Liftoff! Teacher meeting #2 in Heverlee

10.-16.03.2019, Heilig Hartsinstituut Heverlee

In March 2019 it was time for our second teacher meeting. The goal for our week in Heverlee was exciting: Us SpaceTEAM teachers were to build and launch our own High Altitude Balloon. This week would prepare us for the balloon launches we will be doing next year with our students.

"We're putting the band back together."

Back: Mikko, Jani, Niko, David, Heleen, Suso. In front: Gerda, Raquel, Nico. Notably absent from photo: Pieter, the man both pulling strings, and calculating their tensile strength.


Everyone came in prepared: Plans and calculations had been made, Arduinos coded, Helium tanks and hoses lugged around and a bunch of gear and electronics had been brought in from all three countries. Our plan was to do two launches, launch #1 on Tuesday and Launch #2 on Thursday.

Monday: prepare for launch

On Monday morning we set things rolling with some activities and a tour around the campus. After that, it was time to set up mission control.

Right at the beginning we could easily conclude that everyone had been doing an excellent job between our meetings! The teams had made two functioning data loggers: Arduinos that would record conditions both in- and outside the styrofoam box, we had a choice of different sizes for the box that would carry the payload, and alternatives A and B for electronics that would be included on the flights (for a detailed list of what was carried onboard on both flights, click here)

The details for our first mission were:

  • Target altitude: 30 000m
  • Helium needed: 2600 liters
  • Payload weight: 950 grams
  • Carrying: 2 cameras, Arduino data logger, 3 science experiments (plant seeds, rotifer animals, radiation detector), two GPS modules (Spot Trace and TK 102-2 GPS),
  • Ascent rate: 4,6 m/s
  • Prediction: Balloon would land in Germany, 240km from the launch site

Monday was spent putting it all together: Making final touches to the on-board Arduino, carving out places in the box for the cameras, testing out the GPS modules, calculating helium, coordinating the pick-up, insulating the box (and testing it in the freezer), and figuring out many many more details regarding Tuesday's big day. In the end, we all came out of Monday with a deeper understanding of what it takes to launch a balloon up 35 kilometres.

An abundance of moving parts and things to consider.
Tuesday: Launch #1

T-minus 150 minutes to launch: Weather: not optimal, rain and strong winds. The launch window is still set at 11:00, so no time to worry.

Insulation team hard at work fitting everything inside the box.
Lessons learned: Hot glue and duct tape will get you to space
We purposefully tested two different GPS trackers to see which one is more reliable. Results inconclusive, we have posted a comparison below
Arduino up and running!
The onboard computer will measure temperature both inside and outside, air pressure, and gps location and send the data wirelessly through a mobile network.

The science experiments carried on SpaceTEAM #1 included: plant seeds, rotifer animals, and a radiation detector, generously provided by SCK. CEN Academy Mol.

Starting to fill up the balloon. The wind did not make it an easy process.
On the first fill, we fixed a rubber filling nozzle at the end of the hose. This was found unnecessary and was dropped on launch #2
800 gram balloon
Calculated helium: 2600 liters. For a 50l gas bottle filled up to 200 Bar, the pressure would need to drop down by 58 Bar
The calculated neck lift of the balloon was 1,8kg. This means that we could fix a 1,8kg counterweight to the balloon, and once the counterweight held the balloon stationary in the air, we had the correct amount of helium
Balloon filled up, and tied up with two rubber bands and string.
Lessons learned: The filling process takes a lot less time than we thought. We had the balloon ready to go a good 45 minutes before launch.

T-minus 1o minutes to launch: Weather getting worse, the wind is picking up speed.

All systems go!
Ready for takeoff.
"3 ... 2 ... 1 ... Liftoff!"
Bounce 1.
Bounce 2.
Missed the fence by a hair.

Lessons learned:

1: The wind will affect the rate of ascent. Better to have a lot of space (no pun intended) around at the next launch to avoid potential disaster. 2: A crash course on Finnish curse words for the Dutch and Spanish speakers.

A sigh of relief as we're off!
Around 800m, around the height of the tallest building in the world
Around 1300m, hitting the lowest clouds.
5800 meters.
Going up. Ascent rate around 4,5m/s.
Still climbing.
12:04:01, the outside temperature reaches its lowest point at -48 degrees celsius. Box is still well insulated and the temperature inside is a comfortable -5 degrees.
13:20:10, the balloon reaches its peak altitude at 31378 meters. The balloon bursts, and the payload starts to fall back towards the ground.

