NASA Packaged Food Systems
M. Perchonok NASA/JSC Mail Code SF3 2101 NASA Parkway Houston, Texas 77058
The development of space food has been evolving since the Soviet cosmonaut, German Titov, became the first human to eat in space in August 1961. The National Aeronautics and Space Administration (NASA) is currently working towards future long duration manned space flights to the Moon and Mars. The moon missions will be used as a test bed for the future Mars missions. The Mars mission duration will be about 2.5 years requiring a shelf life of 3 – 5 years for the packaged food system. The goal is to provide acceptable foods that are similar to foods we eat here on Earth. Extended lunar or planetary stays will require even more variety and more technological advances.
The development of space food has been evolving since the Soviet cosmonaut, German Titov, became the first human to eat in space in August 1961. John Glenn was the first American to consume food, applesauce, on the third manned Mercury mission in August 1962. Prior to these events, there was no knowledge that humans would be able to swallow and hence eat in weightlessness (Lane et al 1994).
Space food development began with highly engineered foods that met rigid requirements imposed by spacecraft design and short mission durations. The improvements in the habitability of the spacecraft have permitted improvements in the quality of the space food. As the missions became longer, the need for better nutrition, more variety, and easily consumable foods also became more important. Currently, the International Space Station astronauts have a wide variety of foods. The goal is to provide acceptable foods that are similar to foods we eat here on Earth. Extended lunar or planetary stays will require even more variety and more technological advances.
SPACE FOOD – THE PAST
Project Mercury (1961-1963) was the first U.S. endeavor to place humans in Earth orbit. The first two suborbital flights carried no food. John Glenn was the first U.S. astronaut to eat in space when he consumed applesauce directly from an aluminum tube on the third Mercury mission in 1962 (Nanz and Lachance 1967). The package design served the requirements well and did not allow any food to contaminate the cabin. However, eating foods from tubes (similar to today’s toothpaste tubes) had some objectionable features for the astronaut who could not see or smell the food while eating. The texture of the product was also limited to the orifice of the tube and the tube filling processing capabilities.
Besides tube foods, Mercury missions also included cubed foods. These bite-size cubes, approximately one-half in 3, were a high calorie mixture of protein, high melting-point fat, sugar, and fruit or nuts. These foods also had some problems similar to the tubes. Although the starting ingredients were the same as familiar counterparts, for example, sugar cookies pressed into sugar cubes, the engineered cubes did not have familiar texture and mouth feel. Most agreed that the foods provided to the Mercury crew were unappetizing.
The 10 Gemini missions (1965 – 1966) consisted of crews of two in flights up to 14 days. The Gemini food system provided 2500 Kcal per person. Since weight and volume were restricted, concentrated foods were emphasized. In order to ensure maximum safety, specifications and procedures were developed. These processes were the beginning of the Hazard Analysis Critical Control Point system, which is in worldwide use in the food industry (Heidelbaugh 1966). Crews continued to eat bite-size cubes or squeeze foods from tubes. Even though the foods met the description of acceptability in ground based tests, consumption in flight was inadequate and astronauts lost weight (Smith et al 1971).
The Apollo program (1968-1972), with the objective of placing humans on the Moon before the end of the decade, was the most focused space program in the history of U.S. space exploration. The initial Apollo food system was still very similar to the Gemini food system. However, by the later Apollo missions, increased variety and improved quality became important design factors of the food system to encourage consumption of the food. The later Apollo missions’ food system was improved to include the use of retort pouches and cans. The Apollo astronauts were also the first to use irradiated food in space (Bourland et al 2000).
Early in the Apollo program, the spoonbowl package was developed as a solution to the problem of direct package-to-mouth consumption. Apollo astronauts were the first to have hot water, which made rehydrating foods easier and improved the food's taste. Water was added through a one-way water port. Then the top of the package was cut open and the contents were consumed with a spoon. This was the first time utensils were used to consume the food.
Despite the improvements and advances in the in-flight food system over that used on earlier flights, the majority of the Apollo astronauts did not consume sufficient nutrients. It was apparent that adequate nutrition begins with appropriate food presented to the consumer in a familiar form (Smith et al 1975).
The Skylab (1973-1974) food system was the most palatable and varied food system to be used in space to date. There were 72 foods to choose from with a six-d menu cycle. Skylab was the first U.S. space mission to have freezers, refrigerators, and food warmers. From the onboard freezers the crews were able to have foods such as ice cream, filet mignon, and lobster, and from the refrigerator they had chilled beverages and desserts. Added to the conventional knife, fork, and spoon was a pair of scissors for cutting open plastic seals (Turner and Sanford 1974).
