When astronauts head to space, they leave many things behind, not the least of which are gravity, family and normal food.

You think making dinner for your family is hard? Preparing food for astronauts is a monumental task. Space food has be tasty and nutritious, must store easily, and travel well.

NASA food scientist VIckie KloerisNASA food scientist Vickie Kloeris (at right) has worked with space food development and production since 1985. She used to be responsible for food on all shuttle flights and now manages the food system for the International Space Station — which has a four- to six-month supply of 200 different foods and drinks on board at all times. She's in the process of developing food for NASA's future mission to Mars, which will likely take place sometime in the 2030s.

NASA provides food for the United States Operating Segment (USOS) crew on the ISS, which includes U.S., European and Japanese astronauts. Russia provides food for its three cosmonauts.

We talked to Kloeris about the program's challenges, biggest successes (and flops), and what astronauts like to eat when they finally get back home.

What are the challenges that you face when creating food for space?

Vickie Kloeris: Probably our biggest constraint is that we do not have refrigerators or freezers for food, which means everything has to be shelf stable and has to last a very long time. Virtually everything (the astronauts) are getting in their diet is processed food. They get a very, very limited amount of fresh food. When a cargo vehicle goes up and docks — whether from here or from Russia — it will have a very small quantity of fresh food, things like apples. It doesn’t come very often, and it obviously won't last long. When they get it, they usually eat it right away. They crave it. Because there's not a lot of fresh food in their diet, that makes the nutrition challenge even harder.

astronauts get fresh food delivered on the space station

Astronauts on the International Space Station are excited about the delivery of fresh fruit and vegetables. (Photo: NASA)

What's unique about a mission like the one to Mars?

You're looking at roughly a three-year round trip. It will take six months to get there, they'll stay there about 18 months until Mars and Earth realign, and then it's another six months coming back. We pre-position the food — launch it ahead of the crew so it's waiting for them when they get there — so the food they eat on their return trip is going to be 5 years old. You can make shelf-stable food last for a long time, but what will it taste like after five years and how much nutrition will it have in it? Even though it can last forever from a microbiological standpoint, there are still changes that occur: nutritional degradation, color changing, flavor changes.

What potential concerns are there?

If you're short of some critical nutrient, you could be in the situations the early explorers were and all of a suddenly your crew members have scurvy because they're missing some important nutrient. There are a lot of studies to indicate that if food quality is low in a closed food system, people will eat enough to survive but they won't necessary eat enough to thrive.

NASA astronaut Leland Melvin floats with food on the International Space Station

NASA astronaut Leland Melvin floats with a pack of food — and scissors to open it —on the International Space Station. (Photo: NASA)

How much of a psychological impact can food have?

When I first came to work here, all we were flying was shuttle flights and they were only two weeks long. At that point from a psychological perspective, food was not that important. It was kind of like a camping trip: "I'll find something I can eat."

As missions get longer, the importance of food has increased. We have heard from more than one crew member that food is one of the most importance aspects of staying on the space station.

What form is the food in?

food rehydration station on the International Space StationWe use a lot of thermostabilized products — they're like cans but we do ours in pouches because they're lighter in weight. We have rehydratable food [that's a food rehydration station at right], a few meat products that are irradiated, intermediate moisture food like dried fruit and beef, natural foods that we don't further process like cookies, crackers, candy, and nuts, and freeze-dried food where they just add water. Beverages are powdered. They add water and drink them through a straw.

Sometimes they're going to be bringing back frozen medical samples and they have an empty freezer on an uphill trip. So occasionally we can send little cups of ice cream when the freezer is empty. There's no place to store it, so they have to eat it right away, which is fine with them.

Do the astronauts ever have requests?

On the shuttle we used to do a 100 percent personal preference menu. They chose exactly what they wanted from our list of available products. It didn’t work going into the space station. Because of the way cargo vehicles launched and changes to the schedule, we wouldn’t be able to get the food to the crew members. Part of the time they would be eating food someone else had selected. That was a huge psychological issue, and you wouldn’t believe the complaints we got.

On the space station we switched to a standard menu. We allow them to augment that with crew-specific food. They get certain containers during their stay with their name on them, and they select what they want. They also get family-provided crew care packages with commercial products like their favorite cookie or candy.

How do you test foods before you send them to space?

We have a sensory evaluation facility here, a sensory booth. We have a group of volunteers who come in and taste the food for us and the food scientists taste it. We offer to let the astronauts participate too, but they're often way too busy.

NASA food scientist Vickie Kloeris tests food

Kloeris tests space food with panelists, including astronauts. (Photo: NASA)

What have been some of your biggest successes?

One of the things we brainstormed was "What do we need? What are we missing?" And we identified desserts that you could warm up. All we had were commercial off-the-shelf things. We made cobblers, chocolate pudding cake — thermostabilized in a pouch. Those have been incredibly popular, a nice psychological addition to our menu.

Astronaut Sandra Magnus eats food on the International Space StationAny failures?

We used to fly graham crackers. At some point we totally gave up on them because we got so many complaints from the crew about how many crumbs that created in orbit.

There's a lot of research about omega 3 fatty acids from fish being beneficial, so we try to develop more fish products. One of the issues with fish is that it created a lot of odors. It smelled bad, especially in shuttle, because you're in a closed environment. If you opened fish in any form, a lot of people would say they didn’t want it on their flight.

What is the first thing astronauts want to eat when they get home?

I've heard everything from pizza and beer to a salad bar. They've had so little fresh items that they really do crave the fresh stuff a lot. Or it's, "Man, I want a good hamburger." Real ice cream is something they crave when they come back as well. It varies from person to person.

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Bottom photo: Astronaut Sandra Magnus prepares to eat a taco on the International Space Station. (Photo: NASA)

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.