(CNN) -

Around 400 kilometers above the Earth's surface, the International Space Station continues its orbit of the planet.

Since the first crew arrived in November 2000, more than 200 astronauts from 15 different countries have visited the ISS. At its core, it's a floating lab, where for six months at a time six crew members work, exercise, sleep -- and eat.

Providing NASA astronauts with a nutritious diet is the job of food scientists at the Johnson Space Center, in Houston. There, Maya Cooper is part of the team responsible for about 40 percent of the food sent to the astronauts. She says her team tries to strike a delicate balance between providing home comforts and healthy food.

"There are many items that we've had on the menu that were great tasting items but recently we've had a big sodium reduction, trying to get the sodium content on the space menu down," Cooper says. "So we've had to reformulate a lot of those items, preserving the taste and the homely comfort food aspects of the food, while making sure that the nutrition is right where we need for it to be."

If Cooper makes space food sound like a science, that's because it is. Weightlessness requires more energy; your body is never truly at rest at zero gravity, so astronauts must eat accordingly, consuming 3,000 calories a day.

In the controlled environment of the ISS, scientists are able to study the astronauts' physiological processes with great accuracy. "We know exactly what they're eating," Cooper says, "so we have better data in terms of how food actually impacts the body."

Likewise, food is affected by the requirements of space. Food sent into orbit has to be preserved by heat processing which, paired with its long-term storage, causes food to lose some of its nutritional value due to vitamin degradation.

Overcoming these obstacles is one of the challenges facing Cooper, along with how to make such adulterated food appetizing.

Meals through a straw?

Read more here:

Food scientists provide meals for NASA astronauts