Transcript Sample Presentation Title - Georgia Institute of Technology

Design of a Millimeter
Waveguide Satellite for
Space Power Grid
Brendan Dessanti
Richard Zappulla
Nicholas Picon
Narayanan Komerath
Experimental Aerodynamics and
Concepts Group
School of Aerospace Engineering
Conference Papers from Our Team
• B. Dessanti, R. Zappulla, N. Picon, N. Komerath, “Design of a
Millimeter Waveguide Satellite for Space Power Grid”
• N. Komerath, B. Dessanti, S. Shah, “A Gigawatt-Level Solar
Power Satellite Using Intensified Efficient Conversion
Architecture”
• N. Komerath, B. Dessanti, S. Shah, R. Zappulla, N. Picon,
“Millimeter Wave Space Power Grid Architecture 2011”
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Outline
• Introduction to the Space Power Grid
• Space as a Dynamic Power Grid
• Millimeter Waveguide Satellite Design
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Waveguide Subsystem
Antenna Subsystem
Thermal Control Subsystem
Mass and Efficiency Summary
Effect on Overall Architecture
• Waveguide Satellite Design Summary and Conclusions
• Overall Conclusions
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Space Power Grid Architecture
Phase I
• Constellation of LEO/MEO Waveguide Relay Sats
• Establish Space as a Dynamic Power Grid
Phase II
• 1 GW Converter Satellites – “Girasols”
• Gas Turbine Conversion at LEO/MEO
Phase III
• High Altitude Ultra-light Solar
Reflector Satellites – “Mirasols”
• Direct unconverted sunlight to LEO/MEO
for conversion
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Space as a Dynamic Power Grid
Use Space for synergy with
terrestrial power sources
• Phase 1 generates revenue by
using space as means of power
exchange
• Makes terrestrial solar and wind
more viable (and more green, by
eliminating need for fossil fuel based
auxiliary generators)
• Creates an evolutionary path
• Early Revenue Generation
• Modest Initial Investment
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Space Power Grid Architecture
Deviations from Traditional Approaches
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• Use Primary Brayton Cycle Turbomachine Conversion of
highly concentrated sunlight (InCA: Intensified Conversion)
Specific Power, s
• Separate the collection of sunlight in high orbit from
conversion in low orbit
Antenna Diameter
• Millimeter Wave Beaming at 220GHz
Antenna Diameter
• Use Tethered Aerostats
Efficiency Through Atmosphere
• Power Exchange with terrestrial renewable energy
Cost to First Power Barrier
Millimeter Waveguide Satellite Design
Conceptual Design of Phase I SPG Satellite
• What it must do?
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Receive and relay beamed power at multi-MW levels
Maximize efficiency
Minimize thermal losses
Minimize satellite mass
launch costs
Conceptual Design Process
1.
2.
3.
4.
5.
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Define Need and Design Requirements from established SPG architecture
Determine preliminary spacecraft parameters and overall configuration
Calculate power and mass budgets
Develop waveguide subsystem and other subsystems (TCS, antennae…)
Develop spacecraft configuration
Millimeter Waveguide Satellite Design
Defining the Need
Parameter
Value
Orbit Altitude
2000 km
Design Frequency
220 GHz
Design Power
60 MW
Satellite Lifetime
17 years
Total Antennas (per satellite)
3
Space-Space Antennas
2
Ground-Space Antenna
1
Delta II Launcher Class
<6000kg
Design Requirements
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Relay Satellite
Waveguide Satellite Configuration
Parameter
Value
Space-Space Antenna
Diameter
90 m
Space-Ground Antenna
Diameter
50 m
Space orbit propulsion Isp
5300 s
Antenna Mass/Unit Area
0.05 kg/m2
Preliminary Spacecraft Parameters
Configuration
Using initial configuration and parameters, subsystem mass
budgets determined using traditional spacecraft design methods
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Millimeter Waveguide Satellite Design
Waveguide System
Must Transmit Power from Receiving Antenna to Transmitting Antenna At
Very High Efficiency
Proposed Solution: Corrugated Waveguides
• Using HE11 mode, Corrugated structures can be designed to be nearly
lossless (Ohmic Losses)
