Newsletter 2021

Newsletter 2021

For the second year in a row, the coronavirus pandemic has determined almost the entire life of our society, but it was necessary to learn how to deal with it to continue to be successful.

While BUBBLE 2 was able to launch successfully in June, ROACH 2 and the fourth CanSat challenge have suffered severe setbacks and are still waiting for a launch opportunity. SOURCE continues unhindered on its way towards orbit for 2023 and is now under construction. Unfortunately, MICU was only short-lived, but FerrAS was able to create a little brother FARGO and will possibly launch in a double version: on a REXUS rocket in the 14th cycle, and it will be  installed on the ISS as successor to PAPELL. A new CanSat challenge has also been launched. The outreach of our association is growing, and our membership numbers are rising rapidly, which is also reflected in our manpower.

Read the full Newsletter here:

If you would like to make a present for Christmas to our society, we would be very grateful for a donation and would like to refer you to our PayPal or bank account.

Depositor KSat e.V.
IBAN: DE44 6009 0100 0406 8300 02

A donation receipt can, of course, be issued upon request.
Enjoy reading, and we wish you a delightful Christmas season.

Natascha Bonidis, Maximilian Schneider and Mario Spahr
KSat e.V. Board

SOURCE Completes Critical Design Review

SOURCE Completes Critical Design Review

At the end of July 2021, the Review Board of the Fly Your Satellite! Program of the ESA Education Office confirmed the quality and completeness of our satellite design for our SOURCE project. With this, we are now formally ready for the integration phase.

The Critical Design Review (CDR) is one of the most important milestones in any spaceflight project. It concludes project phase C, in which the final design of the satellite is established.

Due to a necessary design change at the beginning of the year, the CDR could not be immediately closed and the review board decided to perform a delta review. This has now been completed. With this, SOURCE has officially entered phase D1, in which all satellite hardware will be built, tested and assembled to a complete spacecraft.

The next milestone is the Manufacturing Readiness Review, currently scheduled for spring 2022. Until then, all components of the satellite need to be tested as prototypes and ready for the construction of the flight models.

The SOURCE team would like to thank all reviewers for their commitment and the time spent to complete the review and the extensive feedback received in multiple iterations and many meetings.

The SOURCE project is carried out with the support of the Education Office of the European Space Agency ESA in the “Fly your Satellite!” program.

BUBBLE 2 successfully launched!

BUBBLE 2 successfully launched!

On June 17, 2021, the long-awaited day had come, BUBBLE 2 could finally launch after a year’s delay due to Corona!

30°C outside temperature in Stuttgart and the team gathered, with negative Corona tests, at the university in Vaihingen to do the last preparations for the balloon launch. Changing batteries, preparing the ropes, gondola and parachute and to finish setting up the ground station. In the process, the software from the mobile ground stations still had to be set up on enough laptops so that tracking of the balloon was possible in each of the three tracking cars. 

Around 12:30 the preparations were finished, all things were packed and the gondola and the helium were brought to the launch site. There the team set up a pavilion for some protection from the sun and started to assemble the gondola and check all the functions. At the same time, the balloon was filled.  Shortly before 4 pm everything was ready and BUBBLE 2 was launched.

A flight time of roughly 3 hours was calculated with an approximate landing site north of Bretten. On a windless day the balloon does not fly too far away, which makes the chase more comfortable, so there was enough time for cleaning up, filling the water bottles and eating an ice cream before setting out. Using the tracking systems integrated in the gondola, the position of BUBBLE 2 could now be pinpointed and the flight route followed. Both the mobile and stationary ground stations were able to receive good data. At an altitude of almost 36km, the balloon burst and the gondola fell in free fall until the parachute was able to brake in the denser atmosphere. BUBBLE 2 glided gently to the ground at 5 m/s for the last few kilometers. The cars drove to the approximate landing site from different directions to increase the chance of recovering the gondola quickly. This is important if, for example, there is a river nearby to be able to rescue the systems in time.

All three chase cars had gathered near the expected landing site shortly before the landing and one of them could even watch the gondola descending. It was an unspectacular landing in the field, far away from roads and towns and during recovery no damage to the gondola or electronics could be detected. So it was a successful flight.