Unlike previous space vehicles, Skylab featured a large interior area where space was available for a dining room and table. Eating for Skylab's three-member teams was a fairly normal operation with footholds available allowing them to situate themselves around the table and "sit" to eat. The dining table had built-in food heaters with timers for advanced preparation of food.
All of the planned food for the Skylab program was launched with the first mission, making it over two years old when the last crew consumed it. Therefore, most of the food was packaged in aluminum cans to maintain the two year shelf life (Klicka and Smith 1982). All aluminum cans were sealed in canisters designed to withstand the pressure changes from 14.7 to 5.0 psi between the ground and the spacecraft (Johnston 1977).
SPACE FOOD – THE PRESENT
The U.S. Space Shuttle (1981-present) missions, for seven crewmembers, are typically about 11 – 14 days long. The food system allows the crew to eat from open containers on a meal tray. The meal tray is a sheet of aluminum with Velcro, magnets, and a bungee cord for restraints. A galley with a rehydration station and convection oven permits addition of hot or cold water and provides the ability to heat food to serving temperatures.
The food is packaged in single service containers in order to provide real-time menu exchanges and to prevent the need to transfer food from one container to another in microgravity. All food is processed so it requires no refrigeration and is either ready to eat or can be prepared simply by adding water or by heating. Since the fuel cells used on Shuttle provide water as a byproduct of fuel consumption, approximately fifty percent of the Shuttle food is dehydrated, including beverages (Bourland 1993). The foods are freeze-dried, thermostabilized (retorted), irradiated, intermediate moisture and natural form foods. The beverages are dried powders. NASA has special dispensation from the FDA to utilize 12 irradiated meat items available through a cooperative agreement with the US Army Soldier Service Center in Natick, MA. (Code of Federal Requlations).
The thermostabilized and irradiated food items, processed to commercial sterility, are packaged in flexible multilayer foil-containing pouches. The pouches, compared to round cans, allow for efficient stowage due to decreased mass and stowage voids. The beverages are packaged in a laminated foil pouch. The freeze-dried foods are vacuum packed in clear, flexible thermoformed packages. Both the beverages and freeze-dried foods are hydrated through a septum assembly which includes a one-way valve to prevent migration of the liquid after hydration through the septum.
Foods such as nuts, granola bars and cookies are classified as natural form foods, while dried fruit is classified as an intermediate moisture food. They are ready to eat, and are packaged in clear, flexible pouches that require no further preparation for consumption in flight. The thermostabilized, irradiated, freeze-dried, natural form, and low moisture foods are cut open with scissors for product consumption. The surface tension of the water in the foods with higher moisture contents prevents the food from leaving the package or the spoon during eating in zero gravity.
There are anecdotal reports from the astronauts that the food does not taste the same on-orbit. And in many cases, the reports are that the food is not as flavorful on-orbit. For those reasons, condiments become an important part of the food system. Condiments include commercially packaged individual pouches of catsup, mustard, mayonnaise, taco sauce and hot pepper sauce. Polyethylene dropper bottles contain bulk supplies of liquid pepper and liquid salt. The pepper is suspended in oil and the salt is dissolved in water.
Shuttle astronauts choose items for their menu from over 200 food options. Each menu is analyzed by the dietitian for its nutrient content and substitutions are recommended to ensure a balanced supply of the nutritional requirements.
International Space Station (ISS)
The ISS (2000 – present) currently houses three crewmembers. During any expedition (mission), one or two crewmembers are from the U.S. with the remaining being from Russia. The duration for the expeditions is typically about 180 days. The United States and Russia each supply approximately 50% of the food system. All crew members have stressed that variety is critical and that the use of Russian and U.S. food together create a unique type of variety (Smith et al 1975).
Unlike Shuttle, the electrical power for the ISS is supplied by solar panels rather than fuel cells. Hence, the extra water from fuel cells is not available for use in the food system and consequently, there is less emphasis on rehydratable foods and more emphasis on thermostabilized foods (Bourland et al 1989). In the last several years, over 60 new foods have been developed by the food scientists at Johnson Space Center providing more variety for the ISS crew members. Many of those have been thermostabilized.
Similar to Shuttle, the ISS menus have been based on the crewmembers’ personal preferences. However, in early 2008, the crew will begin to eat a standardized menu. The food is stowed “pantry style” meaning the foods are organized in the food containers by category (e.g., vegetable, beverage, main entrée) allowing for more freedom of menu choice. The menu is supplemented with personal preference items from the official food list as well as bonus items not on the official food list. The move towards a standardized menu allows for a 16 day menu cycle. Prior to the standardized menu, the menu cycle was 10 days. In the future, the standardized menu will include foods from the International Partners, such as JAXA and the Canadian Space Agency.
