Their first priority is to provide astronauts the balanced diet of an earthbound human, along with an extra helping of omega-3s and an emphasis on low-sodium foods to help prevent the bone loss that occurs in extended space flight. But a high-nutrition pill or meal substitute just won’t do. As anyone who’s ever survived a day of airplane flights on peanuts and Clif Bars knows, variety affects morale. “Here on Earth, we have so many choices. We don’t realize what that choice means to us,” says Douglas. “The station’s crew does, though.”

Kloeris has the rare distinction of managing the food program for astronauts on the International Space Station , the orbiting laboratory that was first launched twenty years ago. She and her colleague, advanced food technology lead scientist Grace Douglas, create recipes and dishes for the six or so American, European, Japanese, and Canadian astronauts aboard six-month expeditions on the ISS at any given time. (Russian cosmonauts bring their own casseroles and borscht, prepared at their country’s space agency.) The women’s mission—to create healthy meals that will not only last at least half a year at room temperature in zero gravity but taste good too—requires them to be part chef, part nutritionist, and part scientist.

There’s only one place in the country that can legally sterilize meat with gamma rays, and it’s not your local butcher shop. “Our beefsteak is pretty good,” says Vickie Kloeris, of the Space Food Systems Laboratory at Houston’s NASA Johnson Space Center . “And we have a thermostabilized cherry-blueberry cobbler that’s just killer.”

To cook the perfect steak, start with a marbled cut of beef one and a half inches thick, work in some good olive oil, rub with sea salt and freshly ground pepper, and throw on a well-heated grill for three to five minutes on each side. To cook the perfect steak for someone orbiting about two hundred miles above Earth, you need to add a key step: zap the meat with gamma rays.

To that end, Kloeris and Douglas have helped devise a menu of two hundred dishes and beverages, covering breakfast (rehydratable scrambled eggs), lunch (thermostabilized seafood gumbo), dinner (irradiated beef fajitas), and dessert (rehydratable strawberries and thermostabilized lemon meringue pudding). Sweet treats are key, especially those that can be heated. “Psychologically, to have dessert you can warm up is a really big deal for a crew member who’s on orbit for a long time,” says Kloeris. A space traveler with a sweet tooth can choose from splurges such as apricot cobbler and chocolate pudding cake.

Since joining NASA in 1985, Kloeris, who has a master’s degree in food science and technology from Texas A&M, has developed dishes for astronauts aboard dozens of shuttles and ISS flights. Relative newcomer Douglas started working at NASA while earning her bachelor’s and master’s in food science and her doctoral degree in functional genomics. She joined the JSC full-time in 2013.

Illustration by Christopher DeLorenzo The Mars Menu A potential Mars exploration in the 2030s will present its own challenges for the NASA food team, who will likely need to ship food long before the crew leaves Earth on a years-long mission. The threat of menu fatigue is strong, says Douglas, who’s leading the Mars preparation.

At the JSC, Kloeris and Douglas lead a team that includes other food scientists, a dietician, and technicians who prepare and package the food. After suiting up in lab coats, face masks, hairnets, shoe covers, and gloves, the technicians cook up two-hundred-serving batches of dishes in a gleaming white kitchen, whipping eggs in an industrial-grade stand mixer, measuring blocks of quiche with a ruler, and inserting a thermocouple temperature sensor to monitor the freeze-drying process. The thermostabilizing is completed at a facility at Texas A&M, where food is packaged in sterile laminated pouches developed by the U.S. military for its combat rations program. The pouches have Velcro on the bottom, which astronauts can attach to the table to enjoy their meal.

For each mission, Kloeris and Douglas include the same balanced diet, along with specialties from each country’s cuisine. “The crew-specific containers contribute a lot to their psychology on orbit,” says Kloeris. The astronauts can also bring a few comfort foods and favorite snacks as long as they’re shelf-stable and sealed, like protein bars—although Kloeris and Douglas have learned the hard way not to allow crunchy foods. In the nineties, several astronauts tried bringing cans of Pringles to the space station, only to find themselves vacuuming crumbled chip pieces floating around the sensitive equipment. “They would come back and say, ‘I should have listened to you,’” says Kloeris. “‘That was a big mess.’”

The team used to send sliced bread on the shuttle, adding it a few days before launch so it would last longer. But in the 1980s, a payload specialist from Mexico brought tortillas on a mission. Once the other astronauts saw how much easier it was to make a PB&J on tortillas, sliced sandwich bread and its pesky crumbs no longer made it into space.

On leisurely weekend mornings above Earth, astronaut Joe Acaba, who recently returned from an ISS expedition, would cook up a meal familiar to any Texan. “We’d have scrambled eggs, tortillas, breakfast sausage links, fresh lettuce [grown as part of a NASA experiment aboard the ISS], and some salsa. It felt like I was out having a pretty tasty breakfast taco.” Condiments and extra seasonings let astronauts improvise changes to a somewhat monotonous menu, especially because any aroma quickly dissipates in zero gravity. When you can’t smell something, it affects how you taste it. (Think of eating all your meals with a cold.) “Over time, I started eating more and more condiments—garlic or mayonnaise,” says Mark Vande Hei, who returned from his six-month stint on the ISS in February. “To add something to change it up a bit was really a source of pleasure.”

The astronauts can also fight off menu fatigue by trading food from each country’s crew-specific options. On his trip to the ISS this winter, Acaba enjoyed swapping dishes with his Japanese crewmate, Norishige Kanai. “He had a wonderful roasted duck in a sauce that was really, really delicious,” says Acaba. “As long as you’re adventurous and willing to try new things, morale doesn’t go down.”

This was especially important during the holidays. “Christmas dinner was one of the most special meals,” Acaba says. The U.S. astronauts had to work, but their Russian counterparts, who traditionally celebrate Christmas in January, stepped up. “They made us a really nice spread of food and found a little Christmas tree we had, so we could float over . . . and have an American Christmas in the Russian segment,” he says.

Despite the tasty tacos and international meals, the ISS crew usually can’t wait to eat Earth food again. For his first meal back on his home planet, Vande Hei asked for guacamole, which the NASA team faithfully made fresh at his landing location in Kazakhstan, with avocados brought from Houston. Homegrown space lettuce is good, but Texas guacamole is even better.