Mars Science Laboratory Descent Stage Thermal Batteries Science Laboratory (MSL) Thermal Batteries ELECTROCHEMICAL TECHNOLOGIES GROUP Mars Science Laboratory Descent Stage Thermal Batteries. ... 1380 seconds

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  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Mars Science Laboratory Descent Stage Thermal Batteries

    W. C. West,a B. V. Ratnakumar,a R. Ewell,a L. Bister,a J. Gathright,b R. Cooper,band D. Bhaktab

    aJet Propulsion LaboratoryCalifornia Institute of Technology

    Pasadena, CA 91109

    bEagle Picher Technologies, LLCC and Porter Streets

    Joplin, MO 64801

    NASA Aerospace Battery WorkshopNovember 16-18, 2010

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Overview

    Mars Science Laboratory (MSL) mission overview

    Thermal battery general design

    Thermal battery requirements

    Flight qualification test protocol

    Results

    Summary

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Backshell model fit-check vs. Mini-Cooper

    Mission Features 10x greater payload mass than

    previous Mars rovers One Mars year surface

    operational lifetime (669 sols) Discovery responsive over wide

    range of latitudes and altitudes Controlled propulsive landing Precision landing via guided entry

    Science Mission Science will focus on investigating the past or

    present potential of Mars to support microbial life

    Remote sensing/contact investigations (e.g. rock crushing for XRD/ fluorescence analyses)

    Suite of environmental monitoring instruments (e.g. pressure, temperature, humidity, winds, ultraviolet radiation levels)

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    MSLThermalBatteries: Resideonoutrigger#4ondescentstage

    PWTBs:ProvidepowertodescentstageduringEntry,Descent,andLanding(EDL)

    PYTBs:FirepyrotechnicdevicesduringEDL

    Batteriesfabricatedandqualifiedatvendorfacility(EaglePicherTechnologies)

    Unactivatedtestingofbatteriesincludingactivationcircuitresistance,polarity,insulationresistance,etc.performedatJPL

    Survivalheaters/PRTsandassociatedharnessesinstalledatJPL

    AdditionalteststocharacterizeperformancecarriedoutatJPL

    MSLFlightDescentStage

    ThermalBatteries(PWTBs,PYTBs)

    MSL Descent Stage Batteries

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    ThermalBatteries: Batteriesaresingleusenon

    rechargeablebatteriesdesignedtohaveoutstandingshelflifeaswellashighdischargerateperformance

    Nearlyindefinitelyelectrochemicallyinertuntilactivated(0Vopencircuit,0Ashortcircuit,>1G impedance,cannotbedischargedorcharged)

    Activatedwithacurrentpulseacrosstwosetsofsquibterminals(onesetredundant)toignitetheinternalheatpellets

    Ignitedheatpelletsmelttheelectrolytewhichallowsthebatterytobedischargedforaslongastheelectrolyteismolten(ca.30minutes)

    Dischargedacrosstwosetsofpowerterminals(onesetredundant) MSLFlightDescentstagewithEMPxTBsinstalled

    EMPowerThermalBatteries(PWTBs)

    EMPyroThermalBatteries(PYTBs)

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    MSLPWTB

    MSLPYTB MER

    Pyro

    MSL Descent Stage Batteries: Design

    Electrode backing

    Li alloy anode

    Electrolyte

    FeS2 cathode

    Heat pellet (Fe + KClO4)

    Current pulse through pyrotechnic initiator ignites heat pellets through centerline, activating battery

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Qualification

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Qualification: PYTBRequirements: Voltage: 26 to 36 V Rise Time: 1.0 sec max to >26 V Operating time after activation:

    1380 seconds (min.) Shelf Life : > 4 years Pulse-type operation required in

    addition to a continuous load

    Load: 1A constant baseload Up to 96 pulses 7A, 20 msec pulses 22 A (3 simultaneous pulses) 120 msec time between pulses

    26V

    36V

    23 min

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Qualification: PWTB

    Requirements: Voltage: 27 to 37 V Rise Time: 1.0 sec max to >27V Operating time after activation: 1380

    seconds Shelf Life : > 4 years Capacity (min): 6 Ah at >27V

    Load: Complex load profile (1000 steps) Variable power loads 300-650W Superimposed 6 30A current pulses Tolerate a reverse current of 16A for 20

    msec

    27V

    37V

    23 min

    27V

    37V

    23 min

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Non- Operational Qualification

