FINAL PAPER

Scalable Lunar Ice Propellant Manufacture Through Modularity
RASC-AL 2016: Lunar Ice Trap ISRU Mining, Processing, and Storage
Infrastructure
University of Minnesota – College of Science & Engineering Team
John Weyrauch (Faculty Advisor)
William Garrard, Ph.D (Faculty Advisor)
Alexander Halaszyn
Karl Thompson
Matthew Eller
Mike Wang
Date of Submission – June 2nd, 2016

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1 Introduction
As we go forward in our efforts to expand
our presence in the solar system, the Moon
will serve as a valuable testbed for
complicated deep-space technologies, and
most importantly as a fuel source for
missions in our solar system and beyond.
As the late space visionary and author
Robert Heinlein stated, “Once you get to
Earth orbit, you’re halfway to anywhere in
the solar system.” Much larger useful
payloads can be packed for the journey if
the fuel is already there waiting to be used.
Therefore, the objective of this program is
to construct an autonomous fuel production
facility on the surface of the Moon. This
facility will not only drastically reduce
costs of future exploration missions, but
will also serve as an important stepping
stone for human colonization of Mars.
Our mission architecture enables
access to huge, untapped in-situ natural
resources through the use of small,
interchangeable structures supported by
autonomous rovers to mine water from the
ice-rich regions of the Moon. These
structures produce electricity, extract and
liquefy oxygen and hydrogen from the
lunar regolith, store these products in
chilled tanks, and control the operation and
optimization of mining activities. The base
functions have been grouped together into a
small number of different structures in
order to simplify base setup, mitigate risk,
and facilitate maintenance. Autonomous
rovers, equipped with interchangeable
toolsets, are responsible for setting up base
components, scouting areas of interest for
water-ice concentrations, and digging and
storing regolith for transportation to ice
processors. Each ice processing unit
contains a three-stage grinder that breaks
the collected regolith into fine particles.
The crushed regolith passes through several
stages of heating in order to extract its water
content and mineral-fixed oxygen, which in
turn is inserted into a high temperature
electrolysis system to split the water into
hydrogen and oxygen gases. Meanwhile,
excess heat is recycled to heat more
regolith. The product gases are
subsequently dried, liquefied, and stored in
cylindrical tanks that are equipped with
multi-layer insulation and active cooling
mechanisms capable of achieving long-
term zero boil-off. The base structure is
transported from lunar-transfer-orbit to the
lunar surface by a reusable tug.
Our design is entirely modular and
scalable in a way that reduces business and
technical risks while increasing mission
flexibility and leveraging economies of
scale to reduce manufacturing costs. The
early phases of the mission will be devoted
to prospecting for water-ice and
demonstrating rover and modular sub-scale
fission power system technologies. The
later phases will focus on initializing the
production and storage of propellants
followed by a steady increase of operations
until the annual production goal is met.
2 Mission Overview
The lunar base will make use of small
interchangeable structures supported by
autonomous rovers to mine water from the
ice-rich regions of the Moon. These
structures will produce electricity, extract
and liquefy oxygen and hydrogen from the
lunar rock, store these products in chilled
tanks, and control the operation and

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optimization of mining activities. These
functions have been grouped together into a
small number of different structures in
order to simplify base setup and
maintenance. The rovers have access to
detachable toolsets that can be used to
sample regolith, assemble base structures,
or gather water ice. Tools will wear out and
break, so these toolsets have been designed
to be replaceable. These toolsets can also be
attached in different combinations by using
an innovative universal connection port
found on all rovers and structures.
Initially, the base will consist of the
minimum number of structures and rovers
needed to begin the mining operations. This
will be the most crucial phase of the
deployment, as there will be few spare parts
at this time. However, in a year, enough
rocket fuel will have been produced and
stored by the initial set of base equipment
to allow for the refueling of the tug.
The Tug is a reusable space truck
with very powerful engines designed to
bring structures and rovers to the base from
orbit. When new structures and rovers are
launched from the Earth, they will not be
given the fuel necessary for slowing down
and landing, only for speeding up away
from Earth and being sling-shot around the
Moon. This means that larger payloads can
be sent with each launch. The Tug, fueled
by propellants made locally on the Moon
rather than carried up from Earth, launches
from the Moon base, catches up to and
docks with these extra-large payloads,
slows them down, and brings them safely to
the base.
To maximize modularity of base
components, a universal interface will be
employed for all transfer lines, power
transmission lines, rover toolsets, and
grapple points on structures. We call this
the Adapter for Communications, Cryogen,
and Electrical Power Transmission
(ACCEPT). They will have RFID tags that
will be able to read by the tugs
communication system and allow for the
tugs to know exactly what port they are
looking at and where it is in the inventory.
As well as pull up maintenance reports on
the component connected to the ACCEPT
port.
Figure 1. Two Base Units in Operation

