Martian Oxygen: Creating Breathable Air with Engineered Ceramics - CoorsTek
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Industry Focus
#aerospace #zirconia
#cermets #composites
Martian Oxygen:
Creating Breathable Air
with Engineered Ceramics
NASA scientists are working on advanced technologies that can one day enable
human exploration of Mars—and engineered ceramics will help.
ized tools. Thankfully, the mission came
By Joseph Hartvigsen, Principal Investigator and Senior Engineer;
equipped with the “oxygenator,” which
S. Elangovan, Ph.D., Principal Investigator and Program Manager; and
took compressed carbon dioxide (CO2)
Jessica Elwell, Program Manager and Chemical Engineer, Ceramatec, a CoorsTek Company
and “passed it over a zirconia elec-
I
trolysis cell to pull oxygen atoms off
n the 2015 film The Martian, based on the novel of the same title by Andy Weir, the CO2.”1 While this sounds closer to
astronaut Mark Watney struggles for survival after his team is forced to evacu- science fiction than science, the truth is
ate Mars due to a violent dust storm—leaving him behind after mistakenly pre- that NASA is implementing such a con-
suming he is dead. The story highlights how a manned mission to Mars will cept on its upcoming mission to Mars.
critically depend on a reliable oxygen supply. Through shrewd engineering and impro-
vising, Watney manages to gather and create the critical supplies needed to survive on The Next Step
Mars until the next mission arrives: food, water, shelter, and oxygen. Watney, a bota- in Exploring Mars
nist and mechanical engineer, plants potatoes in a modified room where he waters NASA scientists are working on
them by burning some of the mission’s fuel supply of hydrazine with oxygen (O2). advanced technologies that can one day
While the “normal” supplies of food, water and shelter were created through enable human exploration of Mars. Set
innovative engineering, establishing a steady oxygen supply required more special- to land on Mars in 2021, NASA’s Mars
10 August 2016 • www.ceramicindustr y.com
2020 mission will launch a new robotic
science rover with seven instruments.
Each instrument was selected to help
determine the potential habitability
of the environment, and to search for
signs of ancient Martian life. One of
those instruments is the Mars Oxygen
ISRU Experiment (MOXIE). The pri-
mary goal of this experiment is to deter-
mine the feasibility of using indigenous
Martian natural resources (referred to
as in-situ resource utilization, ISRU)
to “enable propellant and consumable
oxygen production.”2
Delivering a sufficient, reliable sup-
ply of high-purity oxygen is a major
design challenge when planning long- Figure 1. Illustration of planned Mars 2020 Rover incorporating seven instruments, including MOXIE.
term manned missions. Astronauts (Image courtesy of NASA.)
would consume nearly a full metric ton mum operating temperature. To meet the
of oxygen over the course of a three- strenuous demands of a Mars mission,
year mission. Additionally, preliminary the durable ScSZ ceramic electrolyte is a
models estimate more than 30 metric superior choice for electrolysis over a liq-
tons of oxygen is required to escape uid system. The effect of environmental
from the deep Martian gravity well for conditions on the performance of SOXE
the return trip home. Because of the cermet electrodes is somewhat unknown,
immense amount of oxygen needed for and the MOXIE results will provide
both the astronauts and their return information to build robust, large-scale
trip propellant, a Mars mission supply devices for human exploration.
weight quickly becomes a major con- Electrolysis essentially takes free elec-
cern. Rather than transporting this large trons and uses them to replace one of the
amount of oxygen more than 35 million double bonds to oxygen. Once an oxy-
miles from Earth to Mars, generating gen ion is freed up, it is directed through
oxygen on-site from available resources the electrolyte into the anode. The anode
on Mars would not only reduce the then “oxidizes” the ion, thereby creating
Figure 2. Prototype SOXE stack of ScSZ engineered
landed payload weight required to keep O2. At the same time, the leftover CO is
ceramic electrolytes.
astronauts alive, but also allow more exhausted along with any unprocessed
sustainable and in-depth exploration of much less electric energy than other pro- CO2. The oxygen flow will then be ana-
Mars or other parts of our solar system. cesses, minimizing the consumption of lyzed for purity and output rate.
the limited power in space missions. In The MOXIE technology demon-
Using Engineered Ceramics fact, the SOXE stack operates near the strates what could ultimately become
Unlike Earth, the Mars atmosphere is theoretical efficiency limit. Other elec- a Mars-based oxygen processing plant
predominantly carbon dioxide—approxi- trolysis systems use liquid electrolytes to to support future human missions. The
mately 95% CO2, with the remainder conduct the ions to the anode. However, experiment will be conducted across the
largely argon and nitrogen. MOXIE uses this system needs to remain stable in the seasons of the Martian year (approxi-
a solid oxide electrolysis (SOXE) stack* harsh Mars environment (e.g., extreme mately 687 Earth days) to evaluate its
to produce oxygen from the CO2-rich cold, low gravity and dusty atmosphere). performance and resilience through the
Martian “air.” These custom-engineered These conditions especially influence liq- variety of environmental challenges.
