The Technical Challenges for Space Solar Power

Neville I. Marzwell, Ph.D. Advanced Concepts - Technology Innovations

NASA- Jet Propulsion LaboratoryNeville.I.Marzzwell@jpl.nasa.gov

September 2007

Overview of Forces affecting Space Solar Power Challenges and Opportunities

• Global climate change caused by accumulating concentrations of greenhouse gases in the atmosphere is a growing concern– Continuing improvements in efficiency are being more-than-offset by

rapidly growing global demand for new power plants• Stabilizing the carbon dioxide-induced component of climate change is

an energy problem• By 2050-2100, ~ 15TW to 40TW of Carbon-neutral energy must be

available if CO2 levels are to be stabilized at 2- to 4- times pre-industrial levels

• Only a handful of base load power options exist that can make a meaningful contribution to that level of generation capacity– Space Solar Power (SSP) is one of those options

• A constellation of large Space Solar Power Satellites (SSPS) deployed in a family of geosynchronous Earth orbits has the potential to deliver 10s to 100s of Terawatts to markets worldwide

• The policy environment and programs related to SSPS have varied widely during the past 40 years--and continue to be very uncertain

3

The Energy Challenge: Trends of Concern

Asia56%

Africa13%

Middle East3%

Western Europe 5%Eastern Europe

7%Our Hemisphere

13%(US = 4%)

• By 2025, the world will have added 2 billion more people, 56% of the global population will be in Asia, and 66% will live in urban areas along the coasts

• Increased CO2 production may alter the Earth’s climate, possibly causing:

– Rising ocean levels and loss of coastal areas– More intense tropical storms & humanitarian ops– Agricultural climate change—causing migration,

and shifts in power, ethnic & land based conflict

Climate Change

Population

American Competitiveness

• The U.S. is losing global market share & leadership

• R&D investments & skilled workforce are declining

– "a major workforce crisis in the aerospace industry…a threat to national security and the U.S. ability to continue as a world leader.”

Energy

• Energy growth tracks w/ population & economic growth

• Liquid fossil fuels may peak before alternatives come on line causing inability for supply to match demand, shortages & economic shock, instability / state failure, and great power competition

• Three energy concerns: 1) mobility fuels, 2) base-load electricity, 3) peak-use electricity

4

Breakdown of Energy Use - 2005 Estimated values primarily from EIA projections

• ENERGY USE GLOBAL US• Electricity ~ 2,400 gw ~ 460 gw• Generating Loss ~ 2,600 gw ~ 840 gw• Fuel use: ~ 9,500 gw ~ 2,100 gw• Total ~ 14,500 gw ~ 3,400 gw -

World needs to replace ~ 10,000 Gigawatts– ~ 85% of US use comes from fossil fuels.

– US needs to replace ONLY about 2300 Gigawatts.

5

The Energy Challenge Future Energy Options Must Be…

• Following wood, coal, and oil, the 4th energy must be*:

– Non-depletable - to prevent resource conflicts

– Environmentally clean – to permit a sustainable future

– [Continuously] Available – to provide base-load security for everyone

– In a usable form – to permit efficient consumption & minimal infrastructure

– Low cost - to permit constructive opportunity for all populations

• A portfolio of substantial investments are needed, but options in the next 20-30 years are limited…

* Adapted from Dr. Ralph Nansen’s book, “Sun Power”

SourceSource CleanClean SafeSafe ReliableReliable Base-loadBase-load

Fossil FuelFossil Fuel NoNo YesYes Decades remainingDecades remaining YesYes

NuclearNuclear NoNo YesYes Fuel LimitedFuel Limited YesYes

Wind PowerWind Power YesYes YesYes IntermittentIntermittent NoNo

Ground SolarGround Solar YesYes YesYes IntermittentIntermittent NoNo

HydroHydro YesYes YesYes Drought; Complex SchedulingDrought; Complex Scheduling

Bio-fuelsBio-fuels YesYes YesYes Limited Qty – Competes w/FoodLimited Qty – Competes w/Food

Space SolarSpace Solar YesYes YesYes YesYes YesYes

6

GLOBAL CARBON FUEL REPLACEMENT- 2005 ADEstimated values primarily from EIA projections

69% OR 10,000 GW MUST BE REPLACED~ 31% OR 4500 GW

DOES NOT NEED TO BE REPLACED

10000 GW - 69%Carbon Fuel Use

MUST BEREPLACED

8600 GW - 60 %Carbon Fuels

1900 GW - 14%Renewable

Fuel, ElectricalNOT REPLACED

900 GW - 7%Renewable

Fuels

9,500 GW - 66%Non-Electrical

- Fuels -

1000 GW - 7%RenewableElectrical

1400 GW - 9%Electrical USECarbon based

Generation

2600 GW - 17%Generating

LossesNOT REPLACED

4000 GW - 27%Electrical

Carbon-based

5,000 GW - 34%Electrical Use

And Generation

14,500 GW - 100 %All Global Energy Use

Fuels & Electrical Generation

7

Export MarketsExport Markets

SBSPSBSP

Stable PopulationStable Population

DoD, National, and International Impact Invest, Survive, Flourish and Grow – A Future History