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3 Operations Timeline and Mission
Schedule
The first phase of our timeline is research.
By 2023, all components of our base below
a TRL of 7 (flight test readiness) must be
developed into test-ready hardware.
Between 2023 and 2024, a scout mission
will be sent to the Moon’s South Pole as
part of the second phase of our timeline.
This scout missions will launch on Falcon
9 rockets and will contain one rover and one
fission power plant, and will use the same
avionics system as the Tug for landing. This
test will examine the capabilities of the
rover, power plant, and avionics system. In
the meantime, a completed test Tug will
launch in 2024 on a Falcon 9 to LEO, where
its capabilities will be examined in
maneuverability and durability tests
(similar to the Apollo 9 mission for the
Lunar Module). This makes for a total of 2
scout missions.
In March of 2025 when the moon is
near perigee, the third stage of our timeline
will begin with the launch of two cargo
pallets (one base unit). These two launches
will occur on Falcon 9 rockets. After their
4-day transit to the moon, the cargo pallets
will burn to enter their polar Lunar Parking
Orbit. As soon as possible following these
launches will be the launch of the first true
Tug on a Falcon Heavy rocket. The cargo
pallets can remain in their holding orbit
around the moon indefinitely, in case of
delays in the launch of their partner pallet
or the Tug.
One year later, in March of 2026,
two more Falcon 9 launches will take place,
sending two more cargo pallets to the
moon. By March, the Tug will have
refueled from the base’s production. Once
each pair of cargo pallets have entered their
holding orbits, the Tug will launch from the
moon, intercept the pallets, and land them
back at the base, in a mission lasting 12.6
hours. Each such cargo resupply mission
will increase the base’s ability to produce
and store propellant.
The fourth phase of our timeline
will begin in March of 2027, with the
launch of a second Tug to mitigate tug
failure, and 2 more cargo pallets. From this
point on, the base will be producing surplus
fuel for other missions. Cargo resupply
missions will continue to launch every 6
months, increasing the production
capabilities of the base until it reaches 100
metric tons per year in 2035.
4 Project Budget
In order to ensure the feasibility of such a
large-scale endeavor, a full project budget
analysis was performed using NASA’s
Cost Estimating Handbook (CEH) [1]
and
the NASA/Air Force Vehicle Level Cost
Model (VLCM) [2]
. The models used were
implemented over different years, and so
had differing values of constant year
dollars. These were scaled to 2016 dollars
using the inflation indices provided by the
FY13 NASA Inflation Tables.
The analysis focused primarily on
the costs of systems research, development,
production, launch, and support. In phase 1
of the mission, which extends from 2016 to
2023, the biggest expenses come from the
research and development of key base
components. The orbital tug is the leading
expense with approximately $1.3 Billion

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over 8 years, followed by the mining rovers
with almost $400 Million in required
funding. Overall, it’s estimated that the
total cost of this phase will be almost $2.45
Billion. Phase 2 of the mission will focus
primarily on system testing and technology
demonstration before large-scale system
production starts. It will extend from 2022
to 2025, and will have an estimated overall
cost of $1.17 Billion. The main cost drivers
in this phase are the development and
production of the first orbital tug and the
first base unit as well as required testing
equipment, and launch vehicles. Phase 3 of
the mission will then begin in 2025 with the
production and launch of four enhanced
base units over two years with the main
purpose of producing enough fuel to power
the tug for it to be able to launch from the
lunar base, intercept incoming cargo pallets
carrying additional base units in High
Lunar Orbit, and bring them back to be
deployed at the base. The phase duration is
18 months, and its total cost is estimated to
be $2.31 Billion. Finally, phase 4 of the
mission will be geared towards ramping up
the base’s production levels until the
100MT goal is met. The phase is estimated
to cost $7.55 Billion over the course of 9
years from 2027 to 2035.
Because our base setup is so
modular and each launch is nearly identical,
recurring manufacturing costs were
discounted using an 85% learning curve, as
is typical for the aerospace industry [1]
. The
mission is projected to have a total cost of
about $13.5 Billion from 2016 to 2035 with
an annual budget margin of 20%.
Figure 2. Breakdown of Budget per Fiscal Year
Figure 3. Mission Budget

