Team Aiolos at the European CanSat Competition in Bologna

We were really looking forward to the European CanSat competition, although we had to improve and repair a lot of things on our CanSat during the previous week. Fortunately, we got everything done by Sunday evening and were able to board the train on Monday morning with a big travel suitcase full of tools, spare parts and of course our CanSat.

The congress center where the competition was held is located just outside of Bologna, where we arrived around afternoon. Many of the other teams were already there, so we were able to socialize for the first time. Around 19:00 we were invited to the "Opening Ceremony", where we were officially welcomed together with the 24 other teams from all over Europe and from Canada. The dinner (like all other meals) was taken at very internationally mixed tables. The meals were a highlight every day, because we could talk to other students from all over Europe about our CanSats and the school, but also about completely different things. It was very exciting to hear how other national competitions went or how the school system in other countries differed from ours. In the evenings we often played soccer together, went out for ice cream or talked until late at night.

Of course we also worked on our CanSat. On Tuesday, the "Technical Inspections" were carried out, i.e. checking whether the dimensions and mass of our CanSat are correct. The parachute together with a "dummy" CanSat was brought up to 50 meters on a drone and dropped to test the required fall speed. We passed all tests on the first try, even our last check of the sensors and gas collection bags of our CanSat did not reveal any problems or errors.

On Wednesday, the time had finally come and the launch was about to take place. At 12:30 we were brought to a small airfield where the rocket for the CanSats would start. Before the launch, we were able to check our CanSat briefly - everything was fine. At 14:55 our CanSat was launched together with that of the Canadian team with a solid fuel rocket.

Launch of our CanSat in Bologna

After a total flight time of 128 seconds, our CanSat landed safely in a sugar beet field. Although our CanSat was printed from orange PLA, it took us quite a long time to find it again. When we finally had it, we were very disappointed because the gas collection bags were not filled with air.

Unfortunately, after recovering our satellite, we had to start the error analysis. After ruling out a hardware failure, we checked the software. This was where the error was located: after the German competition, we had replaced the air pressure sensor and exchanged it for a faster and more accurate one. Unfortunately, the new sensor measured in hectopascals instead of pascals like the old one. This meant that our algorithm, which determines the highest point of the flight and thus triggers the filling of the bags, did not work.

The primary mission, on the other hand, worked very well. Due to the new pressure and humidity sensor, the data is much more accurate compared to the German competition and with only a smaller offset (due to the reaction times of the sensors).

Humidity-height diagram

Thursday was completely filled with the presentations of all teams. Each team was allowed to present and explain their results as well as their mistakes for eight minutes. An international jury consisting of prominent figures in European spaceflight as well as professors of aerospace engineering evaluated the successes of the individual teams. We also presented our data from the primary mission, the error analysis and what we would have expected from the samples.

Friday was the last day of this very eventful week in Bologna. In the morning the award ceremony of this year's European CanSat competition took place. The team from Switzerland won the prize for the best CanSat project fully deserved. Congratulations!

Due to our failed secondary mission, we did not win a prize. Nevertheless, we will not forget this week in Bologna. At first, all teams were a bit unsure what to expect. But since very few of the students learned English as their native language, at least the language was not an obstacle: because it meant that everyone spoke English equally well (or poorly). From the beginning, we were a great community where everyone helped one another. If a certain component broke or you needed a certain tool, you could be sure that another team would help and support you as much as possible.

We would like to thank ESA and all the other teams for this unforgettable experience!


1st place at the German CanSat competition!

Our final presentation for the German CanSat 2021/2022 competition took place on May 12 via video conference. At this event, the participant teams presented their elaborated data of the launch campaign in front of the jury and the other teams. This was followed by an evaluation of each team in relation to the entire project, scoring on the criteria of learning progress, scientific work, technical implementation, professionalism and public relations. Afterwards, the first four places were named, where we can proudly announce to have scored as the best team in the German CanSat competition this year!

With this result we have been qualified to participate in the European CanSat competition and will travel to Bologna (Italy) from June 20th to launch our satellite once again, this time against international competition. Until then we have a lot of work to do, e.g. repairs or optimizations of the CanSat based on recent discoveries from the launch campaign. In addition, we have to write a comprehensive report for the European competition and install a radio system in the CanSat, which we can use to send data to a ground station on site.

The realization of the project would not have been possible without the active support of our Sponsors und Betreuer nicht möglich gewesen, weshalb wir uns in diesem Sinne nochmals ausdrücklich bei diesen Bedanken wollen!


