plus cargo (airlock, Sortie Habitat, HabiTanks)
    • Cargo only (but could carry airlock and HabiTanks, or not, as required)
    • Crew exchange (ascent stage only, no airlock or Sortie Habitat)
Lunar Lander “HabiTank” Concept 2

The “HabiTank” concept converts two of the descent propulsion hydrogen tanks into surface habitation units by pre-integrating an airlock between the two tanks. These tanks are fitted with access ports at each end of the tank that are covered by sealing plates for tunnel attachment during the outpost assembly phase. The overall description of the HabiTank’ lander is a two stage lander with an ascent stage and descent stage (fig 2). The ascent stage is a cylindrical aluminum shell cylinder sized to fit four suited crew members—donning a Mark 3 suit—during the descent landing and ascent to the CEV. It is sized for minimum occupancy duration of a minimum of three hours as dictated by the Constellation Program Office (CxPO). However, this design study feels the ascent stage should have a contingency operations timeline built into the design for up to a range of 8-12 hours pending further studies of abort and rendezvous scenarios. Figure 4 depicts the habitable volumes of the lander concept.

The Ascent Stage (A.S.) is a single engine pressure fed propulsion system with a Low Impact Docking System (LIDS) compatible with CEV (figure 10). The A.S. has three windows (two for landing operations and one for CEV rendezvous proximity operations). The A.S. also has two dual common wall tanks for the liquid oxygen and methane. It has the capacity to carry crew provisions, stowage, flight systems, subsystems, and return the required 100 kg of lunar samples.

The Descent Stage (D.S.) is comprised of the main single dual pump fed liquid oxygen and hydrogen engine and RCS system. It has four LO2 tanks and three LH2 tanks. Two of the tanks are the 2.59 m x 2.89 m x 4.57 m “HabiTanks” while the other tank is the vertically oriented sump tank. The D.S. also consist of the main base frame system, airlock, sortie habitat, two deployable & retractable solar disks, two deployable & retractable radiators, and the landing leg system (Figures 5-9). The Airlock has a deployable dust porch and ramp with railings that provide surface access for the EVA crew. The dust porch will be approximately three feet to the surface.

The A.S. is connected to the Sortie Hab via a pressurized tunnel that is capable of separation before the A.S. departs from the lunar surface (Figures 8 & 9). The separation technique is based on the Shuttle “Super-Zip” concept that initiates the pre-integrate zip cord to expand and break the metallic structural tunnel ring. This separation event occurs prior to the crew’s departure after the hatches on both sides have been sealed shut. One of the concerns during ascent is the damage or destruction of the HabiTanks and descent stage system. For this reason a plume impingement analysis was performed to preliminarily understand the plume interactions with the descent systems. The preliminary analysis indicated by the temperature and pressure impingements that a plume impingement shield is required. The plume shield concept is a series of titanium plates attached to the structural frame and tanks for protection. In addition to the side wall shields a conical shield was placed over the descent engine. This helps direct the flow down and out the bottom of the descent stage. It also protects the engine from creating potentially damaging debris to the tanks and back flow to the ascent engine.

The positioning of the four crewmembers in the A.S. is shown in Figure 16 showing an oblique top-view cutaway of the ascent vehicle cabin and in Fig 16. The two crewmembers in front have windows in front for viewing the lunar surface, and at the top of the cabin for viewing the CEV during docking.

For the transitioning of the IVA suits to EVA suits, the crew and the suits must descend from the ascent vehicle through the connecting tunnel to the Sortie Hab, and finally to the Airlock, as depicted in Figure 18. A pressure sealable hatch is opened at the connecting tunnel to allow the crew access to the crew modules below. A discussion on the suit re-configuration required is presented in the descent vehicle section.

For transitioning the EVA suits back to IVA suits for the lunar ascent and return, the paths are reversed. A pressure sealable hatch is opened at the connecting tunnel to allow the crew access to the ascent module from the airlock and sortie Hab modules below. The hatch is closed and secured before ascent, and separation of the ascent vehicle from the sortie Hab occurs at the tunnel interface. The location of the crew in IVA suits in the departing ascent vehicle is shown in Figure 19.

