Microgreens growth tests and space qualification for the GreenCube CubeSat cultivation laboratory

The future of manned interplanetary missions, which will require life support and advanced nutrition systems, is increasing the need of developing and testing autonomous cultivation units. The GreenCube mission aims to demonstrate the possibility to cultivate edible plants in space conditions, using a technological and autonomous cultivation system allocated inside a 3U CubeSat. The payload is a 2U CubeSat unit (~20x10x10 cm) cultivation laboratory, and the remaining unit is allocated for the satellite bus. The cultivation system implements reduced cost and fast prototyping technologies. which are aiming at guaranteeing the growth of the microgreens through a constant monitoring of the plant status, achieved using different typologies of sensors controlling the environmental condition, and a series of actuators providing control over the environmental parameters and watering system. The in-orbit experiment will be compared with an on-ground replica to analyse the specific effects of the space environment on the cultivation system. This mission has been designed and developed thanks to the collaboration between a group of Italian researchers of the S5Lab (Sapienza Space Systems and Space Surveillance Laboratory) from Sapienza University of Rome and the Italian Space Agency (ASI), with the participation of ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) and the University of Naples Federico II (Department of Agricultural Sciences). The GreenCube satellite has been selected, by the European Space Agency (ESA), for a free launch opportunity on the maiden flight of Vega-C which will take the experiment to a MEO circular orbit, at an altitude of 5800 km, in mid-2022. The reliability and validation of the system technology has been proven through fourteen functional tests conducted with different set-up, leading to a “ready to fly” system. The test campaign led to a better understanding of the criticalities that could occur during the assembling of the payload and testing for space qualification, requiring a high level of accuracy during the test operations and a deep knowledge of the involved facilities. If the GreenCube mission has a successful outcome, the developed technology will allow a direct access to cultivation system in space, thanks to the possibility of replication, guaranteed by the utilization of Commercial-Of-The-Shelf (COTS) components, and integration on future CubeSat missions. In this paper, the innovative technologies applied to the cultivation system and to this peculiar mission concept and design are analysed, focusing on the operative methods of the functional tests and the lessons learned.