GEO Spacecraft Development

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OAWL Progress and Plans Christian J. Grund, Bob
Pierce, Jim Howell, and Carl WeimerBall
Aerospace Technologies Corp. (BATC),
cgrund_at_ball.com1600 Commerce St. Boulder, CO
80303July 09, 2008
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Optical Autocovariance Wind Lidar (OAWL)
Development Program

• Internal investment to develop the OAWL theory
  and implementable architecture, performance
  model, perform proof of concept experiments, and
  design and construct a flight path receiver
  prototype.
• Recent NASA IIP win will take OAWL receiver at
  TRL-3, build into a robust lidar system, fly on
  the WB-57, exit at TRL-5.

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OAWL Receiver IRAD Objectives

• Design and fabricate a multi-wavelength,
  field-widened prototype optical autocovariance
  receiver suitable for high altitude aircraft
  demonstration of winds, HSRL, and depolarization
  measurements.
• Develop optical assembly and alignment techniques
  suitable for adjustment free high resolution
  interferometry on flight systems.
• Develop an integrated model for an OAWL receiver
  that predicts OAWL performance in thermal and
  vibration environments that can be used to lower
  risk for a space qualified OAWL, OA-HSRL, and
  OA-DIAL designs.

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OAWL Receiver Design Uses Polarization
Multiplexing to Implement 4-OACF Phase-Delay
Interferometers with the Same OPD

• Mach-Zehnder-like interferometer allows 100
  light detection on 4 detectors
• Cats-eyes field-widen and preserve interference
  parity allowing wide alignment tolerance,
  practical simple telescope optics
• Receiver is achromatic, facilitating
  simultaneous multi-l operations (multi-mission
  capable Winds HSRL(aerosols)
  DIAL(chemistry))
• Very forgiving of telescope wavefront distortion
  saving cost, mass, enabling HOE optics for
  scanning and aerosol measurement
• 2 input ports facilitating 0-calibration

Ball Aerospace Technologies patents pending
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Solid Model of Receiver (detector covers removed)

• - All aluminum construction minimizes DT, cost
• - Athermal interferometer design
• - Factory-set operational alignment
• for autonomous aircraft operation
• - 100 opt. eff. to detector
• - multi-l winds, plus HSRL
  and depolarization for
• aerosol characterization
• and ice/water cloud
• discrimination
• - Compatible with wind and
  HSRL measurements

Detectors 1 532nm depolarization 1 355nm
depolarization 4 532nm winds/HSRL 4 355nm
winds/HSRL 10 Total
Ball Aerospace Technologies patents pending
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Integrated Model Process Developed at BATC

• Goals
• lt6 nm (0.11 rad phase error) vibration induced
  noise), 12 nm accep.
• lt5 visibility reduction due to thermoelastic
  distortions.
• Main system modeling outputs
• Fringe visibility
• Phase noise

References M. Lieber, C. Weimer, M. Stephens,
R. Demara, Development of a validated end-to-end
model for space-based lidar systems, in SPIE vol
6681, U.N.Singh, Lidar Remote Sensing for
Environmental Monitoring VIII, Aug 2007. M.
Lieber, C. Randall, L. Ayari, N. Schneider, T.
Holden, S. Osterman, L. Arboneaux, "System
verification of the JMEX mission residual motion
requirements with integrated modeling", SPIE
5899, Aug 2005. M. Lieber, C. Noecker, S.
Kilston, Integrated system modeling for
evaluating the coronagraph approach to planet
detection,  SPIE V4860, Aug 2002
Ball Aerospace Technologies
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Integrated Model Design IterationVibration-Ind
uced Phase Noise Convergence on Specification
3.5
1900 nm, initial hard mount
3
8.5/ 6 nm, redesigned structure, WC/ nom
40/ 20 nm, 20 Hz isolators added, WC/ nom
2.5
2
Log OPD (nm)
1.5
Requirement lt1m/s/shot/100 ms Random dynamic
error with WB-57 excitation
1
Final design Prediction Feb. 2008 6nm RMS
jitter, exceeding spec and meeting goal, suggests
performance dominated by intensity SNR, not
vibration environment
0.5
0
1
2
3
4
5
WC Worst case
Thermal results model verifies design is
athermal wrt average temperature
Ball Aerospace Technologies
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OAWL Receiver IRAD Progress Major mechanical
and optical components received

• A few simple components
• Detector housings
• Monolithic interferometer
• Covers and base plate
• mount to a monolithic base structure.
• Detector amplifiers and thermal controls
• are housed inside the base structure.