The lander concept is designed with the outpost end-state in-mind. To design a lander for only a sortie mission only and then try to deliver outpost payloads on it is short sighted. One needs to consider the functional uses, requirements and operations to fully define the lander system. The HabiTank Lander concept has two primary configurations; the crewed lander configuration and the cargo lander configuration. The primary focus of the design effort was on the crewed lander. Figure 20 shows the crewed lander and mass properties summary. Figure 21 shows the cargo lander and mass properties summary.

The lander-packaged configuration was designed to fit in the Cargo Launch Vehicle 8.5 m (27.88 ft) diameter shroud, which has an internal working diameter of 7.5 m (24.6 ft), fig 22. The launch support structure and interface to the Earth Departure Stage and shroud was not designed. The mass of this structural interface will be a mass threat to the overall mass budget. The final report covers the details of the LEO MM/OD risk and EDS shared resources while loitering in LEO for 95- days.

The design team performed mission mode analyses to understand the functional capabilities and shared resources of power, thermal, ECLS, crew space, and avionics during the Trans-Lunar coast (fig 23) and Low Lunar Orbit rendezvous (fig 24). Further analyses will be required to flush out the design impacts on the lander from the Constellation system requirements review, Constellation Architecture Requirements Document (CARD) and CEV system requirements document.

The spent descent stages are reused to assemble an outpost based on the nestled airlock and two HabiTanks to form habitation pods that when connected together with the pressurized logistics module (PLM) forms a larger habitation facility. Based on historical volume trends for long duration space missions and the standards for optimal habitable volume per crewmember, a total pressurized outpost volume may range from 60 – 80 cubic meters per crewmember. The PLM is pre-integrated with inflatable tunnels and portals to allow connections to the opposite ends for the HabiTank/Airlock system. The PLM—or utility module— serves as a logistics module to transport the HabiTank outfitting via a cargo flight and is also where the habitation subsystems are integrated and operate. This strategy allowed the outpost to quickly be assembled and become operational earlier than having to install utility systems in each tank. The HabiTanks and airlocks remain intact on the lander super structure to ensure structural integrity while transporting the entire lander stage to the final outpost location. Four descent stages and two PLMs are used to create the required functionality and volume for the outpost to support four crewmembers during their 180 – 210 day surface operations stay (fig. 25). Environmental protection (radiation, thermal, and micrometeoroid) is provided by an air-beam deployable-rigidized Quonset-style concept. Notionally, the shelter is laid out on the surface, regolith pushed on top, and then the shelter inflated—lifting the shield (with regolith) in place. The shield has “pockets” to keep the regolith from sliding off during inflation. The open-ends are “radiation-closed” by berming regolith at the ends to eliminate “line-or-sight” radiation influx. This would be performed robotically prior to moving the HabiTanks into outpost position. The descent stage landers with tanks intact are moved in their entirety. There are a number of options that were explored—including deployable wheels, use of the JPL Athlete concept, and an independent ARC “MULE” concept that attaches to each leg (requiring for units). This study did not baseline the specific concept to achieve lander movement to the outpost since the intent of the study was to focus on feasibility of retrofitting the tanks into habitable volumes for an outpost. The crew performs the change over from a propulsion tank to Habitat element once the lander is on the surface. The two tanks are converted by removing the excess liquid hydrogen from the tanks into the purge tank and then purging the residual gas by venting it into other tanks or overboard. Once the tanks have been warmed to the appropriate internal temperature and breathable air introduced into the tanks, the crew can begin outfitting and surface operations.

