St. Stephen’s Episcopal School, Houston (SSESH) is one of eight host organizations selected by Amateur Radio on the International Space Station (ARISS) to schedule amateur radio contact with the crew on the International Space Station (ISS).

Contact between SSESH and the ISS will now be scheduled in October 2022, provided St. Stephen’s availability and flexibility match up with the scheduling opportunities offered by NASA. As our contact day approaches, Mr. Charlie Larrabee, Lab Guru, da Vinci Lab for Creative Arts & Sciences, would like to share information about our station, some of its capabilities, and some of the challenges we have faced so far.

The da Vinci Lab’s Yagi Antenna
By Mr. Charlie Larrabee

Low Earth Orbit satellites (like the ISS) travel very fast relative to our position on the ground.  Therefore, we will have a short period of time to talk with the astronauts onboard.  It is likely that we will have about ten minutes, give or take a little bit.  Everything has to be ready ahead of time, so our students can have the best experience possible as they talk to our astronauts!

In order to maximize our contact, ARISS has requested that we set up a high-gain Yagi antenna.  In addition, the antenna has to be able to point at the station during our entire contact!  In order for this to work, we have installed a 2-dimensional rotator.  That is, we have a robot arm that can turn our antenna in azimuth (like a compass), as well as in elevation (like a sextant). The rotator has to be quite strong, as it is turning an antenna that is ten feet long!

One of the most challenging parts of the project so far has been the motor control.  Motor control means that the motor (our rotator), has to be connected to a computer which tracks satellites through the sky.  The computer knows exactly when and where a satellite is above us, but it needs to be able to communicate this to the rotator.  That’s where motor control comes in.  We have TWO special boxes to do this, one which plugs into the computer with a USB cable, and a second which sends the electrical power up to the rotator.  There are lots of wires, of course!  It is a delicate dance between the systems, with the computer on one end providing small data signals, and the electric motors on the other end, needing big power and guidance.

It has been my delight to be able to share this build process with my students as the station comes together.  We spent much of the spring semester with our rotator and Yagi antenna in the classroom, observing how they work.  Now that they have been moved up to the roof, my students will have a better understanding of how and why the antenna moves.

The da Vinci Lab

The da Vinci Lab for Creative Arts and Sciences at SSESH is both a program and a place, led by Mr. Charlie Larrabee, Lab Guru. Every student in K – 8th grade learns in this unique makerspace. Students learn core computer skills such as typing, internet safety, and basic coding. The lab also offers St. Stephen’s students the resources and opportunities to explore creative solutions to complex, hands-on problems. Da Vinci students learn from a progressive radio curriculum (including Fox Hunts, Slow Scan TV, and Morse Code) and are avid ISS trackers. Through this partnership with ARISS, SSESH students will have the once-in-a-lifetime opportunity to speak with astronauts in space.

Amateur Radio on the International Space Station (ARISS)

ARISS inspires students, worldwide, to pursue interests and careers in science, technology, engineering and math through amateur radio communications opportunities with the ISS on-orbit crew.  Students have the opportunity to learn about space technologies and the technologies involved with space communications through the exploration of amateur radio. For more information on ARISS, visit

Students learn about space technologies and the technologies involved with space communications through the exploration of amateur radio.