Growing tomatoes in space.
We are getting one step closer of growing plants in life-hostile environments such as on MARS.
Have you ever heard of Space-Farming? It is exactly what it sounds like: farming in space. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) and the Friedrich-Alexander-University in Nürnberg-Erlangen developed a compact satellite with two small greenhouses to send and grow tomato seeds in space. The Eu:CROPIS (Euglena and Combined Regenerative Organic-Food Production in space) satellite launched on 03.12.2018 on a SpaceX Falcon9 rocket into space. The satellite is currently circulating earth at a distance of 600 km. This is a little bit further off than the ISS, which is circulating earth at a distance of 408 km. Goal of this mission is not just to see if it is possible to grow and maintain crops in an unfriendly environment far from earth, but also how we can recycle and use urine from astronauts on a longterm human space flight.
By now, it is already possible to recycle water from urine in human space flights, but one of the main problems is still the processing of the other parts. By current standards, urea and salts are simply disposed, but they could be used to fertilize crops to grow fruits and vegetables. This project aims to test a system in which urine will be recycled and used to grow tomatoes in different gravity conditions (as on the Moon and Mars).
"Ultimately, we are simulating and testing greenhouses that could be assembled inside a lunar or Martian habitat to provide the crew with a local source of fresh food. The system would do this by managing the controlled conversion of waste into fertilizer,"
as stated by Jens Hauslage (biologist of the DLR and head of the scientific part of the Eu:CROPIS project).
What is this so called 'closed system' or 'greenhouse' on the satellite?
The Eu:CROPIS satellite weights only 230 kg and measures 1,10 m in height and 1 m in width. Energy is provided by 4 solar panels. The satellite contains two distinct greenhouses with separated and closed regenerative systems. Core of these systems are biofilters and the algae Euglena gracilis (See the picture below). The biofilter is a 400 ml big chamber containing porous lava stones. The many holes of the larva stones serve as a habitat for bacteria, fungi and protozoa, which are able to convert (in this project: synthetic) urine into nitrate, which then serves as a nitrogen source for the plants. Previously, experiments were conducted to see if the algae is able to orientate itself in space (without gravity). Which it passed successfully.
The algae has two specific roles: On the one side, they produce oxygen for the plant and the bacteria, which is especially important at the beginning of the experiment, when the plants did not grow yet. Later on, the plants will produce enough oxygen on their own. On the other side, they can detoxify the system, in case of a too high ammonia concentration, which could occur during a low nitrification process.
And which tomato variety is going into space? Ths will be Micro Tina. Micro Tina was specifically bred for space missions by the Utah State University. The plants are growing very fast and stay small and compact during their whole life cycle. Furthermore, they don’t need much light and are very easy to grow. First ripe fruits can be harvested after 60 – 90 days.
Of course there is more needed than just nutrition and water to grow plants:
Light is given by LED lamps. They are providing a normal day and night rhythm for the plants. Moreover, a pressure tank is continuously maintaining 1 bar air pressure (as on earth). The satellite is turning on its own axis, which creates a similar gravity as on the Moon or Mars. The whole project is set up in two phases and the experiments only start after 7 weeks in space. Once the satellite reached its distance of 600 km, the algae are “woken up” by a gravity of 0,1 g and by providing them with water and a nutrition solution. They will propagate for 3 to 4 weeks and are active for the following two weeks. Then, the experiment starts by simulating lunar gravity (0,16 times as on earth) for 23 weeks. During this phase only one of the greenhouses is activated. After 23 weeks, it will take 4 weeks to switch from the lunar gravity to the gravity on Mars (0,38 times as on earth) and to wake the the algae in the second greenhouse up. Then, the second phase of the experiment will start and run for further 23 weeks.
The whole experiment is set for 62 weeks. I will keep you updated as soon as there are interesting news!
Source and further links:
Euglena gracilis pictures source: O'neill, E. C., Trick, M., Hill, L., Rejzek, M., Dusi, R. G., Hamilton, C. J., ... & Field, R. A. (2015). The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry. Molecular BioSystems, 11(10), 2808-2820.