The Research

The NASA Twins Study was a 340-day investigation conducted by NASA’s Human Research Program (HRP). It studied identical twin astronauts, both now retired.  Scientists conducted a year-long biomedical study of the health of identical twins — Scott Kelly and Mark Kelly – while Scott was in space and Mark was on Earth.

The Twins Study offered a unique opportunity for NASA to better understand how long-term spaceflight affects a human body. Because identical twins share the same genetic makeup, they are physically very similar.

Find out more about the different research investigations in the NASA Twins Study.

The Results

Even after Scott landed back on Earth, Twins Study scientists continued to gather data and analyze the results from their biomedical investigations.  NASA’s Human Research Program has created infographs, videos, feature stories, and fun shareables to present their research and explain their findings. Read more about the fascinating results of the Twins Study investigations in a special issue of Science. For a shorter summary of the Science article, download this one-page abstract.