SPACE FOOD By Kathy De Antonis

ating in space goes as far back as John Glenn’s first orbit around the Earth in 1962. Given the magnitude of his accomplishment, not much attention was paid to the food that he ate, a paste that he squeezed into his mouth from what looked like a toothpaste tube. It was nutritious for sure, but not very appetizing. nasa

The National Aeronautics and Space Administration (NASA) has much iron in microgravity. In the body, iron is found in the blood. In come a long way in its effort to provide a variety of appetizing foods for microgravity, the body does not need as much blood, so it reduces its astronauts in space. Based upon extensive studies by food scientists the total volume of blood by destroying red blood cells as soon as working closely with astronauts, different types of foods are now pre- they are produced, leading to about 15% less blood in the body than pared and packaged to make them last longer and taste better and to on Earth. The iron that is bound to these red blood cells is released make them easier to transport in space. and stored elsewhere in the body. An excess of iron in the body Vickie Kloeris, a NASA food scientist, leads a team of food scientists, can be harmful, so dietary intake of iron is reduced in space to help engineers, dietitians, and technicians who work at the Johnson Space reduce the amount of extra iron in the body. Center in Houston, Texas, on testing and making many different foods Likewise, astronauts are prone to bone loss during extended mis- for astronauts. sions in space because the body senses that the skeleton is not One of the main challenges for NASA food scientists is to make these required for support in flight as it is on Earth. In the low gravity of the foods tasty, so they try different recipes and keep the ones that work space shuttle and ISS, not as much bone mass is needed to support best. It is a lot of work, but you need to keep the astro- the body as is needed on Earth. When people eat food containing cal- nauts happy, especially if they have to stay in space cium, a critical nutrient for healthy bones, calcium is absorbed into the for months or years on end! bloodstream, where it is delivered to the bones. But because the body is actively trying to reduce the amount of bone, the rate of calcium Meeting astronauts’ absorption from the diet is lower in space than on Earth. Research is ongoing at NASA to learn more about how nutrients nutritional needs are processed differently by the body in space and on Earth. At the Johnson Space Center, the Space Food Months prior to liftoff, each astronaut spends some time in the Systems Laboratory develops food used on the Space Food Systems Lab, sampling an assortment of space foods. space shuttle and the International Space Station Shuttle astronauts select a menu for every meal that they will eat while (ISS) and is working on ways to feed astronauts on in space, and ISS astronauts select food items that complement their longer trips in the future. basic menu. An interesting finding made by NASA scien- tists is that some nutrients in the body behave Eating in space is no differently in space than they do on Earth. picnic, but it would ist o c k For example, astronauts don’t need as be cool to have a picnic on the moon!

chemmatters, DECEMBER 2009 11 What is space Salt and pepper are also modified for use Once he worked past the preparation, Daley food like? in space. They cannot be shaken over food found that most of the foods did not meet his because the particles will float away. So, salt is standards. “Space food isn’t restaurant cook- The Space Food Systems Lab faces many dissolved in water and pepper is mixed with oil. ing; it’s not even takeout. If anything, it’s more constraints when producing space food. Food along the lines of a frozen dinner—but you get must be lightweight, compact, and require Does it taste good? bigger portions from the frozen-food aisle.” minimal preparation. Also, the food must be That said, he was satisfied by some things. well preserved, so it does not spoil in space in Bill Daley, a food critic at The Chicago “I particularly enjoyed the dried peaches, the absence of refrigerators or freezers. Even Tribune, ventured to answer that question. because of their intense flavor and a satisfy- food consistency is considered. Crumbly He sampled and critiqued a dozen space food ing, chewy texture,” he says. foods don’t work well in space because rations that were small particles will float in near-zero delivered to him gravity and potentially get into the as they would Freeze-drying food workings of the spacecraft. be delivered Freeze-drying is probably one of the most To take all these restrictions to astronauts fascinating ways of preparing space food. This into account, scientists at the in space. He process not only removes as much water as Space Food Systems Lab have quickly realized possible from a given food but also preserves come up with different catego- the challenges it for as long as possible. ries of food. For example, soups, that astro- Food spoils when microorganisms, such casseroles, and scrambled eggs nasa nauts face as bacteria, feed on the matter and decom- are “freeze-dried.” After they are in eating a pose it. Bacteria may release chemicals that prepared, water is almost entirely simple meal. cause disease or may just release chemicals removed prior to packaging, making these The serving-size portions were that make food taste bad. Bacteria need water foods lighter to carry and more compact. delivered in plastic pouches, each labeled to survive, so if you remove water from food, Once astronauts are in space, they add water with preparation instructions, such as Critical point back to these foods before eating them. how much water to add or how long 218 atm Some foods, such as to warm it. He was unprepared for the awkwardness of rehydrating freeze- tuna, are “thermostabi- 1 atm lized,” that is, they are dried foods by injecting water into the heat-processed after pouches with a 60-milliliter syringe Water (liquid) they are packaged. Other and reheating thermostabilized food Pressure Ice (solid) foods, such as some pouches in a warm water bath. These meats, are irradiated are cooking techniques that chefs don’t 0.006 atm after they are cooked and frequently use here on Earth. Triple point Water vapor(gas)

packaged. Thermostabili- Daley was surprised to find he anth o n y fe r nan d e z 0.01 °C 100 °C 374 °C zation and irradiation are needed a pair of scissors among his Temperature ways of sterilizing food so utensils. He found it to be a critical Figure 1. Water can take the form of solid, liquid, that it can be stored in the tool—and astronauts use scissors during or gas, depending upon different values nasa absence of refrigerators every meal to open their food pouches. Fas- of temperature and pressure. and freezers. Unlike freeze-dried food, these tened to each pouch is a Velcro disk, which two types of food do not require the addition is of no use here on Earth, but in space, it is it won’t spoil. Freeze-dried foods can be of water and are edible as is. critical for fastening the pouches to a tray so stored for years and then be restored with they don’t float. just a little water. Freeze-drying is different from dehydra- tion, which involves heating food in dry air Try it! until the moisture is gone. But dehydration You may be able to buy usually doesn’t remove more than 90% of the space food at your local water, so bacteria can still grow. Freeze-drying science museum. more successfully removes a much higher percentage of the water. Typically, the foods have less than 3% of the remaining water, and the food’s composition remains otherwise unchanged. Freeze-drying relies on a natural process, called sublimation—the conversion of frozen water present in foods directly to gaseous water. Depending upon the surrounding mi k e ciesiels i

