Cosmic vegetables
Already explored by space probes and robots, Mars could welcome human beings in the not so distant future.
The ExoMars Trace Gas Orbiter (TGO) was launched in March 2016 to detect atmospheric gases such as methane on Mars, and determine if they are of biological origin (reconstruction)
Manned missions to the Red Planet1 are on the agenda of many space agencies. The challenge is how to ensure the survival of astronauts in a hostile environment, where the air is unbreathable and nothing can grow. On this type of long-term space mission, the constraints and complexities are far greater than those of a mission to the Moon, such that, given the limited capacity of current launchers, it will be impossible to bring all the essential supplies from Earth2. So how and what will the astronauts eat?
The MELiSSA project
Scientists are convinced that human beings will walk on Martian soil3. The question is when. Johann-Dietrich Wörner, Head of the European Space Agency (ESA), doubts it will happen before 20504. The September 2015 announcement of the discovery of salt water on Mars revived interest in the question of life on the Red Planet5. Having researched water (with its Follow the Water programme), NASA is now focusing its exploration programmes on investigating the presence of life on Mars (Seek Signs of Life)6. The ESA programme also includes a series of space missions aimed at studying our solar system, and planet Mars in particular. Its objective is to participate in the preparation of a manned mission to Mars in the 2030s.
Since 1989, the ESA has been working on the MELiSSA project (Micro-Ecological Life Support System Alternative), a regenerative life support system that works in a closed circuit. It is an extremely complex project, aiming to create an artificial ecosystem that controls the various interactions between the organisms it comprises: humans, plants and bacteria. Hundreds of scientists are involved in the project. Once it is finalised, MELiSSA will enable the production of oxygen, water and food for astronauts, while recycling the carbon dioxide and waste produced by the crew.
This microsystem is meant to function independently. Plants will be the key component, supplying astronauts with both oxygen and food. A specific number of plants were selected, primarily on the basis of agricultural (ease of cultivation, yield), technological and nutritional criteria, for hydroponic cultivation on Mars7. The plants chosen for the MELiSSA project include soya, durum wheat, soft wheat, potatoes, onions, lettuce, cabbage, tomatoes and spinach. Then, the different stages of food processes were analysed to theoretically determine possible nutritional loss. The Institut Paul Lambin in Brussels (Belgium), collaborated with chefs to develop dishes with high nutrient density and sensory acceptability, using only ingredients produced by the MELiSSA system. They developed and tested a four-week menu which fully met astronauts’ nutritional needs during long-term missions.
Research at the Institute of Life Technologies
Astronauts’ main sources of carbohydrates and protein are potatoes, wheat and soya. These staples are difficult to digest in their raw state, so it is essential to prepare them prior to consumption. For the second phase of the MELiSSA project, the ESA entrusted a consortium comprising the Institut Paul Lambin, the Institute of Life Technologies in Sion (Switzerland) and the companies GEM and SHERPA (France), together with RUAG (Switzerland), with the mission of taking a comprehensive approach to transforming these basic foodstuffs, bearing the challenging conditions in space in mind8.
While the nutritional aspect is dealt with by the Institut Paul Lambin, Laurence Nicolay is in charge of the area of the project related to the preparation and sensory characterisation of food. While at work in her pilot laboratory among a sieving machine, a hydraulic press and a universal cooking vessel, she explained that “First of all, it is about creating the widest possible variety. For example, potatoes can be steamed, boiled (with or without their skin), mashed, made into pancakes or flakes and so on.” The first challenge is to imagine all the different forms a foodstuff can take. Only a handful of plants in the Martian garden must feed the crew for several months, without meals becoming too monotonous.
Soft wheat will be transformed into unleavened bread, without the use of yeast. Laurence Nicolay explained “We must avoid introducing microorganisms to Mars, because they could prove difficult to control.”9Astronauts will use durum wheat to make pasta and bulgur, and soya to prepare pasta, milk, tofu and okara, a by-product from making soya milk, and rarely consumed in Western countries10. Laurence Nicolay underlined that “We must strive to make maximum use of all parts of the crops and create the least possible waste.”
