Crew Biologist report
The regolith microgreen and radish experiments have all been planted and watered. The planting took longer as well as the watering. The Martian regolith emits dust quite readily, absorbs water rapidly and forms a hard consistency when wetted. This caused us to have to use 4 times the volume of water first considered for this primary wetting (20 ml for the radishes and 2 ml for the microgreens). A possible concern for regolith thus appears to be that pedon formation for germination and growth may not be optimal. The particle grain size of the regolith is 94 % sand, 5% silt and 1% clay classifying it as a sandy soil.
Another observation was that boiling and drying the regolith apparently removed about 1/5th of its mass. The boiled regolith supernatant is clearly very rich, thus a filter should be applied or this has to be taken into account for future experiments. Cyprien, Carmel and Vincent all noticed fibers and we even found an unrusted staple in the regolith. The fibers appear to be plant roots, and Cyprien cited the MSDS of the regolith as well as a more comprehensive paper on the regolith in our proposal. It appears that purchased regolith will never be completely the same as the actual soil on Mars.
We have additionally determined that in order to make a better comparison to the situation at FMARS, we should have some replicates growing inside. We have made three replicates of microgreens (regolith control, Earth soil, and regolith + starter + urea. Additionally, we have two replicates of radishes (regolith control and regolith + starter + urea. Though our stay will be short at MDRS, we think that this will be a valuable and necessary part of our research. If necessary (and open for input from research team), indoor replicates can be carried out at CJ’s home in Montana (similar temperature, humidity can be monitored).
At this junction we wait and see what happens with germination, and we will start our watering protocol in the morning. Depending on the rate of dehydration we will have to adjust our watering schedule, but at this junction we anticipate using 5 ml for the radishes and 0.5 ml for the microgreens once every 12 hours.
We will see what happens with germination and growth over the coming weeks, but any follow-up experiments we may plan should take this into consideration.
Potential experiments to be considered could be:
1) Mechanically creating soil structure by poking holes (toothpick or such)
2) Larger pot size and use of earthworms.
3) Other plant species
4) Can pollination dependent plants be possible?
5) Generation propagation experiment
On the basis of what we will see in the coming week and a half, we will attempt to continue this experimental series not just at MDRS and the next two crews but also when going back home. We will discuss and decide on a series together before the end of the rotation obviously dependent on whether space in a proper greenhouse facility can be obtained.
Carmel Johnston, Vincent W. Coljee, and Cyprien Verseux, Crew biologists, 2014. MDRS Crew 142.