Wireless Power Wireless Power TransmissionTransmission

OMVOMV

IndustrializationIndustrialization

TourismTourism

Stellar ProbeStellar Probe

Hurricane Hurricane DiversionDiversion

AsteroidAsteroidDefenseDefense

Space RadarSpace RadarTraffic ControlTraffic Control

““Dredge Harbor”Dredge Harbor”

BeamedBeamedPropulsionPropulsion

Sustainable CivilizationSustainable Civilization

Nations developNations developLess PovertyLess Poverty

DemographicDemographicTransitionTransitionReduce GHGReduce GHG

Reduce ConflictReduce Conflict

Stable ClimateStable Climate

TetherTether

TelecomTelecom

TravelTravel

Reusable Reusable Launch VehicleLaunch Vehicle

Directed EnergyDirected Energy

ISRUISRU

EnergyEnergy InfrastructureInfrastructure

Clean EnergyClean Energy

Growth in GDPGrowth in GDP

8

Capabilities and Challenges If this has been looked at before, what’s changed?

9

The 1 GW system would be BIG • The collector would cover an area equal to

that of a city like Austin or 350 square km.

• It would weigh over 3.5 Million Tons.

• It could cost over $37 Billion dollars.

• It would also need a massive pump-generating storage facility and 2 reservoirs, which would cost about $12 Billion.

• This system as described has no reserve storage to cover totally cloudy days.

10

Components of an SPS in Orbit:• The Solar Collector array in Space consists of

photovoltaic film on a plane several miles across. • Power from the collectors goes via conducting cables

to the phased array Transmitting Antenna.• The Transmitting Antenna is a disk about 1 km

across, attached to the collector array. It sends power to the ground 23,000 miles below.

• The Rectenna (Receiving antenna) is an array of fixed wire dipole antennas covering an oval area on the ground several miles across. It very efficiently captures the microwave energy. This is then converted into usable grid electricity.

SSP - Technology Subsystem Elements

1.2 GW Power to Local

Distribution

Overall Dimensions:

~5 km x ~15 km

6.5 km x 8.5 km RectifyingAntenna

(Rectenna at 5.8 GHz)

High Power Density

Microwave Beam

Structural Elements

Solid State WPT

Multi-Bandgap PV

Optical Elements

RF Elements

Power System Elements

Logistical

Materials

Low Power Density

Microwave Beam

Placed in Earth Geo-stationary Orbit

Typical Scenario

Large SPS in GEO(e.g., 24 Satellites & ~30 GW Total)

Microwave Power Transmission(2.45 GHz or 5.8 GHz)

Power ~ 1.2 GW (Delivered on the Ground at Remote Locations)

12

Launch Challenge: Costs Will Benefit From Economies of Scale

Courtesy of Mr. Gordon Woodcock

Disregard this curve, it was added by someone else

Expendable Launch Vehicles

Fully Reusable Launch Vehicles

13

Solar Power Satellite can be Modular

Technology has improved, even more since 1989,oil is now over $75 per barrel and rising

Size and Structural Challenge:Technology is maturing fast for possible size reduction

.

1 2 3 4 5 6 7 8

TECHNOLOGY READINESS LEVELS

PROOFED CONCEPT

EXPERIMENT

ORBITAL DEMO

ORBITAL FUNCTIONAL PERFORMANCE

CONCEPT CHARACTERIZATION

CONCEPT EVALUATION

TECHNOLOGY FEASIBILITY

STUDY

MECHANICAL DESIGN

DEMONSTRATION

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Ground Demos Flight Demos

SSP System Study Results

• Potential Structural Characterization

•Packaging Efficiency

•Element Deployment Control

•Rigidized Elements

• Controlled/Rigidized Structure

• Launch Restraint/Release

• Ascent Venting Struct. Elements

• Multiple Element Performance

• Geometric Precision

• Thermal Stability

SSP INFLATABLE SPACE STRUCTURESTECHNOLOGY DEVELOPMENT

Scale Hardware

Functional Components

Breadboard/Structural Elements

Very Large Scale High Performance Structure

• Initial Geometry/Precision

• Deployed Stiffness

• Thermal stability

• Launch Release

• Analytical Model(s) Validation

Moderate Size System

SMALL SATELLITE MISSIONS

SMALL REFLECTOR MISSIONS

MODERATE SCIENCE MISSIONS

SUNSHIELD & SOLAR SAIL MISSIONS

• Venting Technique Validation

• Controlled Deployment

• Launch Release

• Deployed Stiffness

• Initial Geometry

Small Prototype Functional System

Large deployable structures

Sub-scale SSP demo

16

Base and Peak Loads…Need Power Storage

Typical Base and Peak Loads for a Large City

0200400600800

10001200140016001800

1:00 3:00 5:00 7:00 9:0011:0013:0015:0017:0019:0021:0023:00

Time of Day - 24 hour clock

Megawatts of Load

PeakBase

17

18

Orbits: SPS in Geosynchronous orbit.

