1374bae[1]

NIAC 8th Annual Meeting: 2006

Photon Tether Formation Flight (PTFF)

Young K. Bae, Ph.D. Bae Institute Tustin, California, USA www.baeinstitute.com

NIAC 8th Annual Meeting: 2006

Participants z

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

z

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

z

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

z

Bob Scaringe, AVG Communications -- Business Development

NIAC 8th Annual Meeting: 2006

Examples of Revolutionary/Disruptive Technologies Key Enabling Factor: Orders of Magnitude Enhancement in Critical Parameters z z z z

Subatomic Dimension -- Particle Accelerators Critical Parameter: Particle Energy Atomic Dimension – STM/AFM Critical Parameter: Scanning Ability/Noise Reduction Molecular to Daily Life Dimension -- Lasers Critical Parameter: Coherence of Photons Astronomical Dimension – Precision Formation Flying (?)

Critical Parameter: Control Accuracy (?)

NIAC 8th Annual Meeting: 2006

Examples of Precision Formation Flying Concepts

TPF

LISA SPECS

MAXIM

SI Mission

NIAC 8th Annual Meeting: 2006

Selected Formation Flying Missions GRACE >1 km SNAP 1 Tsinghua

Control Accuracy

1m

TechSat 21 GEMINI

DARWIN 1 mm

XEUS

ESA Proba-3

Control Limitation with Conventional Thrusters?

1 Âľm

SPECS MAXIM

1 nm 1m

10 m

LISA

FTXR

PTFF 100 m

1 km

10 km

100 km

Baseline Distance

>1,000 km

NIAC 8th Annual Meeting: 2006

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 demonstrate a sub-scale prototype PTFF engine.

NIAC 8th Annual Meeting: 2006

Photon Tether Formation Flight (PTFF) z

Force Structure: Counter Balance of Two Forces: Contracting Force: Tether Tension Extending Force: Photon Thrust - Intracavity Arrangement - Thrust Multiplied by Tens of Thousand Times by Bouncing Photons between Spacecraft

z

Geometrical Structure: Crystalline Structure

z

Interspacecraft Distance Accuracy: better than nm

z

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

z

Can be Used for both Static and Dynamic Applications

NIAC 8th Annual Meeting: 2006

Major Advantages of PTFF z

Ultra-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

z

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

z

Low Power Consumption

z

Low Construction Cost

z

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

z

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

NIAC 8th Annual Meeting: 2006

PTFF System Architecture Nano-Precision Formation Flying System Architecture Satellite II

Satellite I Lens

Photon Thruster System

Intracavity Laser Beam

Interferometric Ranging System

Diode Pump Laser

Ultrahigh Precision CW Photon Thrust

Precision Laser Power Meter

Partial Mirror

Pump Laser Beam

Laser Gain Media

Partial Mirror

HR Mirror

HR Mirror

HR Mirror

Photodetector HR Mirror

Partial Mirror

Tether

Tether System

Tether Reel

Tension Clamp

Piezo-Translator

Stepper Motor

NIAC 8th Annual Meeting: 2006

Photon Thruster System: TRL 3

Satellite II

Satellite I

Laser Gain Media

Lens

Intracavity Laser Beam Ultrahigh Precision CW Photon Thrust

Precision Laser Power Meter z

z

HR Mirror

HR Mirror

Laser System -- Diode Pumped Intracavity Laser -- Lifetime of Diodes 1 Year for Continuous Operation Pump Diode Carousel Design – Tens of Years

Pump Laser Beam Diode Pump Laser

NIAC 8th Annual Meeting: 2006

Intracavity Photon Thrust as a Function of the Mirror Reflectance (R) 10 W System 10000

Photon Thrust (ÂľN)

1000

100

10

Off-the-Shelf Super Mirror

1 Predicted Capability of the Proposed System

0.1 10

100

1000

1 1 - R

10000

100000

NIAC 8th Annual Meeting: 2006 Specific thrusts as functions of Isp of various conventional and photon thrusters.