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A study conducted by NexGen
Space LLC, entitled “Economic
Assessment and Systems Analysis of an
Evolvable Lunar Architecture that
Leverages Commercial Space Capabilities
and Public-Private-Partnerships” [3]
estimated the cost of a similar architecture
to be about $40 Billion (+/- 30%).
However, their architecture was designed to
produce $200MT a year, accommodate
human astronauts, and relay the propellant
to lunar orbit. Hence, our estimates seem to
be reasonable given the capabilities of our
base and the scope of our analysis.
5 Component Breakdown
5.1 Orbital Tug
The Tug is a spacecraft designed for
ferrying cargo pallets from a polar Lunar
Parking Orbit to the lunar surface. The
vehicle consists of tanks for liquid
hydrogen and oxygen fuel, a RocketDyne
RL10-C1 engine, landing legs, attachments
for cargo pallets, RCS thrusters, and an
avionics/communications bay. The tanks
are spherical and made of 10cm thick multi-
layer insulation, and have the capacity for
up to 9000kg of propellant. No active
cooling system is necessary due to the short
duration of the Tug’s primary mission (12.6
hrs.) and the thick insulation. The Tug’s
main engine is capable of producing 102
kN of thrust, more than enough for the
thrust-intensive phases of orbital insertion
and deorbit. The four landing legs are
folded up during the Tug’s initial launch
from Earth, in a manner similar to the
Falcon 9’s legs. These legs then unfold
upon the jettison of the fairing. There are
four attachments for the two cargo pallets
that the Tug can carry, two on opposite
sides of the vehicle, with one upper and one
lower in each pair. The attachments are
designed so that the tug must approach the
cargo pallets tail-first from above; this
arrangement allows the pallets to easily
detach through gravity when on the lunar
surface. The RCS thrusters run on
compressed hydrogen boil-off from the
liquid hydrogen tank. For communications,
the Tug uses a Unified S-band microwave
antenna, the same kind used on Apollo and
the ISS.
The Tug will be launched from
Earth on a SpaceX Falcon Heavy, pre-
loaded with full tanks. Trans-lunar injection
will be provided by the Falcon Heavy
second stage. Upon arrival at the moon (at
pericynthion), the Tug will burn to enter
Lunar Parking Orbit. Two cargo pallets will
already be there, having been launched
earlier by Falcon 9 rockets. The launch of
the Tug will be timed so that the Tug and
cargo pallets will be in phase while in Lunar
Parking Orbit. Once there, the Tug will
slowly dock with the cargo pallets. Any
boil-off that occurred during the transit to
Figure 4. Main components of the Orbital Tug

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the moon will be used as propellant for the
RCS thrusters during docking maneuvers.
Once docking is accomplished, the Tug will
first burn to enter Low Lunar Orbit, and
then deorbit to land on the lunar South Pole.
Range finding for landing will be
accomplished with laser altimeters.
Table 1: Characteristics for the Orbital
Tug
5.2 Cargo Pallets
The cargo pallets are similar in shape,
purpose, and capability to JAXA’s HTV
and ESA’s ATV. Each pallet possesses one
SpaceX SuperDraco engine, with 600 kg
each of dinitrogen tetroxide and
monomethylhydrazine propellant. The total
weight of each cargo pallet is 3600 kg with
fuel, meaning that the total weight that the
Tug must bring down from lunar orbit is
6000 kg. However, unlike the HTV and
ATV, the cargo pallets are not pressurized
and have no outer skin. Instead, an
exoskeleton frame surrounds and supports
the unpressurized cargo.
Figure 5. Two Cargo Pallets attached to the
Orbital Tug
Each cargo pallet will be launched
on a reusable Falcon 9, which will also
provide the cargo pallets with trans-lunar
injection. The cargo pallets will follow a
trajectory identical to the one the Tug
follows on its initial launch. Once at
pericynthion near the moon, the cargo
pallets will burn to enter Lunar Parking
Orbit. There they will await the Tug, which
will deorbit them and bring them down to
the lunar surface.
Figure 6. Orbital Maneuvers in the Moon's
Vicinity
Quantity name Quantity
value
Quantity
units
Total mass 10000 kg
Structure mass 2000 kg
Propellant mass 8000 kg
LH2 tank total
diameter
3.48 m
LO2 tank total
diameter
2.54 m
Diameter 4.6 m
Height (legs
unfolded)
8.4 m