~1980 Reference System

19

Space is the Place for Solar Power

• In Geosynchronous orbit, the Satellite stays over one spot on the equator all the time.

• It faces the sun all the time, generating power 24 hours a day, 7 days a week.

• It only rarely hits the Earth’s shadow.

• The Rectenna does not need to track it.

• Sunlight is 30% stronger in orbit.

• The satellite has virtually no moving parts.

20

GEO, LEO vs. MEO (Part 1)• GEO: Proposed 1980

- Higher launch cost versus MEO/LEO

- Very large path distance requiring antenna/rectenna sizes which far exceed the state of the art frequencies (2.35 GHz, 5.8 GHz)

• LEO Benefits: Proposed IAF 2006- Lower launch cost (7 times cheaper per Kg)

- Shorter beam path distance (500 km vs. 35,680 km)- Antenna sizes 70 times smaller

• LEO Challenges- Orbit used by communication satellites

- Adaptive beam steering, requiring a sophisticated phase array antenna to track rectenna on the Earth with very large relative motion velocity, while simultaneously tracking the sun- Lack of solar illumination (50% darkness), difficulty rejecting heat- Only a small area of the Earth can be covered which necessitates large number of satellites (12) compared to (3) for GSO

• MEO offers the benefits of GEO at lower cost- Altitude of 11,000 - 12,000 km : radiation level low, costs are modest, orbital period of about 6 hrs, so sun synchronous orbit can be achieved with 4 orbits per synodic day- Minimum constellation of 4 satellites in 2 orbital planes. Each orbital plane is orthogonal to the ecliptic, and orthogonal to the orbit plane. Each satellite orbit is inclined at 66.7 degrees to the equator. The ecliptic is the Earth’s orbit around the sun which is at an angle of 23.3 degrees to the Earth’s equator

21

GEO, LEO vs. MEO (Part 2)• Advantages of the Proposed Approach

1) approximately 30% of the Earth's surface is visible to each satellite. Each satellite is in sunlight approximately 90% of the time (most of the year continuous sunlight, for a few weeks in eclipse season satellite is in darkness about 20% of each orbit)

2) Beam path length is about 30% versus GEO, affording corresponding smaller antenna and rectenna. Each satellite in each orbital plane is at 180 degrees to the other satellite in the same orbital plane.

3) Each satellite pair (in one plane) is at 90 degrees phase to the other pair (in the other plane), meaning that a neo-tetrahedral configuration is maintained, thus every point on the entire world is in the field of view of at least one satellite for about 90% of the time.

4) The special distinction versus LEO is that no beam steering is required, so in this respect the satellite design is very similar to a GEO spacecraft. Because the Sun/Earth angle is always 90 degrees, a constant fixed axis rotating antenna despun platform can be employed. The solar array tracks the Sun, and a despun platform tracks the Earth, rotating once every six hours. No dynamic beam steering is required, unless there is a need to serve a different rectenna on the Earth

5) For a nearly half the time, the MEO constellation would be able to provide better service than GEO satellite to rectennas in high latitudes; e.g. north of 34 degrees north (and south of 34 degrees south). This is because for approaching half of each orbit the MEO satellite would be at a higher elevation above the horizon than an equatorial GEO satellite.

22

Advantages of the Rectenna instead of a ground solar collector:

• It is an array of thousands of small wires.• The rectenna also has no moving parts. • Wind, hail, and dust can not damage it.• It is much smaller and uses much less materials

than a ground solar collector.• It collects energy all the time, 4 times more

efficiently than a ground solar collector.• Backup satellites can be switched in very rapidly.

23

Rectenna from above

24

CHALLENGE: SSP Wireless Power Transmission TechnologyAccomplishments:

1. Developed WPT Link Budgets for three 5.8 GHz Systems using Klystrons, Solid State Devices and Locked Magnetrons.

2. Formed NASA WPT Working Group with weekly telecons involving up to 6-NASA Centers, 4-Univ., 4-Industry members,covering Microwave, Laser and Redirected Sunlight WPT systems. Most emphasis on microwaves, but some Lasers.

3. Began NRAs on circularly polarized rectennas, Texas A&M, GaN Class-E amplifier, Rockwell Science Center, Light weightphased array module study, Boeing Phantom Works and a table-top retrodirective phased array demo for public demo, JPL.Demo phased array at JPL terminated due to X3-cost growth. Low-cost phased arrays is an oxymoron.

