This document summarizes a presentation given at the NIAC 8th Annual Meeting in 2006 about Photon Tether Formation Flight (PTFF). PTFF is a proposed technology that could enable precision spacecraft formation flying through the use of photon thrusters and tethers. The presentation discusses the potential advantages of PTFF for enabling new space missions requiring precision control at the nanometer level or below. It also provides an overview of the various subsystems of a PTFF system, including the photon thruster, interferometric ranging system, tether system, and control systems. The technology readiness of each subsystem is assessed, and the goals of the current NIAC Phase II study to demonstrate a prototype PTFF engine are outlined.
6. 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 21stCentury 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.
7. NIAC 8th Annual Meeting: 2006
Photon Tether Formation Flight (PTFF)
zForce 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
zGeometrical Structure: Crystalline Structure
zInterspacecraftDistance Accuracy: better than nm
zMaximum Operation Range: Tens of kms(Limited by Laser Mirror Size)
zCan be Used for both Static and Dynamic Applications
8. NIAC 8th Annual Meeting: 2006
Major Advantages of PTFF
zUltra-High Baseline and Pointing Accuracy
--Baseline Accuracy: better than 1 Nano-Meter
--Pointing Accuracy: better than 0.1 micro-arcsecfor 1 km baseline system
–Enabling Wide Ranges of Imaging Missions
zPropellantless
--System Mass Savings, Contamination Free, Long Mission Lifetime
zLow Power Consumption
zLow Construction Cost
zDual Usage of Photon Thruster Laser for Interferometric Ranging System
--Simplified System Architecture and Control, Low System Weight
zReadily Downscalableto Nano-and Pico-Satellites Usage
--Ideal for Sophisticated Fractionated Spacecraft or Space Structures
9. NIAC 8th Annual Meeting: 2006
PTFF System ArchitectureSatellite ISatellite IIPrecision Laser Power MeterHR MirrorHR MirrorLaser Gain MediaUltrahigh Precision CW Photon ThrustTetherTensionPiezo-TranslatorStepper MotorIntracavity Laser BeamTetherReelClampLensDiodePumpLaserPumpLaser BeamHR MirrorHR MirrorPartal MirroriPhotodetectorPartal MirroriPartal MirroriTether SystemPhoton ThrusterSystemInterferometricRanging SystemNano-Precision Formation Flying System Architecture
10. NIAC 8th Annual Meeting: 2006
Photon Thruster System: TRL 3Satellite ISatellite IIPrecision Laser Power MeterHR MirrorHR MirrorLaser Gain MediaUltrahigh Precision CW Photon ThrustIntracavity Laser BeamLensDiodePumpLaserPumpLaser Beam
zLaser System
--Diode Pumped Intracavity Laser
--Lifetime of Diodes
1 Year for Continuous Operation
zPump Diode Carousel Design –Tens of Years
11. NIAC 8th Annual Meeting: 2006
101001000100001000000.111010010001000010 W System Intracavity Photon Thrust as a Function of the Mirror Reflectance (R) Photon Thrust (μN) 11 - ROff-the-ShelfSuper MirrorPredicted Capability of the Proposed System
12. NIAC 8th Annual Meeting: 2006
Specific thrusts as functions of Ispof various conventional and photon thrusters. Isp (sec) 102103104105106107108 Specific Thrust (mN/W) 10-710-610-510-410-310-210-1100X 1,000X 10,000X 100X 20,000Electric ThrustersPhoton ThrustersIntracavity Multiplication Factors
17. 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 DampingTether Material Friction/ Modulation of Photon Thruster Power•Transverse Tether Wave DampingElectromechanical Damper with Impedance MatchingDamping Applied
Electromechanical Damping
Simulation by Lorenziniet al.
For 1 km Baseline System
18. NIAC 8th Annual Meeting: 2006
Example I: 10 km 1-D PTFF at L2
19. NIAC 8th Annual Meeting: 2006
Example II: 1 km PTFF Telescope at L2
20. NIAC 8th Annual Meeting: 2006
1 km PTFF Telescope: Enables New World Imager Freeway MissionBy 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
21. NIAC 8th Annual Meeting: 2006
More Advanced PTFF TelescopeJames WebbSpace TelescopeStretched Membrane Mirror (NIAC)Image Processing With Real-TimeHolographic AberrationCorrection (NIAC)
22. NIAC 8th Annual Meeting: 2006
Technology Readiness Assessment Summary
zPhoton Thrusters: TRL 3
zInterferometric Ranging System: TRL 5
zTether System: TRL 5
zSystem Integration and Control: TRL 2
zR&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.
23. NIAC 8th Annual Meeting: 2006
Phase II Work Started Since Sept. 1st2006
zProof-of-Concept Demonstration of Photon Thruster
zConstruction of a Thrust Stand with nNAccuracy
zOverall System Stability and Control
zTether Vibration Dynamics
zEnvironment Perturbation
z3-D Simulation
zDesign of Prototype Interferometric Ranging System
zDesign of Prototype Tether System
zDetailed Study of Specific Applications
zIn-Depth Revisits of Existing Concepts --SPECS and MAXIM
zUltralargeMembrane Space Telescopes
zUltralargeSparse Aperture Space Telescopes
zOthers
25. NIAC 8th Annual Meeting: 2006
Conclusions I
zIf successful, PTFF technology will be revolutionary/disruptive technology of 21stCentury in Astronomical Dimension.
zIf 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.
zPreliminary Studies concluded that PTFF system can be implemented with off-the-shelf technologies –This will be tried to be proved during this study.
26. NIAC 8th Annual Meeting: 2006
Conclusions II
•Mission Specific Applications•PTFF Simplifies the Architecture and Reduces the Weight inSpace InterferometeryMissions --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)
27. NIAC 8th Annual Meeting: 2006
“I believe in intuitions and inspirations. I sometimes feel that I am right. I do not know that I am.” by Albert EinsteinThe Support by NIACand NASAfor this project is greatly appreciated.