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In Figure 6, cargo pallets are shown
on their incoming lunar transfer orbit, about
to perform a burn at pericythion to enter
lunar parking orbit. The tug is shown in its
low lunar orbit, about to perform a burn at
pericynthion to enter lunar parking orbit.
The tug and pallets will arrive at
pericynthion isochronically.
5.3 Autonomous Rovers
Many of the functions of our base require
some degree of mobility. To provide the
ability to do general base maintenance,
setting up and building the base, finding
locations of the ice, and collecting the ice
these tasks will be completed by a modified
version of NASA’s Regolith Advanced
Surface Systems Operations Robot
(RASSOR) project (TRL 4), a robotic rover
that has demonstrated itself to be very agile
and multifunctional [4]
. The rover based on
this project will be enlarged and given two
ACCEPT ports, one fore and one aft so it is
able to, recharge it’s Hydrogen fuel cells,
attach multiple tools sets, or connect to
other rovers. There will be three different
tool sets with which to outfit a rover
chassis. 1) A manipulator arm for
construction and maintenance, 2) A self-
contained scouting tool based on the rover
tools in NASA’s Construction and
Resource Utilization eXplorer CRUX
(Construction and Resource Utilization
eXplorer) project to build 3_D maps of the
subsurface of the crater [5]
, and 3) A set of
counter-rotating regolith collection drums
based on the latest RASSOR designs. All
rovers will use a LIDAR system for precise
imaging in the dark crater as well as
multiple Ultra-Wide Band (UWB) antennas
for communication, location, and a ground
penetrating radar.
We chose a modular version of the
RASSOR 2 because in the absence of
routine maintenance, whichever mobility
solutions we employ will need to have
replaceable parts. It is known that lunar
dust, composed of unweathered silicate
shards, is highly abrasive and liable to
severely wear exposed joints [6]
. Activities
requiring part actuation have been
consolidated where possible to better
facilitate replacement and modularity.
Therefore, the scouting of resources, base
construction and maintenance, and the
collection and transportation of regolith
will be accomplished by a multi-use rover
platform. That is able to swap out tool sets
so when one tool set is damaged an entirely
new Rover isn’t needed.
The tools in the scouting toolset
based on CRUX are a drill that can acquire
samples, a borehole neutron probe, a
thermal conductivity and diffusivity probe,
a mechanical properties probe, an electrical
properties probe, a down-hole camera and a
thermal evolved gas analyzer. These tools
with the UWB ground penetrating radar the
Figure 7. Rover Capability by Interchangeable
Toolsets

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rover to entirely characterize and map the
crater’s regolith e.g. giving three
dimensional data on water concentrations,
grain sizes, mechanical and electrical
properties. From this data, the rovers will
optimize pathing and mining activities for
the fastest, most reliable acquisition of
optimally ice-rich lunar regolith.
The manipulator arm will allow the
movement of base objects as well as
remove and replace parts that are expected
to fail over time. When moving large base
objects, rovers will be able to connect to
other rovers for additional carrying
capacity. The manipulator arms will also
allow the rovers to unload the cargo pallets.
A major issue on the lunar surface is
the sharp dust the will be turned up when
anything moves across regolith. To combat
this each rover has a microwave emitter that
uses the Iron rich properties of lunar
regolith to sinter the regolith into a solid
surface [7]
. This process will be used to
build roads to ice rich locations to minimize
dust damage to the Rovers. Also the
microwave emitters will use multiple layers
of sintered regolith to build a landing pad [8]
so the tug won’t kick up massive amounts
of dust and cause dust damage to rovers and
base structures.
The Ultra-Wide Band (UWB)
communications setup allows for high
speed simultaneous communications with
multiple devices even in high-noise
environments while allowing for good error
checking. Placing UWB antennas on base
structures will provide a crater wide
location system accurate to within 20cm [9]
.
Both the communications and location
systems are benefitted by UWB’s ability to
pass through most obstacles. The ability to
pass through obstacles also gives it the
ability to operate as a low powered ground
penetrating radar for scouting for ice.
Another advantage of using a UWB
communication system is by placing RFID
tags onto ACCEPT ports the UWB
antennas can track them close by with sub
inch precision. With some engineering and
research these tasks can be implemented by
a small number of antennas saving on
weight and complexity.
Figure 8. Rovers Moving a Reactor
Figure 9. ACCEPT Universal Port Connector

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5.4 Power Generation, Storage, and
Transmission System
Base operations require considerable
electrical power generation in a region of
the moon that receives no exposure to solar
radiation. We have confronted this
challenge through the implementation of
NASA’s KiloPower nuclear reactors (TRL
4) [10]
. These particular fission power
systems (FPS) are designed to be modular
and scalable, key advantages over the only
other design of similar maturity, NASA’s
SAFE-400 [11]
. Although a single SAFE-
400 would be more than capable of
sufficiently powering our fully operational
base, this reactor would require a special,
individual launch and delivery system as it
would be too massive to carry along with
the other base structures. Furthermore, our
ice processing structures require substantial
inputs of thermal energy to produce
propellant at the efficiencies necessary for
sustained base operations. Were this
thermal energy to be derived from a single
source, the logistics of thermal transport
would introduce considerable complexity
in base design. Finally, without distributing
the generation of electrical power among
many units, the FPS becomes the single
greatest point of failure among all systems
of our mission architecture.
Current research in the KiloPower
program has been directed to develop
individual systems which range between
4.3 kW and 43.3 kW, with specific power
mass per watt increasing with increasing
FPS capability [12]
. Our base will utilize
FPSs capable of producing up to 15 kW
each. These FPS units will provide a
constant, reliable supply of power that,
when not being used, charge backup fuel
cells onboard storage and processing
structures which are discharged during
times of peak load. FPS units contain
fissionable U-235 fuel, which only releases
radiation while under bombardment by a
neutron beam. All such units will be
connected to the base via the ACCEPT
interface and may be attached to any
available rover, structure, or tug port.
Each FPS should be capable of providing
power to 1.5 units of base operations.
Therefore, for every three sent to the lunar
surface, a third will serve as a redundant
source in case of failure. Each manifest of
additional base structures will include one
FPS to power the next increment of base
operations as well as to increase the
redundancy of the overall system
generation capacity. Further, economies of
scale will reduce the overall cost of the
single most expensive component of the
base, the Fission Power System.
5.5 Ice Processing System
The mine must separate water into
hydrogen and oxygen. The same nuclear
reactors that power our mine also generate
waste heat which can be used to run the
Figure 8. The Base’s 15kW Nuclear Reactor