The entire flight was filmed by our GoPro, provides stunning footage and can be viewed in full on Youtube.

The data evaluation now also brings BUBBLE 3 a lot further, as we now know which of our systems worked well and where there are still weak points. Our goal to develop a plug-and-play system for high-altitude balloons, has come a lot closer this day!

BUBBLE 2 successfully performed its system test – ready for launch!

BUBBLE 2 successfully performed its system test – ready for launch!

As temperatures are rising, and winter winds are finally gone, BUBBLE 2 has successfully performed its system test – a critical milestone in the launch preparations. During the 2.5 hour long test run, every functionality such as a strong radio down link connection, battery performance and reliable data recording was tested, and no issues were found. Additionally, the team took the opportunity to work on final launch preparations. A final launch date is yet to be chosen and will be selected quite spontaneous as the launch is dependent on good weather and a promising flight track prediction – however, the team is looking for a launch in June 2021.

BUBBLE is the very own high-altitude program and balloon of the Small Satellite Student Society of the University of Stuttgart. BUBBLE 2 is, similar to the flight of BUBBLE 1, equipped with a sky brightness sensor which is an experiment performed in cooperation with the Institute of Space Systems at the University of Stuttgart. The high altitude balloon will lift a 2 kg gondola carrying the experiment to a maximum altitude of approximately 35,000 m where the balloon will burst and the gondola starts to descend safely on a parachute. The BUBBLE team on the ground will receive radio transmissions from the balloon to localize and recover the gondola after landing.



MICU (Mineral Investigation Camera using Ultra-Violet) will use ultraviolet (UV) radiation to cause fluorescence of lunar rocks through LEDs, which we will then detect with a camera. The on-board image processor will analyse the images for possible fluorescence. Promising images will be released for downstream to Earth for advanced mineral classification.

BUBBLE Team Practices Tracking & Recovery

BUBBLE Team Practices Tracking & Recovery

The BUBBLE team practised for their upcoming launch today by helping to track and recover another private high altitude balloon. The payload was a camera, along with a few personal items. After a launch near the University of Stuttgart and a 2 hour flight with a maximum altitude of 34.8 km, the balloon landed in a forest and got stuck in a tree. With some patience and a 15m long telescopic stick they were able to successfully recover the balloon and its payload. Participating in this kind of operation gives the team a chance to practice for their own launches, and helps to ensure a smooth tracking and recovery later.

Satellite SOURCE in ESA programme Fly Your Satellite!

Satellite SOURCE in ESA programme Fly Your Satellite!

On the way to its first satellite in orbit, the Small Satellite Student Society of the University of Stuttgart, KSat e.V., has taken a major step. In December nine students of the 70-strong team participated in the selection workshop for the Fly Your Satellite! program at the ESTEC research centre in the Netherlands. There they were able to convince experts from the European Space Agency (ESA) with their work to date and were accepted into the program along with two other satellite projects!

KSat had already designed a re-entry capsule with MIRKA2 and a spacecraft maintenance robot with ROACH (both as part of the German-Swedish REXUS/BEXUS programme – also supported the ESA Education Office). With PAPELL the group was able to carry out an experiment on the International Space Station on the behaviour of magnetic fluids. All three series of experiments have the potential to one day carry out important tasks on satellites and other spacecraft.

However, the university group has so far lacked the small satellite that gave them their name. At the end of 2017 long-standing members together with the executive board made the decision to change that: After the successful missions as a payload on REXUS rockets and the ISS and the lessons learned from these, the first self-sufficient small satellite was now to be built.

The ambitious project started with four students and the Institute of Space Systems (IRS) at the University of Stuttgart. Even if the satellite was to be built independently and exclusively by students, this could not be achieved without the expertise and support of the IRS, they agreed. With the Flying Laptop, the IRS had already built the first small satellite at the University of Stuttgart. The Flying Laptop has been successfully operating in orbit since June 2017.

