To Infinity, And Beyond!

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To Infinity, And Beyond!

• Providing Energy for Space Systems

Steven E. JohnsonISS Flight ControllerNASA
Johnson Space Center
NASA/NTSA SymposiumPreparing for the Journey to
Space Energy7 April 2006
Photo taken January 26, 2003 by the crew of Space
Shuttle Columbia
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Overview

• Objectives
• Energy
• Energy Systems
• Solar Power
• Energy Storage
• Nuclear Power
• Review
• Theoretical Applications
• Backup Material

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Learning Objectives

• After reviewing the presentation, participants
  will
• List the three types of spacecraft power system
  types.
• State advantages and disadvantages of spacecraft
  power system types.
• Determine the appropriate power system for
  theoretical applications.

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EnergyIts All About Conversion

• The Law of Conservation of Energy Energy can be
  neither created nor destroyed, it can only be
  transformed (converted) from one form to another
• Energy conversion systems are everywhere
• Chemical to Thermal
• Home furnace using oil, gas, or wood
• Chemical to Thermal to Mechanical
• Automobile engine
• Chemical to Electrical
• Fuel cell
• Electrical to Mechanical
• Electric motor
• Electrical to Radiant
• Toaster, light bulb
• Power plants are energy conversion systems
• On Earth and in space

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Energy Systems 101Powering Spacecraft
Current manned space systems use Photovoltaic
and Chemical power
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Solar PowerApplications

• Near Sun missions
• Venus
• Mercury
• Outbound
• Mars
• Asteroids
• Earth orbital
• International Space Station
• Mir
• Skylab
• Communication satellites
• Earth observation satellites
• Weather satellites
• Global Positioning System
• Surface
• Mars Pathfinder
• Mars Exploration Rover

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Solar PowerApplications
Skylab
ISS
Mir
Mars Exploration Rover
Hubble
GPS
Mir
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Solar PowerEvaluation

• Solar Power Advantages
• Unlimited energy supply
• Mission duration not limited to on-board energy
  consumables
• Modular
• Solar panel systems can be built independently of
  specific space system
• Established manufacturing base
• Cost effective
• Proven technology does not require significant
  research expenditures
• No energy by-products or waste material
• ? Best option for long-duration near-sun missions

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Solar PowerEvaluation

• Solar Power Disadvantages
• Requires a significant illumination source
• Sunlight strength diminishes as the distance from
  the sun increases
• Solar illumination insufficient for most
  applications beyond Mars
• Most solar-powered space systems require
  additional energy storage (battery) systems
• Most free-flight systems are dependant on a
  vehicle control system to point the space craft
  and/or solar arrays
• ? Unfeasible option for deep space missions

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Energy StorageApplications
Apollo Command Service Module
Apollo Lunar Rover
Gemini
Space Shuttle
EMU
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Energy StorageEvaluation

• Energy Storage Advantages
• Allows independent space system operation
• Not dependent on illumination source
• Solar pointing system not required
• Most space craft require control systems for
  attitude control regardless of power system
• ? Best option for limited-duration manned
  missions

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Energy StorageEvaluation

• Energy Storage Disadvantages
• Limited mission duration
• Fuel or battery life are limited-quantity
  consumables
• Limits mission durations to 2 weeks
• Requires custom-built system for each application
• Fuel Cell systems produce by products (water)
  which must be stored/dumped
• ? Unfeasible option for long-duration missions

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Nuclear PowerApplications
Voyager
Viking
Galileo
Ulysses
Cassini
Since 1961, 40 RTGs have been used on 22 US space
systems.
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Nuclear PowerEvaluation

• Nuclear Power Advantages
• Provides a very long-term energy source
• Supports mission duration of tens of years
• Allows independent space system operation
• Not dependent on illumination source
• Solar pointing system not required
• Most space craft require control systems for
  attitude control regardless of power system
• Currently the only viable option for non-solar
  missions longer than 2 weeks and missions
  traveling beyond Mars
• ? Best option for deep-space unmanned missions

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Nuclear PowerEvaluation

• Nuclear Power Disadvantages
• Low power capability
• Highest power application Cassini, lt 1 kW
• Not practical for manned space systems
• Expensive
• Requires custom-built system for each application
• ? Unfeasible option for manned missions

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Review

• What are the 3 types of space power systems?
• Solar power
• Energy storage
• Nuclear power