The Sortie Habitat is used as the primary living quarters and as a 2-person sleep quarters during the 7- day sortie mission. A deployable loft area is used to sleep two crewmembers in the upper section of the Sortie Habitat (fig 26). When configured for day operations (fig 27), the Sortie Habitat provides access to the airlock, computer interface to vehicle systems, hygiene and waste collection facilities (with a privacy curtain), meal prep, and stowage access. The Sortie Habitat is extremely limited in internal volume and is not designed for extensive habitation. The purpose of the sortie mission is primarily EVA driven and it is thus expected that the majority of the crew’s waking time will be spent on the lunar surface, outside the habitat.

The HabiTanks are retrofitted into various functional spaces. The concept is to outfit each HabiTank into crew quarters, a galley and wardroom area, and other surface support areas such as EVA and Mission operations. Figure 28 and 29 show conceptual ideas of how the tanks could be retrofitted using acoustic fabric panels and deployable systems.

HABITANK OUTFITTING

The central feature of the HabiTank Lander concept is the ability to use the lander’s two large hydrogen tanks as habitable volumes in the Lunar Outpost. The design team studied the process required for the conversion of these vessels from cryogenic propellant tank to fully outfitted living and working quarters. The HabiTanks are configured from their initial design with their end state in mind. Rather than optimize them for hydrogen storage, which represents only a small portion of their operational lifetime, they are optimized for their use as habitable elements. This is reflected first in their dimensions. Rather than having a cylindrical cross section, the HabiTanks have a rounded rectangular cross section, with a width of 2.59 m and a height of 2.89 m.

Once the lander has reached the lunar surface, crew or Mission Control personnel can begin to initiate the following steps to make the HabiTanks safe for human entry. First, the propellant tanks are closed-off (deadfaced) and sealed from the propellant feed-lines, tanks quantity sensors, repress lines, etc. Then the ground initiates pump out of residual propellant. Next, the ground or crew initiates purge of residual propellant vapor. There is a time delay for ~13 hours for tanks to thermally condition. After which, the internal atmosphere is sampled. Then we bleed N2 into the HabiTanks to establish the correct PPN2. Once this step is complete then we bleed O2 into the HabiTanks to establish proper O2/N2 mix. Once the HabiTank is thermally stabilized, contains a breathable atmosphere, and is mated to a Pressurized Logistics Module (PLM), it is possible to enter the HabiTank and begin the transformation from tank structure to Outpost habitation module. The PLM is mated to the HabiTanks with extendable inflatable tunnels as depicted in figure 30 and 31. This connection process starts with the Crew Quarters unit.

Beginning with Crew Quarters Module 1, the crew will perform the several steps to prepare the HabiTank for habitation. First the crew will verify the pressure seal in Airlock/Crew Quarters vestibule. Then they will open the equalization valve to equalize pressure between HabiTank and Vestibule. When that is complete, they will open the hatch in the lander Airlock giving access to the Airlock/Crew Quarters vestibule. The crew will then remove the thermal insulation from the vestibule. Once the vestibule is clear, the crew will remove the HabiTank cover plate (fig 32). The passageway from Lander Airlock to HabiTank is now open.

The crew will install temporary lighting, power, and air circulation fans in HabiTank. This will allow the crew to work IVA inside the tank to complete the transformation. The next step is to disassemble the removable sections of vertical baffle 1 and store baffle plates temporarily in Airlock. This step is repeated for the other two baffles (fig 33). Once the baffles have been removed, the crew will verify the pressure seal in Crew Quarters to Pressurized Logistics Module vestibule. After which, the crew will open the equalization valve to equalize pressure between HabiTank and vestibule. Next, the crew will remove the HabiTank cover plate and store it temporarily in Airlock. Then they will open the equalization valve to equalize pressure between the HabiTank and Pressurized Logistics Module tunnel.