The partnership between KSat and the IRS is by no means new; the IRS has always been a supporter and benefactor and at the same time a valuable critic. But this time the cooperation was to go further. Each part of the satellite, called subsystem, is supervised and advised by a PhD student from the institute. In the course of this, students are also able to count their work on the project towards their academic degrees. After a short name search, the name SOURCE, Stuttgart One Unit Research Cubesat for Education, was selected. KSat chose Annika Stier and Robin Schweigert as team leaders for the project, the IRS provided Michael Lengowski, an experienced satellite builder, as project coordinator. In the 2018 summer semester KSat's largest project to date and the lecture "Practise Course CubeSat Technology" could start. The declared goal was the design, construction and operation of a 1-unit CubeSat. A CubeSat is a standard for microsatellites, built of cubes 10x10x10 cm in size and a weight of 1 kg each, called units. For comparison, the Flying Laptop of the IRS weighs over 100 kg and had the dimensions of a washing machine.

Now that the basic conditions had been defined, the team could turn to the first important question: How do you build a satellite?

In their studies they learned all the important basics of their subjects. A student knows the most important equations for calculating an orbit, knows which phases a space mission goes through, knows manufacturing processes and the physics behind radio technology, thermal simulation and attitude control. SOURCE is the first time many students apply these tools.

Ambitious Schedule and Rapid Progress

A weekly meeting becomes the centre of the project. The first meetings resemble a lecture: IRS staff present a crash course in satellite technology to give the students an overview of what needs to be done. From the third week onwards, the meetings are more reminiscent of plenary sessions, in which the subsystem groups present their progress and plans and try to coordinate them with those of the others.

The payload group would like to install a camera to determine the satellite's attitude from the starry sky. The choice is a special image sensor that can only be connected via USB3.0 or a Gigabit network. The search of the group "On Board Computer & Data Handling" for a main computer with a corresponding connection ends without result. Either the necessary interface is missing or the required Space Heritage - meaning the component has never been in space before. For the critical main computer, however, it is essential to choose a model that has "already flown". This is the only way to be certain that vacuum and cosmic radiation will not immediately destroy the component.

After months of research and consideration, an additional computer, which is only used for the camera, is agreed upon. The system comes from the automotive industry and provides the necessary interface - but how reliable it will be in space will only become clear after launch. This is a risk the team is willing to take. A failure would mean the loss of the experiment - but would not endanger the satellite.

After the first semester, the requirements for the satellite are fixed. KSat and the IRS invite internal and external experts from the industry, so-called reviewers, who look at the students' work, criticize it and finally, after some corrections, declare Phase A as passed. This process is to be repeated every semester.

The satellite has grown, one unit has become three. Various new payloads have been added in cooperation with industrial partners. The new name "Stuttgart Operated University Re-search CubeSat for Evaluation & Education" has been agreed upon.

In February 2019 the preliminary satellite design is up for discussion at the second review. The reviewers carefully examine the documentation and present a list of almost 200 points of criticism. After extensive follow-up work, which would last until July, the OK is given to declare Phase B as completed.

New Schedule and new Momentum

With delay due to the follow-up work, the original ambitious timetable can no longer be maintained. The now almost 50 students are becoming increasingly aware that the effort involved in building a satellite has been underestimated. Furthermore very few new students join the team for the 2019 summer semester.

To counteract the slump, the team management now has two systems engineers at its side. All subsystems now have group leaders to coordinate the distribution of work in the group and to coordinate with other subsystems in weekly meetings. The weekly overall meetings are increasingly being skipped in favor of workshop days. On these Mondays, if possible all participants meet and work together for a good eight hours in a lecture hall. Phase C is extended and should now last two semesters and not be completed until spring 2020. During a consultation with a very experienced member of staff from the IRS electronics workshop, he comments that he was convinced that SOURCE would work and fly one day, just not on the original schedule.

State of Affairs Autumn 2019

A third review follows in autumn of 2019, in which only an intermediate status "C1" is shown. The documentation has now reached almost 400 pages in length. To great joy of all involved, the tide has turned again. The feedback is extremely positive, the significant progress is highlighted and the professionalism of the students work emphasized. The turnaround seems to have been achieved, and at exactly the right time. With the "Fly Your Satellite!" programme, ESA Education offers student satellite projects the rare opportunity to test, qualify and fly their satellite together with ESA experts. For SOURCE this is a unique opportunity: To professionally carry out the tests of the satellite and thus qualify it for a launch into space are major challenges where ESA's support is more than welcome.

