Scott Kelly has a habit of floating through the workweek.
For the past year, the American astronaut has orbited Earth inside the International Space Station as part of an audacious NASA experiment.
The 342-day mission’s unprecedented duration and ambitious scientific endeavor — 10 parallel projects involving Scott and his Earthbound twin, Mark — will allow researchers to investigate the effects of space on the human body over time.
Northwestern’s foray into NASA’s Twins Study began about two years before Scott Kelly was launched into space on March 27, 2015.
“The Year in Space mission had already been planned, but the scientific aspects had yet to be completed,” says Fred Turek, director of Northwestern’s Center for Sleep and Circadian Biology (CSCB) and the Charles E. and Emma H. Morrison Professor of Biology, recalling his 2013 visit to the Johnson Space Center in Houston. “We saw a calendar that accounted for every 10-minute segment of Scott’s time and were asked to design research proposals related to the Twins Study that could fit within that demanding schedule.”
Turek, along with CSCB deputy director Martha Vitaterna and collaborators from Rush University Medical School and the University of Illinois at Chicago, comprise the research team studying how space affects the 1,000 or so species of bacteria — the microbiota — living inside the stomach and intestines, or gastrointestinal tract.
The diverse microorganisms that inhabit the GI tract influence a person’s normal physiology and susceptibility to disease. Despite the clear importance of the microbiota for maintaining overall health on Earth, how the rigors of spaceflight affect the gut remains unknown.
NASA’s Twins Study has been designed to integrate Turek and Vitaterna’s work with nine other projects centered on ‘omics,’ the characterization and quantification of large pools of biological molecules that result in the structure, function, and dynamics of an organism. The data-rich biology projects, led by researchers throughout the nation, will also examine bone and muscle loss, vision problems, and more.
“In the months after Scott’s return to Earth in March 2016, we should be able to determine the sequence of events that occurred within his body while he was in space and compare that with similar data collected on his twin brother, Mark, a retired astronaut,” says Vitaterna.
Experts on circadian rhythms, Turek and Vitaterna opted to pursue gut research with NASA following publication of their 2014 PLOS ONE article, “Circadian Disorganization Alters Intestinal Microbiota.” That study showed for the first time that while the microbiome was affected when the circadian clock — the internal regulation of our day-night cycle — was disrupted, the effects were greatly amplified by a high-fat, high-sugar, Western-style diet.
Of Mice and Men
In June, the multi-institutional team began planning for a follow-up to the Twins Study that will involve sending mice to the International Space Station. Preliminary terrestrial research will occur in the coming months to establish a protocol, with the experiments in space beginning in two to three years.
“It’s an honor to be among NASA’s first life science projects funded since the completion of the International Space Station and the rejuvenation of America’s space biology program,” says Turek.
The researchers will study genetically identical mice in space and on Earth. The project aims to examine the effects of long-term spaceflight on hundreds of different microbes in the animals’ GI tracts, as well as the impact of microbiota changes on physiology and behavior.
The mouse study will allow researchers to examine physiological systems that cannot be investigated in the Kelly twins because of limitations placed on human studies.
As longer-duration space missions are anticipated — a trip to Mars and back is expected to take about two to three years — understanding how the gut microbiota might be altered in zero gravity will be important to support crew health and performance for future voyages. Such research can also shed light on other environmental factors associated with humans in space, such as increased exposure to radiation in different forms.
Turek and Vitaterna’s research may also reveal how humans might overcome GI problems here on Earth.
“It’s clear that altering the microbial ecology has implications for immune function, digestive health, metabolic health, circadian rhythms, and stress responses, but we aren’t yet able to predict the optimal state for coping with such health challenges,” says Vitaterna. “Our results are certainly going to provide some surprises, but ultimately they will teach us how to maintain a healthy microbiota in space, and therefore, healthy lifestyles on Earth.”
Three Decades of NASA Collaboration
Turek’s relationship with NASA stretches back nearly 30 years to 1987, when he was appointed to the National Academies of Sciences, Engineering, and Medicine Committee of Space Biology and Medicine. As an oversight committee, the CSBM was responsible for making recommendations to NASA regarding all life sciences issues. Turek remained a CSBM committee member for eight years, serving as chair for the second half of his tenure. Ahead of John Glenn’s historic return to space in 1998, Turek was part of a small working group made up of circadian, sleep, bone, and muscle experts who gave recommendations to NASA on the benefits and risks of putting an older astronaut into orbit. From 2001 to 2007, Turek sat on the board of trustees of the Universities Space Research Association, a nonprofit nongovernment entity that did contract work for NASA. He has also carried out NASA-supported experiments in microgravity during parabolic flights on the KC-135 aircraft. In 2013, NASA asked Turek and other investigators to explore the possibilities of conducting research during the Year in Space mission.