GISMO Airborne Experiment Planning

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GISMO Airborne Experiment Planning

• Proposed Greenland 2006 Campaign
• WFF Meeting Feb. 2006

GISMO Team K.Jezek, E. Rodriguez, P. Gogineni, J.
Curlander, X. Wu, J. Sonntag, W. Krabill, P.
Kanagaratnam, C.Allen, A. Freeman. T. Akins D.
MacAyeal, R. Forster, S. Tulazek, M. Fahnestock,
S. Clifford
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Meeting Objectives

• Review Project Goals
• Objectives for Airborne Experiment
• Aircraft Configuration
• Airborne Experiment Design
• Navigation and location
• Proposed flight lines
• Schedule
• Flight Planning Guidance and Milestones
• Costs

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GISMO Project Summary
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Glaciers and Ice Sheets Grand Challenges

• Understand the polar ice sheets sufficiently to
  predict their response to global climate change
  and their contribution global sea level rise

• What is the mass balance of the polar ice sheets?
• How will the mass balance change in the future?

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GISMO Vision Build an instrument that images the
hidden continental land masses beneath the
Antarctic and Greenland Ice Sheets. Demonstrate
this technology on Earth and apply it to icy
bodies in the outer solar system
National Geographic Magazine
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Primary Challenges
Surface Clutter

• Separate basal return from surface clutter
• Investigate spatial variation in strength of
  basal reflectivity

Weak Echoes Strong Attenuation
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Global Ice Sheet Interferometric Radar (GISIR)
PI Prof. Kenneth C. Jezek, The Ohio State
University
Objective
Filtered basal inferogram
InSAR Concept

• Develop and test radars and algorithms for
  imaging the base of the polar ice sheets
• Investigate interferometric and tomographic
  clutter rejection and basal imaging methods
• 3-d topography of the glacial bed
• Images of subglacial conditions
• Develop multiphase center P-band and VHF radars
• Capable of sounding 5 km of ice
• Single and repeat pass interferometric operation
• Assess the requirements for extension to
  continental scale campaigns

Repeat pass tomography
Approach
Key Milestones

• Use available topography data to simulate
  interferograms for testing the InSAR and
  tomographic concepts.
• Modify the SAR simulator to include operating
  characteristics of several aircraft and several
  radar designs
• Develop UHF and VHF radars and antenna systems
• Test methodology by collecting data over the
  Greenland and Antarctic ice sheets
• Algorithm validation and sensitivity assessment.

1/ 06 Phase History Simulations and Algorithm
Testing 9/06 Radar and Antenna
Development 11/06 First flight test in
Greenland 7/06 InSAR and tomography algorithm
refinement 11/07 Second flight test in
Antarctica 7/08 Algorithm and methodology
assessment 8/08 Requirements doc. for
continental scale imaging
Co-Is E. Rodriguez, JPL P. Gogineni, U. Kansas
J. Curlander, Vexcel Corp. John Sonntag, EGG
C. Allen, U. Kansas P. Kanagaratnam, U. Kansas
TRLin 3
http//esto.nasa.gov
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Prioritized Airborne Experiment Objectives

• Collect field data to test basic interferometric
  and tomographic imaging concepts
• Verify volume clutter is weak
• Image thick and thin ice to measure signal
  strength
• Image crevassed and crevasse-free areas to
  evaluate surface clutter rejection
• Collect single and repeat pass data to test
  interferometric and tomographic approaches
• Evaluate UHF and VHF radar performance
• Investigate transitions in basal conditions

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Aircraft Configuration
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Airborne Radar Depth Sounder Rely on Design
Heritage
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Radars for operation on P-3 or Twin Otter
aircraft
Three more antenna elements are being added on
each wing of a Twin Otter to eliminate grating
lobes
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P-3 Modifications

• Multiple conductors to antenna array (one
  conductor used in past experiments)
• Additional antenna elements beneath wings
• Additional element in the tail
• GPS and Inertial navigation information on
  aircraft position and attitude

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Cable Specs
SMA (2x) on BPE240, bundled With polyolefin jacket
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Airborne Experiment Design
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Single Pass Interferometry
Maximize altitude Maximize antenna array
separation
6 km swath
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Multi-Pass SAR Imaging
Synthetic Aperture
Synthetic Elevation Aperture
Ground Reference Point
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Constraints on Flight Operations

• Fly at maximum allowable altitude
• Limit flight duration to allow for daily data Q/A
  and experiment modifications (about 6 hours
  assuming 150 Gb/hour and 3, 300 Gb disks)
• Allow enough field time to repeat flight lines
• Fly over high and low clutter areas
• Fly over areas where some information on basal
  properties is known
• VHF and UHF radars cannot operate simultaneously
  P-band outbound VHF inbound along same track
  to within 30 m
• Schedule 2 to 4 repeat flights at 30 horizontal
  offsets for tomography

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Aircraft NavigationExpected Performance

• 20 m ground track repeatability
• 0.02 degree post flight knowledge on aircraft
  roll and pitch
• 1 degree post flight knowledge on yaw

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Proposed Flight Lines
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Sonde to Summit

• 780 km outbound
• 3-4 hours total
• 100 m to 3000 m thick ice
• Known basal scattering characteristics around
  summit
• PARCA data available

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Clutter Test and Ocean Cal
a

• 490 Km outbound (about 2 hours)
• Clutter obscures bottom echo for nadir sounder
• Ice edge to 1000 m thick ice

b
X
X
X
b
X
a
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Sonde to Jacobshavn Clutter Experiment
PARCA May 11, 2003

• 480 km outbound (about 2 hours)
• High clutter
• Ice thickness in excess of 2km
• Substantial subglacial relief
• High absorption

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Schedule

• May/June Twin Otter flights will provide crucial
  information for planning
• Optimized flight plan in July
• Earliest flights in November 2006 (cold surface
  timely data available for analysis high project
  costs)
• Latest flights in May 2007 (partner with WFF
  planned activity complementary science data
  shared costs and personnel time warm surface
  late data)

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Beyond 2007

• IPY Proposal for second set of flights
• Flights in 2007/08 to address technology issues
  uncovered in 2006 and to focus on detecting
  transitions in basal conditions

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Additional topics

• Status of P-3
• Condition of existing antenna arrays
• Flight Planning and Costing Guidance
• WFF Milestones
• Efficient planning (flight duration vs number of
  flights vs down time to check data)
• Refine flight lines based on previous PARCA
  flight lines
• GISMO information posted at
• www-bprc.mps.ohio-state.edu/rsl/gismo/