In the summer of 1987, food scientist Vickie Kloeris was busy cleaning out the NASA Space Food System Laboratory offices at Johnson Space Center in Houston, Texas, when she and her co-workers made a curious discovery. They were preparing for the division’s relocation to a new space, sorting through decades of materials and paperwork. Buried underneath, they found a stash of antique astronaut food.

“There were cans and cans of cubed food left from the early space flight era,” Kloeris, the former manager of the International Space Station Food System, tells Mental Floss. “We had to get rid of them. We had no space for them.”

But then Kloeris and her colleagues had an idea. “They had been done in the mid- to late-1960s,” she says. “But they were still safe from a microbiological perspective.” The scientists decided to sample the now decades-old food before discarding it.

They opened the tins and found foods diced up for easy ingestion: cubed cheese sandwiches, cubed bacon, cubed cookies, and “peanut butter stuff.” All of it was shelf-stable, just like commercially available canned goods. A little stale, maybe, but otherwise edible.

The trove of space food was a reminder of how far NASA and space programs had come from the early days of astronaut menus, and how much further it had to go. The practice of consuming food in space has always been a challenge, and cubed cheese sandwiches are only part of the story.

To Boldly Chew

While today’s space meals are planned with taste, nutritional value (usually under 3000 calories, with the proper ratio of proteins, fats, and carbohydrates), and visual appeal in mind, NASA’s earliest attempts at providing sustenance for astronauts was focused mostly on one thing: Could a human even swallow or digest food in space?

Astronaut John Glenn answered that question in 1962, when he became the first American to consume food on board the Friendship 7 spacecraft as part of the Mercury mission. “The original space food was tube foods,” Kloeris says. “These were puréed foods you’d squeeze into your mouth.” Glenn dined on applesauce, and his side dish of sugar tablets and water went down without issue (unless you consider the experience of eating from a toothpaste tube an issue). Applesauce wasn’t the only option, either; if Glenn wanted a fancier dinner, puréed beef with vegetables was available.

A typical astronaut dinner in 1962.National Air and Space Museum // Public Domain

Each subsequent mission improved on the last, both in terms of technology and onboard food. The Gemini program introduced the first freeze-dried foods made in association with Whirlpool and the United States Army Laboratory. Freeze-dried meals are pre-cooked, frozen, and then heated to evaporate the water. After being vacuum-packed, the food is able to be stored safely at room temperatures. When an astronaut wanted to grab a bite, they’d pop a few cubes of freeze-dried grub or simply introduce water into the food's pouch via a valve to reconstitute it. (The Apollo missions added the option of using hot water.)

Astronauts enjoyed chicken and vegetables, butterscotch pudding, and other treats in this manner, most in cube shapes as opposed to squeezing mush; the first food ever consumed on the moon was a bacon cube. A coat of gelatin over the food kept crumbs, which could muck up the sensitive machinery onboard a spacecraft, to a minimum. (Famously, astronaut John Young smuggled a corned beef sandwich aboard Gemini 3 in 1965 and offered to share it with Virgil Grissom, but floating crumbs forced early abandonment of the sandwich.)

These early missions also carried thermostabilized foods, which are air-sealed to avert spoilage and included the canned goods Kloeris later found in the food lab offices. (NASA eventually turned toward a pouch, which was easier and lighter to store.) This approach was championed by Rita Rapp, a pioneering food scientist with NASA who, in the 1960s, also worked to introduce “real” food alternatives—like grits you could eat with a spoon—to the more questionable cubed portions.

Apollo astronauts and those who came later got to try out some of the newer options, including the addition of Meal, Ready-to-Eat (MRE) portions, the exact same food supplied to the United States military. It wasn’t “space food” so much as Earth food blasted into space. “The inclusion of MRE entrees in the Shuttle food system was part of the improvements that were made to get NASA away from the ‘tubes and cubes’ of the Gemini and Mercury era,” Kloeris says.

But not everything was a hit. Among the returned and unopened items from the Apollo missions were beef-barbeque cubes, fruitcake, and powdered coffee with cream, all of which Neil Armstrong passed up during the 1969 Apollo 11 mission.

Because of their long shelf life, thermostabilized and freeze-dried foods were and remain the two staples of astronaut food. But the introduction of Skylab, the first “space station,” in 1973 provided a new addition to galactic food preparation: refrigeration.

“It was the most sophisticated food system NASA had ever flown,” Kloeris says. Skylab used the exterior environment to create a cooling chamber inside. Frozen foods could be stored, heated, and consumed, all thanks to the formidable solar cells used by the station. Astronauts on Skylab sat at an actual table while dining, with their feet in stirrups to keep them in place; usually, they—and Space Shuttle astronauts in the 1980s—used a serving tray affixed to the wall or their lap, opening one food package at a time [PDF].

NASA astronaut Eugene A. Cernan does his best to eat something while on board the Apollo 17 in December 1972.uacescomm, Flickr // Public Domain

Power wasn't the only challenge. When Kloeris came on board in 1985, there was already debate over the nutritional profile of the MREs. High in salt and fat, they were fine for soldiers on the move, but not so much for astronauts in a weightless environment who wouldn't be able to work off the calories. “Around 1994, we started doing product development with our scientists in the lab,” Kloeris says. “We were making our own versions of thermostabilized products.”

