Michele Perchonok sat contemplating a shrink-wrapped brick of freeze-dried mac and cheese just outside the test kitchen at NASA's Johnson Space Center.

The dish has been served countless times on the space shuttle and International Space Station. When astronauts are so far from home, this is the comfort food they crave.

But this particular entree won't be on the menu when astronauts blast off for Mars, scheduled for some time about 2030. The see-through package isn't impervious to moisture and oxygen, so the pasta could spoil before it can be eaten. Simple alternatives, like foil packages, are out of the question: They are too heavy.

"We'd like to have that solved by 2015 or 2016," said Perchonok, NASA's manager of advanced food technology.

It's just one of many issues her staff of 15 food lab scientists must ponder as they come up with a menu that's light enough, nutritious enough, tasty enough and durable enough to withstand a years-long mission to the Red Planet.

There are plenty of technological hurdles NASA must overcome before it sends humans into interplanetary space. Aeronautical engineers will have to control the Ares 1 launch vehicle's tendency to shake violently during liftoff. Usability experts must design more nimble spacesuits. Materials scientists will need to develop a substance to absorb the intense heat the Orion crew vehicle will generate as it barrels through Earth's atmosphere at 25,000 mph.

The food technology team's task may not be rocket science, but it is daunting in its own way, and just as crucial to the mission's success.

Imagine having to pack more than 6,570 breakfasts, lunches, snacks and dinners all at once -- enough meals to feed six people every day for more than three years. Imagine preparing all these meals with an allotment of 3.2 pounds of food per person per day, about one-third less than the average American eats each day on Earth. Imagine that each dish needs to have a five-year shelf life. And imagine having to transport all the meals to a dining table 55 million miles away, where cooking equipment will be rudimentary at best.

Perchonok betrays no hint of panic. Designing a menu for Mars is simply a scientific problem to be solved like any other.

"We will get there, because we won't fly if we can't do it, and I don't want to be the person responsible for that," she said.

Think astronaut food and you're likely to conjure up images of freeze-dried ice cream or Tang (which was invented by General Mills Corp., not NASA).

The first American forays into space weren't long enough to bother with food. When flights got longer, early astronauts were treated to a delicacy originally developed for pilots of U2 spy planes.

"It was like a toothpaste container with a vegetable puree -- jar baby food, basically," said Paul Lachance, a retired Rutgers University professor of nutrition and food science who worked on NASA's astronaut feeding program in the 1960s.

Some of the scientific questions on the early flights were basic. "Would stuff float, or go down the wrong tube?" Lachance said. "They wanted to see that you didn't choke."

By the time of the Apollo missions, meals resembled actual food: dehydrated sausage patties and fruit cocktail for breakfast, say, and spaghetti with meat sauce for dinner.

Today, space cuisine is more sophisticated. Favorite dishes on shuttle and space station missions include freeze-dried shrimp cocktail, irradiated beef fajitas and shelf-stable cherry-blueberry cobbler.

Yet some mundane foods remain beyond the reach of NASA's kitchen wizards. They can't concoct a zero-gravity pizza because the crust would need to be preserved differently than the toppings. Nor can they make a cheesecake that survives the preservation process without hardening.

Tastiness is a high priority, but food safety is the paramount concern for astronauts beyond the reach of advanced medical care.

NASA has multiple strategies for keeping food edible for up to two years, as required for the space station.