4. Developed white-paper on SSP spectrum allocation issues as follow on to SSP Question submited to ITU from Study Group 1A.

5. Performing detailed investigation into high-power microwave waveguide and filters multipacting breakdown margins.(Multipacting=RF synchronous, reinforced multiple electon impacts into parallel electrodes in a hard vacuum yielding secondary emission cascade resulting in an RF short circuit. Fixes are to modify secondary multiplication surface, fill or pressurize guides)

6. Investigating systems for power beam safety and wrote a paper on Space Policy Issues of SSP WPT beams.

7. Provided estimates of areal mass density, specific power, system element efficiencies, voltages, operating temperatures, etc.to the SSP System Study Group. Inputted pointing errors, required surface errors, subarray sizes, etc. to the Structures Group.Operating voltages, currents and regulation required to the PMAD Group. Land area required and biota interactions to theEnvironmental Group. Assembly, maintenance and phase calibration interface data supplied to the Robotics Group.

8. Identified key problems in the RF-Spectrum-EMC, thermal, and grating-lobe control areas, in addition to RF-breakdown.

State of the art (SOA), but applicable quantitative numbers and examples ( mostly Raytheon, ground-based) are given below with corresponding SSP in-space requirements for comparison of the required technology challenges .

25

5.8 GHz GEO WIRELESS POWER TRANSMISSION SYSTEM DESIGN EXAMPLE

DC Power Distribution

DC-RF Power Conversion Efficiency

Waste Heat Removal

Source PMAD

Subarray Aperture Efficiency

Subarray Failures

Amplitude Errors &Taper Quantization

Phase Errors

Electronic Beam Steering Scan Loss

Transmitter Monitor & Control System

BEAM SAFETY SUBSYSTEM

Beam Coupling Efficiency

Propagation Impairments

Polarization Mismatch

Rectenna Aperture Scan Loss

Rectenna Aperture Efficiency

Rectenna RF-DC PowerConversion Efficiency

Waste Heat Removal

DC Power Collection

Load PMAD

Rectenna Monitor & Control System

Dt = 500mDr = 7500 mmkmb = 0.9182Edge Taper = -10.02 dBPeak/Ave P.D. = 2.35

Clear Air = -0.05 dB = 0.9885

4mm/hr Rain @ 0.01 dB/km X 2.5 km = -0.025 dB = 0.994

0.90 -0.458 dB

0.95 -0.706 dB

0.96 2% Random Failures

0.986 10-Step & +/- 1 dB

0. 97 10 deg rms

0..977 -0.1 dB max

0.933

0.918

0.999 +/- 2 deg

0.999 -0.0 dB max

0.95

0.86

EMC & Diplexing Filters

0.794 -1 dB

EMC Filtering

0.891 -0.5 dB

Rectenna Element Failures

0.99 -1%

0.395 Overall WPT Efficiency

RADIATE

RECEIVE

PROPAGATE

WPT SYSTEM PARAMETERS

26

5.8 GHz Magnetron Directional Amplifier (MDA) SSP Subarrays*

Richard M. Dickinson, JPL

4m X 4m Edge Subarray3 X 3 = 9-MDAsYielding ~ 2.8 kW/m2 PFDand thus -9.5 dB Aperture Taper

5 kW RF out, 85.5% efficient Magnetron, ~1kg,6 kV, 1A & 70 W, 5s-Starting Filament & Off

44 cm dia., 350 deg C PyrolyticGraphite Radiator Dumping 850W

Waveguide Phase-Reference, Circulator, Filters, ASIC- MMIC, Buck-Boost Coil, Guide-Tuner and Power Distribution

Portion of 4m X 4mCentral Subarray with 9 X 9 = 81-MDAsYielding ~ 25 kW/m2 PFDfor 1.2 GWe System

Slotted WaveguideTransmitting Antenna~ 6 kg/m2, 0.5 mm (.02’)Aluminum (~ 1100slots/m2)~ 3.2 cm thick (Cross Feeds + Radiating Waveguides)

* Var. of Brown, W. C.,”Satellite Power System (SPS) Magnetron Tube Assessment Study, “ NASA Contract NAS-8-33157, for MSFC, 7/10/80.

