Meteoroid Properties and
Classification Using High Power
UHF Radar
Nick Indriolo
Case Western Reserve University
Outline
• Introduction to Meteor Physics
• Experimental Setup
• Results of July 14, 2004 experiment
– General statistics
– Double vs. single streak statistics
• Explanation of results
Meteor Physics
• Meteor enters Earth’s
atmosphere
• Ablating atoms ionize
surrounding
molecules
• Ball of plasma
traveling with meteor
core produces head
echo; column of
ionized gas is trail.
More Meteor Physics
• Millstone Hill UHF Radar
has high power and
sensitivity
• Radar wave reflects off
ionization
• Back scatter is received
by dish
• Only observes head
echoes; other systems
can observe trails
Our Experiment
• Radar was directed
towards Earth’s apex
– point towards which
the Earth is moving –
to maximize sporadic
meteor detections.
• July 14, 2004
• 3:47 – 9:57 LT
Transmitted and Received Signals
• 40 microsecond pulse at 2 millisecond intervals
• Hard target, so single streak return of pulse length is
expected
• Double streak is unexpected; no energy in center
256
94
Results
Mean
Altitude
(km)
All meteors 109.04
Mean
Range rate
(km/s)
-52.22
Mean
Duration
(sec)
0.092
Single
streaks
106.93
-39.98
0.125
Double
streaks
114.8
-55.88
0.083
Altitude Distributions
Range Rate Distributions
Duration Distributions
Possible Explanations
• Fragmenting meteors
• Doppler interference
• Instrumentation or processing effect
The Answer is…
• Instrumentation or processing effect
• 4 microsecond sampling means visibility to 125kHz
• Doppler shift puts meteors with velocities greater than
42.6 km/s above our window
Typical double frequency
Frequency
cutoff
Summary & Future Work
• Difference between double and single
streaks is based on radial velocity
• Confirmed that faster meteors occur at
higher altitudes
• Future Work
– Revise Lincoln Laboratory Meteor Processor
to better detect single streaks
– Re-process double streaks with larger
frequency range to obtain RCS