Modeling of Infrasound from the Space Shuttle Columbia Reentry

1
Modeling of Infrasound from the Space Shuttle
Columbia Reentry

• Robert Gibson and David Norris
• BBN Technologies
• Arlington, Virginia, USA
• Infrasound Technology Workshop
• La Jolla, California
• 27-30 Oct 2003
• Work sponsored by Air Force Research Laboratory,
  Contract DTRA01-01-C-0084

2
Introduction

• Space Shuttle Columbia Reentry
• STS-107
• 01-Feb-2003
• Loss of orbiter
• 1400 UT
• 0900 EST
• 0600 PST
• Nominal trajectory shown
• Infrasound observed at multiple arrays in North
  America

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Columbia Investigation

• Purpose of this presentation
• Explain the infrasound modeling conducted by BBN
• Present example results
• US Infrasound Working Group formed Feb 2003
• Part of the US DoD Columbia Investigation Support
  Team
• In support of NASA investigation
• Participants
• US Government Army Research Lab, Los Alamos
  National Lab, NOAA Environmental Technology Lab,
  Naval Research Lab
• Industry BBN Technologies, Center for Monitoring
  Research (SAIC)
• Academia Univ. of California-San Diego
  (L2A/Scripps), Univ. of Hawaii (ISLA), Univ. of
  Mississippi (NCPA)

Optical image, showing left wing damage From
AFRL, Kirtland AFB
4
Background

• Infrasound from supersonic bodies has been
  observed
• Bolides
• Concorde
• Rockets (Apollo, Titan, Ariane, etc.)
• Space shuttle launches and reentries
• BBN has used 3-d ray tracing to predict
  infrasound from Space Shuttle launches
• Favorable model vs. data comparisons
• Orbiter ascent
• Solid rocket booster reentry
• Ground truth events are of interest for
  validating or calibrating models
• Propagation models
• Atmospheric characterizations

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Shuttle Modeling Approach

• Source of infrasound is not impulsive, but
  continuous and moving
• Approximate moving source by modeling a series of
  discrete events, each with appropriate time delay
• Use 3-D ray tracing to find eigenrays from points
  on reentry trajectory to infrasound array
• Determine arrival time and azimuth for each
  eigenray
• Combine all predicted eigenray arrivals at each
  array

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Sources of Information

• Shuttle reentry trajectory
• NASA, based on actual GPS
• Propagation model
• InfraMAP tool kit (BBN)
• Implementation of HARPA 3-d ray tracing
• Environmental characterization
• Assimilation of climatology with synoptic model
  output
• NRL-G2S (D. Drob, Naval Research Lab)
• Observations, for comparison
• US and Canadian station operators
• Center for Monitoring Research (SAIC)

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Columbia Trajectory and Arrays
Altitude (km)
Trajectory in white Arrays in red CPAs in
yellow
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Examples of Model Results

• Results are shown for representative arrays
• Short range (in sonic boom carpet)
• Medium range (100 1000 km)
• Long range (gt 1000 km)
• Atmospheric profiles along propagation path
• Variability along path
• Presence or absence of stratospheric duct
• Typical ray paths
• Azimuth vs. time
• Color coded by source location
• Apparent velocity vs. azimuth (polar plot)
• Color coded by signal arrival time

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Station List
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Environmental Variability - SGAR
St. George, UT
(CPA range 23 km)
Atmospheric Characterizations from D. Drob, NRL
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Environmental Variability - TXIAR
Lajitas, TX
(CPA range 522 km)
Atmospheric Characterizations from D. Drob, NRL
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Environmental Variability IS10
Lac du Bonnet, Manitoba
(CPA range 1864 km)
Atmospheric Characterizations from D. Drob, NRL
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Typical Ray Path SGAR
St. George, UT
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Typical Ray Paths TXIAR
Lajitas, TX
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Typical Ray Paths IS10
Lac du Bonnet, Manitoba
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Azimuth vs. Time - SGAR
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Azimuth vs. Time - TXIAR
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Azimuth vs. Time - IS10
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Polar Plot TXIAR(model)
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Polar Plot TXIAR(data)
PMCC analysis of observed data from Garces and
Hetzer, U. Hawaii (ISLA), Summary of infrasonic
detections and propagation modeling estimates
associated with the Columbia reentry of
Februrary 1, 2003, March 2003
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Model vs. Data for Pinon Flat (IS57)
Receiver azimuth (deg)
gmt (hrminsec)
Data analysis by BBN using InfraTool Passband
1-8 Hz
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Conclusions

• Model results largely consistent with reentry
  trajectory
• Arrival time
• Azimuth
• Apparent velocity
• Supersonic events with ground truth trajectories
  represent useful validation sources for
  infrasound modeling techniques
• Modeling of the effects of atmospheric
  propagation was fairly successful but does not
  account for all of the signal complexity at the
  more distant stations
• From Report to the Department of Defense on
  Infrasonic Re-Entry Signals from the Space
  Shuttle Columbia (STS-107), ed. by H. Bass,
  04-June-2003