Now that the passageway tunnel from HabiTank to Pressurized Logistics Module is open, the crew can begin to install the permanent utilities trunk (power, data, comm., air) in the HabiTank ceiling (fig 34). Then they will install the environmental monitoring, alarm, communications systems. The Pressurized Logistics Module airflow is activated to the HabiTank. The crew removes the temporary air circulation fans. They then configure the internal power and data cabling, then they remove the temporary power and stow them. Next the crew installs Install Ortho-grid outfitting connectors and the wall liners (if applicable—some functional areas may leave the exposed aluminum skin). Next they install the permanent ambient LED lighting and activate. The temporary lighting is removed and set up as task lighting. The crew then assembles the HabiTank furniture (chair, bed, desk, stowage, counter, table, etc. as appropriate) from baffle plates temporarily stored in the Airlock and fabric and padding stored in the Pressurized Logistics Module. The crew positions the HabiTank furniture in designated locations in the HabiTank (fig 35). Support cables and additional fabric partitions are installed. The crew then unpacks the remaining crew accommodations equipment (e.g. laptops, displays, crew personal items, etc.) from Pressurized Logistics Module and stow in HabiTank. All the system utilities are checked and verified operational prior to connection of electronic equipment. Then they connect the power and data lines to the electronic equipment and conduct HabiTank systems activation and check out. Upon a successful systems check, the HabiTank crew quarters are ready for occupation (fig 36). This process is repeated for each HabiTank with minor variations driven by the specific items to be outfitted in each HabiTank. The Galley, EVA Maintenance, Geo Lab, Life Science, and Medical HabiTanks will all also include a water line in their utilities trunks.

TECHNOLOGY NEEDS AND DESIGN CHALLENGES

The Lander team identified a number of technology needs and design challenges. The team divided the technology needs into lander and outpost specific needs.

The Lander HabiTank technology needs are the ascent stage main engine development; robotic systems for surface ops; payload unloading & surface transportation; autonomous hazard avoidance and landing; a full-up integrated HabiTank/Airlock/PLM interface testing (seal performance, accessing and conversion of HabiTank, etc.); ascent Stage tunnel separation; and vacuum harden displays (which can piggy back on CEV work).

The Lunar Outpost technology needs are dust mitigation (including dust mitigation development needs to include both ways to prevent dust from entering the habitable environments, ways to manage and remove dust that enter the environment, and dust effects on solar arrays and radiators); radiation protection and the use of unpressurized deployable shelters; medical systems to treat patients in-situ at the outpost; power generation and management systems (specifically regenerative fuel cells, development of ultra-lightweight, thin-film solar arrays, and nuclear power); robotic systems for surface ops (including payload unloading & transportation, and surveying, leveling & surface preparation); and long duration life support (including closed-loop life-support with waste recycling from water, solid waste, or air systems). These are known technology drivers and are technology needs for longterm Outpost operations. Specifically for this concept, developing technologies that are focused on being modular or upgradeable to reuse as much delivered mass as possible from the short duration missions to Outpost class missions).

The sortie habitat life support has a duration similar to previous spacecraft experience, but must be evolvable, must operate in gravity and potentially also in space, and must handle the challenges of lunar regolith contamination and frequent EVA. Dust mitigation is a major design challenge that needs to be addressed with new technology. Waste Collection System design from previous flight capabilities may not be sufficient since the wastes are likely to be left on the lunar surface and the toilet functions will be in a volume eventually incorporated in the Outpost. To avoid duplication of the toilet in the Outpost, some sort of modular or upgradeable design for resource recovery would be necessary.

The lunar Outpost must provide resource recycling capability in the PLMs, but minimize the complexity of interfaces while reusing hardware as much as possible. Closed loop life support is an area where major technology development is still required to mature concepts into technologies that are ready for service in the lunar Outpost. Upgradeable or modular technology that would make best use of the lunar lander components in the Outpost would impose new requirements on the existing concepts.

A single LO2/LH2 descent stage main engine offers benefits and reduces risks by reducing debris damage risks caused by the plume, reducing dry mass and total mass, reducing complexity, and reduced throttling requirements, as compared to 4 engines. A four engine plume causes significant debris to travel up the center of the stage. The main risk for a single engine is the reliability. Advanced technology is required to achieve the necessary reliability for a single engine. The approach could be using redundant pumps as shown or using highly reliable pumps that have significant margin. Technology development is required in this area.

