Astronauts Are Having a Hard Time Eating Space Food, and Scientists Want to Know Why

Researchers from Australia have used virtual reality to understand why astronauts find food tasteless.

On the ISS, astronauts sometimes fail to eat enough food because it tastes bland. But astronaut food is high quality and designed to be palatable and meet nutritional needs. So what's the problem?

NASA has two teams dedicated to astronaut nutrition: the Space Food Systems Laboratory at the Johnson Space Center in Houston and the Space Nutrition Research Center, also in Texas. Both support the production and development of astronaut food, including menus, packaging, and equipment, for all NASA space programs. There’s even an Advanced Nutrition Research Group that plans for future space missions beyond the ISS and low Earth orbit (LEO).

Astronauts have access to a variety of foods. These include freeze-dried or dehydrated foods like scrambled eggs and mashed potatoes, canned foods like ravioli and meatloaf, and irradiated foods like smoked turkey. They even have unprepared foods like nuts and granola bars.

But despite all these efforts to provide a variety of quality, tasty foods, astronauts regularly report that their food tastes bland in space.

Researchers at the Royal Melbourne Institute of Technology (RMIT) are using virtual reality to investigate the cause of this problem. They have published a study in the International Journal of Food Science and Technology presenting their findings. It is calledSmell perception on a virtual spaceship? A ground-based approach to sensory data collection“The lead researcher is Julia Lowe from RMIT's School of Life Sciences.

Scientists — and the rest of us — know that smell and taste are linked. They’re both based on chemistry. The taste buds on our tongues detect five basic tastes: umami, sweet, salty, sour, and bitter. The olfactory sensors in our noses detect thousands of odors. Our brains integrate all these signals, and people who have lost their sense of smell report that food tastes bland.

Do astronauts lose their sense of smell? Is their sense of smell and taste changed in any way while on board the ISS?

“Contextual factors shape the overall food consumption experience,” the authors write in their paper. “Extreme consumption environments such as space pose logistical, ethical, and financial challenges for sensory evaluation of food products.” However, these evaluations are necessary because sensory aspects of taste and variety contribute to psychological and behavioral outcomes in space, they write. Behavioral outcomes are especially important in space for obvious reasons, and NASA and other space agencies have a vested interest in positive outcomes.

In this study, the researchers looked at three powerful food aromas: almond extract, vanilla extract, and lemon essential oil. They tested how 54 adults perceived these different aromas under normal terrestrial conditions and in a VR simulation of the International Space Station.

This image shows a simulation of the ‘space lab’ used in the VR experimental unit for smell assessment. The virtual sample appeared when subjects pressed a red button labelled ‘RMIT University’ (simulating the concept of a sensory tasting booth).

The results showed that two scents, vanilla and almond, were perceived more intensely in the simulated ISS environment. The lemon scent remained unchanged. The researchers found a sweet chemical called benzaldehyde that vanilla and almond share. They believe this chemical may be linked to the change in perception, as well as a person’s sensitivity to a particular scent.

Interestingly, a person's way of thinking and emotions also play a role in the perception of aromas.

“Increased feelings of loneliness and isolation may also play a role, and this research may influence how isolated people perceive smells and tastes of food,” says Lowe.

Scientists have studied these questions before, not just in space but also at closed, isolated Antarctic research stations. They have found that people in such conditions can experience significant changes in their sense of smell. “These results may hint at the potential impact of such conditions on olfactory function,” the authors write.

This image shows an embedded questionnaire in a virtual reality context that appears after the subject interacts with the virtual sample.

Low-gravity environments also affect astronauts. “Space travelers report changes in taste perception, indicating that food is less flavorful/palatable in space,” the authors write. “This change is initially attributed to microgravity-induced fluid shifts, which could potentially affect olfactory abilities.”

On Earth, the planet's strong gravity pulls fluids downward from the body. In the microgravity of space, more fluid can accumulate in the head. When fluid accumulates in the nasal passages, it can interfere with an astronaut's sense of smell and taste. Combined with the stress of isolation and confinement, as well as conditions inside a spacecraft such as humidity and compounds in the air, the result can be tasteless food.

After a few weeks on board the ISS, the effect wears off. However, astronauts still don’t enjoy eating. “Astronauts still don’t enjoy eating even after the fluid shift effect wears off, which suggests there’s something more to it,” Lowe says.

“One of the long-term goals of the research is to create more suitable foods for astronauts, as well as other people in isolated environments, to increase the amount of nutrients they consume by up to 100%,” says lead researcher Julia Lowe. This could extend to seniors in nursing homes, and lead to more personalized food flavors to make nutritious food more palatable. (And if you’re feeling dystopian, this could be used to make Soylent Green more delicious).

“In the future, we’re going to see Artemis missions that are going to be much longer, multi-year missions, particularly when we go to Mars, so we really need to understand the nutrition and food issues and how the crew interacts with their food,” says Gail Iles. Iles is one of the study’s co-authors, an associate professor at RMIT and a former astronaut trainer. “What’s amazing about this VR study is that it really does mimic the experience of being on the space station very closely. And it really changes the way you smell and taste.”

Food chemistry expert and associate professor Jayani Chandrapala is another co-author of the study. Chandrapala highlighted that benzaldehyde, a common chemical compound in vanilla and almonds, played a role in the results.

“In our study, we think it's what creates the intense aroma in the virtual reality environment,” says Chandrapala, from the School of Life Sciences.

Combining taste and aroma perception, emotional settings, and VR, this study addresses one of the rarely discussed aspects of future space travel beyond LEO. When discussing long-term missions to Mars, much of the focus is on protecting astronauts from hazards such as radiation, bone loss, and muscle atrophy. But nutrition is also fundamental to mission success. A successful journey to Mars and back depends on getting all the details right.

But these results also apply to people in isolated conditions here on Earth.

“The results of this study could help personalise the diets of people in socially isolated situations, including care homes, and improve their nutrition,” says Lowe.

“These results open up opportunities for innovation in terrestrial space sensory research and personalized nutrition, improving immersive tools for future research,” the authors write in their conclusion. “Such methods could extend beyond space applications and benefit populations experiencing isolation and/or crowded conditions, such as lonely elderly, military personnel, and people with limited mobility.”