Two Central Devices Diplexedfor Retrodirective Pilot BeamReceiver Function

MLI BlanketsOver 95 deg C Electronics

Peak Mass Density = Transmitter@ 5.7 kg/m2

Antenna @ 6 kg/m2

Absorptive & Reflective Filters @ 2 kg/m2

HVDC Distribution Lines@0.263 kg/m2

TOTAL RF Peak Density = 14 kg/m2

Edge Subarray Density = 7.7 kg/m2

Total “Average” Mass Density ~ 32 kg/m2

NOTE:Not To Scale

Est. PMAD@1.5kg/kW ~20kg/m2

27

SSP Wireless Power Transmission Technology-I

1. SOA DC-RF Conversion -%/W/GHz/C .76/6.9/8.0/125 .83/900/2.45/135 .75/50kW/2.45/100

SSP Required= .90/6-60/5.8/300 .855/6kW/5.8/350 .83/26kW/5.8/500

2. SOA Large Phased Arrays (non Retrodirective) PAVE PAWS@UHF Cobra Dane@L-BandTHAAD ~2mX5m, 25,344 X-Band Elements 31m dia(twin)-3/4MW 29m dia-1MW(TWTs)TRW- Capistrano HPM 48-6ft S-Band Dishes 1,792 active elements of 5354 15,3600 elements

SSP @5.8GHz, 500m dia, ~2 GW CW out, #elements= 83,841,253 381,618 82,589

3. 2.45 EMC dBc/Hz@50MHz & 2ndHarmonic= -150 & -40dBc -190 & -60dBc -160 & -30dBc

SSP EMC Requirement @ 5.8 GHz+/- 75 MHz & Fleet of ~ 100 SSP in View= -174dBW/m2/Hz?

4. SOA Spacecraft Filter Multipacting Breakdown Margin= 6-10dB at C & Ku-Band 10-50W, 13 yrs.

SSP @ 5.8GHz Margin Requirement >6 dB for 40 years= 60W 6 kW 26kW

Solid State Magnetron Klystron Phase Injection Locked

Richard M. Dickinson, JPL

28

SSP Wireless Power Transmission Technology-II

5. SOA CW Microwave Power $/W, GHz, Quan.= $3, 1.9,100s $.025,2.45,100Ks $1.25,UHF,2s

SSP Required CW Microwave Power at 5.8 GHz, Fleet of 100 Quantity = $1-2/W, 105-109

6. SOA Microwave Device, Thermal & PMAD kW/kg= .01 .2 .02

SSP WPT Array System Specific Power (kW/kg) .42 .34 .3

Key Technology Item s GaN@300C PLL-ASIC 5-Stage MDC@500C

Solid State Magnetron Klystron Phase Injection Locked

The near term technology to be developed is the ASIC/MMIC for using modifiedcooker tube magnetrons as phased array sources for retrodirective power transmittingphased arrays in beaming power to station keep geostationary stratospheric platforms for telecommunication and scientific observation applications. ( ~ $ 1-2M/ 1 yr)

50-100V 3.5-6kV 28kV

ASIC=Applicaion Specific Integrated Circuit GaN=Gallium Nitride MDC=Multiple Depressed Collector PLL=Phase Locked Loop PMAD=Power Management & Distribution dBc=Decibels Below the Carrier Level dBW=Decibels Relative to a Watt

Richard M. Dickinson, JPL

29

SSP Wireless Power Transmission Technology-III

To Lower the Barriers to SSP, Technology is Needed to Permit:1. Electromagnetic Compatibility (EMC)-A. Power Beam Frequency Allocation at wavelengths with less than 5% (0.2 dB) atmosphere propagation impairment for 99.5% of a year. Bandwidth at auctionfor less than $100/Hz? WPT Service definition in the International TelecommunicatonUnion (ITU) by over 50% of the 182 member countries.

B. Close-In Carrier Noise and Harmonic Filtering in GEO, with less than 10% (0.5 dB) insertion loss and greater than a safety factor of 2 (Voltage ratio, 6 dB Power) multipacting breakdown margin for less than 2 kg/m2 areal density.Less than 15% (0.7 dB) insertion loss for ground based rectennas at less than $0.2/W.

2. Lifetime- 40 year lifetime for high power microwave devices and parts in GEO.

3. Beam Safety Perception- The “fear of frying” must be overcome by working demosand public education of beam safety marking and intrusion detection with safe beaminterruption and restoration, for less than $.005/kWh delivered energy.

Richard M. Dickinson, JPL

30

Bill Brown’s* Magnetron Directional AmplifierUsing A Modified Cooker Tube

AmplitudeComparator- Driver

Buck-Boost Coil

Modified Cooker Magnetron

Waveguide Reactance Tuner

FerriteCirculator

Directional Couplers

To Antenna

Phase Comparator

RF Driver Amplifier

5- Bit PhaseShifter

Phaser DriverPhaser Commands

Power Output Ref.

2.45 GHz Ref. Signal

React- anceDriver

WCB MDA MMIC-ASIC (TBD)

Power Converter

Supply Voltage

* Brown, William C.,”Development of Electronically Steerable Phased Array Module (ESPAM) with Magnetron Directional Amplifier (MDA) Power Source,”Final Report, Microwave Power Transmission Systems, Weston MA, Texas A&M Research Foundation Subgrant No. L300060, Project RF-2500-95, Sept. 1995.

** McDowell, Hunter L.,”Magnetron Simulation Using a Moving Wavelength Computer Code,”IEEE Trans. Plasma Science, Vol. 26, No. 3, pp.733-754, June 1998.