Space Chefs

With a decline in Space Shuttle missions and a shift to long-duration trips on the International Space Station (ISS) beginning in 1998, Kloeris and her team began to focus more on a menu variety that could sustain astronauts both nutritionally and psychologically. Omega 3-rich foods low in sodium help offset bone density loss common during space exploration. Food also had to be appropriate for the environment.

Most dishes were a success; some were not. “With something like soup, you had to check the viscosity to make sure it was thick enough,” Kloeris says. “It needs to stick to a utensil. If it’s too thin, it will just float.”

Kloeris and her team created freeze-dried scrambled eggs, thermostabilized seafood gumbo, and fajitas. Food was either flash-frozen or superheated to kill off any bacteria, then air-sealed in a process similar to canning. Once a recipe was proven stable after processing—and making it palatable could take numerous attempts—NASA's kitchen would invite astronauts in for a taste test.

Kloeris also noticed that astronauts were requesting comfort foods like Lorna Doone cookies and M&Ms, both shelf-stable. “These are commercial, off-the-shelf items. The moisture content is low enough that they will last a long time at room temperature,” Kloeris says. “We put them in the proper packaging to protect them from moisture and oxygen.”

Eventually, NASA decided that the food lab should attempt more elaborate thermostabilized desserts. At the top of the list was a favorite indulgence for many.

“We attempted cheesecake in a pouch,” Kloeris says. “We were never able to get that. It just did not look good from a visual perspective. It was overly brown.”

Cobblers and chocolate pudding cake were far more successful. Heated up in four-sided conduction ovens, they became so popular with ISS occupants that regular Space Shuttle astronauts began demanding them.

Heating food in the conduction oven or adding hot water is about as far as cooking can go aboard spacecraft because of weight and power restrictions. There was once discussion of a microwave, but Kloeris says that the modifications needed to insulate it from interfering with the onboard electronics added too much weight.

“And when you first turn it on, there’s a big power spike,” she says. “That’s going to be a problem on a space station.”

The dehydrated food enjoyed on the International Space Station.Wikimedia Commons // Public Domain

Baking hasn’t been completely absent from missions. In an experiment sponsored by the Hilton DoubleTree hotel chain in 2019, ISS astronauts baked cookies in a standard-sized oven to see how microgravity and heat affected the treats. But when it comes to appliances, there’s relatively little that needs to be cooked thoroughly that can also be safely stored. “Cooking something in a standard oven, typically that’s something raw or frozen,” Kloeris says. “We don’t have a way to get stuff safely to orbit like that.”

Space Food as Comfort Food

As far back as the Apollo 8 mission in 1968, when astronauts were served thermostabilized turkey and gravy on Christmas Eve, the psychological component to space menus has been important. Food helps keep an astronaut tethered to Earth, even if it’s only emotionally. Astronauts usually get to select a pantry of special requests—typically commercially-packaged snacks—to bring with them. Fresh food lockers allow for perishables like bread and bananas to be enjoyed while they’re still good. (Absent of crumbs, tortilla shells tend to be more popular than bread.)

If astronauts didn’t get their preferences, Kloeris heard about it. “With the ISS, we relied on cargo flights to get food to orbit,” she says. “We weren’t always able to get containers there at the right time for each crew member to eat food they selected. The cargo flight may have gotten delayed. So for part of the time in orbit, they’re eating food out of containers with someone else’s name on them that were left over from a previous crew member. It became a huge psychological issue. We had so many complaints. ‘You promised me I was going to get what I asked for. I had to eat someone else’s food!’”

One of Kloeris’s most memorable requests was from an astronaut who was filling out their preferred menu for 14 days, the length of his Shuttle mission. One of the most popular items since the 1960s has been shrimp cocktail, which consists of freeze-dried shrimp and powdered cocktail sauce. No less an authority than Buzz Aldrin declared the item “delicious.”

This astronaut checked the shrimp cocktail box for each day. And not just once. “He had shrimp cocktail for breakfast, lunch, and dinner,” Kloeris says. “And he did that for more than one mission.”

But We Digest

Save for cheesecake, almost anything terrestrial can be repurposed for space consumption. While some astronauts have complained of a loss of taste in space, that’s never been scientifically proven to occur. It may instead have something to do with fluid shifts causing nasal congestion, Kloeris says. Given enough time to acclimate and enough ketchup or hot sauce to ramp up the flavor, the problem should go away.

Kloeris, who recently retired from NASA after 34 years in the food lab, says that current meal preparation isn’t much different from those early missions, even if the food itself has gotten quite a bit more appetizing. Thanks to shelf-stable dough, pizza is possible. So is beef that’s been irradiated to kill bacteria. In the future, Kloeris’s successors will have to devise ways to design menu items that are safe as well as palatable for the five to seven years it would take to get to Mars and back.

It’s certainly possible. Of those two-decade-old canned goods found in the food laboratory office in 1987, some went to the Smithsonian for posterity’s sake. As for the ones Kloeris and her co-workers sampled? “We tasted each and every one,” she says. “They tasted fine.”