On Saturday, June 6th I had the pleasure of doing a tethered balloon launch as part of the STEM Bridges Program at the Illinois Institute of Technology. This activity is funded by the Office of Naval Research (ONR) under the Critical MASS grant which supports STEM education and service for college bound high school students.
Our goal was to have students build some simple sensors that they would put into a Styrofoam box that will be attached to a rubber balloon and flown at a height of about 100 feet. That was goal when I proposed the project, and that was the goal on the morning of the launch. We were excited and ready to get to work.
There were a total of 17 students from a few CPS Schools (Corliss, Sarah Goode, Lakeview, and Rickover Naval Academy). There was also help from IIT and the City Colleges of Chicago.
Team leader, Heather Nelson, led a group of 8 students on the construction of the BMP180 pressure/temperature/altitude sensor. Her goal was to get it connected to an Arduino, and have it log data on a microSD card that was connected using an Ethernet shield. In about 2 hours, all of Heather’s students built their circuits, and were ready to fly them.
Every time we fly a balloon we we want to take advantage of the opportunity to take beautiful pictures. Recent IIT graduate (and future physics teacher extraordinaire) Ryan Kamphuis led a group of 8 students on building Raspberry Pi cameras that would take pictures of the Chicago skyline. He also worked on USB Infragram camera that would take pictures of plants, and give us information on their photosynthetic activity. We had some issues with the cameras and Pi’s that were going to take some time and attention to resolve, so in the end we built one camera using the visible Pi Camera board, and it was ready to fly.
When we fly these sensors, they need to be secure and protected. We also wanted to show the students how we built foam boxes using 1.5″ thick insulation from Home Depot. Agu Uzoma from the City Colleges of Chicago lead a group of students who built a total of four pods. These were hot glued together and reinforced with carbon fiber rods. They would hold the sensors during the flight.
Flight Part One
We used a 200g balloon from Kaymont. It was relatively small, and would not need a lot of helium to fly. When we connected the pods and made sure that everything was on and working, we started to fill the balloon with helium. Our first problem was that the tank did not have enough helium in it to provide enough lift. This was a strange problem, because we thought we were dealing with a brand new tank. We sent the students to lunch while we got a second tank from the lab. When it was hooked up, there was more than enough helium to get the balloon and pods off the ground.
When the balloon got to a height of about 40 feet, the wind picked up, and the zip ties that were securing the payload and tethering lines to the balloon failed, and payload fell to the ground and the balloon went up in to the sky on its way to parts unknown.
Undeterred and with the students still at lunch, we prepared a second balloon.
Flight Part Two
We salvaged the working sensors and cameras from our previous pods and consolidated them down to one pod. Ryan quickly got another camera up and running, and Heather & Uzoma did all the logistics for preparing a second balloon.
With everything working we filled the second balloon, and saw that we would have plenty of lift. The zip ties were secure, and we had no problem flying at a height of about 100 feet. We wanted to go much higher, but the ground wind brought the tethering lines close to some trees, and so we went with a shorter and lower flight over all.
If our goal was to fly a camera, and a sensor, we succeeded on both accounts. The pictures below show some of the better images we got. The camera was programmed to take a picture every 10 seconds, and save everything locally. The BMP180 took a reading every second and recorded it on a micro SD card. You can see the pictures. Graphs will be there soon.
This was a lot of fun, and we could see that the students were enjoying themselves. Obviously it was embarrassing to have the first balloon fail, but it seemed to be part of the process. We assessed our mistakes, regrouped and got a second balloon in the air. There has got to be a lesson about resilience and perseverance in there somewhere. In the end, students were happy to see what they got, and were asking when they could try this again.
I have been a vocal proponent of the Raspberry Pi and Arduino and their use in education. Programming a computer on the ground, and seeing that it worked in the air is the closest thing to magic that I have seen a long time.