REXUS 2 - The first Eurolaunch Project

Sounding rocket and balloon launches have been conducted since more than 30 years at Swedish Space Corporation (SSC), ESRANGE. MORABA, the Mobile Rocket Base of the German Aerospace Center (DLR), has planned and performed sounding rocket and balloon launches throughout the world since the late sixties. With the creation of EuroLaunch, the long-lasting co-operation of the two complementary technical centres ESRANGE and MORABA is being enhanced and intensified. The REXUS 2 student rocket was the first project to be designed, built and launched under the EuroLaunch cooperation. A driving force in research by means of sounding rockets, has been the German Aerospace Center, which through its Mobile Rocket Base team, has conducted launches and operations all over the world. The Swedish Space Corporation and the German Aerospace Center have now entered into a deeper relationship by establishing a joint co-operation called EuroLaunch. On December 8th, 2003, a co-operation agreement was signed at ESRANGE. The agreement will strengthen the long-lasting and ongoing relationship between SSC and DLR within the area of sub-orbital services for upper atmosphere and microgravity research as well as future fields of research interest. EuroLaunch is currently involved in several projects which aim at strengthening the co-operation and also providing new possibilities to the scientific communities. The first EuroLaunch project was the REXUS 2 student rocket, which was successfully launched on October 28th, 2004 at ESRANGE. Within the REXUS 2 project the flexible work sharing of EuroLaunch has been put to its first test, as personnel from the two organisations have supported each other during heavy workload periods

Entwicklung einer Hochtemperatur S-Band-Sendeantenne für Hyperschall Wiedereintrittskörper zu Mess-Datenübertragung

Im Rahmen des Programms SHEFEX, bei dem unter anderem ein neues Temperaturschutzkonzept für hypersonische Flugbedingungen erprobt wurde, entstanden bei der Mobilen Raketenbasis (MORABA), die für die Durchführung des eigentlichen Flugversuchs verantwortlich war, neue und anspruchsvolle Anforderungen für die Übertragung der Experimentdaten per Telemetrie zum Boden. Während der Experimentphase von SHEFEX, die während des stabilen Wiedereintritts des Flugkörpers im Höhenbereich von 90 bis 200 km stattfand, sollte eine vollständige Telemetrie-Datenübertragung der Sensoren und Experimente gewährleistet sein. Darin enthalten waren die Daten zur Positionsbestimmung über GPS. Seitens der Telemetrie wurden hierzu bisher üblicherweise Blade-Antennen im S- Bandbereich (2.25 GHz) eingesetzt. Da jedoch bei einer stabil eintretenden Nutzlast sehr hohe thermische Belastungen auch der Antennen selbst zu erwarten waren, wurde ein angepasstes Design der Antenne notwendig. Auch können bei sehr hohen Geschwindigkeiten Realgaseffekte wie Teilchenionisation und Plasmabildung auftreten, die Beeinträchtigungen bei der Datenübermittlung über elektromagnetische Felder nach sich ziehen. Dies wurde insbesondere in den späteren, weiter fortschreitenden, Flugexperimenten des Programms signifikant. Um diese Effekte zu berücksichtigen, abzuschwächen oder die Datenübertragung anderweitig robust und zuverlässig zu gestalten, waren weitergehende Untersuchungen notwendig. Der überwiegende Anteil der Nutzlasten von Höhenforschungsraketen ist den Forschungsbereichen „Forschung unter Weltraumbedingungen“ oder „Atmosphärenphysik“ zuzuordnen. In beiden Fällen ist die Experimentphase üblicherweise abgeschlossen, bevor die Nutzlast auf dem absteigenden Teil der Flugbahn wieder auf ingenieurstechnisch relevante Atmosphärendichten trifft. Dies ist bei aerodynamischen oder aerothermodynamischen Versuchen zur Hyperschallströmung nicht der Fall – hier ist das „Experimentalfenster“ meist genau innerhalb der ingenieurstechnisch relevanten Atmosphäre während des Widereintritts, zwischen 90 und 20 km Höhe. Während normale Nutzlasten in diesem Teil der Atmosphäre instabil ausgelegt sind, also unkontrolliert taumeln sollen, um so möglichst stark abzubremsen und die Energie auf den gesamten Körper zu verteilen, ist dies bei Hyperschallnutzlasten nicht möglich. Jedoch haben auch bei Versuchen mit instabil ausgelegter Nutzlast Untersuchungen von geborgenen Raketennutzlasten gezeigt, dass es ein stabiles Eintrittsverhalten geben kann. Dieses führte durch lokale Konzentration der eingebrachten Energie teilweise zu Degradation (Abschmelzen des Antennenleiters und Isolierung) im Antennenkernbereich. Im Gegensatz zu konventionellen Höhenforschungsmissionen, bei denen der wissenschaftliche Schwerpunkt hauptsächlich im exoatmosphärischen Flugbereich liegt, müssen somit für das SHEFEX- Programm und ähnliche Flüge entsprechende Vorkehrungen getroffen werden

