BGB 1

1
Electrical Power Systems (EPS) for Lunar
Exploration Science Working Group (LESWG)

• Bob G. Beaman
• 11 January 2007

2
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

3
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.

4
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

5
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

6
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

7
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

8
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

9
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

80 Ah HST NiH2 ORU
50 Ah XTE/TRMM SNiCd
7.5 Ah ST-5 Li-Ion
NiH2 vs. Li-Ion
Structural Battery
Micro Battery
Flywheel
10
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.