Energy Storage for Ocean Worlds Exploration
Erik J. Brandon, Keith Billings, Kumar Bugga, Keith Chin, John-Paul Jones, Simon Jones, Charlie Krause, Ray Ontiveros, Jasmina Pasalic, Bernard Rax, Marshall Smart, Jason
Thomas and Will WestFebruary 23, 2018
© 2018 California Institute of Technology. Government sponsorship acknowledged.
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Power Options for Ocean Worlds Landers
Pre-Decisional Information -- For Planning and Discussion Purposes Only
Viking (1976)RTG + Ni-Cd rechargeable
batteries
Phoenix (2008)Solar array + Li-ion
rechargeable batteries
MER (2003)Solar array + Li-ion
rechargeable batteries
Juno (2016)Solar array
+ Li-ion rechargeable
batteries
• RTGs provide long life power, but not viable for all architectures and all destinations
• Solar arrays demonstrated at Jupiter distances, but only feasible for orbiters (where very large arrays are possible)
• Remaining option with adequate maturity are primary batteries
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Primary Batteries for Probes and Landers
Pre-Decisional Information -- For Planning and Discussion Purposes Only
Huygens Probe 2004: Li/SO2~2700 Wh<3 hours
Europa Lander scenarios contemplate 480 hours of operation on battery power alone, representing a new paradigm for primary
battery operations
Galileo Probe 1989: Li/SO2~580 Wh<1 hour
Europa Lander: ???~25,000 Wh~480 hours
Artist’s concept
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Europa Lander Concept Battery Needs
• High specific energy per unit mass (Wh/kg)– ~ 35 kWh for 20 day mission to support needed sampling/science
• Low self discharge– It may be 10 years between manufacture of cells and landing
• Must be compatible with planetary protection protocols
• Wide temperature operation may be important– Highly dependent on architecture and mission design
Pre-Decisional Information -- For Planning and Discussion Purposes Only
• Specific energy (Wh/kg) is the most critical metric to target
• More Wh per kg = less lander mass dedicated to batteries
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Extensive Screening of Battery Cell Options
Pre-Decisional Information -- For Planning and Discussion Purposes Only
Cell ChemistrySpecific
Energy, Wh/kg(20⁰C, 50 mA)
Li/SO2 420Li/SOCl2 421Li/MnO2 275Li/FeS2 350
Li/CFx-MnO2 514
Li/CFx 730
Battery Test Chambers at JPL
heritage
new
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Simple Battery Sizing Exercise
Pre-Decisional Information -- For Planning and Discussion Purposes Only
Cell ChemistrySpecific
Energy, Wh/kg(0⁰C, 50 mA)
Total battery with all cellsand packaging for 38
kWh battery (kg)Li/SO2 420 103
Li/SOCl2 421 103Li/MnO2 275 165Li/FeS2 350 130
Li/CFx-MnO2 514 89
Li/CFx 730 63
• Can reduce mass dedicated to battery by ~40 kg vs. heritage chemistries!
• Challenge: cell chemistry has no flight heritage
• Need to consider planetary protection
Location of batteries(notional)
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Planetary Protection Approaches• Typical dry heat microbial reduction conditions are in the range of
110⁰C to 150⁰C for 8 to 140 hours
• Significant loss of capacity observed under these conditions
• Investigating radiation as means to sterilize
• Requires extensive radiation testing
• Engaging Sandia National Lab for long term support
Pre-Decisional Information -- For Planning and Discussion Purposes Only
JPL Radiation Test FacilitiesCells in radiation test
fixtureTest chamber and source
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Radiation Does Not Appear to AffectBeginning-of-Life Battery Capacity
• 0 to 8 Mrad battery discharge curves all look similar = high radiation tolerance• What are the longer term impacts?• What about reliability of components?
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Destructive Physical Analysis of Irradiated Cells
Pre-Decisional Information -- For Planning and Discussion Purposes Only
Tear down of irradiated cell for analysisRolling out the
electrode “jellyroll”
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Separator Key Battery Component
Pre-Decisional Information -- For Planning and Discussion Purposes Only
Polyimide based separator
Conventional separator
Embrittled, with changes in composition after irradiation
no changes after irradiation
• Conventional battery separators appear susceptible to radiation damage
• Identifying alternatives that can better tolerate radiation
Infrared Spectroscopy of Irradiated Separators
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Summary and Plans Forward• Early technology investments by NASA Science Mission
Directorate are paying off
• Identified and developed battery technologies that enable future Ocean Worlds mission concepts
• Continue efforts to improve performance, ensure batteries are compatibility with planetary protection and capable of long life in high radiation environments
Batterymaterials
development
Rapid infusion and cell prototyping
Extensive testing of cells and components
Battery design and qualification
Pre-Decisional Information -- For Planning and Discussion Purposes Only
jp l .nasa.gov
Acknowledgements
This research was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology under a contract with the National
Aeronautics and Space Administration.