Here on Earth, food suppliers face enough challenges when it comes to keeping their products safe all the way from the farm to the dining room.
But for a small team of NASA food scientists, the dining room in question might be 40 million miles from home and on hiatus from gravity when astronauts dig into a salmon fillet or grilled pork chop. If transporting food across the country posits a list of safety considerations, launching it out of the atmosphere exponentially compounds them.
At the Johnson Space Center in Houston, the scientists behind NASA’s advanced food technology (AFT) project are busy devising a safe, nutritious and robust menu to launch with the first manned mission to Mars. Their goal: Preserve 180 foods and beverages to stay safe and nutritious for more than five years. So far, they’ve achieved that with seven products, all meat.
Michele Perchonok, Ph.D, manages NASA’s shuttle food system and works on the AFT project, which she spoke about in a presentation at the fifth annual Food Technology Innovation & Safety Forum in May. When describing the progress NASA’s food program has made during the last 50 years, she borrowed a tagline from the old Virginia Slims advertisements: “You’ve come a long way, baby.”
“In the beginning, we didn’t even know if we could swallow or digest food in weightlessness. No idea,” Perchonok said. “Well, good news is, we can.”
Today’s astronauts benefit in safety and palatability from their predecessors’ less savory mealtimes. No longer do they fly with “tubes and cubes,” the notorious combination of space paste in aluminum squeeze-tubes and gelatin-coated, bite-sized cubes of indecipherable origin.
Instead, modern space food comes in serving-sized, vacuum-sealed packaging, boasting selections such as chicken salad and shrimp cocktail — both part of an essential variety meant to keep astronauts not just full, but content. As Perchonok explained, one crucial element of space travel that many overlook is the psychological comfort that a tasty, varied food supply provides.
“We have these four requirements: nutritious, safe, acceptable and minimizing resources, and ‘acceptable’ includes variety,” she said. “You can’t go to Mars with seven meat items.”
For a trip to Mars, the AFT team needs to plan enough meals to sustain six crew members on a 1,000 day journey — that’s six months each way, plus a year-and-a-half-long spell on Mars until Earth orbits close again. Because of the time it will take to prepare all the food and launch most of it to Mars ahead of the crew’s arrival, everything needs to last up to five years.
But limitations abound. Estimates for the cost of launching one pound of material into orbit often report between $5,000 and $10,000, so when propelling food all the way to Mars, NASA needs to use the minimal packaging necessary. Still, they keep in mind that insufficient or ineffective packaging can lead to faster nutrient decay.
Right now, the plan to launch a 22,000 pounds food stockpile would include roughly 3,300 pounds of packaging with the current plastic vacuum pouches. And while those pouches suffice for shuttle missions and 6- to 12-month stints on the International Space Station, they won’t cut it for a Mars mission.
The problem is: After neutralizing microbe growth in the pouches through high-heat treatment, the sugars and proteins in the food still react over time in an unappetizing chemistry of nutrient degradation. Tests show nutrients like Vitamin A, Vitamin C, and thiamine all dropping in concentration dramatically even after just a year in the pouch. With current packaging, astronauts heading home from Mars would find their once-vibrant fruit salad replaced by blackened, unidentifiable mush.
“No one wants to eat those pears that have been retorted [high-heat sterilized] after two years,” Perchonok said. “Very sad.”
Part of this problem can be solved with new advancements in sterilization, namely pressure-assisted thermal sterilization and microwave sterilization, methods that neutralize microbes without subjecting foods to high levels of heat. These techniques should slow nutrient degradation considerably, but NASA will need new packaging to adopt them.
The AFT team wants to come up with packaging that has the same effective preservation properties as the U.S. military’s foil ready-to-eat meal pouches, but in a plastic. Foil won’t cooperate with microwave sterilization — plus, it’s just too heavy.
In the meantime, the team will try to cut back on packaging overall by loading more nutrients into drinks, reducing water content in food and adjusting toward a diet that uses more calories from fat — efficiencies that could ideally cut down the packaging weight — and waste — by close to 40 percent.
And without the technology to purify and recycle wastewater, aspiring Mars visitors would likely never launch in the first place. A successful mission will require the crew to reuse close to 100 percent of their water, including urine, sweat and everything but the perspiration lost in suits during Mars walks. Even the moisture from feces will be dried out and recycled back through the purifier.
Perhaps the most surprising solution the AFT team has considered, however, is to have the crew grow fruits and vegetables in environmentally sealed chambers during their stay on the red planet. To make it work, they would need to eventually dry out the excess plant material to reclaim the water, but the operation would be a source of fresh, crunchy textures — a delight missing from pre-packaged space food.
By Perchonok’s estimation, NASA’s entire AFT team consists of roughly 3.3 full-time researchers, considering several of them divide their time among multiple projects.
Fortunately, they still have some time to plan. Perchonok said NASA aims to launch a Mars mission by 2035 at the earliest, which she hopes will give her enough time to retire as food program manager before the crew learns they might have to go 1,000 days without coffee.