300-1000 W

3.35-3.85 kV ~ 300mA

~ 1 W

-20dB

~ 30 dB Gain

-50 dB

Notes: By not powering themagnetron, the low powerlevel RF driver signal canbe reflected through thecirculator to the antenna,yielding a two-level unit.

Filament turned off afterstart for clean spectrum**.

~ 2-3 W

~10 mW~ 1/3500 V/W

0.0024 H, 8.6 Ohms

~ 75% Efficient

ASIC/MMICNeeds Developing

Richard M. Dickinson, JPL

31

Slotted Waveguide Subarray Low Cost Manufacture(With Built In Filtering and Multipaction Inhibiting)

Concept by Bill Brown[1]

..... ..... .....

..... ..... .....

PunchRegistration

Cut Tab Relief

BendTab

Form Inter-W/G Wall

Punch RadiatingWaveguide Slots

FormEnd Walls

Heavy Reynolds Wrap or Equiv. Aluminum Sheet Stock

Integrate Halves &Spot Weld Assy.

Add Feed Guide-Filter to Assy. with Magnetron Flange

1. Brown, W. C.,”Microwave Beamed Power Technology Development,” Final Report JPL Contract No. 955104, Raytheon PT-5613, May 15, 1980.

PunchRegistration

8-Slot X 8-StickW/G Subarray

(front view)W/G TOOLING NEEDS TO BE DEVELOPED!

(back view)

Dielectric Cladding

Richard M. Dickinson, JPL

32

WIRELESS POWER TRANSMISSION NEEDS

I. In order to obtain a service definition and frequency allocation for SSP use, it will benecessary to show the ITU that the SSP can be designed and maintained ElectromagneticallyCompatible with other users of the Radio Spectrum.

II. Because of the GW power levels and the rain of electromagnetic energy falling to Earthfrom a fleet of SSP spacecraft functioning under various operational and environmentalconditions, it is required to filter the carrier noise outside the ISM band, to filter the harmonics, to provide notch filters on the spacecraft and possibly on ground radio andradar equipment functioning at certain sensitive frequencies outside the ISM bands. III. There still exist large uncertainties in the WPT performance and the cost impacts due tothe lack of analysis, measurements, models and victim susceptibility data for determiningthe SSP Electromagnetic Compatibility (EMC) requirements.

IV. Furthermore, a functioning WPT facility does not now exist to validate the adequacyof mitigation approaches or the costs both economically and in filters insertion loss required to achieve EMC both on the transmitters and on the rectennas.

V. Will careful engineering design be economically affordable and adequate to preventserious interference to other users of the electromagnetic Spectrum?

Richard M. Dickinson, JPL

33

SPS Microwave Beam is Safe.

• Wireless Power Transmission was first demonstrated at Goldstone, Ca. in 1975.

• Many years of medical tests have shown that microwaves do not harm people, animals or plants unless they are strong enough to actually heat tissue like a microwave oven.

• However, the SPS beam is only 1/4 as strong as sunlight, too weak to hurt anything.

• The beam also uses a frequency that minimizes heating of water (such as raindrops).

34

State-of-the Art PV R&D

• Commercial cells– Typically only 50-80% of these values

University of Maine

Boeing

Boeing

Boeing

BoeingARCO

NREL

Boeing

Euro-CIS

200019951990198519801975

NREL/Spectrolab

NRELNREL

JapanEnergy

Spire

No. CarolinaState University

Multijunction ConcentratorsThree-junction (2 -terminal, monolithic)Two -junction (2 -terminal, monolithic)

Crystalline Si CellsSingle crystalMulticrystallineThin Si

Thin Film TechnologiesCu(In,Ga )Se2CdTeAmorphous Si:H (stabilized)

Emerging PVOrganic cells Varian

RCA

Solarex

UNSW

UNSW

ARCO

UNSWUNSW

UNSWSpire Stanford

Westing -house

UNSWGeorgia TechGeorgia Tech Sharp

AstroPower

NREL

AstroPower

Spectrolab

NREL

Masushita MonosolarKodak

Kodak

AMETEK

PhotonEnergy

UniversitySo. Florida

NREL

NREL

Princeton UniversityKonstanz

NREL

NRELCu(In,Ga )Se2

14x concentration

NREL

UnitedSolar

United Solar

RCA

RCARCA

RCA RCARCA

Spectrolab

University CaliforniaBerkeley

Solarex12

8

4

0

16

20

24

28

32

36

Best Research -Cell Efficiencies

Efficiency (%)

026587136

Research: “Champion Research: “Champion cells”cells”

• Near 25% efficiency in crystalline silicon and high-efficiency processing

• Rapid thermal processing

• Record efficiencies in CIGS (19.2%); CdTe (16.5%)

