The students cheered – the DECAN (Deutsche CanSat Höhenrakete) research rocket took off from the Esrange Space Center in north Sweden at 02:53 on 27 October 2015 and proceeded to reach an altitude of roughly 5.5 kilometres. The rocket was designed, built and launched by a team of students from Technische Universität Berlin (TU Berlin) as part of the new STERN (Studentische Experimental-Raketen) German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) programme. The FAUST rocket, developed by the Leonis team from the Technische Universität Braunschweig (TU Braunschweig), and the HEROS (Hybrid Experimental Rocket Stuttgart) rocket developed by the HyEnD (Hybrid Engine Development) team from the University of Stuttgart completed their successful launches on 22 October. The launch of the second rocket by the DECAN Team, scheduled for 29 October, marked the end of the first STERN campaign.
Perfect launch at the Arctic Circle
"It's mindblowing – we have spent more than three years planning, bolting together and testing our rocket – and now we are just happy that the launch went so well," says Michael Schmid from the DECAN Team at TU Berlin. "Right up to the last minute, we were nervous to find out whether we had done everything right." There was no need for concern, as the team's rocket – roughly three metres long and weighing around 23 kilograms – rose perfectly into the skies above the Arctic Circle. Unlike the two other teams, DECAN used commercial solid fuel engines to accelerate its rocket to almost one and a half times the speed of sound.
Fortunately, the valuable engineering work is not lost once the rocket comes back down in the expanse of forest surrounding the Swedish launch site: GPS is used to locate the landing position, and radio signals facilitate its recovery. A helicopter returns the rocket to the Esrange Space Center, where it is handed over to the HyEnD Team to analyse the flight data.
The STERN programme is unique in Europe
Karsten Lappöhn, STERN programme director at the DLR Space Administration, is satisfied with the results so far: "It is a respectable success. And you simply cannot emphasise the fantastic performance of both teams enough. The students designed almost every individual component themselves, and each one of them is a unique piece." The aim of this new student programme is to enable participants to acquire experience working on a 'real' space project while studying. Here, the students are asked to design, build and launch their own rocket, conduct all tests and submit their creation to five reviews. These reviews put all critical systems through their paces, including the engines, the tanks and the radio system. During the project, the STERN students were mentored by experts from the DLR Mobile Rocket Base (Mobile Raketenbasis (MORABA) des DLR) and the Research, Test and Development Centre for Space Propulsion Systems at the DLR site in Lampoldshausen, where the aspiring engineers can conduct engine tests in addition to those carried out at the DLR site in Trauen.
"The programme is unique in Europe," explains Lappöhn. "We are looking for aeronautics and aerospace students at German universities." There are no restrictions with regard to the maximum altitude. The students can choose to design the propulsion system themselves or to use a commercial rocket engine. One condition for participation is the installation of a telemetry unit in the payload to collect important in-flight data such as acceleration, altitude and velocity, and transmit it back to Earth. Nevertheless, the programme requires more than just engineering skills and technical know-how; the exchange of experiences between the teams is equally important.
'Tailor-made' hybrid engine
The LEONIS Team from the TU Braunschweig is just as relieved at the successful outcome of its mission. Roughly three metres long and weighing 24 kilograms, their experimental rocket named ' FAUST' rose to a height of roughly six kilometres during its flight on 22 October. One special feature of this rocket is its hybrid propulsion system, which the students developed themselves. This kind of 'tailor-made' engine is unique, of course, so the students also had to design a fuelling system. For fuel, they opted for a combination of nitrous oxide and a solid fuel with a rubbery consistency.
The HyEnD Team from the University of Stuttgart developed the most technically sophisticated propulsion system for their HEROS creation: its hybrid engine, which the students also designed themselves, generates over three times more thrust than the strongest propulsion system of the other STERN rockets. Accordingly, the requirements for the parachute system for landing and the telemetry unit are significantly more complex. Here, the fuel combination consists of nitrous oxide and wax. HEROS took off on time from the launch pad just a few hours after the FAUST rocket. Soon afterwards, though, the propulsion system encountered technical difficulties that are currently being analysed. The team immediately set about identifying the causes using the telemetry and the recovered body of the rocket – exactly as they would in a real space mission.
The second DECAN rocket by the team from Berlin launched on 29 October, marking the end of the first flight campaign within the STERN programme. The DLR Space Administration is in charge of programme planning and execution using funds provided by the German Federal Ministry for Economic Affairs and Energy (BMWi).