The Eu:Cropis Assembly, Integration and Verification Campaigns: Building the first DLR Compact Satellite

Eu:CROPIS (Euglena Combined Regenerative Organic Food Production In Space) is the first mission of DLR's Compact Satellite program. The Compact Satellite is a small, highly customizable and high performance satellite bus, providing a platform for scientific research as well as for demonstration of innovative concepts in space tech-nology. The launch of Eu:CROPIS onboard a Falcon 9 is scheduled in Q4 2018 within Spaceflight Industries SSO-A mission. The name-giving primary payload features a biological experiment in the context of coupled life support systems. The stability of such kind of a system shall be proven under different gravity levels with a focus on long term operations. In this context the rotation of the spacecraft will be used to utilize simulated gravity for the first time. A further biological experiment dealing with synthetic biology comprising genetically modified organisms (GMOs) was provided by NASA Ames Research Center as secondary payload. The integration and acceptance of a satellite flight model containing biological experiments faces constraints regard-ing schedule, facility certification and process definition. The driving parameters for the Eu:CROPIS AIV campaign are the degradation time of chemicals stored inside the primary payload, the GMOs used in the secondary payload, which cause handling and transport restrictions due to biosafety regulations, as well as schedule constraints due to the chosen dedicated rideshare mission. Furthermore the development of a spin stabilized system for gravity simula-tion had impact on the overall verification approach, especially towards the attitude control subsystem. This paper describes the model and verification strategies to design and build the spacecraft under said constraints. The applied verification processes comprises the hardware, software as well as all third party payloads and focuses on the utilization of a flexible tabletop engineering model approach. To achieve a smooth transition to project phase E, this concept enables co-alignment of the ground segment development and verification with spacecraft AIV as of early phase C. Furthermore scientific projects like Eu:CROPIS, with small project teams and financial budgets, en-counter few personnel redundancy. The existing structural organization gets confronted with challenges where de-pendability, testability and safety of the processes and the product are expected to be achieved with minimal effort. The paper presents how the technical management adapts work flows, cooperation and tools in project phases C and D to achieve a reliable system realization

The Tape Spring Hinge Deployment System of the EU:CROPIS Solar Panels

Eu:CROPIS is a compact satellite featuring a biological. The cylindrical Satellite of 1m diameter has four deployable panels for power generation. Those panels are connected to the main structure by glassfiber reinforced polymer (GFRP) tape spring hinges. The hinges, comparable to curved metallic measuring tapes, have elastic energy stored when flattened and folded and thus deploy the panels by simply unfolding. When unfolded the hinges snap into their original shape and support the panels with considerable stiffness. No friction or mechanical locking is involved in the deploying process, which increases the systems reliability. Despite all these advantages other design aspects need special consideration. The GFRP needs to be protected against environmental influences like atomic oxygen and heat. Depending on the folded state and the hinge configuration the length of the hinges cannot be chosen freely. The installation process requires consideration as well. While the hinges are very flexible in the folded state they have to be installed quite accurately to be able to snap into their deployed position and fully support the panel. The panels do not deploy around one single axis but also do lateral movements. Even though the hinges are able to support the panels in the deployed position, they provide very low support during deployment. Therefore, gravity compensation is required for testing which should have a very low influence on the deployment. The presented paper gives an insight into the tape spring hinge deployment system of Eu:CROPIS. Design iterations are explained with the background of the decision making process influenced by the overall satellite configuration, tests and testability, experiences gained during integration and PA considerations. Further details of the manufacturing and integration process are described. The verification concept is outlined and explained. Tests performed for verification or gaining experience are described including the setup and considerations for the tests to be representative