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much more efficient High Temperature
Steam electrolysis (TRL 3). A base able to
meet production goals will need 19
processors. Each processor has an
approximate weight of 400 kg and is able to
produce 1 kg of propellant an hour using
3.5kW of electrical power and 2.1 to 3.2kW
of thermal energy depending on regolith
concentrations. 19 processors operating
with an estimated 80% up time would
produce 100 tons of propellant in a year
meeting the goals of the project.
The ice processor is made up of two
sections that can be taken apart by using
ACCESS ports so filters can be accessed.
The first section is the mixture section
where both there is both a mixture of
regolith and ice. The second area is for
when the water has been separated from the
regolith. The ice processor will works by
the RASSOR with an excavation drum
filled with an ice/regolith mix empties the
drum into a hopper that funnels the mixture
into the ice processor. The first stage of the
processor is a pulverizer that insures that all
regolith is in dust to pebble sizes. The
mixture falls past an open sliding door, into
the heating chamber. Once all of the
mixture is in the heating chamber the
sliding door closes and the mixture is
heated turning the water to vapor. As the
water turns to vapor it passes through filters
to keep out any regolith and enters the water
section of processor. Once all the water has
been released a door on the bottom of the
heating chamber opens dumping the waste
regolith below the processor, where is will
be picked up by a rover.
After passing through the filters, the
pure steam is then passed into a heat
Figure 9. Flow Diagram of Ice Processor
Figure 10. Rover Removes Waste Regolith from
Processor

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exchanger that heats and pressurizes the
cool steam from hot steam that needs to be
cooled to be stored. The now warm steam is
passed into another heat exchanger that
uses the extremely hot coolant from the
nuclear reactor to bring the steam to 850°K
and 5MPa. It is then passed into four stacks
of solid oxide electrolyzer cells that are
removable and replaceable using the
ACCESS ports, each stack made from 5
cells. As the steam passes through the
electrolysis stacks the Oxygen is pulled
from the steam and passes through the
electrolyte separating the Pure Oxygen
from the hydrogen and steam mixture.
After the electrolysis stacks the Oxygen
goes through the first heat exchanges giving
heat back to the system, finally the Oxygen
goes to a cryocooler that cools the Oxygen
for storage. The Hydrogen steam mixture is
also passed through a heat exchanger giving
heat back to the system. Then the mixture
goes into a separator where the Hydrogen is
separated from the water. The Hydrogen is
passed into a cryocooler to be cooled to
temperatures for storage and transport
through pipes. The water that is left is
routed back into the start of the electrolysis
process.
A research paper entitled:
“Combined H2O/CO2 Solid Oxide
Electrolysis for Mars In-Situ Resource
Utilization” [13]
estimates that using the
same technology on Mars to make O2 from
CO2 it would take 370kg and 160L of
machinery to produce 1 kg of O2 in an hour.
As the paper is making its estimates for
using High Temperature Steam Electrolysis
on Mars in an atmosphere with CO2 it is also
using a Sabatier reactor to make methane
while our system has no use of a Sabatier
reactor but need additional weight from the
pulverizer. From this estimate we will
assume that each processor will weigh
400kg and be able to produce 24 kg of
propellant per day. The thermal
requirements are calculated by the energy
needed to bring the ice/regolith mixture up
to 100 to bring all materials up to 100°C,
then from there the water up to 850°K and
5MPa.
5.6 Cryogenic Propellant Storage
and Management System
Effective storage of liquefied propellants is
arguably one of the most critical aspects of
our lunar base. Upon examination of all
potential challenges to our mission plan, we
concluded that eliminating propellant boil-
off in storage should be our highest priority.
To achieve this goal, our proposed
cryogenic storage system configuration
utilizes passive thermal control
technologies in the form of low
conductivity structures, multi-layer and
spray-on foam insulation, as well as
pressure control, and active thermal control
systems to maintain propellant storage for
long periods of time without venting[14]
.
Such a system would not only be crucial for
the success of our mission, but would also
Figure 11. Rover Removing a Filter

