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INTRODUCTION
Opening Night (click to enlarge) |
The Yerkes Summer Institute (YSI) is a one-week, immersive, residential
science program for inner-city middle and high school students held
at the historic Yerkes Observatory. The full week duration and morning
till late night schedule encourages the participants to delve deeply
into one particular subject. Perhaps more importantly, the structure
facilitates extended discussions and interactions between researchers
and students, and peer-to-peer communication. The instructional
staff is a mix of research scientists and educators. This mixture
ensures that the science is on track and that the student activities
are grounded in reality. |
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Radio Waves, the theme of 2002 YSI, builds upon the investigations
that the Space Explorers had conducted during the spring when they
constructed old fashioned crystal radio receivers. In addition to
the spring laboratory experiences, the students were provided with
background materials
that helped to prepare them for the institute.
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Star Party (click to enlarge) |
After introductions and an overview of the week, the institute
began with a Star Party hosted by amateur astronomers. The rest
of the week was spent cycling through interrelated daytime
laboratories in small groups, nighttime observations,
peer discussions, and deeper explorations into each laboratory
(see Schedule).
The week culminated with student presentations that engaged their
parents, siblings and younger students in the experiments that
they conducted during the week, and a closing ceremony where certificates
of accomplishment were presented. [more
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DAYTIME
LABORATORIES
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Listening to the Sun
Walter Glogowski & Daisuke Nagai |
 Handout |
Students used a large dipole antenna that they constructed, and
a small 2-meter parabolic dish to make radio observations. By
collecting and analyzing data, the students gained an understanding
of how radio astronomers study the universe. They accomplished
this in two ways.
First, they listened to and recorded the strength of a radio
signal from Fort Collins, Colorado, at 15MHz. The students soon
realized that the only way for this signal to reach Yerkes Observatory
was for it to bounce off the ionosphere and back down to earth.
Through this they learned about the important role the sun plays
in making the ionosphere reflective, and how large- to medium-size
solar flares can cause disruptions in radio signals. They then
applied this knowledge to indirectly monitor solar flare activity.
The students also used a small parabolic dish set to receive
a signal at 1.4 GHz. This conventional radio telescope was used
to both listen to the sun and listen to the galaxy as it rotates
by the earth. This investigation allowed the students to gain
an understanding of how a radio telescope collects and concentrates
radio signal at its foci and how celestial objects produce radio
emissions. [more
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The Other Side of Crystal Radio:
Basics of AM Radio Transmission
Ryan Hennessy & Bill Fisher |
Handout |
This laboratory was the compliment of the spring crystal radio
construction laboratory. The students constructed amplitude modulated
(AM) transmitters and then experimented with them. The construction
process involved wonderful hands-on activities including soldering
and building circuits.
In addition to the abundance of hands-on laboratory techniques,
the laboratory was steeped in the theory of amplitude modulation
radio transmission. Once the students had successfully constructed
and tested their transmitters, they then used them to measure
the effects of distance (1/r2) and orientation (e.g., polarization),
and to transmit to the crystal radio receivers that they had constructed
in the spring. [more
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Resonance, or How to Tune a Radio
Randy Landsberg & Matt Hedman |
Handout |
This laboratory demystified the phenomena of resonance, which
is central to both broadcast radio and radio astronomy.
The students first explored natural frequencies of simple mechanical
systems such as a set of different sized paper rings and a pendulum.
This provided them with physical feel for natural frequencies
and how they can be altered.
Next, the students explored a forced harmonic oscillator and
the effect of altering the frequency at which it is driven. The
dramatic increase in amplitude associated with driving the system
at its natural frequency provided them with a concrete example
of resonance. Examples of good resonance (a child's swing set)
and bad resonance (a building's collapse in an earthquake) were
discussed.
Armed with this mental model, the students then made quantitative
measurements of a radio broadcast as the receiver was tuned and
de-tuned to the signal frequency. [more
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NIGHTTIME OBSERVATIONS
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The evening observations utilized the great 40-inch refractor,
which is the world's largest refractor or lens type telescope;
a number of smaller telescopes that the students were able to
control; the parabolic radio antenna; and their naked eyes. Where
possible, the objects observed were ones that are active in radio
as well as visible frequencies.
These evening observations helped induce a sense of awe and
wonder.
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INSTRUCTORS
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• Charles Brass
• Kyle Cudworth
• Bill Fisher
• Walter Glogowski
• Matthew Hedman
• Ryan Hennessy
• Randall H.
Landsberg
• Daisuke Nagai
• Phil Wisecup
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