Paper Plate Education
"Serving the Universe on a Paper Plate"

Activity: Communicating with ISS

Images courtesy of April Whitt.

This paper plate activity is adapted from one developed by Star Station One™ folks at Bishop Museum in Hawai’i. You’ll need twelve paper plates, six each of two colors OR six paper plates that are a different color on the front and back (the birthday party plates in the dollar store work just fine). I have used the “dessert size” and the “full size” plates; either one has been successful. You’ll also need an image of the International Space Station (which can be downloaded from http://spaceflight.nasa.gov – hunt through the Shuttle mission information for the latest images). Refresh your memory of communications satellites at the web site http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/comm/tdrs/ And this activity requires a fair amount of space – a clear floor area of six meters by six meters works well.

I begin with an image of the ISS, showing it to the students and explain that the station is in orbit around Earth right now, that it looks like this, and that other modules will be added over the next few years. There is a crew onboard now. The station is visible in the night sky and looks like a very small dim star. (If you go to the heavens-above.com web site, you can find out when the ISS will be visible from your back yard.) Four years from now when all the components are assembled, it will be very large, nearly 100 meters across, and will look like a big bright star.

Communication in space is “line of sight” so when the ISS is not over Texas, communication with Houston is impossible. This is demonstrated first with the image of ISS. Facing the students, I move the picture of ISS around me (ISS orbits Earth), while describing the signal traveling straight out in front of me. A student volunteer then becomes the ISS and holds two different colored paper plates (or one bi-colored plate), while I hold the same. The student faces me from meter or so away, and we practice “communicating”, the student switching the plates to match the color I am showing with my plate(s).

The ISS student then “orbits” Earth, switching plate(s) to simulate communication, and when he or she is behind me I make sure the plate colors change. The other students in the group usually laugh or give hints.

When the volunteer ISS is back at the starting point, I ask if s/he could see the plates while s/he was behind me. Usually the student says no, and I repeat the “straight line signal” information. Then I ask students how engineers could overcome the problem, and lead them to the idea that we need four communications satellites, each 36000 km out and spaced evenly around Earth, to relay information from the ground to the space station. Four students volunteer to become those TDRSS satellites. Each holds the plate(s) and stands facing me (Earth). One is about four meters out on my right, another the same distance on my left, the third faces me, and the last is behind me (all about four meters away from “Earth”)

We practice changing plate colors with the TDRSS satellites and the ISS once more; then ISS orbits Earth and watches the satellites for information when out of sight of my plates. The other students watch and comment. I ask the satellites how THEY knew what color to show (information may be relayed through several satellites before reaching the ISS) and we discuss that. At the end I ask the students to applaud for the volunteers (which they usually do enthusiastically).

Collect your plates and leave the image of ISS with the teacher if you can. (I’ve found that many schools don’t have good color printers or easy web access.)

Contributed by April Whitt.

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