Dr. Martha Hotz Vitaterna and Dr. Fred Turek, scientists at Northwestern’s Center for Sleep and Circadian Biology lab, will soon have their hands full of feces – astronaut feces, to be precise.

The researchers will handle stool from Scott Kelly, recently returned from a year in space, and from his twin brother, Mark Kelly, who stayed on Earth. These samples may provide Vitaterna and Turek with part of the key that will unlock the first manned mission to Mars.

Turek and Vitaterna are leading one of 10 research experiments in NASA’s Twins Study, examining the impact of long-term spaceflight on Kelly’s body. While some of the other research teams study changes in things like behavior and genetics, NU’s study measures the effect extended space flight has on what scientists are now calling the body’s “newest organ,” bacteria in the gut.

The Twins Study is the latest in a series of Northwestern-led programs to aid NASA’s efforts to put humans on the Red Planet. In December, two professors and a doctoral student created concrete that could be used to build shelters on Mars, and another team is experimenting with prototypes of a humanoid robot to aid the first astronauts who land there.

What are sleep researchers doing studying astronauts? Turns out, among the myriad impacts on space flight has on the human body – muscle atrophy, changes in eyesight, etc. – is insomnia.

“It’s just hard to fall asleep and stay asleep,” Vitaterna says. “It’s loud, it’s zero gravity, you kind of always have that feeling you’re upside down.”

The analysis Turek and Vitaterna are doing is not your typical high-school microbiology. Rather than looking at DNA and mitochondria, they will examine how different bacteria co-exist in an ecosystem, and what happens when sleep loss disturbs it. Vitaterna compared it to studying rainforest biomes, where changes in the diversity of plants and animals can negatively impact the entire biome. Only instead of plants and animals, bacteria, and instead of the rainforest, the gut.

The balance between “good” and “bad” bacteria is delicate. Intestines are swarming with bacteria, 10 of them for every human cell in the body, Turek says. Scientists have found that the right balance can improve mood, bolster the immune system and can even alter genetics. But the wrong balance can lead to cancer, obesity and mental health disorders such as depression.

“If we can discover which bacteria are most vulnerable to being ‘lost in space’ we may be able to reduce the risk of gastrointestinal illness in future spaceflight missions like Mars,” Vitaterna says, noting that intestinal issues have been a common complaint for astronauts.

Although Turek and Vitaterna will not have all of the data collected until this fall, they predict the diversity of microbiota will drop significantly during space flight, partially due to the limited diet of astronauts. Astronauts eat mostly freeze-dried food because it doesn’t expire, and they rarely have access to fruit and vegetables that replenish some of the good bacteria.

“If we see this big expansion [in a certain type of bacteria] in association with space flight, we’re going to want to take a closer look at that bacteria,” Vitaterna says. “In which situations is this helping, and when is it harmful?”

The study will also investigate other possible reasons for changes in bacterial diversity. Researchers believe the real question will be the extent that the microbiota levels return and whether the loss of bacteria helped their bodies adapt in space.

Researchers will collect and synthesize the results at Stanford University to create a holistic picture of space flight and health, and they hope to take preventative action against in-flight illness. Pro-bacteria measures that could result from these studies include a specially engineered astronaut probiotic, according to Vitaterna. Think interstellar Activia.

“I’ve heard NASA people refer to Scott Kelly as the pre-Martian,” Vitaterna says. “It’s an important step toward getting ready for Mars.”