Meanwhile, back on Earth...

Tracking the GPS data from the SPOT Trace. Signal was lost at around 9500 meters...
Driving towards the predicted landing spot
Signal picked up again! according to the map, the landing spot was near a school in a small German village near Frankfurt.
Success! We get a phone call telling us that our box landed on a house. Everything was safe and we could come pick it up!
Exelcior! As we pulled up to the parking lot, we were greeted by a German couple who had just hours before been shocked by a big bang on their roof. Luckily our box had a note fixed to it which explained that the contents were not dangerous and included our contact information. Everything was still in place, except for the radar reflector. The Gopros had run out of battery during the landing, and the GPS antenna was damaged in the shaky liftoff, but otherwise the box was in excellent condition.

All things considered, launch #1 was a massive success, and we all could move on to work on Launch #2 with a boosted confidence in our abilities. Not too shabby!

Wednesday and Thursday: Launch #2

After the success of our first mission, we set out to work on the second flight with a mindset of trying out new things.

Early on, we decided to aim for a lower burst altitude to minimize the distance that the balloon would travel as the winds were predicted to be stronger on Thursday.

The details for mission #2 were:

  • Target altitude: 24150 m
  • Helium needed: 5200 liters
  • Payload weight: 1150 grams
  • Carrying: 2 Gopro cameras, Arduino data logger, 3 science experiments (same as mission #1), two GPS modules (Spot Trace and TK 102-2 GPS), and a GPS data logger from Stratoflights
  • Ascent rate: 7,5 m/s
  • Prediction: Balloon would land in Germany, south from Tuesday's landing spot
Things done differently: Added GPS data logger, angled Gopro differently and fed power to it by running a charger cable inside and attaching it to an external power bank. This was also going to be a manned mission, with 3 brave astronauts, each representing their own countries.
On Wednesday we had time to analyze the science experiments from flight #1
Found rotifiers that survived the flight!
One small step for Lego. One giant blob of hot glue to hold them in place.
"Yes, we are serious: We're really going to have a bunch of fifteen-year-olds do this in 12 months."
"Fill 'er up!"
Found a spot that was safe from the gusts of wind - better for filling.
The counterweight for Flight #2 was much larger- The balloon would have a neck lift of 5,2kg
Used up all of the helium left in the tank
Flight #2 ran like clockwork. We knew what to expect, and it was easier to synchronize all our tasks without anyone needing to wait around.
And we're off!

Second time's the charm. This time the launch was much smoother, even though the conditions were worse than on Tuesday

The weather conditions were worse, and most of the early footage from the flight is covered in clouds and mist
8700m. Last photo from the outside mounted GoPro. The camera couldn't stand the -35 temperature, and turned itself off after 40 minutes.
22600m. The burst altitude was reached after 1 hour and 10 minutes of flight time. Still a ways to go to reach the moon, which can bee seen in the horizon

Map simulation from flight data

Coming down fast
Off from the predicted landing spot by 5 km.
Enter the retrieval team.
Editor's note. That bush was filled with thorns.
The role of a language teacher on a science project...
Our brave astronauts, back on solid ground, safe and sound!

Flight #2 worked out as well as the first one, and provided us with valuable data and experience that we can utilize as we start to structure the course curriculum and tutorials for our students. Some kinks in the Arduino are still to be figured out, as well as figuring out methods to save battery life on the recording equipment. Nevertheless, now we knew what worked and what didn't. Luckily, we had placed an emphasis on recording as much of the process as possible during the week, so that we'll have as much information as possible in our use for our next teacher meeting.

Soaking in the great results at the celebratory dinner on our final night in Leuven
Friday: Farewell

On Friday it was time for the Spanish and Finnish delegation to bid farewell, and return to their normal teaching duties back home. On a personal note, our week in Leuven was intense, stressful at times (many, many times), and chock full with new learning experiences that are still rattling around my brain. A leisurely culture visit this was not. However, these four days were also extremely interesting and rewarding. Working together with talented and motivated people made me a 100% sure that our project will be a resounding success and a wonderful experience for our students next year. We really put the "team" in STEAM education!

The SpaceTEAM crew


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