Habitability of Icy World Oceans, Especially Europa’s
JPL Project Plan
Kimberly Lykens
Mentor: Steve Vance, Ph.D
Introduction/Background
What is the general technical area in which you will be working?
 My investigation this summer uses the general technical areas of geochemistry
experimentation and chemical modeling to evaluate the composition and transport
mechanisms of potential life of icy world oceans, specifically that of Europa.
What is the problem that you are trying to solve, and how did the problem arise?
 Europa has a unique geologic and oceanic composition compared to that of Earth.
When considering a suspected interior ocean system beneath an irradiated icy
surface, seeking further answers on geochemical redox reactions between the icewater-rock dynamic on Europa will grant insight into chemical and physical
occurrences on this icy satellite and give clues to possible driving factors.
Specifically speaking, the problem I will be addressing in my investigation
involves the assessment of geochemical composition and transport mechanisms
between liquid water and rock on icy satellites. This research investigation is
being introduced based on the need to acquire further knowledge on geochemical
processes found on icy worlds, such as Europa, in the hopes that this knowledge
can be applied or observed on other icy satellites (Pappalardo et al., 2013).
Why is its solution interesting or worthwhile?
 The solution to this research investigation is worthwhile because the chemical
modeling and results of the chemical investigations will grant insight into how the
composition and transport properties of icy world oceans based on geochemical
interactions drive the interior ocean complex. Furthermore, the results of the
experiment can be used to assess the evolution of oceans, habitability, and
potential applications of future mission instruments traveling to icy satellites
(Pappalardo et al., 2013).
What is the status of related research by your mentor or by the group that you will be
joining, and what will be the contribution and significance of your effort if it is
successful?
 Europa is considered a prime candidate for life, as it contains liquid water and
potential chemical compositions suitable for life. Recent funding from the Obama
administration has granted approval for the construction and delivery of a satellite
probe to Europa in the year 2022. The radiation-tolerant satellite known as
Clipper will conduct 45 flybys of Europa and will contain nine approved
instruments, two of which involve spectroscopy to assess chemical composition
of the surface and potential habitable conditions for life. Currently, there are
several teams in place doing necessary research and assessments required before
the 2022 launch data (JPL, 2015). Specifically, I will be working with the
Habitability team as part of the Icy World Astrobiology group here at JPL. My
efforts and experimental results in this summer investigation will be used to
understand more about the geochemical interactions, specifically regarding redox
reactions between the rock composition of hydrothermal vents and the interior
ocean on the icy world Europa. Future surface and subsurface ocean composition
results from the Clipper satellite spectrometer can be used alongside my chemical
modeling and chemical experimental results to understand more completely how
these chemicals and their transport mechanisms allow for internal ocean evolution
and potential opportunities for extant life (Pappalardo et al., 2013).
Objectives
What do you aim to accomplish in your project?
 In this project, I aim to explore the transport mechanism in Shewanella oneidensis
bacteria, a bacterium that can reduce poisonous metals and can live in both
anaerobic and aerobic conditions. This bacteria is specifically interesting in
research with Europa because this bacteria can not only survive in non oxygenrich environmental, but also metal minerals found on rocky surfaces can be used
as a metabolite for this type of microbe. The aim of this project is to collect,
grow, and culture Shewanella oneidensis bacteria and expose these bacteria to
various conditions as observed on Europa, such as salt composition, the
availability of oxygen, and the presence of methane. This experiment will give
insight into how possible forms of microbial life sustain metabolism function in
various conditions. Furthermore, exposing the Shewanella oneidensis bacteria to
higher temperatures, such that of a hydrothermal vent will show how
chemosynthetic bacteria survive in higher temperatures.
What will you measure, and under what conditions; or, what will you calculate, model, or
simulate; or what will you design, and what are the requirements; or what will you build
or test?
 Primarily, I will begin by measuring and controlling the independent variable of
the solution in which the bacteria will be exposed. I will be exposing the bacteria
first to a methanol solution to simulate a methane-rich environment on Europa
created from the hydrothermal conditions on interior surface. Next, I will create a
large collection of different simulate solutions, including various salt and ironrich solutions. I will then expose plated Shewanella oneidensis to the various
solutions and monitor growth rate of the microbe over time.
What is your starting point?
 The starting point of my investigation includes researching the methods and
results of previous investigations exploring surviving life in hydrothermal
conditions and the wide array of metabolites that serve as a required energy
source. Europa is theorized to contain an iron core surrounded by an Earth-like
mantle that comes in direct contact with its interior ocean. In addition, there are
several plumes that have been identified on Europa that cause hydrothermal
circulation. A combination of hydrothermal conditions and an rocky core has
resulted in a theory suggesting that chemical reactions can result in the dissolving
of oxygen from the core, to the icy surface, and eventually dissolve into Europa’s
interior ocean (Coleman, 2013). In addition, some researchers theorize that
Europa is thermodynamically dead; thus, displaying inhabitable conditions for
life. There is, however, evidence of a chemical disequilibrium in hydrothermal
conditions on Europa that would allow for energetic niches for life.
Methanogenesis, or the creation of methane from microbial life, and the reduction
of sulfate are known as common pathways for life; however, there have been
conclusions about oxidants from the irradiated surface that are delivered to the
interior surface, where redox reactions take place and create a chemical
disequilibrium (Hand et al., 2013). More specifically, models have outlined an
autotrophic progression of life on wet, alkaline surfaces that have gone through
carbon dioxide reduction, methane oxidation, and other reactions to create a
thermodynamically rich environment (Russell et al., 2014)
What are your initial assumptions or conditions?