• General Atomics Produces Corrugated Waveguides for various
frequencies (including 220 GHz)
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General Atomics
http://www.ga.com/fusionproducts/microwaves/SCWaveguide/index.php
Millimeter Waveguide Satellite Design
Waveguide System
Parameter
Value
Parameter
Value
Length Waveguide 1
18.5 m
Max Power Transmitted
60 MW
Length Waveguide 2
20.3 m
Attenuation
0.001 db/10m
Total Length
38.8 m
0.99
Material
Copper
Efficiency through
Waveguide
Vacuum
Efficiency WaveguideAntenna Junction
0.99
Medium
Mode
HE11
Total System Efficiency
0.97
Corrugation Period
0.66 mm
Power Loss
1.8 MW
Corrugation Width
0.46 mm
Density Material
8.94 g/cm3
Corrugation Depth
0.41 mm
Wall Thickness
2 mm
Diameter
63.5 mm
Mass/Unit Length
1.81 kg/m
Frequency
220 GHz
Mass
70.3 kg
Waveguide System Parameters
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Millimeter Waveguide Satellite Design
Antenna Sizing Derivation
Fraunhofer Diffraction at a circular aperture
can be represented by the Bessel Function:
Where:
Solving for the first zero (first ring of airy disc), and using geometry gives the
following relationship governing transmitter and receiver diameter and frequency:
From the Rayleigh Limit, the amount of power that can be received is
found using the Bessel Function (84% for the first zero/ring):
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Millimeter Waveguide Satellite Design
Antenna Sizing Plot
X: 8.48
Y: 0.952
X: 2.44
Y: 0.838
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Airy Ring
% Power
J1 Zeros
kR
kD
1st Ring
83.8%
3.83
1.220
2.44
2nd Ring
91.0%
7.02
2.233
4.47
3rd Ring
93.8%
10.17
3.238
6.48
4th Ring
95.2%
13.32
4.241
8.48
5th Ring
96.1%
16.47
5.243
10.49
Millimeter Waveguide Satellite Design
Thermal Control System
Limiting Factor
Equilibrium Temperature
Achieve High K using:
2 Part Separated Spacecraft Main Body
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Millimeter Waveguide Satellite Design
End-to-End Efficiency and Mass Analysis
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System/Subsystem
Mass (kg)
Efficiency Parameter
Value
Payload (3 antennas)
734
0.90
Propulsion
75
Efficiency Through
Atmosphere
Attitude Control
180
0.95
C & DH
64
Ground Receiver Capture
Efficiency
Thermal
989
Satellite Receiver Capture
Efficiency
0.95
Electrical Power
775
0.90
Structure and
Mechanisms
571
Space Receiver Antenna
Efficiency
0.90
Waveguide
70
Space Transmitter Antenna
Efficiency
Communications
64
0.97
Total Spacecraft Dry
Mass
3422
Efficiency of Waveguide
System
Total Spacecraft Efficiency
0.79
Total Loaded Mass w/
Contingencies
4267
End-to-End Efficiency*
0.43
*Power beamed from ground to
satellite 1, relayed to satellite 2,
and beamed to ground
Technical and Economic Results Analysis:
Waveguide Effect on NPV Trough
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Phase 1 Breakeven Occurs Before Satellite Lifetime
Mass Estimate Comes In Under Previously Used Estimate
Phase 1 Costs Very Small Relative to Full Architecture
Phase 1 Launch Cost Not Crucial to Full Architecture
Millimeter Waveguide Satellite Design
Summary and Conclusions
Does the Design Close?
• Sizing estimate fits within bounds of SPG economic
model
• Satellite efficiency values are sufficient to provide power
at reasonable cost to achieve breakeven in 17 year
satellite lifetime
• No anticipated technical show stoppers to millimeter
waveguide spacecraft development
YES
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Overall Conclusions from all 3 Papers
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Conceptual Design of Phase 1 Waveguide
Satellite Refined
Conceptual Design of Phase 2 Girasol 1 GW
Converter Satellite Established
SPG Architecture Updated With
Large Improvements and Reduced Uncertainty
"The problems of the world cannot possibly be solved by
skeptics or cynics whose horizons are limited by the
obvious realities. We need men who can dream of things
that never were." – John F. Kennedy
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Questions?
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Backup
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Backup
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