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serve as an important technology
demonstration for future Mars missions.
The base’s cryogenic propellant
storage and management system (CPSMS)
consists of two main components: the liquid
hydrogen storage and management
subsystem and the liquid oxygen storage
subsystem. Both subsystems receive
electric power from the nuclear power
generator and propellants from ice
processors through the base’s network of
transfer lines that connect to the ACCEPT
universal ports attached to the sides of each
unit. Once connected to the rest of the base
unit, the storage subsystems are designed to
keep their respective cryogen below
saturation temperatures with zero net boil-
off (ZBO).
Cooling the hydrogen to prevent
boil-off is critically important, and doing so
over the entire mission introduces a
significant engineering challenge[15]
. The
liquid hydrogen storage subsystem is
composed of an Aluminum 2219
cylindrical cryogenic tank with 50 layers of
self-supporting multi-layer insulation
(SSMLI), a broad area cooling (BAC)
shield and a single stage turbo-Brayton
cryocooler[16]
. SS-MLI was chosen instead
of the conventional MLI because of its
improved thermal performance per layer,
lower estimated fabrication and installation
cost as well as its predictable and repeatable
performance. In addition, integrating the
cryocooler and the tube-on-tank BAC
shield [17]
, where a tubing loop is attached
directly to the outer tank wall, helps greatly
to intercept some of the external heat before
it reaches the tank.
The maximum storage capacity of
the 3.1 x 9 m, 350 kg liquid hydrogen
storage unit is 1.25 MT. This capacity was
chosen to meet the tug fueling needs in
phase 3 in conjunction with propellant
production capabilities. As a result, only 12
storage units would be sufficient to store
the approximately 15 mT of liquid
hydrogen required for a total storage of 100
Figure 12. Liquid Hydrogen Storage Subsystem

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mT of propellant with a mixture ratio of 6:1.
However, accounting for potential loss of
individual units either in launch or in transit
as well as potential operational failures over
the course of mission timeline, 20 total
units are tentatively planned for production
and launch in phases 3 and 4 of the mission
between 2025 and 2035 until the annual
production goal of 100 mT of propellant is
met.
Liquid oxygen storage subsystem,
on the other hand, relies on the same
passive thermal control technologies
employed in its liquid hydrogen
counterpart, but has no active thermal
control component. Upon reviewing
literature on the general conditions in
craters in the Lunar South Pole and based
on data collected by NASA’s Lunar
Reconnaissance Orbiter Diviner Lunar
Radiometer[18]
, it’s estimated that the
average temperatures in South Pole craters
range from 35-70K. These temperatures fall
well below liquid oxygen’s boiling point of
90.19 K, hence the use of a cryocooler is
deemed unnecessary to achieve long-term
ZBO in this case. The subsystem is 2.2 m in
diameter, 4.6 m in height, weighs
approximately 130 kg, and is capable of
holding up to 7.5 MT of liquid oxygen.
Similar to the case with liquid hydrogen
storage subsystem, 20 total units are
planned for production and launch in order
to decrease overall mission risk and
increase system redundancy.
Figure 13. LRO Lunar South Pole Average
Temperature Map
Figure 14. Liquid Oxygen Storage Subsystem

14 | P a g e
6 Risks and Failure Modes
The failure modes of the system are mostly
related to rover operations, nuclear reactor
safety mechanisms, the structural integrity
of the liquid propellant storage tanks, and
loss of a tug. The failure mode with the
highest impact was determined to be a
contained, full-snuff meltdown of a nuclear
reactor. All electrical power output would
cease, as would the transfer of thermal
energy to the attached ice processing
structure resulting in significant electrolysis
efficiency. Such an occurrence would be
detected using internal error reporting
hardware and mitigated through the
utilization of multiple small reactors.
Furthermore, due to the relatively small
scale of the reactors and the modularity of
the structures, a replacement reactor could
be delivered to the moon as part of a re-
configured cargo manifest returning the
base to optimal performance. The second
failure mode in terms of risk priority is the
over-pressurization of cryogenic propellant
storage tanks, which could result in the
rupture of the tanks. This would be detected
by a comparative analysis of tank pressure
and temperature sensor data, and mitigated
by venting the excess boil-off into a
recovery mechanism. Another high-impact
failure mode is the obstruction of rover
visual sensors by the accumulation of lunar
dust, resulting in partial or total suspension
of propellant production operations. Such a
failure mode would be detected by a rover
vision test on a standard piece of equipment
and mitigated through the use of magnetic
dust repellant or if severe possible gentle
expulsion of excess LOX over the sensor.
The loss of a tug is comparatively low-
impact, because such a loss would only hurt
the base’s ability to expand, and would not
hurt its ability to operate. The presence of a
second Tug in phase 4 of our mission
dramatically reduces the risk of this mode
of failure.
7 Project Development
Once approved, this program will begin in
the summer of 2016 with nine years of
rigorous development and testing. Three
different lines of development will be
pursued, each focusing on the advancement
of a technology from lab-proven to ground
testing, from ground-testing to space-
testing, or from space-testing to
implementation on the lunar surface. Where
possible, these groups will operate in
parallel. Category I will contain
technologies that are in their infancy. Such
hardware will require research and
development on the ground, and includes
our liquid hydrogen cryocoolers. Category
II will be comprised of technologies that
have been proven in the lab, but have yet to
be demonstrated in a simulated
environment. Such hardware includes our
compact fission power plant, the multi-use
rovers with attachments, and the liquid
hydrogen cryocoolers. Hardware showing
promise will be transported for testing to a
region of Moses Lake, WA that has been
previously used as a simulated lunar
environment. Category III technologies
will be selectively chosen from the most
critical systems to have passed through
Category II and will be flown to the
International Space Station and/or to the
surface of the Moon for space-worthiness
tests. Such technologies include our system
for low-g water electrolysis and the
autonomous deployment of modular base
components.

