Plants germinated in International Space Station to be analysed

Humans have been cultivating on the face of the earth for about 10,000 years. It is a skill that has given us the knowledge necessary to survive as a species on the planet, but when it comes to space, human agricultural experiences are really scarce, despite the great interest of the major space agencies. A future mission to Mars or the establishment of new fixed settlements beyond the International Space Station (ISS), for example on the Moon, would entail loading hundreds of tonnes of dehydrated food and water on board, and "every kilo that goes into space entails a cost of about € 5,000. It is possible to ship food regularly to the ISS, where astronauts stay for up to a year. It is not too far, but even there it would be interesting to produce 'in situ' in the future," states José Eduardo González-Pastor, researcher at the Department of Molecular Evolution of the Centre for Astrobiology CSIC-INTA. It is not just about the cost; having vegetables is the only way to consume fresh food in the missions, and this has quite a psychological impact on astronauts. Not forgetting that they can guarantee a supply of oxygen.

Just a couple of years ago, three ISS astronauts did a live tasting of the first lettuce grown in space. NASA's Veggie project may have been the most attractive for the media because of it giving us the first space salad, but it is not the only study being conducted. "Veggie was important because it showed that plants are able to grow by overcoming microgravity conditions, but from a scientific point of view, that experiment was not fundamental, because it was not explained how they do it; that is, there was no study of the physiological factors of the plant's development, nor of the biological keys of its adaptation to microgravity environments," explains Javier Medina, a researcher at the Centre for Biological Research at the CSIC.

Genetic responses
His team leads the Seeding Growth-3 experiment, which aims to study these mechanisms that allow plants to grow in space (with the participation of the European agency ESA and the North American agencies NASA, the University of North Carolina, and several European laboratories). The goal is to automate the biological processes to ensure that the crops can be cultivated systematically in space, without depending solely on chance. To this end, some boxes were sent from Cape Canaveral to the ISS containing seeds of Arabidopsis thaliana; a species related to cabbage, turnip and radish. It is a plant that is common all over the world, with no agricultural interest, but adaptable to extreme conditions, such as high salinity waters (an increasingly common phenomenon on the Earth's soil), and so studied that it is something like the vegetable equivalent to white mice for laboratory experimentation.

After the shipment, the plants were germinated and allowed to grow for six days. Then some of them were kept with chemicals and another part was deep-frozen. In this manner, they were brought back to Earth for a thorough examination. These seedlings are already being analysed in the laboratory. "We are interested in seeing how microgravity affects genes and the cell cycle of plants, because this can compromise their development in the long run," explains Medina.

The fact is that being in space entails a wide range of difficulties. Gravity, temperature, atmosphere, ultraviolet radiation and light all have consequences on the cellular proliferation of plant organisms. In other words, the growth process of plants is altered in space. "We are trying to counteract the effects of microgravity with light, which could guarantee the full development of plant species," states the researcher responsible for the project.

It should also be taken into account that, for plants, the conditions in space, especially the absence of gravity, represent "a stress comparable to salinity, drought, cold and heat, so the experiment to be carried out will use methods similar to those used in research on the response of plants to climate change on Earth," explained the researcher.

This means that, as in other fields, research and technological development derived from this and other projects will likely have consequences on Earth, although they may be more indirect in agriculture. Thanks to the Veggie project, a new line of air purifiers and new water saving systems have been devised, and an automatic cultivation box called FixBox has been created in Spain for the Seeding Growth-3 project, consisting of a cover and a base, which closes automatically while using vibration to release the chemicals that the seeds need.

In addition to applied technology, "this type of experiments give us plenty of information on how to cultivate crops using a minimum amount of water and energy, helping us learn about the mechanisms that plants have to respond to changing climatic conditions, given that these species, unlike animals, are unable to move and run away from situations of stress. This capacity to adapt is the one that researchers are interested in, as even though gravitational stress and others like hydric stress are not the same, the response to them is," emphasises Medina.

In addition to this cabbage, other plant species are also being tested. There is a joint research project between the International Potato Centre of Peru and NASA called "Potatoes on Mars". Recently, these two agencies announced that they have found the most resistant and best adapted potato variety to be grown on Mars. The tuber grew in a soil with 30% salt, a 10% concentration of CO2 (on Mars, it reaches 95%) and a temperature oscillating between -5 °C and 20 °C (those of the Red Planet reach -60 °C). For its part, the German Aerospace Centre is due to send its satellite Eu:Cropis; a structure that will reproduce both the Martian and lunar atmosphere for six months at an altitude of 600 kilometres. A tomato plant is expected to germinate inside it. The plan is for the plant to be fed by a drip filter that will convert synthetic urine into easily absorbed fertilizers. A pressure tank will reproduce the Earth's atmosphere, while an LED lighting system will provide the daylight intervals. "The only way to cultivate in space is to copy the conditions of Earth, using artificial light and greenhouses and making sure that CO2 concentrations and temperature oscillations. Furthermore, the greenhouses could be designed to make use of astronauts' waste. Closed life and death systems are a trend in the aerospace sector," affirms González Pastor.

What the agencies aim to create in the long run is self-sufficient spacecraft which imitate nature, require no inputs from outside and in which waste (also the organic one) is recycled. That is where the ESA's Melissa project (acronym for Micro-Ecological Life System Alternative), which has been active for more than 25 years, comes into play. The point is that creating a circular ecosystem without more input than an energy source won't only get us closer to Mars, but will also help us tackle any possible changes in the Blue Planet.


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