Space Solar Power

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Space Solar Power

• Thomas Lynch
• Boeing

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Sun Tower Concept
15 kM bed length 3 GW output beam lt 5
cents/kW-Hr 125B Fab Estimate
Microwave beam to earth mounted Rectenna
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Introduction
Introduction
Laser Beam to Existing Photovoltaic Solar Array
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Satellite Concept of Operation
1. Concentrator focuses sunlight on space-based
PV array
2. PV array powers laser diode
3. Laser diode pumps fibers
4. Light from fibers is fed to optics and
transmitted to Earth
7. Power is distributed to consumers
6. DC electricity is converted to AC
5. Terrestrial PV receiver array converts
sunlight to DC electricity
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Transmitter Face and Robot
83,841,250 Radiating Elements 2.141 GW Radiated
Microwave (5.8GHz)

• Two robots placed symmetrically on transmitters
  frontside
• Robots move on a rail connected at perimeter and
  center

Robot assembles and repairs transmitter modules
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Solar Cell Efficiency vs Wavelength
1kW/m2 Sun on EarthTypical earth mounted
solar array has 14 efficiency
Visible Light(reference)
Example Laser Diode Array achieves 40 with
LASER SSP Photovoltaic ground Array
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Economic and Market Factors - General Cost
Findings

• For 1996, U.S.
• Generating costs for new plants averaged about
  3.8 /kWh (EIA, 1997)
• For 2020, U.S.
• A reference case for generation costs in 2020
  is 3.2 to 3.3 /kWh
• World Bank experts suggested an average
  generating cost, 2020, for rapidly growing
  economics, of 5.5 /kWh
• Under following conditions
• Deregulation of foreign electric power markets
• Resource inputs trade in a world market at world
  prices
• Globalization of investment and technology
• Interfuel competition holds costs down

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SSP Economic Market Analysis Team
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Preliminary Observations - Market
Growth In Electric Capacity Supply1995 - 2020
(GW)
World Energy Prospects to 2020, IEA, 1998
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SSP Economic Market Analysis Team
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SPG Pointing Accuracy, Structural Control Trades

• Pointing
• Off pointing of capture (2 degrees of
  control)
• Surface accuracy requires active control
• 1-2o for PV concentrator cells
• Each concentrator needs its own control
• Disturbance while pointing may impact WPT
• Station keeping
• Lifetime (40 yrs)
• Rotating machinery
• Concentrator Materials
• Actuator control

Pat George
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Robotics

• SSP must be managed by robotics
• Installation
• Perform maintenance
• Affect repairs
• All are imperative to achieve cost objective of lt
  5 cents per kW-Hour

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LEMURLegged Excursion Mechanical Utility Robot
LEMUR A new type of autonomous n-pod walker
called LEMUR has been developed for assembly,
inspection, and maintenance. This robot
demonstrates multi-mode operations (mobility,
inspection, and manipulation) with a modular and
multifunctional toolset.
LEMUR Configuration

• Demonstrated fine manipulation and tool based
  operations
• Examined payload identification methods
• Implemented fiducial markers for encoding payload
  identification, orientation, and characteristics
• Performed visual inspection of payloads and robots

Stereo Cameras
4 DOF Hex Driver Leg
4 DOF Gripper Leg w/ in-line camera (Palm-cam)
3 DOF Gripper Leg
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LEMURLegged Excursion Mechanical Utility Robot

• Accomplishments
• Designed and integrated LEMUR mobile platform
• Developed a three-fingered manipulator with
  compliant grasp adjustment for manipulation of
  fine/delicate payloads
• Developed a hex driver end-effector with
  retractable foot
• Developed a miniature macroscopic imaging camera
  (Palm-cam) for integration into grasping
  manipulator
• Developed algorithms and computer code for stereo
  vision and pattern recognition using wavelet
  decomposition of fiducials
• Demonstrated visual object and self-inspection
  using the Palm-cam
• Current Work
• Developing software for autonomous navigation,
  inspection, and manipulation of target

Three-fingered manipulator with integrated camera
optics
Hex driver with retractable foot
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Hyper Redundant Intelligent Systems

• Description
• Develop small, identical robotic elements that
  can accomplish tasks collectively that are well
  beyond the capabilities of its individual
  members.
• Approach
• Utilize serpentine chain of linkages with
  integrated computing, sensing, and power as
  testbed for cooperative robotics executing
  construction, inspection, and maintenance
• Participants
• NASA - Haith, Wright, Loch, Thomas
• CMU - Howie Choset
• Industry - Randy Sargent (Newton Labs)

• Technology Elements
• Mechanism Configuration advanced actuators,
  packaging, lightweight structure, power,
  biomimetic skin
• Single Robot Control force and redundancy
  control strategies, communication, simulation
  modelling of hyper-redundant systems
• Cooperative Robot Control AutonomyMobility
  planning in complex structures, payload
  strategies, data sharing/sensing

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Hyper Redundant Intelligent Systems

• Benefits
• Highly Redundant (gt 7 DOF) serial link
  manipulator chains
• Capable of long reach into highly constrained
  spaces (trusses, frames)
• Capable of prehensile grasping, limbless
  locomotion
• Redundant to multiple joint failures
• Research Challenges
• Path and motion planning to arbitrary locations
  in a complex 3D structure using generalized
  voronoi graph search

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Assessing Technology Readiness Levels
System Test, Launch Operations
Actual system flight proven through successful
mission operations Actual system completed and
flight qualified through test and demonstration
(Ground or Flight) System prototype demonstration
in a space environment System/subsystem model or
prototype demonstration in a relevant environment
(Ground or Space) Component and/or breadboard
validation in relevant environment Component
and/or breadboard validation in laboratory
environment Analytical and experimental critical
function and/or characteristic proof-of-concept Te
chnology concept and/or application
formulated Basic principles observed and
reported
TRL 9 TRL 8 TRL 7 TRL 6 TRL 5 TRL 4 TRL 3 TRL
2 TRL 1
System/Subsystem Development
Technology Demonstration
Technology Development
Research to Prove Feasibility
Basic Technology Research