Search and Rescue: Development and Verification of a Modernized Passive Floating System for Payload Sea Recovery

For most suborbital space flights, the successful recovery of the experimental payload is a critical point at the very end of the mission. Beside land based recovery, particular missions require a sea recovery in the Arctic Ocean. Therefore, a variety of passive floating systems have been developed and used by DLR's Mobile Rocket Base (MORABA). Using the vast experience of multiple successful sea recoveries over the last decades, some of the latest development work has been dedicated to a modernised version. In cooperation with TEXCON GmbH, improved Long-term floating behaviour and a considerably reduced packing volume have been achieved by using innovative materials and manufacturing technologies. Prior to the first successful operation of the improved passive floating system, various tests had to be performed to verify the floater's functionality and durability. In this context, the Neutral Buoyancy Facility's (NBF) diving pool of ESA's European Astronaut Centre (EAC) in Cologne was offered for investigating different recovery scenarios. This paper describes the development and verification process of the modernized passive floating system. Furthermore, results of the first successful operation during the PMWE mission are presented

European Recovery System (ERS)

Up to the TEXUS-44 microgravity research mission, successfully launched in February 2008, the payloads of the TEXUS vehicles were exclusively equipped with the Magellan (former Bristol Aerospace Ltd.) ORSA recovery system, integrated into the ogive nose cone. With the intention to gain more independency from the North American market and the inherent procurement and ITAR regulations problems, the European Space Agency (ESA) has taken initiative to contract industry for the development and built-up of a new European Recovery System (ERS) in 2006. For the design, manufacturing and qualification task sharing, a cooperation of DLR Moraba and the Kayser-Threde GmbH has been initialized. The ERS is designed to recover payloads of up to 450 kg mass and 17 inch (438 mm) diameter by a two-stage subsonic parachute system. It features a separating ogive nose tip with a forward deploying recovery parachute. The assembly incorporates a 3:1 fineness ratio ogive which forward portion is ejected exo-atmospherically to permit subsequent parachute recovery system operation. The aft ogive houses the parachute system, autonomous redundant pyrotechnic ignition system, housekeeping electronics, TM interface, beacon system, camera system and pyrotechnic and electronic batteries. The parachute system activation is controlled by barometric switches on the descent trajectory at a nominal altitude of 15 kft (4.6 km) in the combination of an electronic timing activation unit (ignition unit). Together with the heat shield ejection the drogue parachute is deployed and the payload is mainly stabilized from flat spin and decelerated. After complete stabilization the drogue parachute is separated and extracts the main parachute out of the deployment bag. At fully opened main parachute the final sink rate is around 8 m/sec

Sounding Rockets as a Real Flight Platform for Aerothermodynamic CFD Validation of Hypersonic Experiments

This paper describes the possibilities of sounding rockets to provide a platform for flight experiments in hypersonic conditions as a supplement to wind tunnel tests. Real flight data from measurement durations longer than 30 seconds can be compared with predictions from CFD calculations. This paper will regard projects flown on sounding rockets, but mainly describe the current efforts at Mobile Rocket Base, DLR on the SHarp Edge Flight EXperiment SHEFEX

SHEFEX 2 - The Vehicle, Subsystems and Mission Concept for a Hypersonic Re-entry Flight Experiment

The first launch of the SHarp Edge Flight EXperiment (SHEFEX) was from Andøya Rocket Range (ARR) Norway, in October 2005. Its purpose was to investigate the aerodynamic behaviour and thermal problems of an unconventional shape for re-entry vehicles comprising multi-facetted surfaces with sharp edges and an asymmetric form and to provide a correlation of numerical predictions with the flight results for velocities up to the order of Mach 7. The success of the first mission has led to the approval of the SHEFEX 2 project which will involve a facetted but symmetrical fore body with a canard control system to obtain further data on the aerodynamic and thermal effects at hypersonic velocities. The canard system should provide control in all axes and predefined angles of attack of up to +/-5 degrees during the re-entry phase. The Mobile Rocket Base (MORABA) of the German Aerospace Centre (DLR) is again responsible for the vehicle, payload, service systems and test flight of the SHEFEX 2 experiment on a two-stage, solid propellant, sounding rocket

The Hypersonic Experiment SHEFEX - Aerotheromdynamic Layout, Vehicle Development and First Flight Results

