Near-Space Balloon

The Physics Club at my school recently completed our second-annual near-space balloon launch and recovery. Our goal was to launch the balloon payload to over 100,000 feet. We planned to record pressure, temperature, and radiation data; test the effects of altitude on biological samples; capture photos and video; and, ideally, recover the payload! While we didn’t achieve every goal, the launch and recovery was a resounding success.

An alumni of the Physics Club worked with Ken Walczak from the Far Horizons project at Adler Planetarium last summer and suggested that we contact Ken. The students contacted and met with Ken on their own, set the goals for the project, and designed and constructed almost every element of the balloon. (Ken provided the pressure and radiation sensors, while I provided the Arduino and temperature data logger.)

This project was a good excuse for me to buy a new Arduio Uno and the Data Logger shield from Adafruit. The data logger shield was easy to assemble, simple to interface with via the Arduino, and convenient to retrieve the data due to the SD card storage.

Armed with our supplies, we met up with Ken in El Paso, Illinois (selected due to its launch-friendly park and sufficient distance from Lake Michigan). With his experience, Ken provided many tips as well as the 1000-gram balloon!

We inflated the balloon:

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… assembled the payload and connected it to the parachute and balloon:

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.. and the president of Physics Club let go! (That process took over two hours!)

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The camera captured a great arial view of El Paso, Illinois:

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… and quickly rose above the clouds:

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While not definitive, based on our data, we estimate that the payload reached at least 105,000 feet:

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… before the balloon popped and the payload fell to earth:

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We used a cell phone that sent GPS coordinate to a web site to track the balloon. Unfortunately, the cell phone stopped sending coordinates immediately after launch. As a result, we had no idea where the balloon was until the payload landed back on the ground, two hours and forty minutes after launch. Fortunately, it landed in a vacant lot in a subdivision relatively close to the predicated location. We were able to retrieve the payload, recover all the data, and be home for dinner.

We had some issues with the data logging. The pressure data wasn’t valid (we were having issues before even launching; so, we weren’t too surprised). Also, the Arduino got too cold when falling and some of our temperature data may be suspect. Regardless, the graphs of temperature vs. time correlated with radiation counts will provide some authentic data for our freshman earth science class next year:

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Next year, we plan on replacing our cell phone-GPS tracking system with a GPS receiver connected to a APRS transmitter. We don’t like losing contact with the payload during launch. We also hope to invite our district’s middle schools to design experiments to include in the payload. The students also expressed interest in adding a camera facing upward to capture a new perspective.

If you are interested in launching your own near-space balloon, feel free to contact me and, while limited, I’ll share our experiences!

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