Feature

New Heights - Part 1

High Altitude Weather Balloon

Nolan Sobel-Read

Issue 66, January 2023

Can a Year 10 student get his STEM project into space?

It wasn’t that long ago when students' projects were basically an idea hand-drawn onto a poster, an object made from paper mache, or something constructed from icy pole sticks or polystyrene. These days, students have access to all sorts of technology and resources to design, build, test, and present their projects.

Recently, DIYODE was contacted by a young secondary school student, Nolan, who needed funding to build and launch a high-altitude weather balloon and take measurements high up in the stratosphere (That’s over 30km in altitude or roughly 100,000 feet!). Nolan outlined the goals for the project and what electronics he needed. We were only too happy to help out, and started sourcing the parts Nolan needed.

As a trade, we’ve asked Nolan to document his journey so that we can share it with our readers who may want to do something similar or be inspired by the work that he’s doing.

The following is an introduction, and we will publish more throughout the next few issues as Nolan’s project progresses.

Hi, my name is Nolan Sobel-Read and I am a year 10 student at the Hunter School of the Performing Arts in Newcastle, Australia. At the start of year 9, I enrolled in a STEM elective that was a two-year course, and was very excited when it ran. The first year was mostly term-long class projects, where everyone did the same project and bounced concepts off each other. When year 10 started, our teacher Mr Moore told us we could do our own projects, and they could last anywhere between one term (ten weeks) and the full year.

I have been obsessed with space for many years now, and the free range of the project got me thinking: “What is the closest to space I can get with a year 10 STEM project?” I thought for a while and eventually I started thinking about weather balloons. Weather stations launch weather balloons very high up every single day (BOM launches 58 from 38 locations all across Australia and its territories, including Antarctica, every day), so why can’t I?

I did some quick “googling” and came to the conclusion that it was indeed possible, and others had done so before too. I also found out that the balloons could be bought by the general public for a few hundred dollars. Next, I called CASA (Civil Aviation and Safety Authority - the gods of the sky here in Australia) to ask if it was actually legal. They said that it was (although you need to ask for permission regarding a specific launch site/day/time and not do anything stupid), and the project was on its way.

I started researching different sensors I wanted to have on board, and decided to use an Arduino as the flight computer (a decision I later changed).

I decided I would have a temperature sensor, humidity sensor, pressure/altitude sensor, a gyroscope/accelerometer so I could see how stable the flight was, and, of course, a camera. The temperature sensor was the trickiest to find, as the temperature on the way up to 100,000 feet (30km) can go down to -55/-60 degrees Celsius. Most small sensors only go down to negative 40, if that. I opted to go with an extreme type of temperature sensor which is called a thermocouple, which operates by having two metal wires inside of different metals, and then a sensor measuring the difference in charge between the two which changes as the temperature increases and decreases.

The pressure sensor will also double as an altimeter, as the pressure directly corresponds with the altitude, to a degree I had no idea of before this project.

The pressure sensor I ended up going with is the MS5637 pressure module.

The thermocouple is the MAX31855, but I had to get an additional adaptor because the thermocouple cannot directly connect to the Arduino.

As for the humidity sensor, I am using a DHT22.

The gyroscope/accelerometer is an MPU6050.

And, the camera is a Lightdow LD4000, which is commonly used in ballooning, and much cheaper than a GoPro, in case it gets lost. Importantly, the LD4000 can charge while in flight, which is very important as there are almost no cameras that can last the entire 4+ hour flight without an external battery.

I was able to buy most of all these components locally, which was helpful in regard to shipping times, although some I needed to ship from the US as they were parts I could not find elsewhere which was a bit annoying.

The next challenge was how to pay for all of this. The school did not have much money that could be used for my project, and most of that just came from the small class fee at the start of the year. Mr Moore and I started talking about ways to get funding, and the idea of sponsorship came up.

I was talking to my friend Miles the day after, and he mentioned that I should get in touch with DIYODE. He had previously published in DIYODE, in the January 2020 issue (Issue 30) he wrote about his virtual bike on Google Maps project which I got the privilege to try at his house, and it was indeed very cool. I had heard very positive things about the magazine before, so I wrote to DIYODE with my proposal, and to my great joy, Rob wrote back and said that they were happy to sponsor me!

This is when the real project started, as I now had all of the components I needed. I then had another problem. I didn’t know how to code very well. I knew the basics, but needed a mentor for something this complicated. Mr Moore then got me in touch with Cameron Owen, founder and director of Saphi Engineering, who is a good friend of his and kindly agreed to help me.