12 Chemmatters, DECEMBER 2009 www.acs.org/chemmatters temperature and pressure, water can exist as a solid, a liquid, or a gas. By varying the temperature and pressure, it is possible to see water go from one of these forms to another. The temperatures at which water goes from solid to liquid (melting), liquid to gas (boil- ing), and solid to gas (sublimation) vary with nasa the surrounding pressure (Fig. 1). There is one value of temperature and pressure (0.006 Space food of the atmosphere of pressure and 0.01 oC)—called the triple point (Fig. 1)—for which water coex- future ists at equilibrium as a solid, a liquid, and a nasa In the future, NASA is looking to send gas. At any pressure below 0.006 atmosphere, astronauts to outposts on the moon and Mars. liquid water cannot exist and ice is converted into electricity. In a battery, the chemical reac- Although the target for liftoff for the moon directly to water vapor—that is, it sublimes— tants are limited to what is contained inside; mission is not until 2020, efforts are already when heated. so, once they are consumed, the battery runs under way at the Space Food Systems Lab. The process of freeze-drying takes advan- out of power. In contrast, a fuel cell can con- Scientists in the Advanced Food Technology tage of this property, as follows: First, the tinue working as long as the chemical reac- group, led by NASA food scientist Michele temperature is reduced below 0 oC until all tants are added to the cell from the outside. A Perchonok, are developing foods that are water present in a given food is frozen solid. byproduct of the chemical reactions occurring “nutritious, good tasting, and provide variety Then, pressure is reduced below 0.006 atmo- in a fuel cell is water vapor, which can be con- for a 3-year mission.” sphere, and the food is slowly warmed to a densed into liquid water and stored. The biggest challenge for these future temperature above the freezing point. With In a fuel cell that is used on the space missions is a food’s shelf life. “For an initial time, the water sublimes and is drawn away shuttle, electricity is produced via two reac- trip to Mars, you will need products that by vacuum. Over many hours—sometimes tions that occur simultaneously near two con- have a 5-year shelf life,” Kloeris says. The even days— 97% or more of the water is ducting materials, called anode and cathode only foods that have currently shown such removed, leaving the freeze-dried food. (Fig. 2). Hydrogen gas (H2) is delivered to the a long shelf life are a few thermostabilized anode and oxygen gas (O2) is delivered to the foods, which is not enough to provide a bal- Rehydrating freeze- cathode. Near the anode, hydrogen reacts with anced diet, Kloeris says. hydroxide ions (coming from the cathode) to Perchonok and her team are looking at dried food produce water and electrons: ways to improve packaging materials that will Aboard the space shuttle, water is pro- provide a better barrier to water and oxygen— – – duced by battery-like devices, called fuel H2 + 2 OH ➞ 2 H2O + 2 e which can cause food to spoil. This way, the cells, which also provide electricity. Each shelf life for many current food items can space shuttle is powered by three fuel cells Near the cathode, oxygen reacts with water be extended. Another area of research is to that are tucked beneath the cargo bay. Each and the electrons to produce hydroxide ions develop ways to transport some foods—such one weighs about 225 pounds and is 45 (OH–): as wheat berries and soybeans—in bulk to inches long, 15 inches wide, and about 14 reduce the amount of packaging materials – – inches high. O2 + 2H2O + 4e ➞ 4 OH used and to minimize waste. Like a standard battery, a fuel cell converts “A 1,000-day mission to Mars for a crew energy produced through chemical reactions The hydroxide ions then move to the of six will need about 10,000 kilograms if we anode, and the cycle starts again. The elec- went with our packaged food system,” Per- Electrical current trons that are produced at the anode are chonok says. “If we can save on that by grow- e- e- routed into an electrical circuit that powers the ing some items, by bringing some items up in Hydrogen in Oxygen in shuttle. bulk, it will be a lot easier.” H O 2 e- 2 The net result of the two reactions, called e- oxidation (at the anode) and reduction (at the Selected references Freeze drying: http://www.aboluteastronomy.com/ e- e- cathode), is water: topics/Freeze_drying [July 2009] OH– e- – – NASA: Fuel Cell Power Plants: e- Anode 2[H2 + 2 OH ➞ 2 H2O + 2 e ] H2O – – http://spaceflight.nasa.gov/shuttle/reference/ e- Cathode O2 + 2H2O + 4e ➞ 4 OH shutref/orbiter/eps/pwrplants.html [July 2009] Water and e- Net Reaction 2H + O ➞ 2 H O heat out e- 2 2 2 Space Travel and Nutrition: http://www.faqs.org/ e- nutrition/Smi-Z/Space-Travel-and-Nutrition.

anth o n y fe r nan d e z html [July 2009] Taken together, the fuel cells can produce Anode Cathode Electrolyte up to 25 pounds of water per hour, which is more than enough to meet the astronauts’ Kathy De Antonis is a science writer who lives Figure 2. Schematic representation of what in Old Saybrook, Conn. This is her first article in happens in fuel cells used on the space shuttle. needs. ChemMatters.

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