Ball Aerospace Technologies
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OAWL IIP Lidar System Objectives

• Demonstrate OAWL wind profiling performance of a
  system designed to be directly scalable to a
  space-based direct detection DWL (i.e. to a
  system with a meter-class telescope 0.5J, 50 Hz
  laser, 0.5 m/s precision, with 250m resolution).
• Raise TRL of OAWL technology to 5 through high
  altitude aircraft flight demonstrations.
• Validate radiometric performance model as risk
  reduction for a flight design.
• Demonstrate the robustness of the OAWL receiver
  fabrication and alignment methods against flight
  thermal and vibration environments.
• Validate the integrated system model as risk
  reduction for a flight design.
• Provide a technology roadmap to TRL7

Ball Aerospace Technologies
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IIP Program Elements and Schedule
Ball Aerospace Technologies
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IIP System Concept for WB-57 Tests
Pallet Cover
6 Pallet (WB-57 form factor)
Custom Pallet-Mounting Frame
Telescope
IRAD - Receiver
Laser Source
Custom Window
Ball Aerospace Technologies
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IIP Test Plans

• Ground Tests Fall 2009
• In Boulder, CO
• Intercomparison with NOAA system (possibly HRDL)
• Fixed pointing along a slant path
• Airborne Testing
• WB-57, 3 flight segments
• Houston to Boulder, pick up many wind profilers
• Multiple terrain backgrounds
• Multiple cloud conditions
• Racetrack Boulder and Platteville
• NOAA Ground Lidar validation
• High resolution PBL winds
• wind profiler whole atmosphere
• Boulder to Houston, pick up wind profilers
• Multiple terrain backgrounds
• Ocean background and PBL
• Multiple cloud conditions

Boulder, CO
Platteville, CO
Houston, TX
Ball Aerospace Technologies
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OAWL Receiver IRAD Progress Schedule and Status

• Receiver Status (Ball internal funding)
• Optical design PDR complete Sep. 2007
• Receiver CDR complete Dec. 2007
• Receiver performance modeled complete Jan.
  2008
• Design complete Mar. 2008
• COTS Optics procurement complete Apr. 2008
• Major component fabrication complete Jun.
  2008
• Custom optics procurement complete Jun. 2008
• Assembly and Alignment in progress Aug. 2008
• Preliminary testing scheduled Sep. 2008

Ball Aerospace Technologies
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Taking an OAWL Lidar System Through TRL 5

• NASA Funded IIP Plan
• Program start, TRL 3 expected Jul. 2008
• Receiver shake and bake (WB-57 level) assume
  7/1/08 start Oct. 2008
• Lidar system design/fab/integration Oct.
  2009
• Ground Tests completed Mar. 2010
• Airborne tests completed TRL-5 Dec.
  2010
• IIP Complete thru tech road mapping to TRL-7
  May 2011

Ball Aerospace Technologies
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Conclusions

• Optical Autocovariance Receiver IRAD is on-track
  to final assembly and test in September 2008. So
  far, so good.
• Optical Autocovariance Lidar is on a path to TRL
  5 in 2010 thanks to NASA IIP award.
• IIP science advisory board partially assembled.
  Mike Hardesty and Bruce Gentry so far. Intend a
  third member, probably from University, TBD.
• Ground testing in late Fall 2009 along side NOAA
  lidar (possibly HRDL)
• Airborne testing from WB-57 in Fall 2010.
• Possible multi-l co-validation of HSRL during
  IIP. Proposal in progress to leverage this
  element to the IIP (non-interference basis).

Ball Aerospace Technologies