    VisualRadiographyLeak checkTorqueNon-op electricalsThermal vacuum (min. 3 cycles -55oC to +75oC)

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Qualification: Random Vibration

    Zone/Assembly

    Frequency,Hz

    Flight Acceptance Level

    Qualification/ Protoflight

    Level

    Descent Stage Mounted Assemblies

    20 4040 - 450 450 2000Overall

    + 6dB/octave0.04 g2/Hz- 6 dB/oct5.6 grms

    + 6 dB/octave0.08 g2/Hz- 6 dB/oct7.9 grms

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Qualification: Operational Pyroshock

    Zone Frequency, Hz Qual Peak SRS Response (Q=10)

    Descent Stage Zone 2 100100 1,6001,600 - 10,000

    20 g+ 10.0 dB / Oct.2,000 g

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    0

    5

    10

    15

    20

    25

    30

    35

    40

    -5

    0

    5

    10

    15

    20

    25

    30

    35

    -0.5 0 0.5 1

    PWTB: A8-7-2

    Voltage

    Current

    Current (Power)

    Vol

    tage

    (V) Current (A

    )

    Time (s)

    0

    5

    10

    15

    20

    25

    30

    35

    40

    -5

    0

    5

    10

    15

    20

    25

    30

    35

    -0.5 0 0.5 1

    PWTB: A8-7-3

    Voltage

    Current

    Current (Power)

    Vol

    tage

    (V) Current (A)

    Time (s)

    Initiate at -35oC Initiate at +35oC

    Start-Up

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    JPL Activities JPLAcceptanceTests

    Visual(burrs,weldingflaws,glassmetalseals,activationindicators)

    Activationcircuitresistance Polarity Isolation(case,activation

    circuit,+and terminals)

    Heater/PRTinstallation Harnessinstallation Massproperties(Centerof

    Gravity,MomentofInertia)

    EMIsensitivitytesting ATLOactivationandload

    testing

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Mass Properties Testing

    Momentofinertia(MOI)test Usedtodescribeunitsresistancetoachangeinrotation

    Preciselyweighunitthenmountunitonspintable Lockthebottomofthespintablerotationshaft Displacetheplatformbyafewdegrees,andthenrelease

    shaftactslikeatorsional spring,andtheplatformwilloscillateatthenaturalfrequencyofthesystem

    PeriodofoscillationisusedtocalculateMOI

    CenterofGravity(CG) test Usedtoidentifyaveragemasslocation

    ofunit

    Preciselyweighunitthenmountunitonspintable

    Measure appliedmomentat4positions90o apart

    Divide byweighttocalculateCG

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    EMI Testing Atlaunch,spacecraftwillbe

    exposedtotrackingradarandotherEMIsources

    Question:willtheinitiatorcircuitdegradeorinitiateinEMIfield?

    Tests:Exposethermalbatteryandmockharnessestopulsemodulated5.45.9GHzRF at100V/m(at1m,yieldsca.53Wexposure)

    Repeattestatoppositepolarization

    Recordinitiatorresistancebeforeandafter

    Outcome: No battery initiation on RF exposure No change in initiator circuit resistance

  • Exploration Systems Research &Technology

    Mars Science Laboratory (MSL) Thermal Batteries

    ELECTROCHEMICAL TECHNOLOGIES GROUP

    Thermal batteries, once activated, need to be discharged at some minimum current to prevent safety issues (thermal runaway).

    Self discharge can occur, likely through dissolution of FeS2 into electrolyte, and/or generation of sulfur via a decomposition of cathode, which would eventually trigger run away.

    The recommended solution is to discharge the battery at small currents, such that the electrode surface is continuously modified.

    Such discharge is required only for PYTB. The PWTBs would not need any such discharge since there a continuous load impressed upon them after activation.

    The base load adopted for the MER batteries in the past was 0.5 A. Based on the larger capacity of the MSL PYTBs, a current of ~ 1 A was recommended.

    Baseload Resistor Assembly (

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