Since then, I have been going to his office to meet him every Friday afternoon and he has been incredibly helpful in all of the coding aspects of my project.

There were two more main technical problems to solve, as well as a logistical one. The first one was how to keep the electronics and payload warm throughout the flight, as temperatures drop down very low during the flight.

We decided that the payload shell would be made of a styrofoam cooler the size of a six pack (for insulation because no wood, metal or carbon fibre are allowed for the shell, as it poses a risk to aircraft), and have an Adafruit heating pad on the inside which will turn on and off as needed.

To keep the heater from flicking on and off rapidly around a certain temperature, I will set a minimum and maximum temperature. For example, when it reaches down to 0°C it will turn on, and then when it gets up to 10°C it will turn off and cool down to 0° again. In code it will look somewhat like this:

If temp < 0°
   digitalWrite (HIGH)
If temp > 10°
   digitalWrite (LOW)

I then tested the heater system at room temperature values and held my hand over the heat sensor to make it warmer, and sure enough, it turned on and off at the desired levels.

The second problem to solve was how to track the probe, both to know where it is for the duration of the flight and also so that I can retrieve it at the end once it has landed. For this, there are a few different options.

The first you might think of is sending up a cheap phone, and using its tracking software to see where it is. Unfortunately, it uses the regular phone network towers which are designed to blanket the ground in coverage, but have no need to reach above a few kilometres (noting that the balloon will go above 30km in altitude).

The second option is using a hiking GPS emergency tracker, such as the SPOT tracker. The problem with these is that they (at absolute max) only go up to around 10km (remember Mt. Everest is 8,849m, so no need to go much higher than that), so that is only one third of the altitude I am going to. The third is getting an amateur radio license and tracking it via radio, but that takes a lot of time and can be very complicated. The fourth option is using a satellite tracker, which is the option I have chosen to go with.

I am using the Artemis Global Tracker, which can track location accurately to 2.5 metres anywhere on Earth with clear skies. It can also send short messages of up to 50 bytes each, which I will use to send back readings from all of my sensors in CSV format to conserve characters. For example:

<temp>,<pres>,<lat>,<long>,<humid>,<accel x>,<accel y>,<gyro x>,<gyro y>

I will send this data back once every minute from the probe while in flight, this will enable me to see all the data in real time, as well as get a data return even if I lose the probe on decent/landing (the data will save on an SD card on board every second however, which I can retrieve and get super

accurate readings from assuming I can recover it). The Artemis itself is a circuit board that runs off similar code to the Arduino, so the current stage in the project I am up to is a breadboarded test of all sensors on the Arduino, which I can now transfer over to the Artemis using basically the same code.

The logistical problem is where I will launch the balloon from. As a rule, a weather balloon will go east due to the Earth’s rotation, and that can range anywhere from a couple of kilometres to almost 100 or more depending on winds.

There are three places I cannot have the balloon land: in the ocean (as it will sink and be unretrievable), in a city (because of the danger to humans and aircraft, not to mention how hard it would be to find), and on a mountain (as it will be hard or impossible to retrieve).

In short, I need to go far enough west of the Great Dividing Range so that as it drifts east it will land in a field well before the mountains. This will most likely be around Parkes NSW, maybe a bit further west. It depends on what balloon and parachute size I get, both of which impact the distance it will fly (due to a longer/shorter ascent/descent, and also how high it goes, giving access to more and different types of winds).

Lastly for this article, I will explain how a weather balloon works and its various components.

There are three main parts to a weather balloon: the balloon, the payload and the parachute. On the ground, the balloon is about two metres in diameter and is filled with helium. When it reaches 100,000 feet the pressure is 1% of that at sea level, so the balloon expands to a radius of 10 metres, and eventually pops. The parachute then takes it down (fingers crossed) to a soft landing.

During launch and ascent, the balloon is at the top of the mechanism with a rope suspending to the payload. In between there is a parachute, so when the balloon pops the parachute is what is holding the payload up, and guides it to a soft landing.

Currently, I am working on integrating all of the sensors into the Artemis, and then doing full integrated payload tests. I will put the payload into a freezer and do cold tests as well. The current targeted launch time is around late January, but that could change depending on how smoothly the last part of the project goes.

I hope to be back in an issue or two, with exciting new details about the project and (hopefully!) launch!