VIBRATION TESTING OF THE Eu:CROPIS SATELLITE TEST STRUCTURE

In the DLR (German Aerospace Center) compact satellite program the life supporting experiment Eu:CROPIS is developed. It is a small satellite weighing slightly more than 200kg. The proposed launch option is the Falcon 9 using the CASA adapter where it is placed on a balcony like support structure. The Eu:CROPIS satellite is being designed, produced and tested by DLR. Structural test for qualification are static and random loads, the random loads being the most demanding test. The static loads are tested using a sine burst test. As the structural test model is a prototype and as the project does not provide much time to repeat tests, the test sequence has been carefully chosen so as to limit structural damages before the end of the test campaign. Thus as many tests as possible are performed before the most demanding tests. Loads, stresses and deformations have been simulated by FEM-analyses before the tests. Still there are some uncertainties in the simulation due to the predicted damping and due to assumptions made to reduce the size and complexity of the model. Especially the random loads transfer into structural strain responses is very sensitive to the dynamic behavior. Therefore it is of interest to compare the assumed finite element structural response to the real measured one. For this purpose the test structure has been equipped with strain gauges to measure the peak strains in the primary structural parts in addition to the usual acceleration sensors. In this paper the test philosophy is explained using the prediction of structural stresses to sort the tests by intensity and thus by potential damage done to the tested structure. The measured natural frequencies, acceleration loads and internal strains are compared to the predicted ones. Reasons for deviations are given. The last test run showed significant changes in some acceleration responses. The search for the cause by analyses of the different acceleration responses is described

Gossamer-1: Mission concept and technology for a controlled deployment of gossamer spacecraft

Gossamer structures for innovative space applications, such as solar sails, require technology that allows their controlled and thereby safe deployment. Before employing such technology for a dedicated science mission, it is desirable, if not necessary, to demonstrate its reliability with a Technology Readiness Level (TRL) of six or higher. The aim of the work presented here is to provide reliable technology that enables the controlled deployment and verification of its functionality with various laboratory tests, thereby qualifying the hardware for a first demonstration in low Earth orbit (LEO). The development was made in the Gossamer-1 project of the German Aerospace Center (DLR). This paper provides an overview of the Gossamer-1 mission and hardware development. The system is designed based on the requirements of a technology demonstration mission. The design rests on a crossed boom configuration with triangular sail segments. Employing engineering models, all aspects of the deployment were tested under ambient environment. Several components were also subjected to environmental qualification testing. An innovative stowing and deployment strategy for a controlled deployment, as well as the designs of the bus system, mechanisms and electronics are described. The tests conducted provide insights into the deployment process and allow a mechanical characterization of that deployment process, in particular the measurement of the deployment forces. Deployment on system level could be successfully demonstrated to be robust and controllable. The deployment technology is on TRL four approaching level five, with a qualification model for environmental testing currently being built

Feasibility-Study OOS-RAV

With the objective of designing a mission to validate the DEOS robotic arm, a CE study named OOS-RAV (On Orbit Servicing– Robotic Arm Verification) was conducted. The defined mission was to approach a target satellite (either one already in orbit or a target satellite specifically designed and carried along with our spacecraft), and in close distances to grab it with the robotic arm. The CE study for OOS-RAV took place from 4th to 8th May 2015 in the Concurrent Engineering Facility of the DLR Bremen. The domains were occupied by members of various DLR sites depending on their expertise

MASCOT—The Mobile Asteroid Surface Scout Onboard the Hayabusa2 Mission

International audienceOn December 3rd, 2014, the Japanese Space Agency (JAXA) launched successfully the Hayabusa2 (HY2) spacecraft to its journey to Near Earth asteroid (162173) Ryugu. Aboard this spacecraft is a compact landing package, MASCOT (Mobile Asteroid surface SCOuT), which was developed by the German Aerospace Centre (DLR) in collaboration with the Centre National d'Etudes Spatiales (CNES). Similar to the famous predecessor mission Hayabusa, Hayabusa2, will also study an asteroid and return samples to Earth. This time, however, the target is a C-type asteroid which is considered to be more primitive than (25143) Itokawa and provide insight into an even earlier stage of our Solar System