The Eu:CROPIS Mass Property Campaign: Trimming a Spin-Stabilized Compact Satellite for a Long-Term Artificial Gravity Experiment

Ansgar Heidecker,Sebastian Kottmeier,Robert Klöpper,Oliver Kolakowski,Fabian Orlowski-Feldhusen,Franco Bernelli-Zazzera,Olaf Mierheim

doi:10.1155/2020/9193740

Abstract

Eu:CROPIS (Euglena Combined Regenerative Organic Food Production in Space) is the first mission of DLR’s compact satellite program. The launch of Eu:CROPIS took place on December 3rd in 2018 on-board the Falcon 9 SSO-A mission. The satellite’s primary payload Eu:CROPIS features a biological experiment in the context of closed loop coupled life support systems. The Eu:CROPIS satellite mission uses spin stabilization along its Z -axis to provide defined acceleration levels for the primary and secondary payloads to simulate either a Moon or Mars gravity environment. For the payload performance, it is vital to achieve a minimum deviation between spacecraft Z -axis and the major moment of inertia (MoI) axis to minimize the offset of the envisaged acceleration levels. Specific moment of inertia ratios between the spin- and minor axes had to be maintained to allow the attitude control system to keep the satellite at a stable rotation despite environmental disturbances. This paper presents the adaptive and flexible trimming strategy applied during the flight model production, as well as the mass property measurement acceptance campaign and the respective results.

Highlights

Eu:CROPIS is the first satellite of the German Aerospace Center (DLR) compact satellite program
For the payload performance it is vital to achieve a minimum deviation between spacecraft z-axis and the major moment of inertia (MoI) axis to minimize the offset of the envisaged acceleration levels
This paper presents the adaptive and flexible trimming strategy applied during the flight model production, as well as the mass properties measurement acceptance campaign and the respective results

Summary

Introduction

Eu:CROPIS is the first satellite of the German Aerospace Center (DLR) compact satellite program. The post processing of test measurement data is done with this mathematical model to calculate mass properties for the relevant satellite configurations, especially for nominal Launch and Flight configurations. Considering the possible interaction between pumps, valves and magnetic torquers, a rotation by 40° in clockwise direction was performed to adjust the two minor MoIs. As second step, four different locations were identified for adding trim masses (Figure 7) each exhibiting different effects on the principal MoIs and deviation moments due to their position relative to satellite’s CoM: P/L1 adapter cone, Top Plate and two positions on the MDPS. After refurbishment of the tape springs, the solar panels were re-integrated in Stowed configuration and mass properties measurement of the satellite in Stowed configuration was conducted (Figure 15).

Results

Conclusion

Conflicts of Interest