1. Piezo Dust Detector
Frank Odom III, Ben Martinsen, Grant Richter, Jimmy Schmoke, Mike Cook,
Jorge Carmona Reyes, Truell Hyde
Baylor CASPER Group
REU Program 2014
Overview
There is a large amount of man-made
debris that is in orbit around the Earth.
These debris particles are travelling at
very high velocitiestextemdash greater
than 1 km/stextemdash and pose a
threat to satellites that are put into orbit.
Much of it cannot be tracked by the
telescopes on Earth, however, because
they are not sensitive enough to observe
particles smaller than about 10 cm in
diameter. In order to protect sensitive
equipment such as externally facing
cameras, there must be a device on board
the satellite that can detect such debris. If
impacts begin occurring at a higher rate,
the camera lens can then be shielded,
protecting it from further harm. A piezo
detector has been designed to perform
this task on board the ARMADILLO
nanosatellite, which is being constructed
by students at the University of Texas at
Austin.
Figure 1. PZT signal.
Piezoelectric Effect & PZTs
In certain materials, an externally
applied stress can produce an electrical
charge from the material. This is the
piezoelectric effect. For that reason,
piezoelectric materials can be very useful
as detectors. Lead-zirconate-titanate
(PZT) is a common piezoelectric material,
and has been used to create the Main
Detector Unit (MDU) of the PDD.
Fourier Analysis
There are both mechanically and
electrically resonant frequencies within
the signal data.
Figure 2. Fourier transform
Figure 3. Energy plot.
Identifying a Broken PZT
When a plate breaks, it essentially
changes the boundary conditions of the
plate. This changes the resonant
frequencies, the width of the fourier
peaks, and the decay rate of a signal.
Vacuum Test
Electronics produce a lot of heat. In a
vacuum environment, there is much less
heat dissipation to the environment. So,
there is a risk of the electronics stack
overheating, burning up one of the chips.
Vacuum test temperature data
The memory chip had the greatest
temperature in the vacuum, at 51 degrees
Celsius. This is well below is maximum
operating temperature. So, the
electronics should be able to withstand a
vacuum environment.
Integration with Electronics
When the signal is sent through the
electronics stack, there is an upshift in
frequency and a significant loss in data
resolution. 200 data points are collected,
each one microsecond apart. This gives
only a short portion of the complete
waveform and resolution of 5000 Hz on
the fourier transform.
Signal after passing through electronics
and its fourier transform.
Acknowledgements
Jorge Carmona Reyes, Grant Richter,
Jimmy Schmoke, Mike Cook, Truell Hyde,
Lorin Matthews, and the rest of the Baylor
CASPER group.
National Science Foundation
Grant No. 1262031
Results
It appears that the PDD will be able
to withstand the space environment in
LEO. The linear model proposed with
Figure 3 provides a means for predicting
impact energy. Also, a method has been
developed for identifying a broken PZT
from the signal data.
The fundamental mechanical and
electrical frequencies are 210 Hz and 98
kHz, respectively (which can be seen as
peaks in the fourier transform).
Voltage vs. Impact Energy
As impact energy increases, the PZT
produces a greater voltage. By plotting
the energy against impact energy, it can
be seen that there is a linear relationship
between the two.