 My initial assumptions or conditions come from my knowledge on Shewanella
oneidensis bacteria. Shewanella oneidensis uses toxic metals to acquire energy
and it is theorized that there are metal sulfides on Europa that could be potential
metabolites for life. Shewanella oneidensis exposed to an anaerobic environment
can uptake iron, lead, and various sulfates to use in their cellular respiration
process. Understanding how these metals found on Europa interact with
Shewanella oneidensis will grant insight into a possibility of life on this icy world.
What will be the result or product of a successful outcome for your project?
 A successful outcome of this project would include receiving data/results on how
metals found on Europa effect the survivorship of a chemosynthetic organism.
Shewanella oneidensis is unique and can be found in non-ideal conditions for life.
Simulating Europa-like conditions for the bacteria can show which metals have
the largest effect on the ability of the Shewanella oneidensis bacteria to sustain
life. Data would include results on chemical composition vs. growth surface area.
What are the criteria for project completion or for success? (In other words, how will you
know when you have accomplished what you set out to do?)
 I know that I have accomplished what I have set out to do when I have a clear
depiction of how metals interact with the Shewanella oneidensis bacteria under
various conditions. Understanding the differences between these metals will
allow for fundamental knowledge on the survivorship of this microbial life, most
specifically how it interacts with various salt structures.
Approach
Specifically, how will you reach your objective or produce your desired final product?
 To reach my objective, I will first acquire the supplies for the experiment (step 1).
This would involve making a list of supplies I would need. Secondly, I will need
to plate the Shewanella oneidensis bacteria in an anerobic environment and allow
the samples to grow (step 2). I would then expose the plates to various solutions
(step 3). Lastly, there are a couple options I could choose in quantitatively
measuring the amount of growth for the bacteria. I could first use a flow
cytometry technique that would give me a cell count of growth (step 4). This
would allow for a final product graph showing the relationship between metal and
cell growth (step 5).
What are the principal steps or milestones along the path?
 The steps (listed above) will need to be taken in order to achieve a final product or
result. The milestones I will reach along the way include primarily obtaining the
supplies to carry out the experiment. I will need to make a list of supplies and
there is a waiting time in obtaining these materials from the supplier. Secondly,
developing my own procedure and experiment will also be a milestone. Unlike
previous summers, my mentor is encouraging me to develop my own procedure
and carry out my own design. This is exciting, yet it may serve as a milestone
later on if the design is not thorough enough.
How long will each take?
 Acquire the supplies for the experiment (step 1) will take about 2 weeks.
 Secondly, I will need to create the simulant solutions (step 2) will take about 1
week.
 Plate the Shewanella oneidensis bacteria in an anerobic environment and allow
the samples to grow (step 3) will take about 2 weeks.
 Use a flow cytometry technique that would give me a cell count of growth (step
4).
 This would allow for a final product graph showing the relationship between
metal and cell growth (step 5).
What steps promise to be the most difficult, and how will you overcome the difficulties?
 The steps that will be the most difficult are steps 1, 2, and 3. Step 1 will take a lot
of time because it will require a lot of background reading. I will need to know
what chemicals will interact with Shewanella oneidensis and to what extent. Step
two will take the most time because I will need to organize the simulants based on
my background research and communication with others in my group. Step 3 will
take time simply because I will be waiting on bacterial growth.
What equipment or other resources will you need?
 The resources I will need include petri dishes, agar, bacteria, and various
minerals/chemicals. The equipment I will need is the equipment for the flow
cytometry technique that can measure cell count.
Which of these are inherited, and which will you have to make or procure? With what
other people or groups will you be collaborating?
 This procedure was mostly created entirely by myself in conjunction with
background research. The groups/people I will be collaborating with include
Laurie Barge (in charge of the lab) and the space microbiology team here at JPL.
The space microbiology team is willing to work with me to conduct cell count.
Will completion of your project depend on results from other people in related projects?
 No, the completion of this project does not depend on results from other people’s
project.
Project Schedule
Week Two
Create a completed experimental design/order appropriate materials
Week Three
Create the simulant solutions
Week Four
Plate bacteria and expose simulant solutions
Week Five
Collect cells and give to Space Microbiology Lab
Week Six
Analyze data and assess next test
Week Seven
Create simulant solutions/plate next round
Week Eight
Give to microbiology lab and analyze results
Week Nine
Assess future tests
Week Ten
Develop presentation on results
References
R. Pappalardo, S. Vance, F. Bagenal, B. Bills, D. Blaney, D. Blankenship, W.
Brinckerhoff, J. Connerney, K. Hand, T. Hoehler, et al. Science potential from a Europa
lander. Astrobiology, 13(8):740–773, 2013.
Jet Propulsion Laboratory. Mission to Europa: Europa Mission. (2015). Retrieved
from http://www.jpl.nasa.gov/missions/europa-mission/
Coleman, M. (2015). From Deep Sea to Europa. Schmidt Ocean Institute.
http://www.schmidtocean.org/story/show/1510.
Kevin P. Hand, Robert W. Carlson, and Christopher F. Chyba. Energy, Chemical
Disequilibrium, and Geological Constraints on Europa. Astrobiology. December 2007,
7(6): 1006-1022. doi:10.1089/ast.2007.0156.
Russell Michael J., Barge Laura M., Bhartia Rohit, Bocanegra Dylan, Bracher
Paul J., Branscomb Elbert, Kidd Richard, McGlynn Shawn, Meier David H., Nitschke
Wolfgang, Shibuya Takazo, Vance Steve, White Lauren, and Kanik Isik. The Drive to
Life on Wet Icy Worlds. Astrobiology. April 2014, 14(4): 308-343.
doi:10.1089/ast.2013.1110.