A Q&A with Christel Paille (ESA, MELiSSA) about AstroPlant

Good news! We’ve been working hard to get the first prototype finished today (see image right). In the end, what can we do without ducktape, cardboard, scissors, and glue?


When you’re deep into the creative mode, it can be a good thing to take a step back and reflect on what we are doing and why. So we’ve recovered this Q&A with ESA’s Christel Paille, a chemist and long-standing member of the MELiSSA consortium. She knows everything about regenerative life support systems and will be there at the upcoming AstroPlant challenge, don’t miss this opportunity to hear her and talk with her about the challenges of extra-terrestrial life.

1. KIT DESIGN: State the objectives of the kit: what should be the results? What should come out of it?
The intention of the kit is first of all to benefit the will and participative interest of the people to help science. In terms of scientific objectives is to collect architectural data of the plant. That means for instance the development of the plant, number of leaves, orientation, number of nodes, size of the leaves, time of flowering, to to get fruit, ripening. Those aspects are captured afterwards into mathematical models to allow us to have a prediction of how the plants grow under certain conditions. To correlate these data and the environment (temperature, humidity). To keep it simple – first to monitor, not to influence it.

Ultimately using the full potential of plants to grow for humans (under controlled conditions this is possible if your truly understand how they grow).

Besides, the kit has to be an instrument for participants to develop and improve their knowledge and skills regarding plant biology and growth.

2. Describe the scientific process of plant characterisation, in the context of a citizen science project: who does what? Step by step.

Plants to use decided based on dietary need and menu. (Space Recipe). It’s pretty clear what to provide. Also regarding life support systems criteria (lots of biomass waste > not interesting).

  • First an overall analysis of the processes fulfilled by the plant – i.e. photosynthesis, nitrogen distribution, etc. (all intertwined).
  • We look at the process that is the critical path – the limiting one. The process that imposes how the plant will develop.
  • Then we decide with the scientific community how to address it/how to analyse it. The whole methodology (scientific requirements, methodology, measurements, solutions) – sometimes constructing new research facilities and instruments.

What part citizen science? People need to work with procedures/protocols that have been defined. Then more free-wheel to let people experiment. Protocol brainstorm:

  • The kit provides standardized seeds, recipes for hydroponic medium, protocols to start
  • Protocols to follow the different parameters – e.g. the length of the plant (how to measure), size of the leaves (taking pictures), — uniform application to upload the data. → Open Data Format.

3. What should be measured? (critical/desired/optional)
See the table in the working doc: bit.ly/MELiSSA_Kit – it includes

Plant data

  • Stem length*
  • Stem diameter*
  • Number of leaves*
  • Number of branches*
  • Size of the leaves*
  • Leaf temperature*
  • Length of the root*
  • Network structure of the root*
  • Weight of the total plant*
  • Weight of the fruits*

Environmental data

  • Humidity of the air*
  • Temperature of the air*
  • Temperature of the water*
  • PH of the water*
  • CO2 of the air*
  • Water condition (samples?)*
  • Nutrition (supplied by ESA)*
  • Light intensity and color (closed box?)*

4. What kinds of plants are currently under consideration? And what is the preferred growth system? (aeroponics, hydroponics)
// Potatoes, several types, bread wheat, durum wheat, soybean, onions, lettuce, rice, tomato, kale
// Aromatic herbs (basilicum, coriander, etc.
// Strawberries (very few fruits) – problematic*

[[Editor’s note: I found this interesting article about crop selection if you want to dive into this a bit deeper]]

We go for hydroponics, but we may look into aeroponics if there are significant advantages.

5. What sensor technologies are available to do the measurements? What kinds of casings and lighting systems?
This is a question for the community!

6. Some challenges
This list contains the most important challenges and design choices to be made:

  • Open vs Closed kit. Closed version: temperature related issues, i.e. heat distribution, light dissipation (increases the temperature) > to deal with plant transpiration and humidity..
  • Artificial light vs sunlight? If the light is standard you don’t need to measure it. A simple kit (without LED) needs to monitor incoming light. Mixed light sources makes measuring more complex. Closed box maybe less attractive? Design challenge: how to make a closed box more attractive or engaging. Also to make people not forget to do their measurements. What about building a window on the kit? #hours of light depending on plant (soy: 12-12, lettuce 16-8, etc. > defined in the growing protocol)
  • Root system analysis > during growth (building a window at the bottom of the kit?)
  • Microbiological issues (often where the roots are) – bacterial or funghi > procedure and checking regularly visually)
  • What to do with the different types of water sources being used for the kit: We may ask participants to send in water sample (+ important: include nutrient / watering protocol)
  • Design: different versions of the kit. Cheap/basic/easy (different target group) + advanced/integrated (with artificial lighting etc.)
  • Design: Optional idea to include a stop-motion camera inside the kit that takes a picture every day (modular so people can take it out afterwards).
2 years ago