• Three-junction GaInP2/GaAs/Ge cell with >35% efficiency

• At up to 400 suns• New PV technologies

emerging• Dye-sensitized cells (up

to 11%)• Organic and polymer

cells (3-4%)• Nanostructured

35

PV R&D Needs

• Two main directions for PV technology development– Ultra high efficiency cells:

• Efficiency target: > 40%

– Low-cost, large scale production cells:• Minimum efficiency target: 15%

• Additional needs:– High voltage cells– High temperature cells– Large deployable arrays

• Both rigid and flexible technologies

36

TRL Status of Advanced Solar Cell/ArraysOhmic contacts

AR coatingP-type cap

Quantum Dots

N-type cap

Ohmic contact

Ohmic contacts

AR coatingP-type cap

Quantum Dots

N-type cap

Ohmic contact

Phoenix Ultraflex Array ( 100 Wh/kg)TJ Cells ( 27% eff)

TRL 6-7

MRO Rigid Panel Array (60 W/kg)TJ Cells ( 27% eff)

TRL 8-9

NM ST-8 Ultraflex Array ( 180 Wh/kg)TJ Cells ( 28% eff)

TRL 5

Quantum dot Solar CellsEff (> 40%)

TRL 1-2

Four Junction solar Cells Eff (> 35 %)

Experimental .CellsTRL 2-3

TJ Cells ( 27% eff)In production

TRL4

37

   

www.aec-able.comTel: 805.685.2262Fax: 805.685.1369

Able Engineering CompanyCorporate Headquarters, 7200 Hollister Ave., Goleta, CA 93117

Advanced Array Designs

UltraFlex CellSaver

SquareRigger

FTFPV Solar Array

38

SSP Robotics Challenges• Major Barriers

– Scale of SSP Systems• hundreds of autonomous agents• multiple kilometer structure to assemble and maintain• millions of individual elements that may need to be replaced or repaired

– Ability to conduct continuous operations over two decades – Ability to conduct maintenance during continuous operations– Force Rejection/ Balancing during materiel movement and placement in micro g environment – Knowledge regarding how EM, thermal and constrained access SSP environmental issues affect

robot operating conditions

• Technology Needed to bring to Reality– Coordinated multiple autonomous robotic platforms– Ability for robotic systems to reconfigure themselves and adapt to changing tasks– New and/or unique robot physiologies– How to walk/manipulate softly– Smart mechanization– Intelligent systems and platform for continuous diagnostics– Hierarchy of robot and platform state assessment

39

Challenges to Traditional Approach for Autonomy and Robotics

• Competitive pressures are moving robotic manufacturing and assembly toward shorter product cycles, lower inventories, higher equipment utilization, and shorter lead times, as a result scheduling and control gained priority.

• Scheduling and control has been a process of command and response that relies heavily on hierarchical models.

• Centralization leads to complexity: The control software must handle the entire system and anticipate every circumstance than can arise. Changes in the configuration of the system require changes in the control software. The central computer and database are a bottleneck that can limit the capacity of the performance , and constitute a single point failure that can bring down the entire facility.

• Hierarchy also leads to complexity: Hierarchical control schemes bind workstations into groupings that are difficult to change as the system operates. The hierarchical rule of information flow through supervisors means that naturally occurring lateral information flows are often duplicated, leading to needless redundancy and the possibility of inconsistency between the two versions

N. Marzwell

40

SSP Robotics Roadmap• Development for Next Year

– Initiate experiments in heterogeneous, multiple platform cooperative activities, for example, simultaneous cooperative operation of LEMUR and Skyworker

– Development of smart mechanization and structures

• Needed in 2 Years to Bring Space Based Construction a Reality– Integrated technology demonstration showing autonomous grasp and locomotion of antenna

elements– Integrated technology demonstration of mating tasks with two multifunctional cooperative systems– Proof of concept materiel mobility with disturbance rejection– Demonstrate strategies for operations in off - lighting conditions– Simulation and visualization of assembly activity

• Needed in 5 Years To Bring Space Based Construction a Reality– Demonstrate payload balancing with multiple agents– Integrated technology demonstration of cooperative attachment and inspection operations with

robust control – Demonstration mobility with payload interaction for expanding structure in testbed– Refinement of rejection of disturbance forces for low stiffness structures– Refined vision system for speed and anomaly rejection

41

Near Term Flight DemonstrationPurpose: A near term flight experiment that demonstrates the

key SSP operations of panel placement, localization and assembly to build and inspect a segmented transmitter array

Approach: • Use an advanced LEMUR configuration and a modified

MPL Robotic Arms for grappling and locomotion of simulated transmitter segments that incorporate smart mechanization for assembly operations

• Utilize a Hitchhiker carrier pallet through STS Small Packages Program. Operations will be conducted within self-contained contained structure to simulate SPP activities