The purpose of the SHarp Edge Flight Experiment SHEFEX was the investigation of the aerodynamic behaviour and thermal problems of possible new shapes for future launcher or re-entry vehicles. The main focus was the improvement of common space vehicle shapes by application of facetted surfaces and sharp edges. The experiment has permitted the accurate investigation of the flow effects and their structural solution during the hypersonic flight from 90 km down to an altitude of 20 km. The project, performed under responsibility of the German Aerospace Centre (DLR) was launched from Andoya Rocket Range, Norway on October 27th 2005. This paper introduces the mission, describes the layout of the experiment and the re-entry vehicle, as well as the development process of the complete flight vehicle and initial post flight results

SHEFEX - Hypersonic Re-entry Fllight Experiment - Vehicle and Subsystem Design, Flight Performance and Prospects

The purpose of the Sharp Edge Flight Experiment (SHEFEX) was to investigate the aerodynamic behavior and thermal problems of an unconventional shape for re-entry vehicles comprising multi-facetted surfaces with sharp edges. The main object of this experiment was the correlation of numerical analysis with real flight data with respect to the aerodynamic effects and structural concept for the thermal protection system (TPS). The Mobile Rocket Base of the German Aerospace Center (DLR) was responsible for the test flight of SHEFEX on a two-stage unguided solid propellant sounding rocket, which was required to provide a velocity of the order of Mach 7. The SHEFEX vehicle was launched on the 27th of October 2005 from the Andoya Rocket Range, Norway. This paper presents the main design features of the vehicle and subsystems, the flight performance and the current plans for our next hypersonic project

SHEFEX-2 - Development Status of the Vehicle and Sub-Systems for a Hypersonic Re-Entry Flight Experiment

The SHarp Edge Flight EXperiment (SHEFEX) is a DLR program to investigate aerodynamic behaviour and thermal protection problems of re-entry vehicles at hypersonic velocities, using unconventional shapes comprising multi-facetted surfaces with sharp edges. SHEFEX 1 was launched on a parabolic trajectory from Andøya Rocket Range in 2005 to provide a re-entry velocity in the order of Mach 7. To obtain greater velocities in the order of Mach 10, without reducing the experiment time, a larger vehicle and a flatter re-entry trajectory are required. A Brazilian VS40 motor system will be used, whereby the S40 first stage will provide a conventional spin stabilized unguided flight, but a pitch down precession manoeuvre of the S44 second stage will be performed prior to its ignition above the atmosphere. This will result in a suppressed trajectory and a re-entry angle of the order of 40 degrees. In addition to the thermal protection experiments, a canard system will provide data on the aerodynamic control parameters at hypersonic velocities. A further experiment comprises a separate inertial navigation system with a star reference update and GPS, which should determine the instantaneous flight vector and provide fine corrections to the main payload attitude control system to reduce any angle of attack inaccuracy

REXUS-4 - Vehicle and Experiments, Outlook on the REXUS/BEXUS Student Programme

On the 22nd of October 2008, EuroLaunch launched the REXUS-4 rocket at Esrange in Northern Sweden. EuroLaunch is a joint venture of the DLR Mobile Rocket Base and the SSC Esrange Space Center. REXUS-4 was a two-stage unguided solid propellant sounding rocket. The vehicle consisted of a Nike motor as 1st stage, an Improved Orion motor as 2nd stage, a motor adapter, a recovery system, a service system, two experiment modules, and a nosecone. The REXUS-4 payload was comprised of five technological experiments from German and Swedish Universities. The rocket was spin-stabilized during the ascent. After the burn-out of the 2nd stage a yoyo system de-spun the rocket to a rate of only a few degrees per second. At an altitude of 71 km the nosecone was jettisoned. The payload reached its apogee at 175 km. The REXUS-4 mission was also the maiden flight of a newly developed rocket service system. After this successful demonstration, it has been implemented into the REXUS/BEXUS programme. This German-Swedish student programme offers annual flights for student experiments on sounding rockets and stratospheric balloons. This paper gives a short overview on the development of the REXUS service system and points out the advantages of using standard interfaces for student experiments. Furthermore it contains a description of the REXUS-4 vehicle, the mission, the campaign and the experiments. Some experiments are described in more detail. During the ballistic flight the MIRIAM experiment of the University of Armed Forces in München and the Mars Society Germany was separated from the main payload to test a balloon system that will be used for the entry of a probe in the Martian atmosphere in the future. Several cameras on the REXUS-4 payload as well as cameras and telemetry on the MIRIAM flight system monitored the separation and inflation during the ballistic flight phase. The VERTICAL experiment from the Technical University München verified the start-up procedures of the CubeSat MOVE and its solar panel deployment under real spaceflight conditions. The paper also gives an overview on the REXUS/BEXUS programme and its chances for students