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Abstract
Purpose
My journey to the stars began as I – along with the whole world – stood still and watched Neil Armstrong take those first small steps on the Moon. Fast forward 50 years and NASA astronauts Scott Kelly and Christina Koch each spend nearly a year in space aboard the International Space Station (ISS), a remarkable multinational collaborative project and floating U.S. National Laboratory that has supported continuous human presence in low Earth orbit for the past 20 years. Marking a new era of human space exploration, the first commercial rocket, SpaceX Falcon 9, recently launched NASA astronauts Doug Hurley and Bob Behnken in the Crew Dragon spacecraft Endeavor to the ISS and returned safely to Earth. NASA and its commercial partners are rapidly advancing innovative space technologies, and with the recently announced Artemis team of astronauts, plans to send the first woman and next man back to the moon and establish sustainable exploration by the end of the decade. Humankind will then be poised to take the next giant leap – pioneering human exploration of Mars.
Conclusions
Historically, fewer than 600 individuals have participated in spaceflight, the vast majority of whom have been middle aged males (35-55 years) on short duration missions (less than 20 days). Thus, as the number and diversity of space travelers increase, a better understanding of how long-duration spaceflight affects human health is essential to maintaining individual astronaut performance during, and improving disease and aging trajectories following, future exploration missions. Here, I review findings from our NASA Twins Study and Telomeres investigations, highlighting potential mechanistic roles of chronic space radiation exposure in changes in telomere length and persistent DNA damage responses associated with long-duration spaceflight. Importantly, similar trends were observed in prostate cancer patients undergoing intensity-modulated radiation therapy (IMRT), additional support specifically for the role of radiation exposure. Individual differences in response were also observed in both cohorts, underscoring the importance of developing personalized approaches for evaluating human health effects and long-term outcomes associated with radiation exposures, whether on Earth or living in the extreme environment of space.
Acknowledgements
The authors express their sincere appreciation to the NASA astronauts and volunteers, and the Baylor Scott & White prostate cancer patients who made the studies highlighted here possible. They also thank the NASA Twins Study investigators who contributed to these studies.
Disclosure statement
S.M.B. is a cofounder and Scientific Advisory Board member of KromaTiD, Inc.
Data availability statement
Raw and processed individual telomere length (Telo-FISH) data files and chromosome aberration score sheets (dGH) are available for download at https://github.com/Jared-Luxton/.
Additional information
Funding
Notes on contributors
Susan M. Bailey
Susan M. Bailey, PhD, is a Professor of Radiation/Cancer Biology in the Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado USA.
Jared J. Luxton
Jared J. Luxton, PhD, received his PhD in Cell and Molecular Biology from Colorado State University researching health effects of long-duration spaceflight. He is a Data Scientist at the United States Department of Agriculture.
Miles J. McKenna
Miles J. McKenna, PhD, received his PhD in Cell and Molecular Biology from Colorado State University researching health effects of long-duration spaceflight; his interests include cytogenetics and microscopy.
Lynn E. Taylor
Lynn E. Taylor, MS, is a Senior Research Associate in the Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado.
Kerry A. George
Kerry A. George, is a Senior Scientist at KBR, Houston, Texas, who specializes in the cytogenetic effects of space radiation and supports NASA's Human Health and Performance Program.
Sameer G. Jhavar
Sameer G. Jhavar, MD, PhD, is a radiation oncologist at Baylor Scott and White Hospital in Temple, Texas; his interests include translational cancer research.
Gregory P. Swanson
Gregory P. Swanson, MD, is an Affiliated Professor of Radiology at Texas A&M College of Medicine and Clinical Professor of Radiation Oncology at the UT Health Science Center San Antonio; he has treated 4000-5000 cancer patients with radiation therapy.