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.


ROACH2 Preliminary Design Review (PDR)

ROACH2 Preliminary Design Review (PDR)

ROACH2 Preliminary Design Review (PDR)

Selection workshop in Bonn

The PDR (Preliminary Design Review) of our project ROACH2 took place on the 12th of February 2019 at the DLR in Oberpfaffenhofen as part of a Students Training Week.
ROACH2 is like its predecessor mission ROACH part of the REXUS/BEXUS program. A program sponsord by the German and Swedish space agencies (DLR and SNSA) to give students the opportunity to develop experiments launched onboard high altitude rockets or balloons.
ROACH2 is a rover which is supposed to drive a parcours in zero gravity only supported by electroadhesion on the inside of a REXUS rocket.

On the first day of Students Training Week the DLR and SNSA as well as ESA were introduced to us. We also got information on the REXUS Service System and on how to design our experiment for implementation. In the evening we had the chance to meet the other teams.
Throughout the week we had workshops about subjects like thermal design, software development, power systems, flight requirements, flight safety and system engineering as well as information about our next steps, as wel as the PDRs, 20 minute presentations followed by questions by the review board. They gave us some useful tips on things we need to improve.
The opportunity to question experts about our challenges that we encountered was really valuable to us. We were also informed on which rocket our experiment would be launched.
The last evening ended with a joint visit to the "Flugwerft Schleißheim".



SOURCE Preliminary Design Review

On February 2nd, 2019 the PDR of SOURCE took place at the Institute for Space Systems of the University of Stuttgart (IRS).
The aim of the day was to conclude project phase B, in which the preliminary design of the satellite had been developed. In addition to a project milestone for SOURCE, the review represented an examination performance at the end of the semester for all participants of the corresponding lecture.
Besides the reviewers, who came from Tesat-Spacecom, Thales Alenia Space and Airbus as well as from DLR Bremen and Baylor University, the SOURCE team also welcomed numerous guests. Among them were not only members of the IRS institute and employees of the SOURCE project partner IRAS, but also students of the friendly student society TU Darmstadt Space Technology e.V. (TUDSat). This way, the SOURCE PDR had more than 70 participants in total.
The review began at 10:00 a.m. with the presentation of all subsystems, the system engineers and the team lead. Within about two hours, the current status of the entire satellite system was presented. In the following break the team already got many positive remarks about the endurance and motivation with which the students are working on SOURCE. In the afternoon, reviewers and guests had time to ask questions and make comments.
Following the review, the supervising university teacher Professor Sabine Klinkner was very satisfied with the professional conduct of the review, "I was particularly pleased with how confidently the students answered the experts' questions. They really impressed the space professionals".
Despite the rather cool weather and the onset of darkness, the SOURCE team let the evening end on the roof of the institute, while the Review Board discussed the outcome of the review.
In the end, the Review Board agreed on recommending to continue with Phase C once all RIDs (Review Item Discrepancies) had been processed. The result of the review is thus, as in Phase A, a conditional pass, so the next goal is to close all the RIDs by the beginning of the next semester in order to start phase C in time.
The SOURCE team would like to thank all guests and especially the reviewers for their interest and commitment in making the PDR of SOURCE possible.

ROACH2 accepted into REXUS program

ROACH2 accepted into REXUS program

ROACH2 accepted into REXUS-program

Selection Workshop in Bonn

After applying for the new REXUS cycle we were invited to present our experiment ROACH2 at the DLR (German Aerospace Center) in Bonn. Three of our team members went there to present the project.

At the two day event we met our fellow applicants for both the REXUS (Rocket Experiments for University Students) and BEXUS (Balloon Experiments for University Students) program. Besides the presentations of the projects there were a few additional presentations. Some about the program itself and some about the space industry, for example about risk management for space missions.

Each team had twenty-five minutes to present their Experiment and the same amount of time for questioning by the jury, which is formed by experts from the different program partners.

We were accepted!

On December 7th we received the letter officially confirming that ROACH2 will be part of the new REXUS cycle. With this begins a one and a half year long phase of intense engineering, testing and building, leading up to launch and (hopefully) a successful experiment execution.

The next milestone will be the PDR (Preliminary Design Review) for which we have to define our experiment setup, its features and how we intend to build it. At the PDR we will once again present our detailed concept to the jury, which can then give feedback and possibly demand changes.

More information about the REXUS/BEXUS programme and the other teams that were selected can be found on the ESA-Website.



