Twins Study FAQs
- What was the NASA Twins Study?The NASA Twins Study encompassed ten separate research teams that coordinated and shared their data and analyses as one large, integrated research team. It studied identical twin astronauts, both now retired, and provided broader insight into the subtle effects and changes that may occur in spaceflight as compared to Earth. This is done by studying two individuals who have the same genetics, but are in different environments for one year. While Scott Kelly spent 340 days in space his brother Mark Kelly was on Earth.
- What is the difference between the Twins Study and the One-Year Mission? Scott Kelly’s One-Year Mission was a joint U.S.-Russian expedition that took place from March 2015 to March 2016. American astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko spent 340 days aboard the International Space Station (ISS) to study the long-term effects of living and working in space. For additional information on results of the Kelly-Kornienko One-Year Mission and the research conducted, click here.During Scott’s stay aboard the space station, scientists were also able to contrast the effects of spaceflight on Scott with his identical twin brother, Mark Kelly, who remained on Earth. The resultant Twins Study was composed of ten studies under the broad categories of human physiology, behavioral health, microbiology/microbiome and molecular/omics.
- Why did NASA decide to do the Twins Study?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. Twin studies provide a way for scientists to explore how our health is impacted by the environment around us – mostly independent of the physical variations that naturally occur between most of us as individuals. Scott Kelly provided a test case to measure in space with Mark Kelly providing a baseline test case on Earth.
- So it was a “nature vs. nurture” study?Yes, and epigenetics played a big role in this research. This Twins Study, however, was targeted to better understand the effects of exposure to the unique environment of space, which is very different from the environment we’re used to on Earth.Observing what physical and cognitive changes were happening to Scott in space, and comparing those changes to Mark on Earth, helped NASA understand how spaceflight influences the health of astronauts. The yearlong mission was a stepping stone to longer duration missions, like a three-year roundtrip to Mars.Mark and Scott Kelly are both former astronauts. The fact that each of these twins had shared a common career path meant that, as twins, Mark and Scott Kelly represented an exceptional case for the NASA Twins Study landmark research effort.
- What were the goals of the Twins Study?The main goal of the Twins Study was to observe what physical, molecular, and cognitive changes could happen to an astronaut from exposure to the environment of space, as opposed to regular day-to-day life on Earth. The study also helped NASA examine genomics (a field of science focusing on the structure and function of DNA) and multi-omics (multiple layers of biological data). Ultimately, the knowledge gained from the NASA Twins Study may be used to lessen the health risks to astronauts traveling in space.
- What are some of the key findings?Results from NASA’s Twins Study may guide human research for years to come. There were three major findings from this study.
- Gene Expression Changes: Samples taken before, during, and after Scott Kelly’s 340 days in space revealed some changes in gene expression (the process by which our DNA instructs body cells to make valuable components like proteins, which are used to build and repair tissue). According to the team of scientists leading the study, these changes were likely attributable to Scott’s lengthy stay in space. Mark experienced changes in gene expression on Earth but not the same as Scott in space.
- Immune System: Preliminary data from the Immunome Study indicates that the immune system responds appropriately in space as it does on Earth, should a vaccine ever be needed during long-duration missions.
- Telomeres: The ends of each strand of DNA are called telomeres. These endcaps protect chromosomes, like plastic handles protect jump ropes. Without telomeres, DNA becomes ‘frayed” and damaged, and cells don’t work properly. One of the most striking discoveries from the NASA Twins Study was that Scott experienced a change in telomere length dynamics during his flight. These changes may help evaluate general health and potential long-term risks.
- What differences and similarities did you uncover between Scott and Mark Kelly during the year in space?Retired NASA astronaut Scott Kelly (left), and retired astronaut Mark Kelly, are pictured at NASA’s Johnson Space Center.Credits: NASAThe differences and similarities between Scott and Mark Kelly during the Twins Study are still being investigated. To find out more, explore the infographs, videos, feature stories, and shareables that NASA’s Human Research Program created to present Twins Study research and explain results.
