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Goddard Space Flight Center

Electrical Power Systems (EPS) for Lunar Exploration Science Working

Group (LESWG)

Bob G. Beaman11 January 2007

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Goddard Space Flight Center Power Branch Objectives

• Provide Knowledge and background of the Code 563 Power Branch experience and capabilities.

• Listen and work with Scientist on future Lunar Science proposals.

• Provide assistance on Proposal submissions• Feed back into Technology Development needs to

support Lunar Science.• Ability to build, test, launch and operate space

components and systems.• Point of Contact

– Bob G. Beaman 6-2538– Thomas Y. Yi 6-5845

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Goddard Space Flight Center

Power Branch Design Capabilities

• Sizing and Study of Mission Craft parameters to meet Science Objectives.

• Defining derived EPS requirements for Mission Craft and Science Instruments

• Mission Craft may be a orbiting spacecraft like Lunar Reconnaissance Orbiter (LRO) or perhaps several forms of surface crafts.

• Ability to work with Integrated Design Capability (IDC) ISAL and IMDC study planning and design sessions.

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Goddard Space Flight Center Lunar Environment

• Orbital Environment• Surface Environment

– Temperature range +120 deg C to -160 deg C– 14 day, (24 hour days) in sun and night– Almost no atmosphere, direct effects from solar mass

emissions– Loose soil and dust on surface.– 1/6 of Earths Gravity

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Goddard Space Flight Center

GSFC Power Systems Branch Capabilities

• World class development laboratories and experience

• Leading technology development to improve overall power system performance and flexibility

– Continuously striving to reduce cost, mass, and power consumption of electrical power systems

• High power output capabilities/condensed packaging, working closely with industry to develop radiation hard high reliability critical components

• Adopting new FPGA capabilities to reduce power system electronics size and complexity resulting in fewer EEE parts in design

• More software driven high reliability systems approach

• Optimizing overall power system parameters to reduce cost and provide more efficient delivery systems

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Power System Development Flexibility/Expertise

• Nanosat Integrated Power Systems– Nanosat technology (ST-5) for low power

levels utilizes low voltage approach (6-8 Vdc unregulated bus) to provide low power solution while integrated with observatory avionics in one component

• Small Explorer Class Power Systems– Unique development of “Feed Forward”

performance control loop for Small Explorers class missions (Triana) to reduce size and increase efficiency for system sizes up to 500 Watts

• Medium Class Power Systems– Condensed single fault tolerant design for

moderate/high power 28V systems (SDO) provides high reliability and modular functionality for systems up to 1500 Watts

• High Voltage/High Power Systems– First NASA high voltage 120 VDC

observatory launched in December, 1999 (EOS Terra) provided high reliability and low harness mass/low harness loss solution for systems typically larger than 1500 Watts

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Goddard Space Flight Center

Power Generation/Collection

• Solar Arrays. Capability to work with many different types of Solar Array: Silicon 11.2 % ~25 W/kg to Triple junction Gallium Arsenide 28.5 % ~150 W/kg.

• Solar Array Development areas.– Electrostatically Clean Arrays– FAST Cost Approximately 8 times a “vanilla” array– SBIR with Composite Optics Inc., now ATK, for an Inexpensive,

Reliable ECSA.– THEMIS Cos Approximately 1.3 times a “vanilla” array– SBIR on-going with AEC-Able, now ATK, for an ECSA

• Other Power Sources– Radioisotope Thermoelectric Generators (RTG)– Solar/Lunar Thermionics

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Power System Electronics

• Modular Design• Avionics Concepts• Science interface

compatibility• Performance parameters

– XTE 1995• 40.4 Watts/kg• 0.03 Watts/cm3

– MAP/EO-1 2001• 70.7 Watts/kg• 0.04 Watts/cm3

– SDO 2008• 65.6 Watts/kg• 0.05 Watts/cm3

– LRO 2008• 123.7 Watts/kg• 0.13 Watts/cm3

Solar Array Module

x14

Solar Array Segments

28v

Bu

s B

ack

pla

ne

Ibatt

Batt tlmRly Drv

Special Commands I/F

SA temp

Uart / Rs422

1553

Test Con.5v & +/-15v

PSE Monitor Card

Test Con.

DPC/GSE input

x12 switched

x3 unswitched

Output Module Loads

Sec

ond

ary

Bu

s

x12 switched

x3 unswitched

Output Module Loads

x12 switched

x3 unswitched

Output Module Loads

x12 switched

x3 unswitched

Output Module Loads

2

1

11w/ OVbckp

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Goddard Space Flight Center Energy Storage

• Batteries GSFC “Pioneered” the rechargeable secondary battery for aerospace application since early 1960

• Identify the maturity of a rechargeable secondary battery cell chemistry for aerospace use

• Test and validate the matured cell for aerospace application

• Design, test, qualify, and infuse the advanced battery into spacecraft

• Manage on board battery operation for a successful mission

• Structural Battery• Micro Battery• Flywheels• Fuel Cells

50 Ah XTE/TRMM SNiCd 80 Ah HST NiH2 ORU

NiH2

Li-Ion

NiH2 vs. Li-Ion 7.5 Ah ST-5 Li-Ion

Structural Battery Micro Battery Flywheel

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Instrument Converter Technologies

• Custom Designs for Unique Instrument Power Requirements– Low Voltage– High Voltage– Low Noise– Isolated Outputs– Radiation Hardened/Tolerant Components

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Power Branch Summary

• The Power Branch is willing to listen and add our expertise to the Lunar Science future proposals.