Update 09.05.2022

On Monday, May 9, we focused on the analysis of our gas samples, and for this purpose we had an appointment with Dr. Saathoff at the KIT . At the Institute for Atmospheric Aerosol Research (AAF) he explained us how the proton transfer mass spectrometer works and how the measured values are analyzed. In addition, we enjoyed a very interesting guided tour through the institute, especially the impressive cloud simulation chamber within the facility. Thereby, we were able to follow the analysis of our gas samples at close range, learning a lot about atmospheric aerosol research. We received the final results shortly after our visit in the following days.

We would like to thank Dr. Saathoff and Yanxia Li for the evaluation of the gas samples and the detailed insight into the IMK-AAF.

Measuring instruments at IMK-AAF
Cloud Simulation chamber (outside)


Update 10.04.2022

In the meantime we have got our CanSat back. First things first: all sensors and actuators worked as planned and we were able to read out the data on the SD cards. In addition, the gas collection bags are filled.

Due to a defect on the rocket, our CanSat flew twice, because on the first flight the release mechanism did not work. Therefore, we now have two data sets that we can evaluate. What is not so good, however, is that the two flights have mixed up the samples in the gas collection bag. Together with KIT, we will check to what extent the air samples can still be used and what insights can be gained from them.

We have already started to evaluate the collected sensor data. On 12 May 2022, the virtual final event of the competition will take place, where we will present our results. Here is a first preview of the evaluation:

temperature-altitude profile

The temperature-altitude profile shows the temperature at different altitudes. It can be seen that, as expected, it is significantly warmer at ground level than at higher altitudes. In addition, the temperature decreases rather quickly and reaches its minimum at about 500 metres altitude. Surprisingly, the temperature increases by another 1 degree Celsius at about 600 metres.


Start campaign 05.04.2022

On Tuesday afternoon, we eagerly followed the rocket launch of our probe via livestream. The live stream started at 5 pm and presented the participating teams in just under 40 minutes, as well as summaries of the pre-recorded rocket launches and recoveries of the CanSats. The individual teams were able to present themselves and their project via self-created videos. The replay of the official livestream and our team presentation are linked below:

After we got back our probe together with the gas samples, our project is not over yet. Before the virtual final presentation on 12 May, the samples will be analysed with the help of a KIT proton transfer mass spectrometer. How useful the collected data will ultimately be therefore remains to be seen.


Update 27.02.2022

As we are slowly approaching the submission of our CanSat for the launch campaign, we continued with the completion of the probe last Saturday. For the first time, we were able to fully integrate the pump system, for which all components were finally available to us, into a test print of our structure. As a result, we noticed a need for optimisation of the outer shell in some places, which would not have been possible during the planning in the CAD model, as the dimensions of individual components often deviate from the specified ideal value in reality. In addition, it was difficult to plan the hose routing of the pump system in advance, as we had to bend the hoses inside a lot without them kinking and thus reducing the inner diameter. This revealed clear space problems inside. Especially in places where cable management and pump system cross each other, we had to spend some time trying to fit everything in. We can now use the knowledge we have gained to design another and possibly final version of our structure.

The illustration shows the pump system inside the designated segments of our structure. The top level in which there is a holder for the pump, as well as the three threaded rods for connecting all the segments, have been omitted for better clarity.

You can see the three two-way valves (dark blue and white) and the pump above them (black and grey). Three transparent gas collection bags can be seen at the edge of the orange outer shell.

We also completed the parachutes for 11 m/s and 15 m/s fall speeds, which until now had been missing the attachment of the parachute to the probe via eight nylon cords. We used a lighter to fuse them together under heat at the knots.

We were also able to continue working on the electronics of our CanSat. First, we assembled the industrially manufactured circuit board that we had received from Tesat by soldering on the Arduino, connectors and other components. We then checked the functionality one by one by linking all the sensors and other components to the Arduino via the board and running our test programmes. Fortunately, no problems were encountered.

The picture shows our finished board with the Arduino soldered on.
Some of our components are connected via provisional plug connections for testing.

We are already working on the correct cable connections to ensure a secure connection between the sensors and our board..


Support from Tesat-Spacecom

To control the electronics of our probe, we need a lot of cables and smaller components like transistors, which would take up a lot of space inside the shell. Therefore, we use a circuit board from which we can connect all electronic components to the microcontroller and our power source in a space-saving and clearly arranged way.

Since the PCB plays a central role in our CanSat, it is important to us that it is optimally designed and manufactured with professional equipment. We would therefore like to thank the German aerospace engineering company Tesat-Spacecom for their kind offer to support us with valuable expertise and an industrially manufactured PCB. Thank you very much for your support!