Our experiment PAPELL will fly to the ISS aboard SpaceX CRS-15 on Friday, June 29th, from the Kennedy Space Center, Florida.

We invite everyone interested in space to our launch-event celebrating the safe flight. There will be presentations on our experiment as well as on others, and a livestream of the SpaceX launch. We start at 9:45 and finish around 12:30 at the Institut für Raumfahrtsysteme at Pfaffenwaldring 29.

Experts visit PAPELL

Experts visit PAPELL

The Überflieger project from the DLR includes a visit of three experts from the space companies DreamUp and NanoRacks from the USA for the PAPELL team.

The experts wanted to get to meet the team in person and see how the progress of the experiment was. Further more they needed to make sure, our experiment does in no way harm or influens the crew on the ISS. The experts were satisfied with our progress and PAPELL could match all their restrictions.

Beginning with a short introduction and a brief presentation of our PAPELL experiment, the experts were shown the main components of our experiment and their functionality. This includes the experiment area 2, the actuators for pumping the ferrofluid, the onboard computer with the power supply and several sensors. In order to keep the overview, a complete integration was not done and insted of ferrofluid, collered water was pumped in the presentation. This had no influence for the tests or the functionality of our experiment. Experiment area 1 was due to time aspects not yet ready but this was no problem because the components are simulare to experiment area 2. Further more the injectors of experiment area 2 were not functional because they still have a minor mechanical issue, due to getting stuck in their reservoir. A further iteration to solve this problem is allready ordered and in manufacturing.

caret-down caret-up caret-left caret-right
Martin Siedorf: Member of the software team for PAPELL
We worked like crazy over the weekend and therefor much more is functioning. We couldn't do all tests but the ones we did were enough to satisfy our guests. We showed them, that we can make it in time!

The biggest worry for our guests were the magnetic interferences during our experiment phase, which could compromise the other modules of the ISS. The induced magnetic field of PAPELL stays far below the requested limits of NanoRacks. Including this aspect, there is no further issue in the way for PAPELL to work on the ISS.
The additional tests concluded as expected and bigger problems did not accure. Further more, one big drop of ferrofluid could be transported from one magnet to the next without any leftovers on the surface. This is shown in the video.

Our guests were also welcomed by our head of the Institute for Space Systems, Prof. Fasoulas. The visit was concluded with a guided tour through the institute and its labratories by Mr. Herdrich.
The day was finalizied with a dinner in citycenter which the experts and many team members participated.

Beacon Test

Beacon Test

On Thursday the 23rd of July we had our first beacon test in collaboration with the AKAFUNK Stuttgart team. The beacon is a small transmitter that sends a simple ping signal approximately every second on a specified frequency. By measuring the signal strength we can evaluate the position of the capsule after landing using triangulation.

These beacons are often used to track wildlife in their natural habitat and are therefore very small in order not to hinder the animals or change their behaviour. Due to their small size and robustness they are perfect for our experiment. We were also very fortunate that we were provided with the XXX by NamTrack Namibia for our mission. 
The tests we conducted in the surrounding fields and woods of the University of Stuttgart, where meant to determine the maximum reach of the beacon in different environments (in the wood, in the field, with and without capsule). 
The tests were very positive. With our very basic equipment we could track the beacon to a range of up to 1km. Since we used a very simple receiver, this value could also be drastically improved. However once inside the capsule, the aluminium front-body acted as a faraday cage and reduced our range to about 100m. The Whipox material we use for the back shell of our capsule had no impact on the range. 
Placing the beacon approximately one meter below the wet ground provided a similar range reduction. This could happen if the capsule lands in snow or dirt. We simulated these effects by placing the beacon in a plastic tube in a canal with about one meter of earth above it.100 meter sounds like a very small range. However, we are very confident that we will be able to further improve this value and 100 meter will probably be sufficient as even with a very bad GPS-signal we should be able to locate our capsule up to a few hundred meters. Therefore we should be able to find our capsule if we acquire at least one GPS signal.
Finally we had two scavenger hunts where two of our members hid the beacon and the rest had to search for it using the receiver and the ping sent from the beacon. We found the beacon in both cases in only 25 minutes and 20 minutes! However, it was relatively easy to get close to the beacon (approx. 10m) , but finding it proved to be hard as the signal around the beacon was so strong it scattered from various surfaces and made it really difficult to locate it. 
All in all the tests where a great success and a lot of fun!                                                                                                                                                                  Thanks to all the participating KSat members and the AKAFUNK team!