Dec. 20, 2004 -- Hungry? Chances are you can satisfy your craving pretty easily. But imagine you are encased in a small craft hurdling some 30 million miles from Earth and there's nothing good in the fridge -- actually, there's no fridge.
It's a scenario that NASA is working hard to avoid, especially as it looks toward a possible future manned mission to Mars. But recent events show how tricky supplying adequate and appealing food in space can be.
Since October, the two men posted at the International Space Station had been eating a hearty diet of about 3,000 calories a day and unknowingly burned through much of their food supply. While they have enough to last awhile (on a slightly reduced diet), the space program is now depending on a Dec. 25 delivery to avoid a possible food shortage.
The Progress resupply ship will hold 70 containers or 2.5 tons of food, as well as other supplies and some Christmas presents for the crew.
NASA officials have described the situation as tight, but not dire. Still, even the possibility of a food shortage on the ISS highlights the importance of the work by NASA's food scientists who are looking toward the day when astronauts will be so far from home, there will be no possibility of replenishing their pantry.
"Running into a situation where food is running out would be catastrophic on a mission to Mars," said Lisa Mauer, a food scientist at Purdue University in West Lafayette, Ind. "It's a huge issue."
The goal of NASA's food scientists is two-pronged. One is to ensure that astronauts on board a spacecraft for long periods could have access to food that is safe and enjoyable to eat for five years -- with no refrigeration. The other is to develop systems to grow, harvest and process foods on the surface of the moon or other planets such as Mars.
From Squeeze Tubes to Beef Tips
Space food has already come a long way since the days of the Mercury program when astronauts had to force down freeze-dried powders and gel-like substances squeezed from aluminum tubes. Now space station residents select their own menus before blasting to space and use a specially equipped dining table to rehydrate, heat and eat their meals that range from chicken à la king to beef tips with mushrooms.
Most of the foods are preserved in MRE-like containers, not a refrigerator. There is a refrigerator on the space station, but food scientists are reluctant to rely on one.
"If we're depending on a refrigerator or freezer and it contains 30 percent of the food supply and it goes out, that's a big loss," explained Michele Perchonok, a food scientist at NASA's Johnson Space Center in Houston.
While the meals may be tastier than what astronauts ate in years past, most of the packaged meals have a maximum shelf life of one year. Scientists calculate that food would need to last a minimum of five years for a round trip to the Red Planet.
"The goal is to prepare foods for the six- to eight-month flight out and then having a good supply with a five-year shelf life for the return trip," said Mauer.
To stretch the shelf life of foods, researchers are looking into new packaging materials as well as high-pressure treatment and microwave processing. These methods aren't yet approved by the Food and Drug Administration, but Perchonok said "they're showing promise."
Space radiation is another factor that Perchonok and others need to consider since three different kinds of it would be pervasive in a journey to Mars. Tests show it can change the rancidity of oil and other foods and change their taste.
"Anywhere there is oil, it's possible there will be off flavors," Perchonok said.
To boost food's resistance to radiation, Mauer is looking into ways to increase anti-oxidant levels in regular foods, such as spaghetti, as well as emphasize foods that already have high antioxidant levels, such as prunes and berries.
Food From Scratch
One food that is clearly vulnerable to the effects of radiation is tofu. The team's tests have shown that exposing tofu to certain levels of radiation can make it change to unappetizing tones of brown or gray. That's an important consideration since soy -- the bean that tofu is derived from -- looks to be a major component of a possible Mars menu.
Once space travelers reach the moon or Mars and set up base camp, the hope is they'll be able to plant crops such as potatoes, soy beans, wheat, rice and vegetables. A crop team would harvest the foods, said Perchonok, then another team would use special equipment to process it into items like flour, cereals, pasta, oil, tofu, soy milk and sugars.
Scientists across the country are now working on devices to make the processing step easier and less time-consuming. Paul Singh at the University of California at Davis has constructed a fruit and vegetable processing system that can slice, dice, crush and juice tomatoes. Clint Rappole of the University of Houston has been working with Johnson Space Center researchers to create a device to process soy beans into a range of products, including soy milk and tofu.
"We could have as many as 40 food processors up there," said Perchonok. "The galley will probably look like a gourmet kitchen at home."
It won't be enough, however, to simply produce foods that can last the trip; they have to taste good too. Studies show astronauts generally lose weight during their stay in space. This may be due to the fact that, despite NASA scientists' best efforts, space food is never quite like home cooking.
While it may be tough to match Earth-bound cuisine, research has shown that offering space travelers choice in their menu is important.
"What's the first thing a college student complains about -- the food," said Perchonok. "It has to do with choice -- food is something you really want control of and if you don't, it can make life miserable."
Even with choice, there will be some limits. Meat-lovers traveling to Mars, for example, may have to go without. While developing an aquaculture might be possible, it's not feasible to raise livestock in space. And shelf life for meats on board a spaceship will likely be limited.
"Animals would be competing for the same resources as you -- oxygen, space and food," explained Mauer. "It only makes sense to rely on a plant-based, vegan-like diet."