We Don't Know Enough About the Biomedical Challenges of Deep Space Exploration

Although humans have flown to space for decades, the missions have primarily been in low-Earth orbit, with just a handful of journeys to the Moon. Future missions with the upcoming Artemis program aim to have humans living and working on the Moon, with the hopes of one day sending humans to Mars.

However, the environments of the Moon and deep space present additional health challenges to astronauts over low-Earth orbit (LEO), such as higher radiation, long-term exposure to reduced gravity and additional acceleration and deceleration forces. A new paper looks at the future of biomedicine in space, with a sobering takeaway: We currently don’t know enough about the biomedical challenges of exploring deep space to have an adequate plan to ensure astronaut health and safety for the Artemis program.

International Space Station
The International Space Station stretches out in an image captured by astronauts aboard the SpaceX Crew Dragon Endeavour during a fly-around in November 2021. Credit: NASA

Experiments have been ongoing for two decades on the International Space Station to assess the physiological and psychological challenges of long duration spaceflight. A suite of human studies called Complement of Integrated Protocols for Human Exploration Research, or CIPHER, are giving researchers the chance to assess the whole human response to time spent in space, and learn more about how the various systems of the body, such as the heart, muscles, bones, and eyes, adapt to long-term spaceflight.

However, the assessment in LEO might not be enough. In the new paper, “The Biomedical Challenge Associated with the Artemis Space Program,” the authors say that while the medical risk in LEO is well characterized and can be confidently managed, “the risk for extended missions far from LEO – as such required to reach the Moon and eventually Mars – would likely increases exponentially.”

“CIPHER experiments and the overall knowledge gathered on the ISS are priceless, no doubts on that,” said lead author Professor Mariano Bizzarri from the Department of Experimental Medicine at the University La Sapienza in Rome, in an email to Universe Today. “However, conditions on the Moon’s surface and, more generally, those far from LEO, cannot be simplistically equated to the ISS environment. Not only does gravity differ, but also the impact of radiation hazards and the absence of Earth’s magnetic field shall have a significant impact.”  

Bizzarri said the most significant challenge is dealing with the effects of weightlessness or reduced gravity.

Sample collection on the surface of the Moon. Apollo 16 astronaut Charles M. Duke Jr. is shown collecting samples with the Lunar Roving Vehicle in the left background. Image: NASA

“First, we are expecting that lunar gravity could impair a number of functions in a way that looks quite differently from that investigated on board of the ISS, where the body is fluctuating [being in] free fall,” Bizzarri said. “How different g values can impair biological functions still awaits a proper model of investigation.”

Therefore, an entirely new set of experiments should be fostered to cope with a number of unexpected threats, he said.

What will likely be mandatory, Bizzarri continued, is counteracting microgravity effects in some way. Perhaps the best or easiest method would be having devices to allow exercises in an artificial gravity condition.

Even better, according to the paper, would be the development of artificial gravity devices, which would pose a huge technological hurdle. Other important mitigation efforts would be a proper radiation shielding strategy, and an integrated network of biosensors that could provide a timely detection of health markers.

“[This] constitutes indispensable requirements in supporting the next generation of human space flights,” the researchers wrote. “Thereby, to achieve such endeavors we need to bring in multidisciplinary skills and technologies in an integrated way. The Artemis program offers the opportunity to advance the basic knowledge and medical technologies in fulfilling such requirements, while adopting the prudent strategy of reducing to a minimum short- and long-term risk that space travelers shall face.”

Along with NASA’s research, ESA began in 2012 to develop a comprehensive program aimed at finding some countermeasures, namely against microgravity, by assessing the usefulness of artificial gravity tools based on a short-arm centrifuge. The THESEUS program (Towards Human Exploration of Space: A European Perspective) identified three main ideas: (1) identify disciplinary research priorities, (2) put emphasis on those fields that may potentially evolve to support technological transfer for Earth’s benefit; and (3) build a network to support the program.

However, in this new paper the researchers write that an integrated, international roadmap for investigating all the issues that are critical in establishing a convincing program of medical interventions is still lacking. They suggest the main fields of research include investigations on Systems Physiology, Human-Machine Systems interactions, Radiation, Health Care and Habitat Management

Chris Cassidy, an Expedition 36 flight engineer, tests his eyesight aboard the International Space Station. Credit: NASA

But the ‘unknown unknowns’ are what likely will turn out to be the biggest challenges. For example, the recent findings that astronaut vision can be tremendously affected in space is considered a risk to human health in long-duration spaceflight. Blurry vision – or even loss of vision – would be detrimental to the success of any mission.

“What we do not know about human physiological limitations hinders our ability to plan a human exploration campaign beyond LEO,” the team said in their paper. “The most limiting factor that makes human space exploration a risky endeavor is strictly dependent on safety issues. Therefore, the principal barriers to human exploration far from LEO are those given by the limits of medicine. Namely, the question is how to assess an acceptable level of risk that can be reasonably tolerated?”

Bizzarri noted that most people – as well as space agencies — underestimate how difficult it will be health-wise for people living in space.

“People have a naive faith (fueled by media or science fiction) that on the Moon, or elsewhere in space, life can be ‘continued’ with some ’adjustments,’” he said. “There are more issues and the question is a little bit more complicated. For instance, I think that morphogenesis (the biological process that causes a cell, tissue, or organism to develop its shape) and reproduction can hardly be performed in microgravity.”

Bizzarri said his team is carrying two experiments on the ISS about these topics.

“Probably we can stay in outer space,” he continued. “Nevertheless, what can we say about the possibility of colonizing it? What will happen to our microbiota? Will our symbiotic microbes evolve into aggressive species? Does prolonged exposure to radiations/cosmic rays will exert sub-liminal effects? Conclusively, much more research and new models of inquiry are urgently needed.”

Space exploration remains a challenging task, the researchers write, and the uncertainties cannot be restricted to just the technological challenges.