stacks are comprised of scandia-stabilized uid electrolytes, as their phases and vol-
zirconia (ScSZ) electrolytes with ceramic umes are dramatically affected by exter- Preparing for
anodes and cermet (ceramic-metallic nal temperatures. In addition, dust con- Human Exploration
composite) cathodes on opposite sides. tamination will decrease the effectiveness All seven instruments on the Mars 2020
As compressed CO2 flows through of the electrolyte. mission are designed to further its four
the powered SOXE stack, electrolysis On the other hand, the solid-state goals: look for habitability, search for
breaks out oxygen ions. Using the solid ceramic will be able prevent the con- biosignatures, obtain and cache sam-
electrolysis system is important for three tamination due to its hard surface and ples, and create preparations for human
reasons: efficiency, durability and stabil- exhibit excellent volume and phase con- exploration. While many of the instru-
ity. Solid oxide electrolysis consumes trol, remaining solid even at the maxi- ments will capture and analyze data on
*Developed by CoorsTek company Ceramatec.
www.ceramicindustr y.com • August 2016 11
] Breathable Air with Engineered Ceramics
Due to the potential need for high
production volume and the vitality
of having a constant oxygen supply,
MOXIE focuses on the use of solid
engineered ceramic ScSZ electrolytes
over other methods for superior effi-
ciency, durability, and stability, which
are critical to flight qualify this ISRU
concept. The inherent durability of a
scandia-stabilized zirconia electrolyte
comes from its ceramic nature. As with
most ceramics, the ScSZ is very hard
and resists wear better than most met-
als. These properties are vital for the
mission, as the secondary nature of the
project is to analyze how the system
stands up to surface operations in the
severe Martian environment. On top of
Figure 3. Schematic of electrolysis using SOXE stack. its durability, SOXE has the advantage
of working in a solid state throughout
the whole process. MOXIE’s electrolysis
cells will not have the inherent problems
of controlling the phase and volume
that stem from using liquid electrolytes.
By testing and proving the con-
cept behind MOXIE, NASA hopes
to verify that SOXE can be used as a
viable source of oxygen on Mars, and
to understand how dust will affect
any surface operations. These two ele-
ments will be vital for human explora-
Figure 4. The process of solid oxide electrolysis converts CO2 to O2. tion of Mars. By eliminating the need
to shuttle in oxygen for astronauts and
the Martian environment, MOXIE’s having hospitable air is an intuitive for return flight fuel, future manned
purpose is to actively use and change requirement for manned missions, missions will be able to include better
that environment. This will drive the the ability to produce oxygen from equipment and dramatically extend the
goal of preparing for human explora- the atmosphere will allow on-site fuel potential scope of missions. MOXIE
tion through proving both the science production. Using the produced oxy- will help open a new frontier for space
behind the experiment and the feasibil- gen, those missions could land on and travel and exploration.
ity of using in-situ resources to supply explore Mars, and then return to Earth
the necessary amounts of oxygen. Fac- or continue exploring other sections of For more information, email jelwell@ceramatec.com or
tors for a successful mission will include the solar system. visit www.ceramatec.com.
durability of the vital system, ensuring
the energy consumption matches antici- A New Frontier Acknowledgements:
pated values, and that production levels With success, the MOXIE project will not MOXIE development is supported by the NASA Human
and purity meet what would be needed only prove the science behind The Mar- Exploration and Operations Mission Directorate (HEOMD)
for human exploration. tian, but also shape the vision of what and NASA’s Space Technology Mission Directorate (STMD).
Beyond the 2020 mission, SOXE long-term space exploration missions
technology could be used for expand- could look like. This technology uses the References
ing the concept of space exploration. concept behind solid oxide electrolysis to 1. Weir, Andy, The Martian, The Crown Publishing
Group, Random House, New York, N.Y., 2013,
Because the conversion of CO 2 uses take energy and break the bonds in CO2
p. 231.
Mars atmosphere instead of transported to free up an isolated oxygen ion—mean- 2. M.H. Hecht, J.A. Hoffman, “The Mars Oxygen ISRU
O2, future manned and unmanned mis- ing a CO2-rich atmosphere on Mars can Experiment (MOXIE) on the Mars 2020 Rover,” pre-
sions may have the potential of reduced be used to create oxygen, eliminating a sented at 46th Lunar and Planetary Science Confer-
payload, cost, and complexity. While heavy part of the mission’s payload. ence, 2015.
12 August 2016 • www.ceramicindustr y.com
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