Differential Effects on Telomeres and Telomerase in Twin Astronauts Associated with Spaceflight (Twins Study - Bailey) - 05.30.18

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Although identical twins are genetically almost the same, differences in environment, diet and other outside factors can affect their health in different ways. The Twins Study is an integrated compilation of ten studies at multiple research centers that examines the effects of space travel on twin astronauts, one of whom stays on the International Space Station for one year, while his twin remains on Earth. Differential Effects on Telomeres and Telomerase in Twin Astronauts Associated with Spaceflight (Twins Study – Bailey) explores differences between the twins’ telomeres, protective “caps” on the ends of chromosomes that shorten as a person ages as well as when they are exposed to a variety of life stresses, to see if telomeres respond differently to spaceflight (as compared to life on earth), and then how such changes relate to the various endpoints studied by other Twins Study investigators.
Science Results for Everyone
Information Pending

The following content was provided by Susan Bailey, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Susan Bailey, Ph.D., Colorado State University, Fort Collins, CO, United States

Kerry George, Wyle, Houston, TX, United States

NASA Johnson Space Center, Human Research Program, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

Research Benefits
Space Exploration, Earth Benefits, Scientific Discovery

ISS Expedition Duration
March 2015 - September 2015

Expeditions Assigned

Previous Missions
Information Pending

^ back to top

Experiment Description

Research Overview

  • The Twins Study provides the extraordinary opportunity to control variables of individual genetic differences, susceptibilities and lifestyle factors, making differential effects observed between the twins spaceflight-specific.
  • The Differential Effects on Telomeres and Telomerase in Twin Astronauts Associated with Spaceflight (Twins Study – Bailey) investigation aims to identify spaceflight-specific factors that influence telomere length and telomerase activity, which are informative biological indicators of aging and age-related degenerative diseases (e.g., cardiovascular disease and cancer).
  • The study also seeks to establish whether accelerated telomere shortening and elevated telomerase activity are associated with spaceflight.


NASA’s Human Research Program (HRP) and the National Space Biomedical Research Institute have instituted a program to compare the effects of spaceflight accumulated over one year and observe changes in the genetic makeup between twin brothers. This project initiates a pilot demonstration focusing on the use of integrated human analyses to better understand the biomolecular responses to the physical, physiological, and environmental stressors associated with spaceflight. The project emphasis is on the collection of biological specimens and psychological testing from one twin in orbit on the International Space Station (ISS) and the collection of corresponding samples and data from his twin on the ground. Sample collection and data analysis occurs before, during and after the one-year mission.
This portion of the overall Twins Study investigation, Differential Effects on Telomeres and Telomerase in Twin Astronauts Associated with Spaceflight (Twins Study – Bailey), evaluates changes in telomere length and telomerase activity associated with the upcoming year-long ISS mission in the space- vs. the earth-bound twin astronauts, in order to identify spaceflight-specific factors that influence these informative biomarkers of aging and age-related degenerative disease (e.g., cardiovascular disease and cancer). It is hypothesized that accelerated telomere shortening and elevated telomerase activity is associated with spaceflight (as compared to the ground-based control), in a duration and severity-dependent manner; i.e., telomere shortening and telomerase activity is more affected as the time spent in space increases and as the conditions encountered on the ISS (e.g., radiation dose, nutritional, psychological, and physical stressors) increase in severity. Therefore, data sharing is especially critical to data interpretation.

^ back to top


Space Applications
Telomeres “cap” the ends of chromosomes, protecting them against damage and making it possible for cells to continue dividing. Every time a cell divides, telomeres get shorter and shorter until eventually, the cell can no longer divide and either becomes inactive or dies. This shortening process is associated with life stress, aging and age-related diseases like cancer. This investigation studies changes in telomeres and telomerase (the enzyme that maintains them) that occur during a long-duration space mission, and how these changes relate to radiation exposure, oxidative stress, immune function, metabolism, gastrointestinal microorganisms, and genetics. Results are expected to improve understanding of the effects of spaceflight on the process of aging and could lead to better countermeasures to protect crew health.

Earth Applications
Aging and age-related diseases, like cardiovascular disease and cancer, are associated with shortening of telomeres. By comparing changes in telomeres and telomerase in twin astronauts, unrelated crew members, and ground controls, this investigation seeks to identify spaceflight specific and individual factors that may make people more (or less) susceptible to accelerated shortening of telomeres. Results may improve efforts to mitigate the effects of aging and disease in people on Earth.

^ back to top


Operational Requirements and Protocols

^ back to top

Decadal Survey Recommendations

Animal and Human Biology AH16
Behavioral and Mental Health B3

^ back to top

Results/More Information

Information Pending

^ back to top

Related Websites
Main Twins Study

^ back to top


Telomere length will be assessed using TELO-FISH: Florescence in situ Hybridization (FISH) with telomere probe on chromosomes and/or interphase nuclei, which is monitored as Relative Fluorescence Intensity (RFI). Collections are coordinated with previous and on-going biodosimetry studies utilizing chromosome aberration analyses.

+ View Larger Image