The TU Wien Space Team and the University of Würzburg is starting an ambitious project: Measuring instruments will be ejected from a rocket and return to earth without a parachute.
As part of the REXUS/BEXUS program, the TU Wien Space Team is working together with students from the University of Würzburg:
It is a rather daring idea and no one is quite sure whether it will work- a cylindrical measuring instrument will be transported with a rocket to an altitude of 75 Kilometres and is supposed to return to earth unharmed by itself. Should this endeavour work then this technology could set the foundation for many new interesting tools for the future of metrological research.
The basic principle
The principle the measuring instrument is based on is a maple seed, which slowly falls to the ground due to its long wings.
The cylindrical probes, so called Space Seeds, is also fitted with similar wings.
The onboard computer of the Space Seed and the ejection mechanism are designed and produced by the TU Wien Space Team.
Mechanical Design of the Ejection Mechanism
As part of the Daedalus project 3 Space Seeds will be started at the same time. During the launch of the REXUS rocket the Space Seeds will be inside the nosecone.
The Space Seeds (with folded together wings) are hidden inside three tubes made of fibre glass. These tubes are also the ejection mechanism: The Space Seeds are sitting on a spring that is being compressed with a steel rope. A lot of thought was put into the choice of materials in order to ensure a high strength and a minimal amount of weight.
At the apogee, which is at around 75 Kilometre, the steel rope will be cut with Pyro-Cutters and the Space Seeds will be ejected. This process was captured in the following video which was recorded during a Hot Countdown during a Bench-Test of MORABA(DLR)
The onboard computer is an adapted version of our Flight-Management-Systems 3. The power supply had to be adapted since NiMh-batteries were required to be used for this launch. Since the start will take place in the winter in the north of Sweden, the batteries will be warmed up before the launch in order to ensure the full performance of the batteries.
Besides the XBEE shortange modules (which are used for the communication between the Seeds and the on-rocket-computer), there will also be satellite communication modules from Iridium which will send the coordinates of the Space Seeds after landing.
“REXUS/BEXUS” is a cooperation of the German Aerospace Centre with the Swedish National Space Board and ESA. There is an annual launch event from REXUS in Sweden where two rockets are launched and which carry instruments and experiments designed and constructed by students to an altitude of around 80 Kilometres.
For the REXUS23 campaign specific milestones had to be reached and tests in the laboratories from DLR, ZARM, and SNSB had to be passed. Here are some selected photos of these events:
The launch of the REXUS23 rocket including the Space Seeds was actually planned for March 2018 in Kiruna, Sweden. After the student teams arrived in Kiruna their experiments were integrated into the rocket and various tests were performed. This was to ensure that the launch procedures would take place without a hitch and to ensure that the experiments would not influence each other nor the launch itself.
After a faulty start of REXUS24 the launch campaign was stopped and the launch of REXUS23 was delayed by a year.
In March 2019 it was finally time for REXUS23 to launch before REXUS 25/26. The three Space Seeds were brought to an altitude of around 75 km and released. The seeds remained in radio contact throughout its flight and were salvaged the next day with a helicopter.
The following video shows the sequential release of the three Space Seeds at around 75 km.
The analysis of the recorded data proved that the Space Seeds stabilised themselves during reentry into the thicker atmosphere as planned and began to rotate. This rotation decelerated the Seeds from around 800m/s at an altitude of 35km to around 25m/s during landing, which the Seeds survived without damage.
The Space Seeds landed around 33km away from the launch site. The following image shows the flight parabola of the REXUS23 payload section and the path of the Space Seeds, which already had a GPS connection at an altitude of 15km.
Animation of the flight parabola of REXUS23
Project Daedalus was a complete success. Many smaller successes for us were reached with this project such as:
- The TU Wien Space Team were able to take part in the German-Swedish REXUS/BEXUS program
- Members of the Space Team were able to attend two launch campaigns in Kiruna, Sweden, and create new international contacts
- The boardcomputer FMS, which has been part of our rocket projects such as STR and The Hound, was used in Daedalus and brought to an altitude of 75km.
Daedalus in the Media (In German)
- Pressrelease March 2018: Künstliche Ahornsamen aus der Rakete
- Pressrelease March 2019: Ohne Fallschirm vom Weltraum zur Erde
- Conference Article ESA PAC Symposium 2019
The following members of the TU Wien Space Team were part of this project (in alphabetical order)
- Christoph Fröhlich (Project leader)
- Alexander Hartl
- Patrick Kappl
- Christian Plasounig
- Reinhard Rath
- Stefan Schaffer
- Manuel Schleiffelder
- Sebastian Seisl
- Andreas Sinn