RF Blackout During

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RF Blackout During RLV Reentry Public Safety
Implications
COMSTAC RLV Working Group Pradipta Shome 17 May
2007
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Summary of conditions that lead to blackout

• High reentry velocity
• Steep angle of attack
• Body shape contributes to electron density
• Velocity is the major determinant of flow field
  temperature and level of ionization
• Onset of blackout 300,000 ft and 25,000
  ft/sec
• End of blackout approx 80,000 ft and 18,000
  ft/sec
• ATC Implications
• Maintain continuous communications

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Radio Frequency Blackout During RLV Reentry
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Why we should care
Orbital vehicles slated to come before AST in
near future may be subject to blackout e.g.
Rocketplane Kistler OV and SpaceX two-stage
reusable booster. Future RLVs could remain in
attenuated or blackout mode for extended periods,
during a critical phase of the flight Sub-orbital
s might not blackout fully but experience
communication degradation To meet public Safety
concerns, may need to maintain - Communications
for telemetry and vehicle control - Navigation
and Tracking of vehicle
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Radio Frequency Blackout During RLV Reentry
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Future Concerns

• Blackout remains a concern for space vehicles
  during critical phase of flight
• Need to derive feasible frequency bands from
  atmospheric and plasma attenuation
  considerations
• If frequency band is chosen, how to implement
  in spectrum management scheme
• Spectrum plan may be changing
• Spectrum is a finite resource
• Spectrum allocation is a lengthy process

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Radio Frequency Blackout During RLV Reentry
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