Farmers in the outer space?

Instead of heavy, bulky and not very environmentally friendly light bulbs, experts believe that red and blue light emitting diodes will be the solution for growing plants (such as lettuce and tomatoes) in space, even during long-duration missions such as the one on Mars.
Future astronauts destined for long-duration missions as to Mars, and, who knows, even further, to be – as much as possible – and this can only be self-sufficient by growing plants. Not for exclusive scientific experiment (such as those already in progress on the International Space Station), but above all for their livelihood. Among the major obstacles of the exploratory missions of long duration in space is precisely the need for artificial and self-sufficient ecosystem that mimics the Earth’s biosphere. A journey of a round-trip to Mars for a crew of six astronauts, for example, may take about 1,000 days, and above all, more food, water and oxygen than the spacecraft currently in use can bring the weight would be very limiting. For this it is necessary to develop a module for crops that grow efficiently by allowing the crew to grow food in total autonomy, without having to wait months for a supply from the Earth. There are several researches on the subject currently under review by the scientific community, such as Purdue University, where a group of researchers has suggested an alternative method to provide enough energy to light and then shoots: the red and blue LEDs that could be useful for crops within the space modules. Think of a greenhouse on the moon.


Credit: Lucie Poulet

The study was led by Cary Mitchell and by Lucie Poulet, who have found that the lettuce leaves grow if illuminated by a set of LEDs (light emitting diodes) for 95% red and 5% blue. The technique could be very useful, especially given the reduced energy supplies in space: using the LEDs will save about 90% energy compared to a traditional form of lighting for greenhouse cultivation. The experts, however, suggest that this new method could be useful for farming systems and agricultural systems controlled vertical well on our planet. Mitchell said: “On Earth, everything is driven by sunlight and photosynthesis. The problem that arises is how to replicate this phenomenon in space. If you need to generate light with limited energy resources, then the LEDs are the best choice. ”
Until now the main challenge for the creation of a module for growing space is the energy cost of the large and heavy high-pressure lamps traditional 600-1000 watts, typically used to simulate sunlight and stimulate photosynthesis in plants synthetic environments, such as laboratories or greenhouses. In addition to the expenditure of energy, the risk is also to burn these plants if the lamps are positioned too close (for now the upper limit is about 120 centimeters) and this requires, in addition to the rest, also a cooling system. Poluet said: “We would need a nuclear reactor to feed four people daily with plants grown using the traditional electric light.”
To this it was thought a more efficient system: LEDs require 1 watt each and are much smaller and longevity compared to bulbs that are normally used. Furthermore, LEDs do not put heat (even touching them there is burning), and then they can be placed very close to the plants (also only 4 centimeters distance) directing light better and saving space on the module without the risk of burn and send in smoke – it must be said! – A crop that space can be vital. The secret is to choose the right amount of red and blue LEDs for the adequate supply of light for photosynthesis and plant growth. The next step will be to understand how and when to increase and decrease the light depending on the various stages of growth, especially to save energy.

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