While it's not exactly five-star cuisine, astronauts survive on more than the freeze-dried "space food" found in museum gift shops. To get a look inside NASA's kitchen, I spoke last week with Michele Perchonok, Shuttle Food System manager at Johnson Space Center.
How has astronaut food evolved over the years?
In the beginning, we didn't even know if people could swallow in microgravity. We didn't know how much was due to the muscles contracting and how much was due to gravity. The good news is they can eat and digest their food in microgravity. [Early astronaut food] was basically tubes and cubes: pureed applesauce in a toothpaste tube or compressed cubes of sandwiches or breads or desserts. The astronauts said it tasted OK, but it just wasn't satisfying because it wasn't close to what they were used to. We started developing some products or taking commercial products that were appropriate and sending those up. We had freeze-dried items, like shrimp cocktail which has been with us for many years.
About the year 2000 when we were starting to be on International Space Station up to six months, there was a need for more variety. We started developing our own product formulations. When we started on International Space Station, the crew was on a four-day menu cycle. Every four days, the menu would repeat itself. Half the food on International Space Station is U.S. food and half is Russian food. We're now up to a 16-day menu cycle. We've been able to increase our offerings and the Russians have also gone to that 16-day menu cycle. Eight days of food is U.S. food or other international partners, such as the Europeans or Japanese, and the Russians have half the food.
What are some of the challenges you face when producing food for space?
All of our food has to be shelf stable, meaning is has to be safe to eat when stored at room temperature. In addition, it's very difficult to transfer food from Point A to Point B. The astronauts eat their food within the food package most of the time. They will use tortillas like a wrap or a sandwich. We want the astronauts to be able to eat out of the food package with utensils. There is a property called 'surface tension' [meaning] if the food is wet enough, but not too wet, it will stick to a surface such as the food package or the utensil. We have to make sure that our food is not too runny and we have to make sure the food has a sauce.
Because crumbs will float around -- they can get everywhere from in your eye to into equipment -- there are fans and filters to circulate the air and get any foreign matter caught. But you don't want to be changing the filters all the time. That's one reason we don't bring up a lot of bread or cookies because they create crumbs. We do bring up some crackers, [but first] we did an assessment to find the cracker that won't break too easily. If they're on International Space Station, there's a little suction where the garbage goes. [The astronauts] can sit over that, so the crumbs will go right into the suction.
All of our beverages are pre-formulated. If you drink your coffee with cream and sugar, we have to add the cream and sugar to the package before we send it up. If they think they like black coffee and they get up there and say, 'I really want it with cream,' unless they beg, borrow or steal, they don't have that option.
We've gotten a lot of anecdotal reports that the food just doesn't taste the same on orbit. In most cases, the comments are that the food has lost flavor. That's probably a combination of phenomena. In microgravity, more fluid is in the upper part of the body, including the head [and] they can't smell as easily. About 85 to 90 percent of what you taste is really what you smell. In addition, in microgravity hot air doesn't rise, so the aromas could be going to your feet. We don't heat our food up piping hot because of power limitations, [so] there may not be as many aromas coming out of the food.
The last piece is psychological. While they're away from home -- even though it's a wonderful and exciting opportunity -- [astronauts are separated] from family and friends. You may crave comfort foods you grew up with, whether it's macaroni and cheese or meatloaf or mashed potatoes. Some of the other items may not taste as good as they would have if you were at home.
Do astronauts determine their own menus?
We have approximately 180 items on our food list. We just had a food session for a [potential] launch at the end of June. [The crew] tasted about 60 of the 180 items and rated them 1 to 9. Anything rated 6 or higher is fair game. We could put that on their menu. They do have choices on shuttle. Do you want to develop your own menu? Do you want to take a menu and change a few items? Or do you want our dietitians to develop a menu based on your preferences?
On International Space Station, they get 'preference bonus containers,' which are items they like on the official food list or they're fresh food items [such as] meats and candies. Many crews will host a special meal with the International Space Station crew. For example, the crew that's hopefully going up in the beginning of December is hosting a meal which has spreads, cheeses, meats, a few entrees and cookies for dessert.