The deadline for submission of the application only a few weeks after the review requires full commitment and sometimes night shifts from all parties involved. Late in the evening of the 13th of October, the team leaders upload the finished document.

With over 20 registrations for the course and 15 more interested students, phase C2 is starting with a strengthened team. "We had so many people interested in a place in the structures and thermal subsystem that for the first time we had to disappoint some students - but only because they are picky with their tasks, in the other seven subsystems further helpers are still welcome".

The chairwoman of KSat e.V., Franziska Hild, is pleased about the lively interest that all projects received in 2019: "We are more diverse than ever before". In addition to students of aerospace engineering, the participants increasingly include students of computer science, electrical engineering, physics, simulation technology and social sciences. She continues: "Space travel is not an isolated field, but an application of many diverse disciplines.”

"A great experiment is of little use if the communication fails, the control software breaks down or the power goes out", Michael Lengowski begins the introduction for the new SOURCE members. From the ground, all three cases would look the same: No signal. "That's why we have to design our satellite to be robust and above all test, test and test".

Selection Workshop for the ESA programme Fly your Satellite!

On November 7th, the project management receives the good news: "We will be at the selection workshop for Fly Your Satellite!" project coordinator Daniel Galla writes in the project chat.

In this selection process, a delegation of four students from each applicant team is invited to the ESA ESTEC research centre in the Netherlands. Five more travel at their own expense. At the end of the process, the expenses are evenly divided between all of them.

In a presentation followed by a question and answer session, the students face the ESA experts. Here will be determined whether SOURCE can prevail against the European competition. Who has the most exciting experiments on board? Which team can show that it is capable of successfully constructing its satellite? To secure the financing for the construction? "The fact that we are allowed to participate in the Selection Workshop is already a huge success," says project leader Annika Stier happily. Not all teams from Germany, Austria, Sweden, Spain, Greece, Finland and Great Britain will be accepted into the coveted program.

After a full day of presentations from every attending team the rest of the week is spent with lectures from ESA specialists in all areas of satellite design. The team receives a wealth of helpful information and, even more importantly, an opportunity to directly discuss their current challenges with some of the top experts in these fields. At the end of the week the team goes back to Stuttgart to continue working on the satellite.

Then, at the end of February the eagerly awaited confirmation comes in: "The message from ESA just came in: We have been accepted into Fly Your Satellite!. Congratulations to all of you, this would've never been possible without your work and perseverance", the team leader writes in the group chat. Professor Sabine Klinkner also offers her congratulations: “It was a great team effort to prepare the documentation for ESA and to present SOURCE in such a compelling way on site. Many thanks to all for the amazing commitment!”

There is a lot more work to do and many challenges to overcome for the SOURCE team before they can launch their spacecraft. But with a large motivated team and the now secured support from ESA everyone feels it really is now a matter of when, not if, it will fly.

What is KSat?

The Small Satellite Student Society of the University of Stuttgart was founded in 2014 by aerospace engineering students. It enables students to work on real space missions during their studies and thus gain practical experience. KSat organizes conferences and design competitions and creates platforms for exchange and cooperation between students, institutes and industrial partners. KSat is recognised as a university group and registered as an association.

What is the IRS?

The Institute for Space Systems at the University of Stuttgart

SOURCE Fact Sheet

Size: 3U+ (10x10x36 cm)

Start of Development: 2018

Planned Launch: 2021 / 2022

Team: 70 students, advised by PhD students from the IRS

Team Structure

Project Leaders: Annika Stier, Robin Schweigert

IRS Project Coordination: Daniel Galla, Michael Lengowski

Systems Engineers: Adrian Causevic, Klemens Boltenhagen

Subsystems: Attitude Control (ACS), Power (EPS), Communications (COM), On-Board Datahandling (OBDH), Structures and Thermal (S&T), Simulation and Testbed (Sim), Payload (PL), Operations and Ground (Ops)

Payloads: Meteor-, star and horizon camera (MeSH-Cam), sensors for heat flux and pressure, photodiodes, atomic oxygen sensors (FIPEX), 3D-printed sandwich structure with embedded electronics, smart heaters, thin film solar cells, earth observation camera

More Information

Contact for press inquiries

SOURCE Website

Fly Your Satellite! Website

The SOURCE project is carried out with the support of the Education Office of the European Space Agency, under the educational Fly your Satellite! Programme.