- What are the most relevant obstacles to long-duration human missions?The most relevant obstacles to a long-duration human mission include five known hazards: radiation, isolation and confinement, distance from Earth, altered gravity fields, and hostile/closed environments.
- What countermeasures are being considered for an extended stay in space?Preventative measures, or countermeasures, for mitigating the challenges associated with extended stays in space include exercise, nutrition, radiation protection, a reasonable workload, careful crew selection, new technologies for on-orbit diagnostics, and others. NASA’s Human Research Program investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration.
- When do you expect the final results to be published?An integrated paper appeared in a special edition of SCIENCE in April 2019. Individual papers may be published after the release of the integrated paper.
- Will there be more Twin Studies?Twin astronauts are very rare. In fact, Scott and Mark are the first. While a few other astronauts have had, or have, a twin, there have been no other monozygotic (identical) twins where both siblings were also astronauts.
- What are the long-term effects of being in space? How different is this mission compared with a mission to Mars, in terms of changes to human body?A mission to Mars would likely be a two- to three-year endeavor, while space station missions are typically six months in duration. A Mars mission would mean increased exposure to space radiation, higher degrees of isolation and confinement, altered gravity fields, and others. To read more about what happens to the human body in space, visit Five Hazards of Human Spaceflight or read The Human Body in Space.
- How do findings from the Twins Study help other astronauts?The findings from the Twins Study help other astronauts mostly by indicating areas for future focused research. While all research questions are not answered from this unique and isolated study, future research can be narrowed or refined from evaluating Twins Study results.
- How did the Twins Study investigations integrate with one another?From the beginning, Biochemical results were planned for inclusion with the Metabolomics and Proteomics studies because there are inter-relationships between genetics, vitamins, and ophthalmic changes. After investigators began to evaluate their findings, there were many other points of sharing. For example, Scott’s reduced body mass (Biochemical profile) correlated with spaceflight specific Telomere dynamics.Relationships were identified with comparative Immunome findings. The Microbiome team detected changes in the presence of microorganisms in the gut that correlated with multiple other spaceflight-associated changes.Just as the Biochemical Profile results supported and helped explain findings in other studies, the Gene Expression data also corroborated several research results. Gene Expression data supported the molecular basis for all of the other findings in the study, including the body’s response to DNA damage, telomere regulation, bone formation, and immune system stress.The Epigenomics team found several of the same cellular response pathways that were altered during spaceflight as other Twins investigators, suggesting that these areas may be of particular importance for long duration spaceflight. Finally, the Integrative Omics team analyzed all the biomedical and molecular data collected from the other nine research teams to produce a single, comprehensive view of how a human body responds to spaceflight.
- How can the results of the individual investigations help us on Earth?The Twins Study may improve the understanding of how spaceflight stressors alter a human’s cognitive function, metabolism, gastrointestinal flora, immune system, and genetics. Results could be used to develop new treatments and preventative measures for stress-related health risks on Earth. For example:
- Telomeres: Results from the Telomeres and Telomerase investigation may improve efforts to mitigate the effects of aging and disease in people on Earth by identifying spaceflight specific and individual factors that may make people more (or less) susceptible to telomere dynamics.
- Metabolomics: This study could provide new insight into how system-wide changes in the body, including environment-related changes in gene expression and metabolism, are related to risk factors for diseases like atherosclerosis.
- Immunome: This study contributes to a better understanding and treatment of individual immune responses to seasonal flu vaccinations.
- Proteomics: Results from this study could have implications for research on traumatic brain injury, hydrocephalus and other ailments related to increased intracranial pressure, as well as research on glaucoma and other diseases of the visual system.
- How was the Twins Study unique? Did it break any new ground for science?The Twins Study provided the first integrated molecular view into how a human body adapted to the spaceflight environment. Results indicated the dynamic nature of the responses to spaceflight, and the multitude of changes happening inside a human body. Many of the findings are consistent with previous data, and confirmed research already being pursued. Additionally, the study demonstrated how a human body remains robust and resilient even after spending a year in space. For more information, click here.