Will Demonstrate:• Materiel movement with MPL robotic arm• LEMUR providing stand-off visual sensing for robotic arm • LEMUR conducting fastening, asssembly and inspection

operations• Cooperative robotics between two systems• Semi-autonomous operations• Mobility and materiel movement in micro-g

Budget•Year 1 $ 3 Million•Year 2 $ 4.5 Million•Year 3 $ 6 Million•Pallet Cost: $1.5 Million

Side walls removed for clarity, full extension of pallet work area not shown

42

SSP Robotics Roadmap

• Needed in 10 years– Flight demonstration of

multiple robotic systems conducting assembly operations

– Large scale cooperative systems that demonstrate payload exchange handling and assembly

– Adaptation and learning for unknown payloads and disturbances and failure compensation

Sky worker and LEMUR working cooperatively to assemble, inspect, and conduct maintenance on a SSP structure

43

Scaling It Up to 300 GW• The US has a Base Load of over 300 GW.

• A Base-Load Solar Power System providing 300 GW would require storage reservoirs totaling 1/3 the Area of Lake Erie.

• The Collector Site would cover an area of ~90,000 km sq. or 30% the area of Arizona.

• It would cost about 10 trillion dollars and weight about 1 billion tons.

44

Est. Cost: One 10-GW SPS breakdown (use advanced R.L.V.)

• Fabrication of SPS modules - 5 Billion

• Construction of Rectenna - 5 Billion

• Launch Components to LEO* - 3 Billion

• Transport to GEO & Deploy - 2 Billion

TOTAL COST ~ 2030 AD - 15 Billion

* Using 40% efficient solar film - Total Mass = 12,500 tons

launch via Reusable Launch Vehicle @ ~ $220 / kg.

45

Global Warming Fix Methods: Cost Comparisons for 2030 AD

• Kyoto (partial) ground source ~ $ 40 trillion

• Complete* ground sources ~ $176 trillion

• Complete* SPS- shuttle, etc ~ $463 trillion

• Complete* SPS - adv. RLV ~ $ 18 trillion• Complete* SPS via Elevator ~ $ 14 trillion

* Assume a complete fix requires ~ 18,000 GW, using 40% efficient film on ground & in space. Global Economy in 2030 ~ $80 Trillion / year.

46

Capabilities and Challenges Security & the Space Solar Power Option

• Space Based Solar Power (SBSP) is an attractive long-term technology option that involves a compelling synergy between Energy Security, Space Security, and National Security

• Japan, China, India & EU already see the potential• The most significant technical challenges are the

development of – Low-cost re-usable space access– Demonstration of space-to-Earth power beaming– Efficient and light space-qualified solar arrays– Space Assembly, Maintenance and Servicing, and– Large in-space structures

• These are in areas that already interest the DoD and others – and with modest departures to current R&D efforts could retire many of the technical barriers to Space-Based Solar Power

47

DoD, National, and International ImpactProposed Vision & Objectives of Space Solar Power

Assured U.S. Preeminence in Space Access and Operations through Dramatic Advances in Transformational Space

Capabilities

Innovation that Creates Novel Technologies and

Systems Enabling New, Highly Profitable Industries on Earth

and in Space

Assured Energy Security for the U.S. and Its Allies through Affordable & Abundant

Space Solar Power with First Power within 25 years

- VISION -The United States and

Partners enable – within the next 20 years – the

development and deployment of affordable Space Solar Power systems that assure the long-term, sustainable energy security of the U.S.

and all mankind

48

Where Should We Begin?…how to evolve?

A Candidate “New Start” for the NationRenewed Study of SSPS…why: To assess ROI for economy, health benefit, security, prevent terrorism

• Solar Powered Blips for Communication, Climate Monitoring, Surveillance, local/regional power to developing regions

• Validation of Concept, architecture and financial model for a Modular Reconfigurable High Energy Power System (MRHE)…payoff to ground and space industries and revenues for global economy

• Power for Space Transportation• Power for Space Infrastructure (L1, L5, etc)• Power for Robotic Lunar Exploration and Space Business

Development

Where can we be much later?• Robotic Lunar Exploration - A NASA “New Start”

• Produce propellants from lunar ice and / or regolith (LO2 is over 85% of propellant mass)

- Produce metals for use in construction

- Produce regolith paving & blocks for construction

- Produce photovoltaic power supplies in space and on the Moon (Space Station, Hotels, Spacecrafts, Propulsion)

- Conduct microwave beaming to Earth, Moon and Beyond

- Build an infra-structure for autonomous deployment and robotic assembly supported by future supervised human crews

50

How Should We Start?

• Renew Study of Solar Power Satellite (SPS)– Update the 30 years old baseline

• Demonstrate broadly distributed RF transmitters and the much longer range transmission of power

• Reflect present & projected future economics• Involve new expertise from construction &

energy industries• We can save our planet from “peak oil” and

“global warming” if we hurry

•Let’s do something!