# Presentation: 024042

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

- Bob G. Beaman
- 11 January 2007

## 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

## 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.

## 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

## 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

## 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

## 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

## 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

## 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 vs. Li-Ion

- 7.5 Ah ST-5 Li-Ion

- Structural Battery

- Micro Battery

- Flywheel

## Instrument Converter Technologies

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

## Power Branch Summary

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