The storage of LH2 on the descent stage during the 95 day LEO loiter requires a vapor cooled shield on the LO2 and LH2 tanks. This vapor cooled shield can be cooled using LH2 and LO2 boil-off that is vented from the EDS. The alternate technology is a GHe loop cooled shield that uses a cryo-cooler.

The Descent stage RCS uses pressure-fed LO2/LCH4 to avoid plume contamination of the surface and to allow simple safing of the system. The alternate technology, MMH/NTO, would remain in the lines after landing and would require heaters to avoid freeze/thaw rupture of the lines. The technologies required for this cryogenic RCS are similar to the ascent stage, and requires developing an engine that provides repeatable pulses and reliable ignition, and developing a cryogenic feed-system using a thermodynamic vent system.

The ascent stage is an integrated main engine and RCS, such that the RCS provides back-up to the main engine in the later part of the ascent burn. The propellants are LO2/LCH4 to enable a pressure-fed system, higher performance, and non-toxic plume. Zero boil-off is achieved by using the sub-cooled property of the propellant at high pressures with a GHe pressurant. The advanced technologies required are a composite over-wrapped aluminum lined pressure vessels, long duration passive cryogenic storage and acquisition, a cold GHe pressurization system, a high performance 1587.6–3402 kg-f LO2/LCH4 main ascent engine with fast start and redundant ignition system, electro-mechanically actuated valves, and a cryogenic RCS that is similar to the descent stage RCS. The LO2/LCH4 RCS requires a similar technology development and the descent RCS. The highly reliable main engine ignition is achieved by redundant igniters that are of different type, such as spark, pyrotechnic, glow-plug, etc. The main engine thrust of 3402 kg-f is only required if commonality with CEV SM is maintained, otherwise a minimum of 1587.6 kg-f will work.

SUMMARY AND CONCLUSIONS

The Lunar Lander study team designed the corresponding subsystems and developed a number of products during this study. The details of these subsystems and products are documented in the ‘Lunar “HabiTank” Lander Element Conceptual Design Report,’ JSC-63600.

The Lander HabiTank concept offers a number of advantages to the strategy of an outpost development and lander design. These advantages are four, or more, fewer heavy-lift launches needed to get to same Outpost end state. This is approximately 38,555 kg less accumulated mass taken to lunar surface to get to Outpost end state. Therefore, the capability for long-term human presence is developed quickly and the flexibility of creation of alternate Outpost sites compared to deployment of an entirely new habitat and infrastructure. The outpost layout with closed loops of pressurized tanks is failure tolerant; is flexible to easy expansion of habitable space of the Outpost; and makes maximum utility of all lander elements. With this approach much less hardware is discarded—thus a smaller lunar junk yard. In addition, it makes maximum utility of airlocks, has good redundancy, and does not throw away hardware with each flight. If a HabiTank has a mission failure on a flight (e.g., cannot relocate, or cannot access) subsequent flights can provide the replacement with little overall manifest impact. Another advantage is that more useful volume comes with every flight (tanks, airlock, sortie habs etc.) and is not locked into one Exploration or Outpost concept. Sortie Landers with keep a live capability can be deployed at different geographical sites on the lunar surface to support an extended sortie strategy of exploration (“Cabin in the Woods”).

A specific advantage to this lander configuration is a single descent engine configuration meets reliability and redundancy requirements; spent descent stages do not create a field of impacted debris; packaging brings airlock porch close to surface; it has good visibility for crew during landing; propellant feed problems of large tanks are mitigated with sump tank strategy; it uses a minimally-sized approach Ascent Stage (separation of A.S and airlock, so the airlock is not thrown away with each flight); only one lander platform/vehicle is needed to achieve a variety of missions; the outpost is achieved with crew and cargo lander volumes (Airlock, sortie Hab, HabiTanks).

Sample Mars Base 1

MARS ICE HOME

When astronauts set foot on Mars, they may stay for months rather than days as they did during Apollo missions to the moon. The surface of Mars has extreme temperatures and the atmosphere does not provide adequate protection from high-energy radiation. These explorers will need shelters to effectively protect them from the harsh Martian environment and provide a safe place to call home.