15 | P a g e
Space-tests for all systems will
culminate in 2023 with a launch of The
Tug, fully fueled, on the SLS or Falcon
Heavy. For two years, The Tug will reside
in low Earth orbit (LEO) to be thoroughly
tested. Mock docking procedures will be
carried out to ensure that the autonomous
algorithms function properly. Following
the success of these mock tests, the initial
set of base components will be launched in
2024 by a combination of SLS, Falcon
Heavy, and Falcon 9 flight vehicles. The
initial set of base assets will consist of a
single SAFE-300 Nuclear reactor structure,
a central communications and power relay
structure (the CCPRS), four rovers, and
several propellant processing and
propellant storage structures. The Tug will
dock with these components under the
supervision of ground control. The Tug will
depart from Earth in 2025 with all the
supplies needed to begin producing rocket
propellant from ice on the Moon.
Subsequent launches of base assets
are determined by the refueling rate of The
Tug and by needs of the base. The base will
determine the density of water ice in the
vicinity of the base, and will requisition
additional structures needed to optimize the
propellant production. This requisition is
received by Mission Control and a launch is
prepared for the next window of
opportunity on either the SLS, the Falcon
Heavy, or the Falcon 9. Once aloft, the
structures and rovers are inserted by the
launch vehicle’s second stage into a
hyperbolic lunar transfer orbit (HLTO).
The Tug is then launched from the lunar
base and loiters in a lunar polar orbit while
awaiting payload rendezvous. As the
payloads begin their closest approach to the
Moon, The Tug intercepts, docks with, and
decelerates the payloads from HLTO to a
trajectory that will bring the components to
the lunar surface near the lunar mine and at
a safe distance from any base operations.
The total mine presence on the
Moon will meet and exceed the target
production of 100 metric tons of propellant
in the year 2035, growing to a hypothetical
maximum level which is only limited by the
number of craters found to have sufficient
water-ice density.
8 Conclusion
Through the implementation of a highly
modular design, our mission architecture
provides the greatest degree of risk
mitigation, while enabling scalability to suit
the local resource density and targeted
production goals. Furthermore, the use of
The Tug transfer vehicle allows for greater
launch mass to the lunar surface, lowering
program costs and paving the way for the
system’s utilization by manned space
vehicles on missions of exploration.

References
[1] NASA, “Cost Estimating Handbook”, v 4.0, 2015.
[2] Johnson Space Center, “Spacecraft/Vehicle Level Cost Model”, 1999.
[3] Miller et al., “Economic Assessment and Systems Analysis of an Evolvable Lunar
Architecture that Leverages Commercial Space Capabilities and Public-Private-Partnerships”,
NexGen Space LLC, 2015.
[4] Muller et al. “Regolith Advanced Surface Systems Operations Robot (RASSOR)”, 2014.
[5] Xiaomeng et al, “Development of a Drilling and Coring Test-bed for Lunar Subsurface”,
2014.
[6] Street, Schrader, and Rickman, “Some Expected Characteristics of Lunar Dust. A
Geological View Applied to Engineering”, NASA MSFC, 2008.
[7] Taylor, and Meek, “Microwave Sintering of Lunar Soil: Properties, Theory, and
Practice”, 2005.
[8] Hintzel, and Quintana, “Building a Lunar or Martian Launch Pad with In Situ Materials:
Recent Laboratory and Field Studies”, JOURNAL OF AEROSPACE ENGINEERING, 2013
[9] Saeed, Khatun, et al., ”Performance of Ultra-Wideband Time-of-Arrival Estimation
Enhanced With Synchronization Scheme”, ECTI Transactions On Electrical Eng., Electronics,
AND Communications, Vol.4, No.1, 2006.
[10] Don Palac et al, “Nuclear Systems Kilopower Project Overview”, 2015.
[11] Poston, Kapernick, and Guffee “Design and Analysis of the SAFE-400 Space Fission
Reactor”, AIP Conference Proceedings, Vol 608, p. 578, 2002.
[12] Marc Gibson et al. “Development of NASA’s Small Fission Power System for Science
and Human Exploration”, 2015.
[13] Sridhar and Iacomini “Combined H2O/CO2 Solid Oxide Electrolysis for Mars In Situ
Resource Utilization”, 2014.
[14] Plachta, et al., “Cryogenic Boil-Off Reduction System Testing”, Propulsion and Energy
Forum, 2014.
[15] Muratov, “Issues of Long-Term Cryogenic Propellant Storage in Microgravity”, 2011.