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Review

• What is the primary advantage of solar power?
• Unlimited energy supply
• What is the primary disadvantage of solar power?
• Requires a significant illumination source
• What is the primary advantage of energy storage?
• Allows independent operation
• What is the primary disadvantage of energy
  storage?
• Limited mission duration
• What is the primary advantage of nuclear power?
• Provides a very long-term energy source
• What is the primary disadvantage of nuclear
  power?
• Low power capability

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Theoretical Application 1

• Engineering is developing an Extra-Vehicular
  Activity (EVA) free-ranging, semi-autonomous
  robotic assistance device for ISS.
• The robotic device will need to operate for the
  duration of an EVA (7 hours) or be operated
  independently from ISS for external inspection
  and have a mass of 8 kg or less.
• The robotic device will require the following
  systems
• Video camera 12 V, 100 W
• Still-picture camera 12V, 25 W
• Flood light 14 V, 250 W
• Attitude control system 8 V, 25 W
• EMU-to-ISS Radio Signal Relay 12 V, 80 W
• Command Telemetry System 12 V, 60 W
• What type of energy system should this system
  utilize?

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Theoretical Application 1

• Energy Storage (battery)

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Theoretical Application 2

• A mission has been requested for sun surface
  observation and space environment sensing
• A space system is required which will have the
  following mission parameters
• Operate in a solar orbit between Venus and Earth
  for 4 years
• Observe the sun with filtered video and
  photographic equipment
• Sense space weather events
• Monitor solar electromagnetic, ultraviolet,
  infrared, and x-ray radiation
• Send scientific data back to an Earth control
  center
• What type of energy system should this system
  utilize?

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Theoretical Application 2

• Solar Power

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Theoretical Application 3

• A space system is required to investigate Neptune
• The mission will have the following requirements
• Be inserted by a Delta II launch platform
• Payload up-mass 1,900 to 4,700 lb
• Payload Diameter up to 10 feet
• Payload Length up to 22 feet
• Translate from Earth to Neptune in 14 years or
  less
• Operate in orbit around Neptune for 2-4 years
• Enter Neptunes atmosphere on a ballistic
  trajectory and gather atmospheric data and
  imagery
• Send scientific data back to an Earth control
  center
• Receive instructions from an Earth control center
• What type of energy system should this system
  utilize?

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Theoretical Application 3

• Nuclear Power

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Summary

• Space systems use three types of power systems
• Each system has advantages and disadvantages
• Space system and mission requirements dictate the
  appropriate energy system

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Back Up Material
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Contents

• Low Earth Orbit Overview
• ISS
• Overview
• Electrical Power System
• Shuttle
• Overview
• Electrical Power System
• EMU
• Overview
• Electrical Power System
• References

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Low Earth Orbit (LEO)Overview

• Insolation
• (Sunlight)

• Earth Orbit

Manned vehicle LEO altitude 115-400
miles Orbital Period 90 minutes Insolation
45 minutes Eclipse 45 minutes

• Eclipse
• (Night)

Diagram Not to Scale
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Manned Space Systems

• There are currently manned space systems
• ISS
• Shuttle
• EMU
• ISS is powered by a solar power energy system
• Also has an energy storage (battery) component
• Shuttle is powered by a energy storage system
• Fuel cell
• EMU is powered by a energy storage system
• Battery

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International Space StationOverview

• International Space Station (ISS) is a manned
  Low-Earth Orbit vehicle
• Launched in November 1998
• Manned since October 2000
• Mission Control Center (MCC) in Houston, TX
  maintains primary responsibility for vehicle
  monitoring and operation
• Theres no cockpit in ISS its flown from MCC
• Assembled up in stages, estimated completion of
  2010
• ISS is the largest space vehicle ever flown
• Currently
• 170 feet long and 240 feet wide
• Mass of gt 404,000 lbs
• Assembly complete
• 240 feet long and 350 feet wide
• Mass of gt 1,000,000 lbs
• Largest solar arrays ever flown
• All electrical power is generated from solar
  energy
• Each solar array is 120 feet long
• Each of the 8 assembly complete solar arrays
  generates up to 16 kW of power

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International Space StationElectrical Power
System