Laurence Nicolay and her team work in the Institute laboratories, studying the whole preparation process from raw material to finished product. To analyse the preparation of unleavened bread, for example, the starting point is the grains of soft wheat, which pass through different stages: milling and sieving in a pilot mill to obtain flour, adding water and mixing in an electric kneading machine, rolling the dough out manually and cutting it, and then baking it in an oven. All the stages are meticulously documented to identify not only the amount of wheat required, but also the amount of water and electricity, and preparation time. They also record the volume and weight of the equipment used.
Each food preparation process undergoes a weight appraisal: How much weight has been retained? How much has been lost? Foodstuffs are precious in the MELiSSA ecosystem, so the aim is to obtain maximum yield. In addition, everything will function as a closed circuit. Thus, questions that might seem innocuous on Earth, take on an entirely different dimension when transposed to the Red Planet. As Laurence Nicolay asked “Should we peel the potatoes or not? If we peel them, what do we do with the peelings? Can they also be used as food?”
Another key aspect is the amount of nutrients in food both before and after preparation. Laurence Nicolay pointed out that “We must know the amount of macro and micronutrients.” Such data is essential, as it enables the preparation of meals that suit the specific needs of astronauts. Their calorie requirement can vary greatly, especially when it comes to spacewalks11. On space missions, energy intake is often inadequate: “Studies have shown that astronauts may be undernourished, because the food is repetitive and they lose the will to eat,” Laurence Nicolay continued.12 "For short voyages, the body’s natural reserves ensure this deficit is not overly damaging. However, for long-term journeys, such as those proposed to Mars, such a shortage could undermine the success of the mission and even the survival of the astronauts."
Hence the need to assign as much importance to the nutritional aspect as to the sensory impact: “Our goal is for astronauts to remain both physically and mentally fit. They must be able to vary and enjoy their meals so as not to become depressed or lose weight. They shouldn’t gain weight either, as they still have to fit into their spacesuits!” added Laurence Nicolay in jest.
Countering the loss of appetite proves to be vital. Despite its duration, a manned mission to Mars is more than likely to see the best-fed astronauts. Until now, astronauts took pre-packaged meals on their missions and had to put up with them. According to Laurence Nicolay, “Sure, they could choose what they wanted to eat but, sometimes, once on the mission, they lost interest in the meals they had opted for while on Earth.” The unique aspect of the MELiSSA project is that it will enable astronauts to produce and prepare their food themselves, while on the mission. This means meals can be personalised, which is quite a bonus when it comes to their acceptability.
A kitchen in space
There will be no chef on Mars. Each member of the crew will take turns to prepare the meals for the others. This raises the question of what equipment will be needed to prepare and cook the food they grow. Laurence Nicolay explained that “The existing equipment is not adapted to cooking in space.” The main problem is the difference in gravity, which affects heat transfer, flow, transfer of products from one recipient to another, and so forth. It is essential to design specific equipment that is suited to working in reduced gravity and meets the extremely strict standards of space. The equipment should also be able to multitask: “We aim to create multifunctional machines that have to meet several different criteria. The lightest possible, the most energy efficient, the easiest to clean (to avoid contamination) as well as using as little water as possible and being the safest, to reduce the risk of burns. Laurence Nicolay explained that “It will be a question of finding the right balance among these goals.”
The crew only have a limited amount of time to cook and to clean up. As indispensable as it may be, it cannot take too long. Thus, intelligent multi-cookers could be used, to reduce the amount of time spent cooking for example. 3D printers may even be employed “to emphasise certain ingredients and improve textures. This is an idea to be studied, but is not currently a priority. We have to admit that the technology is not ready yet; today’s printers create waste, such as cartridges,” noted Laurence Nicolay. Eventually – by 2030, or according to the evolution of socio-economic conditions and technological progress – the aim is to design a lab-kitchen integrated into the MELiSSA system, a single production unit in which astronauts will be able both to produce and cook their food.
Transforming food to obtain a wide range of dishes, working out how to optimise preparation processes, designing machines able to meet the significant demands of space: These are all steps towards the final goal of securing food for astronauts on a mission to Mars. As Laurence Nicolay explained: “The goal is for the astronauts to succeed in their scientific mission: They must feel well, both physically and psychologically. The crew must also bond well. What better way is there to bring people together than sharing a good meal? Conviviality and compassion will be just as important as safety.”