Intracavity Multiplication Factors

0

10

X 20,000 X 10,000

-1

Specific Thrust (mN/W)

10

-2

10

Photon Thrusters

Electric Thrusters

-3

X 1,000

10

X 100

-4

10

-5

10

-6

10

-7

10

10

2

10

3

10

4

10

5

Isp (sec)

10

6

10

7

10

8

NIAC 8th Annual Meeting: 2006

Mirror Diamter (cm)

Photon Thruster System: Mirror Diameter vs. Operation Distance

10

1 0.01

0.1

1

Intersatellite Distance (km)

10

100

NIAC 8th Annual Meeting: 2006

Interferometric Ranging System: TRL 5

Satellite II

Satellite I Precision Laser Power Meter

Lens

Pump Laser Beam

Laser Gain Media

Parti al Mirror

Intracavity Laser Beam Ultrahigh Precision CW Photon Thrust HR Mirror

HR Mirror

HR Mirror

Partial Mirror Photodetector

Partial Mirror z

HR Mirror

Dual Usage of Photon Thruster Laser for Interferometric Ranging System Source Laser -- System Architecture Simplification -- System Mass Reduction

Diode Pump Laser

NIAC 8th Annual Meeting: 2006 Heterodyne Interferometric Ranging System Integrated with Photon Thruster System

Satellite II

Satellite I Lens

Laser Gain Media

Parti al Mirror

Intracavity Laser Beam Ultrahigh Precision CW Photon Thrust

Precision Laser Power Meter

HR Mirror

HR Mirror

Beam Splitter

AOM

AOM

Mirror

Retroreflector Measurement Detector

ODL

Reference Detector

Pump Laser Beam Diode Pump Laser

NIAC 8th Annual Meeting: 2006

Tether System: TRL 5 Satellite I

Electromechnical Damper

Satellite II

Tether Tether Reel

Clamp

Inchworm Piezo-Translator

z

Coarse Control: Reel System-- mm Accuracy

z

Fine Control: Inchworm or Stepper Motor-- Âľm Accuracy

z

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

NIAC 8th Annual Meeting: 2006

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 Damping Tether Material Friction/ Modulation of Photon Thruster Power • Transverse Tether Wave Damping Electromechanical Damper with Impedance Matching Damping Applied

Electromechanical Damping Simulation by Lorenzini et al.

For 1 km Baseline System

NIAC 8th Annual Meeting: 2006

Example I: 10 km 1-D PTFF at L2

NIAC 8th Annual Meeting: 2006

Example II: 1 km PTFF Telescope at L2

NIAC 8th Annual Meeting: 2006

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

NIAC 8th Annual Meeting: 2006

More Advanced PTFF Telescope

Image Processing With Real-Time Holographic Aberration Correction (NIAC)

James Webb Space Telescope

Stretched Membrane Mirror (NIAC)

NIAC 8th Annual Meeting: 2006

Technology Readiness Assessment Summary z

Photon Thrusters: TRL 3

z

Interferometric Ranging System: TRL 5

z

Tether System: TRL 5

z

System Integration and Control: TRL 2

z

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.

NIAC 8th Annual Meeting: 2006

Phase II Work Started Since Sept. 1st 2006 z

Proof-of-Concept Demonstration of Photon Thruster z Construction of a Thrust Stand with nN Accuracy

z

Overall System Stability and Control z Tether Vibration Dynamics z Environment Perturbation z 3-D Simulation

z

Design of Prototype Interferometric Ranging System

z

Design of Prototype Tether System

z

Detailed Study of Specific Applications z In-Depth Revisits of Existing Concepts -- SPECS and MAXIM z Ultralarge Membrane Space Telescopes z Ultralarge Sparse Aperture Space Telescopes z Others

NIAC 8th Annual Meeting: 2006

Prototype Sub-scale PTFF Engine Demonstration Counter Weight

Interference Pattern Corner Cube

Optical Fiber Torsion Fiber

Photo Detector for Fringe Monitoring

Low Power Laser

Concave HR Mirror

Windows Laser Media

HR Mirror

Pump Laser Diode

Intracavity Laser Beam

Tether Laser Power Meter

Vacuum Chamber

Computer

Piezo-Translator

Feedback Electronics

NIAC 8th Annual Meeting: 2006

Conclusions I z

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

z

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.

z

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

NIAC 8th Annual Meeting: 2006

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 Resolution Monitoring at GEO with 200 m Mirror)

NIAC 8th Annual Meeting: 2006

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

“I believe in intuitions and inspirations.

I sometimes feel that I am right.

I do not know that I am.�

by Albert Einstein