A groundbreaking campaign for team Selenar Fungi

In order to gain a deeper understanding of the impact of mycorrhizal symbiosis on plant growth and to enhance the prospects of successful germination on future lunar missions, the Selenar Fungi research team initiated an experiment involving the cultivation of seeds in a regolith simulant with and without the addition of a mycorrhizal fungal substrate. Initially, the experiment was conducted in the RPM, which was set up to provide an environment of 0.16 g which is the lunar gravity. However, to gain further insight into the influence of gravity on plant growth, the team later extended the experiment to include the LDC, which generates a simulated 2 g and 4 g gravity environment. 

The initial challenge was to design the experimental boxes, which required the selection of appropriate materials, the prevention of leaks, and the determination of the optimal configuration for the seed compartments. This approach aimed to maximize the number of samples while maintaining a consistent gravitational environment. The second challenge was to test the operational efficacy of the systems in order to optimise the growth of the plants. During the testing phase, the functionality of the light system was evaluated, as well as the growth of plants in the regolith. Finally, the ability of the box to retain seeds and substrate when inverted was assessed.

In February 2024, Project Selenar Fungi was selected to participate in the ESA Academy Experiments Programme. The objective of the programme is to study the growth and cultivation of lettuce with mycorrhizal fungi in a regolith simulant under conditions of varying gravity levels at ESA ESTEC in the Netherlands. The four dedicated students developed their project in an efficient manner, performing the design, assembly, and testing of their experiment in a timely fashion to ensure readiness for the campaign, which was conducted from 9 September to 9 October 2024.

The campaign was divided into three visits to ESA ESTEC's facilities, each of which enabled the continuous running of two sets of experiments. In each case, either the RPM and the LDC were in operation for the full two-week period, or only the RPM was in operation.

On the first trip on 9 and 10 September, the team was initially provided with a comprehensive safety briefing, which included instructions on the precautions to be taken when manipulating the regolith. Subsequently, the seeds were placed in boxes and subjected to the designated conditions of 4 g and 2 g in the LDC, as well as ground conditions for the control group. For each gravity level, two boxes were prepared, one containing the control substrate and the other the experimental substrate (mycorrhizal fungi). In order to achieve both 4 g and 2 g simultaneously, the boxes are positioned at varying distances from the centre on the LDC.

Consequently, despite the LDC spinning at the same rate, the boxes situated at the end of the arms receive 4g, while those closer to the centre receive 2 g.  Then, three boxes containing seeds with the control substrate (i.e., without mycorrhizal fungi) were prepared and placed in the RPM at 0.16 g (lunar gravity) and on the ground for control. The RPM rotates any enclosed experiment randomly to minimise the influence of Earth's gravity, thereby simulating what would be experienced at gravity between 0 g and 1 g. For this experiment, the RPM was set up to have a gravity of 0.16 g.

Following a two-week period during which the LDC and RPM were operational, the team returned to ESA ESTEC for a second visit between the 23 and 25 September. The team's initial task was to unload the boxes from LDC and RPM and take measurements, including taking pictures, counting leaves, and weighing all samples both before and after drying. Finally, three boxes were prepared with the aforementioned experimental substrate (mycorrhizal fungi) and one was placed in the RPM at 0.16 g, while two were designated as on-ground controls.

On the final excursion, on  9 of October, the team was able to unload the boxes from RPM, which had remained there for a period of two weeks. They proceeded to take measurements, including the taking of photographs, the counting of leaves, and the weighing of all samples both before and after the drying process.

The four students returned to their home university, where they will process the data and prepare scientific publications. Subsequent analysis of the samples will be conducted at the University of Iceland. The ultimate objective is to identify a statistically significant relationship in the data that could offer valuable insights into sustainable lunar space exploration and habitation.