Since the food is prepositioned and the mission length is about 180 days, the required shelf life of the food items is 18 months. The packaging material used for the rehydratables and natural form foods does not have adequate oxygen and moisture barrier properties. For that reason, these items are overwrapped with a multi-layer foil containing material.
SPACE FOOD – THE FUTURE
On January 14, 2004, President Bush announced a new vision for NASA. Included in the vision was the return to the moon no later than 2020 in preparation for human exploration of Mars and other destinations. The primary goal of the food system in these exploratory missions is to provide the crew with a palatable, nutritious and safe food system while efficiently balancing appropriate vehicle resources such as mass, volume, and crewtime.
One of the reasons to return to the moon is to validate technologies needed for Mars missions. Although initially the moon missions will be about 2 weeks long, the plan is to build a habitat allowing for full time occupation, similar to the ISS, with crews rotating every six months. These moon missions will allow for testing of technologies in partial gravity in an integrated environment.
The duration of the Mars missions may be as long as 2.5 years and will likely include an 18 month stay on the planetary surface. Since this mission may also preposition the food in Mars orbit or on the planetary surface, another 2 years should be added to the planning.
The paramount importance of the food system in a long duration manned exploration mission should not be underestimated. During long duration space missions, several physiological effects may occur. Furthermore, the food system provides not only the nutrients needed for the survival of the astronauts but it also enhances the well being of the crew by being a familiar element in an unfamiliar and hostile environment.
The acceptability of the food system is of much higher importance due to the longer mission durations and the partial energy intake that is often observed in space flights (Lane and Smith 1999). The decreased energy intake might significantly compromise the survival of the crew. A large variety of food items are recommended to provide the crew choices and to avoid menu fatigue (Vodovotz et al 1997). The food will not only provide the needed nutrition but mealtimes will also provide a major socialization event. Highly acceptable foods can play a primary role in reducing the stress of prolonged space missions.
This food system will initially emphasize technologies for space vehicle applications (ISS and Shuttle), then slowly increase focus on technologies toward tasks that support exploration. The development of the exploration food system will require a dual task approach (Perchonok et al 2001). The packaged food system will be used during the transit and the initial stays on the lunar or planetary surface. The Lunar/Planetary Surface Food System will introduce food processing of raw ingredients into edible ingredients and products, as well as food preparation in the galley using the edible ingredients, freshly grown vegetables and packaged food. This technically challenging food system will save on mass and volume of the total food system.
Packaged Food System
One of the biggest challenges for these 2.5 year-long missions will be to provide a food system that is safe, nutritious and acceptable for three to five years . Clearly safety is the primary consideration. In addition, since the food system is the sole source of nutrition to the crew, a loss in nutrition may determine when the shelf life endpoint has occurred. However, due to the importance of overall acceptability, ultimately the shelf life is often determined by the change in quality factors of the product whether they are appearance, texture, or odor.
There is no plan for extensive use of refrigerators and freezers. The majority of the food items in the Packaged Food System will be foods that will resemble the products used on Shuttle and International Space Station. In addition to the current preservation methods, other technologies, such as high pressure processing and microwave sterilization will be considered, especially if these methods provide extended shelf lives, improved acceptability, and/or improved nutrition.
In order to reach a five year shelf life, the packaging material used in the food system must have excellent barriers to water and oxygen. The current thermostabilized packaging, a multilayer foil laminate, has excellent barrier properties. However, the foil layer of the packaging does not allow for efficient incineration of the packaging material, one proposed method for disposal of trash on the Mars surface. Hence, development of high barrier, non-foil containing packaging materials, that are also compatible with current and future preservation technologies, is a NASA priority.
Efforts are also underway to identify a packaging material for the freeze-dried and natural form foods that will not require the additional overwrapped material. This material must also be flexible enough to allow for the food to be vacuum packed. It is estimated that the waste generated by the food packaging will be a major contributor to the total waste produced during the transit to Mars. It would be an added value if the packaging materials are biodegradable, reusable, or edible. However, the barrier properties of the packaging material are of highest priority. It is very important that the food maintains its shelf life (safety, nutritional profile, and acceptability) throughout the duration of the mission.
Much progress has been made from the first tubed food and more progress will be made as longer duration missions occur. Since many years will pass prior to the anticipated future missions with a stay on a planetary or lunar surface, much can still happen. Research continues in the food and nutrition science community on how to maintain our health and psychological well-being. Much of this research is on foods and their components. It is hard to predict how the food system will develop. However, it will be safe, nutritious, and acceptable.
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