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ROACH2 Integration-week

ROACH2 Integration-week

ROACH2 Integration-week


The REXUS Integration Week took place at ZARM in Bremen from 9 to 13 December. During this week the experiment was assembled, subjected to vibration analysis on a vibration table and tested for compatibility during the bench test.


On Monday we packed the rest of our things and loaded the car. Afterwards we went on a long trip north. The arrival at the hotel in Bremen was in the evening.


Tuesday was completely dedicated to the assembly of the experiment.


On Wednesday we had actually planned our shaker test. Unfortunately we were not yet ready for it, so it was postponed to Thursday. So this day was also spent with assembling. In the evening there was a discussion whether our experiment should be moved to another rocket, because there were compatibility problems with two other experiments. So we sat down in the hotel in the evening and discussed the effects of these changes on our experiment. Our final conclusion was that this change would endanger our and other experiments due to vibrations.

After we had posted a picture of our rover in the club's chat, some memes came back, which we don't want to withhold here.


In the morning we made last preparations before we went on the shaker in the late morning. After a few exciting minutes it was over. The inspection showed that we had some cracks in some parts. But all in all nothing bad and unexpected happened. In the afternoon we had some free time, where we waited for the third team on the rocket, before we had the benchtest in the evening. After one of the experiments had induced a wrong signal on the second one, the test was cancelled and postponed to Friday.


On Friday the Benchtest took place. At the Benchtest all experiments are set up together with the Service Module and the entire flight sequence is simulated. The goal is to find out if the experiments work and to make sure that the experiments do not influence each other. This test went quite smoothly, so we finished testing and packing at 11am and were ready to go home. We arrived back in Stuttgart late in the evening.

ROACH2 Critical Design Review (CDR)

ROACH2 Critical Design Review (CDR)

ROACH2 Critical Design Review (CDR)

CDR at DLR Oberpfaffenhofen

As part of the Critical Design Review of Roach-2, a soldering course took place again this year at the DLR site in Oberpfaffenhofen. A representative of the teams from all over Europe was introduced to the guidelines and practice of THT (Through Hole Technology) and SMD (Surface mounted devices) soldering.


After we arrived well on Monday despite the most difficult weather conditions, we started on Tuesday. On the first day, THT soldering was the main topic at DLR's well-equipped soldering centre (see picture on the right). After we learned the standards in the first half of the day, we could finally try it out for ourselves after a delicious lunch. We worked on 2-layered boards as well as on 4-layered boards (how they are used in the Roach-2 Rover). After we mastered this with success, we went out for dinner with the other teams.


The next day we continued with SMD soldering. In the first half of the day we devoted ourselves to theory again and in the second half we tried to put it into practice. This was clearly more difficult than the THT - soldering since the connections were considerably smaller.

When this was successfully mastered, we received our certificate.


Translated with

On Wednesday the other three team members arrived by train. That evening we also met some other teams at the local pizzeria in Steinebach, a small town near DLR. The following day we had time for ourselves until late afternoon. We used this time to explore the surroundings and after some communication problems with the bus driver on the way to the campus we rehearsed our presentation.

Our first appointment was a presentation about environmental testing. In this lecture we talked about the loads during the mission and the tests for those loads.

In the evening we had a meal together with our supervisors and all teams in a restaurant directly at the lake.

Friday was the day of our CDR (Critical Design Review). As the last team we presented our progress and got valuable feedback. The experiment in general was well received, but we must work on our documentation. After the 20-minute presentation to experts from the participating partner organizations, we answered all questions and received valuable comments and hints.

Immediately afterwards, there was an interface discussion in which possible influences from other experiments were discussed to prevent or minimize mutual interference.