Tuesday, June 26, 2007
Writer: Shanna Relford
news@utsi.edu
Joseph Speakman, who will start his senior year at the Air Force
Academy in Colorado Springs this fall, spent some time at the
University of Tennessee Space Institute this summer as part of the
Cadet Summer Research Program (CSRP). Cadet Speakman explained that
cadets have to do two programs in the summer and then get a
three-week summer break. The Summer Research Program is a highly
competitive program that allows cadets to gain real-world experience
in their fields. CSRP sends cadets to Air Force bases all over the
country and the cadets can submit a “wish list” of places and
projects. Cadet Speakman is majoring in Astronautical Engineering
and put Arnold Air Force Base on his wish list of places to go for
the Summer Research Program.
UTSI Professor Dr. Trevor Moeller is currently working on a project
for Arnold Engineering Development Center to develop a new kind of
thrust stand to measure the thrust exerted by electric propulsion
thrusters, a type of space rocket. Cadet Speakman spent a month
researching this project with Dr. Moeller at UTSI, from May 20 to
June 21. On Earth, electric propulsion thrusters don’t provide much
thrust, and would not be able to launch, or even budge, a satellite.
However, in the space environment with very little atmosphere, the
small amount of thrust that these propellant-efficient thrusters
generate is useful for adjusting the attitude of satellites and
maintaining their orbit.
In order to test the performance of these thrusters on Earth,
experiments must be run inside a vacuum chamber. Cadet Speakman
helped Dr. Moeller with a series of related experiments to research
the performance of a critical component of the new thrust stand he’s
developing, using gallium, a non-toxic liquid metal.
To measure the thrust, electricity must be transferred from
stationary to moving parts on the thrust stand without bending a
wire and introducing unwanted forces. In order to eliminate this
solid wire connection, Dr. Moeller and Cadet Speakman ran
experiments with two pieces of copper wire moving freely in a pool
of liquid gallium. It has been thought by some rocket scientists
that gallium should not be able to carry more than 15 amps of
current, but Dr. Moeller’s calculations indicate the liquid metal
can handle a higher level of electric current. Dr. Moeller said that
the successful use of gallium is a critical part of the design of
the new thrust stand, and, judging from the results of experiments
to this point, it looks like it will work.
Cadet Speakman performed several tests to see how much current could
safely pass through the gallium. “I did the experiment inside a
vacuum chamber to simulate the actual environment in which the
thrust stand will be used, and I found that the gallium can handle
at least 50 amps of current for long periods of time,” said Cadet
Speakman.
Cadet Speakman is very interested in thrusters since he hopes to
work with satellites in the future. In fact, he’ll be building a
satellite next year as a senior at the Air Force Academy.
“I had a great experience at UTSI,” said Cadet Speakman. “The
experiment I performed in the lab really helped me apply the
concepts that I learned in the classroom, and I was able to benefit
UTSI and AEDC, as well. Dr. Moeller and Research Specialist Doug
Warnberg were great mentors, and they helped me solve the problems I
encountered and helped to make my project a success.”
Dr. Moeller was very pleased with the results of the experiments
performed by Cadet Speakman. “Joe did an outstanding job with this
experiment, and his hard work has helped support the feasibility of
the critical role the gallium electrical pot will serve in the
thrust stand that we are developing,” Moeller said.
MEDDLING WITH METALS AT UTSI—Air Force Cadet Joseph Speakman and
University of Tennessee Space Institute Professor Dr. Trevor Moeller
are shown above studying an experiment within a vacuum chamber. Dr.
Moeller and Cadet Speakman are running an experiment using a liquid
metal, called gallium, as part of Dr. Moeller’s work to design a new
rocket thrust stand for AEDC.
--UTSI Photo by Shanna Relford
