1374 bae[1]

NIAC 8th Annual Meeting: 2006

Photon Tether Formation Flight (PTFF)

Young K. Bae, Ph.D.Bae Institute

Tustin, California, USAwww.baeinstitute.com


ParticipantsJoseph Carroll, Tether Applications Inc.-- General Tether Aspects and Hardware

Claude Phipps, Ph.D., Photonics Associates-- Nano-Newton Thruster Stand

Eugene Levin, Ph.D., STARS, Inc.-- Dynamics of Tethers and Formation Flying

Bob Scaringe, AVG Communications-- Business Development


Examples of Revolutionary/Disruptive Technologies

Key Enabling Factor: Orders of Magnitude Enhancement in Critical Parameters

Subatomic Dimension -- Particle AcceleratorsCritical Parameter: Particle EnergyAtomic Dimension – STM/AFMCritical Parameter: Scanning Ability/Noise ReductionMolecular to Daily Life Dimension -- LasersCritical Parameter: Coherence of PhotonsAstronomical Dimension – Precision Formation Flying (?)Critical Parameter: Control Accuracy (?)


Examples of Precision Formation Flying Concepts

TPF SI MissionMAXIM

LISA

SPECS

NIAC 8th Annual Meeting: 2006Selected Formation Flying Missions

Con

trol

Acc

urac

y

Baseline Distance

>1 km

1 m

1 mm

1 mµ

1 nm

1 m 10 m 100 m 1 km 10 km 100 km >1,000 km

GRACE

LISAPTFF

SNAP 1Tsinghua

ESA Proba-3XEUS

DARWIN GEMINI

MAXIM

TechSat 21

FTXR

SPECS

Control Limitation with Conventional Thrusters?


Nano-Meter Precision Spacecraft Formation Flying: -- is able to cover most of critical missions planned-- enables many other new missions

• Thus, it is Potentially a Revolutionary/Disruptive Technology of the 21st Century in Astronomical Dimension.

• So far, its Enabling Technology has been illusive.

• We believe that PTFF could be the Enabling Technology,if successfully demonstrated.

• The Primary Goal of this NIAC Phase II is to demonstratea sub-scale prototype PTFF engine.


Photon Tether Formation Flight (PTFF)

Force Structure: Counter Balance of Two Forces:Contracting Force: Tether TensionExtending Force: Photon Thrust

- Intracavity Arrangement- Thrust Multiplied by Tens of Thousand Times by Bouncing

Photons between Spacecraft

Geometrical Structure: Crystalline Structure

Interspacecraft Distance Accuracy: better than nm

Maximum Operation Range: Tens of kms (Limited by Laser Mirror Size)

Can be Used for both Static and Dynamic Applications


Major Advantages of PTFFUltra-High Baseline and Pointing Accuracy-- Baseline Accuracy: better than 1 Nano-Meter -- Pointing Accuracy: better than 0.1 micro-arcsec for 1 km baseline system– Enabling Wide Ranges of Imaging Missions

Propellantless-- System Mass Savings, Contamination Free, Long Mission Lifetime

Low Power Consumption

Low Construction Cost

Dual Usage of Photon Thruster Laser for Interferometric Ranging System -- Simplified System Architecture and Control, Low System Weight

Readily Downscalable to Nano- and Pico- Satellites Usage-- Ideal for Sophisticated Fractionated Spacecraft or Space Structures


PTFF System Architecture

Satellite I Satellite II

Precision Laser Power Meter

HR Mirror HR Mirror

Laser Gain Media

Ultrahigh Precision CW Photon Thrust

TetherTension

Piezo-Translator Stepper Motor

Intracavity Laser Beam

TetherReel

Clamp

Lens

DiodePumpLaser

PumpLaser Beam

HR Mirror

HR MirrorPart al Mirrori

Photodetector

Part al Mirrori

Part al Mirrori

Tether System

Photon ThrusterSystem

InterferometricRanging System

Nano-Precision Formation Flying System Architecture


Photon Thruster System: TRL 3


Precision Laser Power Meter HR Mirror

HR Mirror

Laser Gain Media


Intracavity Laser BeamLens

DiodePumpLaser

PumpLaser Beam

Laser System-- Diode Pumped Intracavity Laser-- Lifetime of Diodes

1 Year for Continuous OperationPump Diode Carousel Design – Tens of Years


10 100 1000 10000 1000000.1

1

10

100

1000

1000010 W System

Intracavity Photon Thrust as a Function of the Mirror Reflectance (R)

Phot

on T

hrus

t (µN

)

11 - R

Off-the-ShelfSuper Mirror

Predicted Capability of the Proposed System


Specific thrusts as functions of Isp of various conventional and photon thrusters.