• Energy is collected from solar radiation
• Power is converted from collection (primary)
  power levels to user (secondary) power levels
• Primary power is also stored in chemical
  batteries to be used in eclipse
• Secondary power is distributed throughout the
  vehicle for system and user loads

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International Space StationElectrical Power
System
Batt (Battery) ECU (Electronics Control
Unit) PVA (Photo Voltaic Array) BCDU (Battery
Charge Discharge Unit) MBSU (Main Bus Switching
Unit) PVCU (Photo Voltaic Control Unit) BGA
(Beta Gimbal Assembly) RPDA (Remote Power
Distribution Assembly) PVR (Photo Voltaic
Radiator) CC MDM (Command Control
Multiplexer-DeMultiplexer) PFCA (Pump Flow
Control Assembly) SARJ (Solar Alpha Rotary
Joint) DDCU (DC to DC Conversion Unit) PMCU
(Power Management Control Unit) SPDA (Secondary
Power Distribution Assembly) SSU
(Sequential Shunt Unit)
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Space Transportation SystemOverview

• The Space Transportation System is an ascent, Low
  Earth Orbit, and return space vehicle
• Comprised of 3 elements
• 2 Solid Rocket Boosters (SRBs) Jettisoned 2
  minutes after launch and recovered by ship from
  Atlantic Ocean
• External Tank Provides 500,000 gallons of
  hydrogen and oxygen fuel to Shuttle Main Engines,
  jettisoned after fuel expended and burns up in
  Earths atmosphere
• Space Shuttle orbiter Orbits Earth for up to 18
  days and then returns as a glider
• First and only operational space vehicle which is
  reusable
• SRBs, Shuttle orbiter, and main engines are
  refurbished and resupplied for subsequent
  missions
• Only space system which allows heavy down-mass
  capability
• Orbiter power is provided by 3 oxygen-hydrogen
  fuel cells
• Each fuel cell generates up to 7 kW of continuous
  power
• Each fuel cell can generate up to 16 kW of
  short-term (15 min) power
• STS is the only manned US heavy-lift and
  ascent/return system
• Weighs 4,500,000 lbs at lift off
• Carries payloads up to 63,500 lbs
• Crewed by up to 8 astronauts

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Extra-vehicular Mobility UnitOverview

• The Extra-vehicular Mobility Unit (EMU) is a
  self-contained spacesuit used by crewmembers to
  perform Extra-Vehicular Activity (EVA)
• The EMU contains all necessary elements for a
  crewmember to operate outside of a vehicle
• Battery power system
• Pressurized environment
• Life Support System
• Communication system
• Computer, data, and biomedical monitoring system
• Urine collection device
• Lighting and camera system
• Drinking water
• EMU can operate independently for 7 hours
• The air scrubbing cartridge lifetime is the
  limiting factor in EVA
• Similar Russian designed and built EMU (Orlan)
  used on ISS

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Extra-Vehicular Mobility Unit Power System

• EMU battery operates at 16.8 V
• Capacity 26.8 A-Hr
• Produces 70 W of power
• Useful power supplied for 7 hours
• Separate individual batteries are used for other
  EMU systems
• Helmet light
• Helmet camera
• Glove heaters
• Simplified Aid For EVA Rescue (SAFER)(contingency
  jet pack)

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Extra-Vehicular Mobility Unit Power System
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Extra-Vehicular Mobility Unit Power System
ISS Aux Power
SSER
Batt/SCU Sw
Coolant Iso Vlv
Motor
EMUBatt
Fan Sw
Fan
Pump
H2O Sep
Feedwater Iso Vlv
H2O Sw
CWS
RTDS
CCA
Display Sw
OBS
DCM
Batt (Battery) SSER (Space-to-Space EMU
Radio) Iso Vlv (Isolation Valve) SCU (Signal
Conditioner Unit) H2O Sep (Water Separator) Sw
(Switch)CWS (Caution Warning System) RTDS
(Real Time Data System) CCA (Communication
Carrier Assembly)DCM (Display Control
Module) OBS (Operational Bioinstrumentation
System)
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References

• NASA Homepage
• www.nasa.gov
• NASA Missions website
• http//www.nasa.gov/missions/highlights
• NASA Human Spaceflight website
• http//spaceflight.nasa.gov
• Wikipedia
• http//www.wikipedia.com
• The magnificent brain of Steven Johnson
• steven.e.johnson_at_nasa.gov
• 281-483-9534