For researchers at NASA’s Langley Research Center in Hampton, Virginia, the best building material for a new home on Mars may lie in an unexpected material: ice.

Starting with a proposed concept called “Mars Ice Dome,” a group of NASA experts and passionate designers and architects from industry and academia came together at Langley’s Engineering Design Studio. The project was competitively selected through the Space Technology Mission Directorate’s (STMD) Center Innovation Fund to encourage creativity and innovation within the NASA Centers in addressing technology needs. This is just one of many potential concepts for sustainable habitation on the Red Planet in support of the agency’s journey to Mars.

“After a day dedicated to identifying needs, goals and constraints we rapidly assessed many crazy, out of the box ideas and finally converged on the current Ice Home design, which provides a sound engineering solution,” said Langley senior systems engineer Kevin Vipavetz, facilitator for the design session.

The team at Langley had assistance in their concept study, as a collaborative team from Space Exploration Architecture and the Clouds Architecture Office that produced a first-prize winning entry for the NASA Centennial Challenge for a 3D-printed habitat (Mars Ice House) played a key role in the design session.

The “Mars Ice Home” is a large inflatable torus, a shape similar to an inner tube, that is surrounded by a shell of water ice. The Mars Ice Home design has several advantages that make it an appealing concept. It is lightweight and can be transported and deployed with simple robotics, then filled with water before the crew arrives. It incorporates materials extracted from Mars, and because water in the Ice Home could potentially be converted to rocket fuel for the Mars Ascent Vehicle, the structure itself doubles as a storage tank that can be refilled for the next crew.

Another critical benefit is that water, a hydrogen-rich material, is an excellent shielding material for galactic cosmic rays – and many areas of Mars have abundant water ice just below the surface. Galactic cosmic rays are one of the biggest risks of long stays on Mars. This high-energy radiation can pass right through the skin, damaging cells or DNA along the way that can mean an increased risk for cancer later in life or, at its worst, acute radiation sickness.

Space radiation is also a significant challenge for those designing potential Mars outposts. For example, one approach would envision habitats buried underneath the Martian surface to provide radiation shielding. However, burying the habitats before the crews arrive would require heavy robotic equipment that would need to be transported from Earth.

The Ice Home concept balances the need to provide protection from radiation, without the drawbacks of an underground habitat. The design maximizes the thickness of ice above the crew quarters to reduce radiation exposure while also still allowing light to pass through ice and surrounding materials.

“All of the materials we’ve selected are translucent, so some outside daylight can pass through and make it feel like you’re in a home and not a cave,” Langley Mars Ice Home principal investigator Kevin Kempton said.

Selecting materials that would accomplish these goals was a challenge for materials experts.

“The materials that make up the Ice Home will have to withstand many years of use in the harsh Martian environment, including ultraviolet radiation, charged-particle radiation, possibly some atomic oxygen, perchlorates, as well as dust storms – although not as fierce as in the movie ‘The Martian’,” said Langley researcher Sheila Ann Thibeault.

In addition to identifying potential materials, a key constraint for the team was the amount of water that could be reasonably extracted from Mars. Experts who develop systems for extracting resources on Mars indicated that it would be possible to fill the habitat at a rate of one cubic meter, or 35.3 cubic feet, per day. This rate would allow the Ice Home design to be completely filled in 400 days. The design could be scaled up if water could be extracted at higher rates.

Additional design considerations include a large amount of flexible workspace so that crews would have a place to service robotic equipment indoors without the need to wear a pressure suit. To manage temperatures inside the Ice Home, a layer of carbon dioxide gas would be used as in insulation between the living space and the thick shielding layer of ice. And, like water, carbon dioxide is available on Mars.

It’s important, Kempton said, for astronauts to have something to look forward to when they arrive on the Red Planet.

“After months of travel in space, when you first arrive at Mars and your new home is ready for you to move in, it will be a great day,” he said.

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