Isp (sec)102 103 104 105 106 107 108

Spec

ific

Thr

ust (

mN

/W)

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

X 1,000

X 10,000

X 100

X 20,000

Electric Thrusters Photon Thrusters

Intracavity Multiplication Factors


Intersatellite Distance (km)0.01 0.1 1 10 100

Mirr

or D

iam

ter (

cm)

1

10

Photon Thruster System: Mirror Diameter vs. Operation Distance


Interferometric Ranging System: TRL 5Satellite I Satellite II


HR Mirror HR Mirror

Laser Gain Media



DiodePumpLaser

PumpLaser Beam

HR Mirror

HR MirrorPart al Mirrori

Photodetector

Part al Mirrori

Part al Mirrori

Dual Usage of Photon Thruster Laser for Interferometric Ranging System Source Laser

-- System Architecture Simplification-- System Mass Reduction


Heterodyne Interferometric Ranging System Integrated with Photon Thruster System



HR Mirror HR Mirror

Laser Gain Media



DiodePumpLaser

PumpLaser Beam

Part al Mirrori

Beam Splitter

MeasurementDetector Reference

Detector

AOM AOM

Retroreflector

Mirror

ODL


Tether System: TRL 5


Tether

ClampTetherReel Inchworm

Piezo-Translator

Electromechnical Damper

Coarse Control: Reel System-- mm Accuracy

Fine Control: Inchworm or Stepper Motor-- µm Accuracy

Ultrafine Control: Piezo-Translator (off-the-shelf) -- 0.1 nm Accuracy


Method of Tether Vibration Suppression• Major Tether Vibrations will Result from Reorientation of the Whole Formation Structure, and other Sudden Environmental Perturbations, such as Meteoroid Impacts.

• Longitudinal Tether Wave DampingTether Material Friction/ Modulation of Photon Thruster Power

• Transverse Tether Wave DampingElectromechanical Damper with Impedance Matching

Damping Applied

Electromechanical DampingSimulation by Lorenzini et al.For 1 km Baseline System


Example I: 10 km 1-D PTFF at L2


Example II: 1 km PTFF Telescope at L2


1 km PTFF Telescope:Enables New World Imager Freeway Mission

By Prof. W. Cash – 2005 NIAC Fellow Meeting-- Searching for Advanced Civilization in Exo-Planets

• 300 m resolution at 10 parsecs = 0.02 nano-arcseconds• 500,000 km based line distance between Collectors• Huge collecting area – one square kilometer


More Advanced PTFF Telescope

James WebbSpace Telescope

Stretched Membrane Mirror (NIAC)Image Processing

With Real-TimeHolographic AberrationCorrection (NIAC)


Technology Readiness Assessment Summary

Photon Thrusters: TRL 3

Interferometric Ranging System: TRL 5

Tether System: TRL 5

System Integration and Control: TRL 2

R&D3: II - III (moderate -high) (Degree of Difficulty)-- Requires to optimize photon thrust design based on the current laboratory system and system integration, and to develop control system.


Phase II Work Started Since Sept. 1st 2006Proof-of-Concept Demonstration of Photon Thruster

Construction of a Thrust Stand with nN Accuracy

Overall System Stability and ControlTether Vibration DynamicsEnvironment Perturbation3-D Simulation

Design of Prototype Interferometric Ranging System

Design of Prototype Tether System

Detailed Study of Specific ApplicationsIn-Depth Revisits of Existing Concepts -- SPECS and MAXIMUltralarge Membrane Space TelescopesUltralarge Sparse Aperture Space TelescopesOthers


Prototype Sub-scale PTFF Engine Demonstration

Laser Power Meter

Concave HR Mirror HR Mirror

Laser Media

TorsionFiber

CounterWeight

Vacuum Chamber

Interference Pattern

Low Power Laser

Corner Cube

Windows

Optical Fiber

Photo Detectorfor Fringe Monitoring

Pump Laser Diode

Piezo-Translator

Tether

Intracavity Laser Beam

Computer

FeedbackElectronics


Conclusions I

If successful, PTFF technology will be revolutionary/disruptive technology of 21st Century in Astronomical Dimension.

If successful, PTFF technology will open new innovative (revolutionary) ways to implementing new and existing mission concepts at very affordable costs. -- Many applications can be implemented at fractional costs of HST.

Preliminary Studies concluded that PTFF system can be implemented with off-the-shelf technologies – This will be tried to be proved during this study.


Conclusions II

• Mission Specific Applications

• PTFF Simplifies the Architecture and Reduces the Weight in

Space Interferometery Missions -- TPF, DARWIN, MAXIM,

SPECS, FTXR etc.

• Ultra-large PTFF Space Telescopes -- For New World Imager (300 m Resolution – Freeway

Mission with km Mirror) -- Earth imaging/Monitoring/Surveillance (10 cm

ResolutionMonitoring at GEO with 200 m Mirror)


“I believe in intuitions and inspirations. I sometimes feel that I am right.

I do not know that I am.”

by Albert Einstein

The Support by NIAC and NASA for this project is greatly appreciated.

1374 bae[1]

Documents

annual meeting

photon thruster system

proposed system

niac phase

simplified system architecture

system mass savings

system mass reduction

laser mirror sizezcan