Launch and Early Operations of Eu:CROPIS

Kurzfassung

Eu:CROPIS (Euglena and Combined Regenerative Organic-Food Production in Space) is a German Aerospace Center (DLR) small satellite launched on December 3rd 2018 to a low Earth orbit in a ride-share launch on a Falcon 9 rocket. The primary payload developed by DLR-ME (Aerospace Medicine) and the University of Erlangen comprises a pair of greenhouses in which tomatoes were to grow under simulated Mars and Moon gravity. Being a spin-stabilized spacecraft, the most distinctive feature of the satellite is that its spin rate is set so that the simulated gravity level on the biological payloads can correspond to Moon or Mars gravity, as well as that of orbital space stations in near zero-g. The sequence of events planned for the three days of the Launch and Early Operations Phase (LEOP) is explained. The main driver of the planning was the solar panel deployment. The release of the four panels is done in a non-explosive manner via shape memory alloy actuators (SMA), which are connectors that are fractured if heated to a sufficient extent. The deployment of the panels can only be verified indirectly with this system and a risk of having a partial deployment of panels had to be considered. In addition, the attitude control of the spacecraft is solely done by magnetic torquers. Therefore, the actions after the initial satellite health check at the first acquisition of signal in space targeted a verification of all the critical capabilities and system redundancies on-board required to perform the safe release of the solar panels. Secondly, this paper reports the highlights of the LEOP. The first planned contact with Eu:CROPIS failed mainly as a result of a misconfiguration on the ground systems. Furthermore, later in the LEOP after the checkout of the platform, the panel deployment was initially unsuccessful as only two of the four panels deployed. Finally, towards the end of the planned LEOP, a severe anomaly on the flight software prevented transmission of telemetry and reception of telecommands by the spacecraft for three days, after which an automated failure detection and isolation reaction recovered the system. Finally, the anomaly analysis performed and decisions taken by the operations team are critically assessed in retrospective. A handful of lessons learned from the experience with Eu:CROPIS are collected for future missions and LEOPs.