Update 04.01.2022 to 09.01.2022

Last week, from Tuesday 4 January to Sunday 9 January, our focus was on completing the structure, circuit board and main software of the probe. For this we met partly in presence, while on other days we worked individually from home. By using our GitHub repository and some communication programmes, we were able to organise ourselves well. Unfortunately, we were not able to complete the CanSat before the end of the holidays as planned, because some orders for important components were delayed.

As far as the structure is concerned, we had the opportunity to manufacture the necessary metal parts for the lid and base plate of the probe. We chose aluminium as the material for these, as it ensures the required stability without adding too much weight to the probe. In addition, the use of aluminium in the hull had already proven itself in previous projects. There has also been considerable progress in creating a final structural design: Not only has the arrangement of the sensors and placement of the circuit board in the lower part of the CanSat been fully worked out, but we have now also been able to find a suitable solution for attaching the pumping system, especially the gas collection bags, to the outer hull. All in all, we will soon be able to finalise the planning of the structure and turn our attention to the construction of the entire system.

3D model of the probe without
the shell of the upper segments

In the illustration, aluminium parts such as the recently milled lid or the three threaded rods that hold the individual segments of the probe together can be seen in grey.

Immediately below the lid, in blue, is the pump system, consisting of three two-way valves and the air pump itself.

Above the orange segment at the very bottom, which is the outer shell of the lower section, is the circuit board and microcontroller, also in blue. On the right side of the orange area is the on/off switch. For the sake of clarity, the sensor system and the outer shell of the upper section of the probe are not included in this illustration..

Metal parts in manufacturing
Aluminium top cover

The planning of a preliminary board concept, optimised for the structural and technical requirements of our CanSat, was also completed at the beginning of the week. A cost-effective way to have this printed by a professional company is also already in prospect. However, we are still waiting for the expertise of a professional to have our design checked again.

3D model of the PCB during the planning stage

After we found out during the calibration of our sensors in December that the response times of our temperature sensor did not meet our expectations, we ordered a different type of sensor early on and got it working this week. Whereas before we needed more than a minute for temperature fluctuations of several degrees Celsius to be displayed to one decimal place, with the new sensor this happens almost directly within a few milliseconds.

Finally, we have begun to merge the individual programmes of the various components into the main software programme and to incorporate them into the main programme flow. This will require some tests in the near future, which are aimed at determining some time values for controlling the pump system.


Support from MediSense

For our secondary mission, we need three gas collection bags into which we can pump the various air samples. In order for us to get the most unbiased results possible, the bags must be resilient and sterile, so gas collection bags for laboratory use are particularly suitable.

e are very grateful that the Dutch company MediSense reduced the minimum order quantity from ten to six bags for us. This allowed us to use their Tedlar Bags with polypropylene valve for our CanSat. Thank you very much for your support!


Update 03.01.2022

After a somewhat longer break in December, we met again on Monday in Presence to continue working on our probe in the coming week and to complete it as far as possible. The main focus today was on soldering a first prototype for our board. The microcontroller and most of the wiring will be placed on this board to save space. However, since we were still working on the circuitry for the pump system and had difficulties with the soldering equipment, the completion of the board has been delayed.

Furthermore, we were able to test the recently ordered gas collection bags in connection with the pump system today. Thanks to the support of MediSense , we were able to obtain these special polypropylene-coated gas collection bags as private customers and in smaller quantities. Since it is essential for a precise analysis of the air samples that they are sterile, we first selected three bags for testing purposes and marked them accordingly. When starting the probe, we then use the remaining, completely unused and still sterile bags.

Testing of our airpump system

In addition, we directly tried out experimentally how the gas collection bags have to be attached to the outer shell so that they can unfold as easily as possible when inflated. The biggest difficulty here was not to exceed the maximum dimensions described in the requirements. We found a solution to the problem in the use of thin rubber bands, which fix the gas collection bags to the outer shell when unfilled and slip off them when filled. However, since the bags did not lie ideally against the shell during testing and we only had a 3D-printed test cylinder available for the test trials so far, we will have to optimise the concept a bit more.

As already mentioned in the last report, we noticed some errors in the self-test programme of the sensors. For example, it was planned that the readout of a sensor should be aborted if a certain period of time was exceeded in order to prevent the whole programme from hanging up in case of a loose contact. Although we have been able to detect such a timeout so far, we have not yet found a solution to cancel the function for reading out the sensor.

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