Twins Study

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Space Station Live Video NASA Commentator Pat Ryan talks with Dr. Craig Kundrot, the deputy chief scientist of NASA’s Human Research Program, about the Twins studies focusing on astronaut Scott Kelly during his upcoming yearlong mission to the International Space Station. Kelly and his twin brother, former astronaut Mark Kelly, will be subjects for a series of ten experiments in which scientists hope to learn more about how living in the space environment impacts the human body by studying identical twins, one on orbit and one on the ground.

Image Credit: NASA

Twins Front View (01/19/2015) --- NASA Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly at the Johnson Space Center, Houston Texas speak to news media outlets on Jan.19, 2015. The subject is Scott Kelly's upcoming 1-year mission aboard the International Space Station.

Image Credit: Robert Markowitz

Kelly Spin Chair (03/21/2015) --- Expedition 43 NASA Astronaut Scott Kelly takes part in the spin chair training during media day, Saturday, Mar. 21, 2015, Baikonur, Kazakhstan. Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) are scheduled to launch to the International Space Station in the Soyuz TMA-16M spacecraft from the Baikonur Cosmodrome in Kazakhstan March 27. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016.

Photo Credit: (NASA/Bill Ingalls)

Twins Study

Twins Study

The Twins Study is ten separate investigations coordinating together and sharing all data and analysis as one large, integrated research team. NASA has selected 10 investigations to conduct with identical twin astronauts Scott and Mark Kelly. These investigations will provide broader insight into the subtle effects and changes that may occur in spaceflight as compared to Earth by studying two individuals who have the same genetics, but are in different environments for one year.

The Twins Study is unique demonstration research to further NASA’s use of personalized medicine.

The Twins Study is multi-faceted national cooperation between universities, corporations, and government laboratory expertise.

The Research


 1. Human Physiology  

These investigations will look at how the spaceflight environment may induce changes in different organs like the heart, muscles or brain. 


 2. Behavioral Health  

This investigation will help characterize the effects spaceflight may have on perception and reasoning, decision making and alertness. 


 3. Microbiology/Microbiome  

This investigation will explore the brothers’ dietary differences and stressors to find out how both affect the organisms in the twins’ guts. 


 4. Molecular/Omics  

These investigations will look at the way genes in the cells are turned on and off as a result of spaceflight; and how stressors like radiation, confinement and microgravity prompt changes in the proteins and metabolites gathered in biological samples like blood, saliva, urine and stool. 

Media Items






To learn more about NASA’s Human Research Program, follow these links to: videos, engagement and communications’ articles and scientific briefs explaining physiological changes to the human body in space.

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Page Last Updated: May 28th, 2015
Page Editor: Timothy Gushanas