If you think astronauts just want dehydrated dinners and freeze-dried ice cream, think again. After a few days in space, they start reaching for the hot sauce.

In fact, they may start craving foods they didn't necessarily like on Earth.

"They crave [spicy] peppers, they crave sour and sweet things," says Jean Hunter, a food engineer at Cornell University. That means Tabasco sauce was definitely on the menu for space shuttle astronauts.

Why this sudden interest in hot peppers? Part of the reason may be that after arriving in space, astronauts lose their sense of smell, which largely governs the pleasurable taste of food. An example of this is coffee. "If you hold your nose and sip your coffee, you're getting just a bitter liquid," says Hunter.

Why do astronauts lose their sense of smell, and what's this got to do with a preference for fiery food? No one is sure, but there are some plausible ideas.

Michele Perchonok leads NASA's food science program. She says one possibility is what happens to the fluids in your body in a weightless environment. On Earth, gravity tends to drag those fluids downward, toward your feet. In space they go everywhere, including to your head, so after arriving in space, you begin to look like a cartoon character.

"We call it the Charlie Brown phase, because their faces have gotten more round," says Perchonok. Round, because they are retaining fluid in their heads. "And as they retain fluid, they also feel like they have a cold or they're congested, and again they're not smelling as much."

Perchonok has asked Hunter and her crew at Cornell to test the stuffy nose theory. To do that on Earth, volunteers will spend several weeks in a bed where their heads are lower than their feet to try to re-create that Charlie Brown effect.

As for the preference for hot peppers, one theory is that as the sense of smell is blocked, another starts to take its place: the heat of the peppers.

Kimberly Binsted at the University of Hawaii, Manoa is trying to figure out what the best menu options are for people whose sense of smell is diminished. And she is now recruiting participants for a Mars habitat simulation.

She plans to stock the habitats with spices and herbs and duck fat. She says duck fat doesn't weigh any more than margarine, is just as stable, and tastes better.

She's also going to encourage her participants to experiment in their food preparation. Even without fresh fruit and vegetables, Binsted says it's possible to make some interesting culinary creations.

"With powdered milk alone you can make a pretty poor mozzarella," she says. "But it's a mozzarella anyway, and after you've not had fresh cheese for several months, even a little bit of not-very-good mozzarella is a wonderful, wonderful thing. You can melt it on some toast, you can make a basic pizza. It becomes a real treat."

And besides, figuring out new food combinations can help take your mind off the stress of being locked up in a tiny space with a half-dozen others.

If the idea of pretending you're on Mars for four months is appealing to you, Binsted is still taking applications from people who want to join her simulation.



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If you're planning to take a long space voyage, say nine months or so to Mars, here's some advice: bring Tabasco or the hot sauce of your choice. That's because there's evidence that astronauts like to spice things up in space. And since NASA likes to keep its astronauts happy, the space agency is asking food scientists to help them craft a better menu for future missions.

NPR's Joe Palca tells us what might be on it.

JOE PALCA, BYLINE: After a while in space, astronauts start craving foods they might never have liked on Earth.

PROFESSOR JEAN HUNTER: They crave peppers. They crave sour and sweet things.

PALCA: Jean Hunter is a food engineer at Cornell University. She's one of the scientists who will be helping NASA design the menu for future space voyagers. Besides a taste for hot peppers, Hunter says there are other kinds of changes.

HUNTER: Foods that rely on odor are less preferred.

PALCA: That's because most of our sense of taste is based on smell, so a food that is only pleasurable for its smell isn't as yummy in space. For example, Hunter says the pleasure of coffee comes largely from its aroma.

HUNTER: If you hold your nose and sip your coffee, you're getting just a bitter liquid.

PALCA: So why do you lose your sense of smell in space? No one is sure. But there are some plausible ideas. Michele Perchonok leads NASA's food science program. She says gravity or, more properly, its absence, may be part of the problem. Hot air doesn't rise in a weightless environment.

DR. MICHELE PERCHONOK: And so, the aromas aren't necessarily going to your nose. They may be going to your elbow.

PALCA: Another possibility is what happens to the fluids in your body. On Earth, gravity tends to drag those fluids downward, toward your feet. In space they go everywhere, including your to your head. So, you look a bit like a cartoon character.

PERCHONOK: We call it the Charlie Brown face, because their faces have gotten more round.

PALCA: Round because they are retaining fluid in their heads.

PERCHONOK: And as they retain fluid, they also feel like they have a cold or they're congested. And again, they're not smelling as much.

PALCA: Perchonok has asked Hunter and her crew at Cornell to test the stuffy nose theory. To do that on Earth, volunteers will spend several weeks in a bed where their heads are lower than their feet, to try to recreate that Charlie Brown effect.

Kim Binsted, at the University of Hawaii at Manoa, says there's actually an upside to losing your sense of smell in a small, enclosed environment like a spaceship or a tiny Mars outpost. She spent four months with six decidedly non-claustrophobic colleagues in a tiny, sealed cabin in the Arctic - a Mars habitat simulation. No fresh air, no fresh food, limited water so showers were once a week. She says it was cramped, but no one complained of the smell.

PROFESSOR KIM BINSTED: We felt it was pretty normal, until we went outside at the end of our four months. And, you know, we spent a little time in the fresh air, and then went back into the habitat. And, ooh, Lordy.

(SOUNDBITE OF LAUGHTER)

BINSTED: It was rank. Absolutely rank.

PALCA: So what do you put on the menu for people who are losing their sense of smell and can't get fresh supplies for months on end? To answer that question, Binsted is now planning to run another of these Mars habitat simulations to help NASA come up with some ideas. She says because you can store it for a long time, a staple on these menus is typically textured vegetable protein.

BINSTED: It's OK. I mean, it looks like dog food. It tastes a little bit like dog food. But it can be - with a bit of creativity, it can be made into quite good food.

PALCA: And that's the direction Binsted is heading. She wants the people who will take part in her simulations to be creative with their cooking, so they can please their changing palates. She plans to give them a wide variety of spices and herbs, and as many different non-perishable ingredients as she can think of.

BINSTED: And this is great because they then take advantage of combinatorial explosion. So, from a limited set of ingredients you can get thousands and thousands of dishes.

PALCA: Even without fresh fruit and vegetables, Binsted says it possible to make some - shall we say, interesting culinary creations.

BINSTED: With powdered milk alone, you can make a pretty poor mozzarella, but it's a mozzarella anyway. And after you've not had fresh cheese for several months, even a little bit of not very good mozzarella is a wonderful, wonderful thing. You can melt it on some toast. You can make a basic pizza. It becomes a real treat.

PALCA: And besides, figuring out new food combinations can help take your mind off the stress of being locked up in a tiny space with a half dozen others.

If the idea of pretending you're on Mars for four months is appealing to you, Binsted is still taking applications from people who want to join her simulation. There's a link on our website, NPR.org.

Joe Palca, NPR News, Washington. Transcript provided by NPR, Copyright NPR.