Journalist Report – February 28th

Sol 7 – From Interstellar to gravitropism experiment

Author : Nicolas Wattelle

Rest has been great (we all appreciated Christopher Nolan’s movie), now it is time to go back to efficient work! And I think we did: our schedule was not really full so we took advantage of it to prepare the next days, and to do what we usually have not the time to. The upcoming days are very exciting, this is partly due to the weather improvement, so we can broaden our EVA plans and make the mission go forward.

During the day, our focus was thus on planning, data processing and maintenance. For the planning, discussions have taken place during the whole early afternoon on the upper deck, and one of the great news is concerning the geological field study (mainly for Marine and Léa who are in charge of it) that might begin no later than tomorrow. Cerise, our commander, make a great job everyday to handle the tricky moving planning, dealing with all constraints (even the last-minute ones), and she always tries to satisfy each of us’ interests. She is a great commander (honestly, without any will to become the favourite).

In the middle of all this, two remarkable novelties: Elena has started the preparation of a spirulina culture; and Mathéo tried for the first time to pilot the drone from inside the Hab during an EVA. Léa who was Habcom at this moment, found this very useful to be able to follow the astronauts this way, it is much easier to understand their progression with this point of view (can you spot the astronauts on the today’s drone shot?).

Also, maintenance has been performed on the Solar Musk cupola, on the field mill (we had a mishap with it during the last EVA) and on the gravitropism experiment.

But what is gravitropism? Plants grow, we already know that, but in fact, they grow in response to stimuli. The stimulus can be various things: light, water presence, heat, fertilizer… In these cases, we respectively speak about phototropism, hydrotropism, thermotropism and chemotropism. Each plant is sensitive to these phenomena, like in a competition between the latter, and each plant is more or less responsive to a phenomenon. We know since the XVIIIth century that plants react to gravity. Gravitropism (and so gravity) is one of the reasons why roots go down and rods go up.

During our mission, and in collaboration with middle and high school students, we try to observe and disturb gravitropism. How do we do this? Thanks to inertia! We grow plants (ones with rapid growth, like lentils, beans, wheat…), on a turning wheel (almost 30 cm of radius), in order to make seeds feel centrifugal force. This way, when you add the contribution of this force to gravitational force, you obtain an inclined resultant (the force is not purely vertical anymore). And we might be able to see modifications in the growth. This is the idea of an historic experiment named “Knight’s Wheel”.

We had some trouble doing this experiment during our first week, but today, we took this experiment back to zero, hoping it will show interesting things before next weekend. Plus, we plan to experiment another unperformed protocol during our last week: what if we turn the wheel vertical? We are very curious to produce data on it!

PS: In addition, you can find in the daily pictures the M81 galaxy 11,74 million of light years away, observed by Marine. A picture like this might leave us dreamers, imagining a solar system similar to ours, and who knows… An inhabited planet like ours?

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