What are some of the most popular food items for astronauts?
Shrimp cocktail is very popular. Some of our meat items, like barbecue brisket or meatloaf, can be popular. Tortillas are extremely popular. It depends on their own personal tastes.
[Fresh foods are defined as] foods that aren't on our official list. They can bring up items like apples or oranges. Carrot sticks and celery will last a little while. Some will bring up more delicate items, such as tomatoes or kiwi or avocado. But if there's any delay or they forget to transfer it over for International Space Station, it could get soft before it's ready.
Some of them, instead of using the peanut butter in a pouch that we provide to them, will ask to bring up their favorite commercial item in a jar. Or maybe they ask for special candies or chocolates or a beef jerky of their preference or hot sauce. A lot of the ways they get around the flavor loss issue is by adding condiments -- whether it's mustard and ketchup or hot sauce, soy sauce, horseradish.
How do you maintain the nutritional value of foods when they require a shelf life of several years?
That is a huge, huge challenge and we're still not there. We are analyzing somewhere between 15 and 30 items a year for nutritional content. Then, we store them at room temperature for one year and then for three years and do the nutritional analysis again. Some of the vitamins are significantly lost. Once we have all the data collected, we'll have a better idea of what we need to work on. But we do know the methods we're using to preserve the foods are part of the culprit for losing the nutrition. And, of course, nutrition gets lost over time.
There are two new emerging technologies [related to this problem]. One is pressure-assisted thermal sterilization, or high-pressure processing, where you heat the food and then hit it with high pressure. That kills the cell walls of the microorganisms and maintains the quality and nutrition of the food at a higher level. The other process is microwave sterilization -- killing the microorganisms in the microwave. That also is providing a higher quality product. Hopefully by the time we're ready for Mars mission, those kinds of technologies will be very common.
Once we're on a surface, whether it's Mars or somewhere else, we have the advantage of some partial gravity. Maybe we can start growing some fruits and vegetables or process wheat flour and make pasta or breads or make a pasta sauce. We're looking at what kinds of recipes we would use and how much time they would take. As we go from simply hydrating or heating the foods to preparing a meal, that will provide some fresher foods and therefore foods that are higher in nutrition.
How else are you preparing for the possibility of a Mars mission?
We've worked for several years trying to find a high-barrier packaging material that does not contain foil. If we go to high-pressure processing or microwave sterilization, we can't use the foil pouch we're using now. That foil pouch has wonderful barrier properties to oxygen and water, which is what we want. We know that if we store the food at a higher temperature or if we adjust the formula a little bit, we may be able to get away with lesser packaging materials.
We're starting to look at how we can possibly use probiotics in our foods. We know probiotics are good for the digestive system and also seem to help the immune system. But, by definition, probiotics are bacteria. How do you make sure those grow, but the [bad bacteria] don't? Are probiotics a direction we might want to go into and, if so, are there shelf-stable products that already have probiotics in them?
We're looking at how [food] accessibility affects crew members' moods. For example, [is it worthwhile to celebrate] a birthday or a holiday, which may require some extra food items? Gut feeling says yes, but we need to get that answer.
How did you get into this work and why is it important to you?
I got into [food science] due to a summer job. I was a chemistry major in college and got a job at Dunkin' Donuts in their research and development lab. The entire summer, the director of the lab was trying to persuade me to go into food science. I gave chemistry a try the following summer and decided I wanted food science. I love it. It's an applied science and it's multidisciplinary.
My goal had been to work for a food company and develop food products for them, which is what I did for about 16 years. I got a job here about 10 years ago. It's certainly the most exciting job a food scientist could ever have. It's constantly changing. I have to know what's going on in all the areas -- whether it's packaging or chemistry or biology or micro-engineering. It's special working here. Every once in awhile I have to pinch myself. I'm working with the astronauts. I'm developing food for Mars. It makes the job very special.
Image, top: As seen in artist's rendering, astronauts exploring Mars will build hydroponic growth labs where vegetables can be grown. These crops will provide the crew with added nutrition and variety. / Courtesy of NASA
Image, bottom: Michele Perchonok