[16] Guzik, and Tomsik, “A Scaling Tool For Modeling Single Stage Reverse Turbo-Brayton
Cycle Cryocoolers With A Broad Area Cooling System For Cryogenic Propellant Tanks”,
TFAWS, 2012.
[17] Guzik, and Tomsik, “An Active Broad Area Cooling Model Of A Cryogenic Propellant
Tank With A Single Stage Reverse Turbo-Brayton Cycle Cryocooler”, NASA Glenn Research
Center, 2011.
[18] David A. Paige, et al., “Diviner Lunar Radiometer Observations of Cold Traps in the
Moon’s South Polar Region”, Science 330, 479, 2010.

2016 RASC-AL Technical Paper Compliance Matrix
Lunar Ice-Trap ISRU Mining, Processing and Storage Infrastructure Page #
Is the overall system infrastructure sufficiently addressed? 1,2
Have you proposed synergistic application of innovative capabilities and/or new technologies for evolutionary
development that enable future missions, reduce cost, or improve safety?
5-13
Does your scenario address novel applications (through scientific evaluation and rationale of mission operations)
with an objective of sustaining space exploration by NASA, the international space community and/or industry?
3,4
Have you considered unique combinations of the planned elements with innovative capabilities/technologies to
support crewed and robotic exploration of the solar system?
5-8
Have you addressed reliability and human safety in trading various design options? 9-11,14
Have you identified the appropriate key technologies and TRLs? 7,9,10
Have you identified the systems engineering and architectural trades that guide the recommended approach? 3-5
Have you provided a realistic assessment of how the project would be planned and executed (including a project
schedule with a test and development plan)?
3,14,15
Have you included information on annual operating costs (i.e., budget)? 3-5
Have you given attention to synergistic applications of NASA’s planned current investments (within your theme
and beyond)?
*Extra credit given to additional inclusion of synergistic commercial applications*
7-13
Does your paper adhere to the 5-10 page limitation and other formatting guidelines? yes
Summarize Critical Points Addressing Theme Compliance and Innovation
 Systems and operational requirements for developing, deploying and operating a lunar resource production plant, including
transportation systems to deliver ISRU plant/facility/infrastructure
o Our modular base structures take up each of these categories.
 Use of 1 or more Expendable Launch Vehicles (ELVs)
o Our launch plan uses Falcon 9 launches for basic base units and Falcon Heavy launches for the lunar tugs.
 Capabilities to produce not less than 100 t of oxygen/hydrogen propellant annually by 2035 with capability to scale to
higher production levels
o Each processor will have the ability to produce 7 tons of propellant per year, with 19 processor the min can
produce 133 tons of H2O per year to meet the required amount of 100 tons of propellant.
 Power source capable of operating the resource collection, processing, product storage and other required systems
o Each base unit has a 15kW power supply and the main base functions are the processors using 3.5 kW of power
and the storage system using 8kW of power the rovers will recharge periodically when the cryocoolers aren’t
running so very little stress will be placed on the system from the rovers. Allowing for a spare 3.5kW of power to
help run other base aspects when a reactor needs to go down for maintenance.
 Autonomous operation capabilities
o All base systems have redundant computer systems that can talk through the coms ports in the pipes and the UWB
communication system. The scout mission build a subsurface map of best places to mine for ice. The best ice
locations will then have roads sintered out to them reducing travel times. Also the surface maps will provide the
geometry on how the base will expand around local geography.
 Budget accurately reflects the constraints listed in the themes description
o The total system budget is $16.4 Billion for the entirety of mission life. The highest annual budget occurs in 2027
and is equal to $1.38 Billion.
 Innovations in technology and operations that prepare and assist for future, further destinations
o We are storing the excess O2 that is not needed in the propellant and this could be used on manned missions as
extra O2
o The spare power could power other NASA missions that would do well in the permanent Dark such a lunar
telescope that is always in the dark.
Team Info Graphic of Concept/Technology

University of Minnesota
undergrad
University of Minnesota – College of Science & Engineering Team
John Weyrauch (Faculty Advisor)
William Garrard, Ph.D (Faculty Advisor)
Alexander Halaszyn(Team Lead)
Karl Thompson
Matthew Eller
Mike Wang
(Insert graphic/image(s) here)

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