Dr. Dean M. Olson | Photo: Dr. Dean M. Olson
U.S.A. As humans conquer new frontiers in outer space, we are met with further challenges to our health. Researchers and scientists, especially those who focus on aerospace medicine, are working to better understand what exactly space travel and no gravity do to our bodies both physically and mentally. Here Dean M. Olson, M.D., M.S., M.S., director of the Division of Aerospace Medicine at the Wright State University Boonshoft School of Medicine, sheds some light on the impacts of space travel on human health, overcoming these obstacles and the ethics of sending astronauts to space.
New missions and research reveal constantly new health risks and issues that arise during space travel. What are some of the most recent discoveries and do they have long-term effects?
Dr. Dean M. Olson: Some of the recent discoveries pertain mainly to astronauts who are on long duration missions. Most recently this includes visual impairment and increased intracranial pressure. This was discovered several years ago; however it was unknown at the time whether the changes that took place would be permanent or not. It appears that with some astronauts changes have remained and with others their condition has improved. One must remember that there is biologic variation from one person to another and although there may be a general response across a population, there still may be individual variation. There are current efforts looking into the cause of the physiologic changes as well as why some people recover and others don’t.
Because of the high radiation levels in space, the National Aeronautical and Space Administration attempts to regulate radiation exposure to astronauts during missions. A rule states that astronauts can be exposed to radiation as long as their chances of cancer do not increase by more than 3%. How is that controlled for, and is this an exact science?
Radiation exposure measurement and management is not an exact science. The basic approach to management is to keep an ongoing radiation exposure record for each astronaut. The record includes any exposures from the period before they became employed as an astronaut, such as any prior occupational exposures or medically related imaging exposures. While employed as an astronaut, exposures are monitored and recorded. Radiation monitoring also takes place in flight and is recorded in the astronaut’s records. In-flight monitoring takes place within the spacecraft and on the astronaut using dosimeters. The dosimeters can provide information on the type, the dose, and the dose rate of the radiation. Also, chromosomal abnormalities can be measured in blood cells of astronauts before and after flight to aid in determining the dose of astronaut radiation exposure. This is called biodosimetry and it can also give an idea of the biologic effect of the exposure. Based on the measurements and exposure history, decisions can be made about future job duties and mission assignments.
One element of astronaut health that is often overlooked is the psychological effects of space travel. What are some aspects of mental health that astronauts struggle with during and after missions?
There are significant challenges to long duration spaceflight from a behavioral health perspective. These include psychiatric and cognitive disorders. Psychological adaptation both in the space environment and upon returning to Earth can be a significant challenge. During flight, stressors that can affect astronauts include isolation, sleep and circadian rhythm disorders, and interactions from a human perspective with the spacecraft systems. Earth-based isolation studies have reported apathy, depression, and anxiety in some volunteers. Upon returning to Earth astronauts have significant demands including debriefing from the flight portion of the mission, continuation of the mission through ongoing medical testing, and time demands for public affairs. Not only can this be a stress on astronauts, but it can also have a significant impact on their family. NASA behavioral health programs are proactive in monitoring and facilitating astronaut behavioral health both on earth and during flight.
Scientists have developed exercise regimes for astronauts to counter bone deterioration during space missions. What are some other health issues that can be preventatively targeted aboard a spaceship?
To name a few, other health issues associated with long duration spaceflight in microgravity include muscle loss, neurovestibular effects, cardiovascular changes, immune system changes, and gastrointestinal changes. Currently, countermeasures are targeting these changes with varying degrees of success.
Humans are clearly made for Earth, not space. Do you think we’ll ever be able to overcome all of our physical limitations to space travel or will there always be some unforeseeable obstacles?
It should be expected that no matter what new endeavor we undertake as a society, we will always experience unforeseeable obstacles. As our knowledge increases and new discoveries are made, I do believe we have the ability to overcome our physical limitations to space travel. This may come in the form of new engineering technology or advanced biomedical capabilities or a combination of both. The key at this point in time is to continue our efforts at making new discoveries.
As space voyages increase in length, what further health impacts on the human body do you anticipate?
This is a very complicated question and there is no simple answer. Biologically speaking, within the multitude of factors, it partially depends on the genetics of the selected individuals, the spacecraft environment, the mission goals, the duration of space flight, the design and type of spacecraft, and any potential planetary bodies encountered. These few factors are very significant, but are within a sea of factors that could affect astronaut health.
Another significant and interesting factor to consider, as an example, is the distance traveled away from Earth. No one has traveled further than the moon away from Earth. Earth has always remained relatively large within our view. As astronauts travel far enough away, say to Mars, the earth will simply become another star to be seen out the window of a spacecraft. A great example of this was the photograph of Earth from the surface of Mars taken by NASA’s Curiosity Mars rover that was in the news in early February of this year. This could have a significant psychological impact on the astronauts who first have that experience. Perhaps we will live to see the day where that mission is undertaken and we have a chance to make new those new discoveries.
Because a lot is still unknown about the impact of space travel on the human body, is there an ethical component to space programming and research? How do scientists decide when astronauts can take certain health risks?
You’re correct, there are significant risks associated with space flight and there is an ethical component that needs to be considered. At this point it is known that long duration spaceflight in microgravity can cause significant temporary and permanent physiologic changes. I would venture to say that every astronaut is well aware of the known risks involved. Many people have argued, however, that humans have a strong desire for exploration and discovery. Although space travel may pose significant risks, it is not much different in concept than early sea travelers sailing out on the ocean in search of new discoveries and foreign lands. There were many inherent and deadly risks associated with sea travel until our knowledge grew and our technology improved to make it a safer endeavor. We will experience a similar situation with any new form of exploration. Space travel is no exception. Additionally, our efforts in spaceflight have brought about many significant advances in scientific knowledge, technology, and improvements in our lives. Although these risks currently remain, many are willing to venture into this environment in search of rewarding societal benefits and new discoveries. The goal is to continue to discover and learn in order to make spaceflight as safe as possible.
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Dean M. Olson, M.D., M.S., M.S., is the director of the Aerospace Medicine Residency Program and an assistant professor of community health in the Division of Aerospace Medicine at the Wright State University Boonshoft School of Medicine. Wright State University’s NASA-funded program is the oldest civilian aerospace medicine training program in the United States. Dr. Olson earned a master’s degree in engineering mechanics and astronautics from the University of Wisconsin in 1993. He earned his medical degree from Medical College of Wisconsin in 2000. He completed a residency in family medicine at St. Mary’s Family Practice in Colorado in 2003. He also earned a master’s degree in aerospace medicine and completed his residency in aerospace medicine from the Wright State University Boonshoft School of Medicine in 2012. He is certified by the American Board of Preventive Medicine in aerospace medicine.