Around the time of Apollo 11, Wernher von Braun stated that “political will” was the main barrier to sending humans to Mars. However, recent events, such as a medical evacuation from the International Space Station in January, indicate that politics might not be the biggest issue. Instead, the challenge may lie in keeping humans healthy and performing well enough to justify the trip.
Yes, we can send humans to Mars today with the right rockets and spacecraft. The crew might survive and return to Earth, but it’s not guaranteed. However, it’s unlikely they would be able to conduct a thorough exploration and discovery that justifies the personal and national effort and sacrifice needed for the mission.
The ISS orbits 400 kilometers above Earth, shielded from radiation by the magnetic field, allowing for quick aborts and instant communication with mission control. Missions usually last six months, occasionally extending to a year.
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Lunar missions, Apollo, and now Artemis, present exciting and unique challenges that inspire innovation and resilience. The Moon, approximately 1,000 times farther away than the ISS, drives advancements in radiation protection, and while abort options require a bit more planning, they lead to robust mission designs.
Communication with mission control, though slightly delayed by seconds, fosters adaptive teamwork. Missions lasting a few weeks allow for remarkable discoveries and experiences. Apollo embarked on a bold journey filled with ambition and the spirit of exploration.
Mars is another leap entirely. On average, it is about 500 times farther from Earth than the Moon. There is no abort capability and little to no assistance from Earth due to distance and communication delays of up to 20 minutes one-way. A Mars mission would last roughly three years. It is most assuredly not just “more of the same” of what it took to get people to the Moon.
Various specific aspects of this type of mission are already under study. ISS missions provide data on long-duration weightlessness. Extended time in closed habitats, such as NASA’s HERA or CHAPEA, mimics the isolation and confinement of spaceflight.
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Antarctic winter-overs simulate these same conditions, with the added factor of an extreme environment. Weeks or months of bed rest with the head tilted down by 6 degrees can even replicate some of the effects of extended weightlessness, such as muscle atrophy and fluid shift toward the head.
But an actual trip to Mars will be the first time all of these stressors are present at the same time, for a long period of time, with no way to exit early, and with no chance for help from mission control. A Mars mission has the additional factor of extensive deep-space radiation, which is not a factor in other spaceflights.
It is the interaction of multiple stressors across multiple body systems and spacecraft systems that defines the true challenge of sending humans to Mars and demands new ways of thinking.
Many of the medical risks are understood, even if not fully solved. The body is smart and resourceful. If it doesn’t need a specific function, it gets rid of it to save energy. In space, without gravity, the body doesn’t have to work hard to stay upright or keep blood flowing to the head, which leads to weaker bones and muscles.
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Astronauts on the ISS exercise for about two hours daily to help counter these effects, but there may not be enough space for that on a Mars spacecraft. It’s unclear if Mars’ 0.38g gravity would help prevent these health issues on the surface.
The immune system and microbiome change in space. One key change is “viral shedding,” where dormant viruses like chickenpox and shingles can reactivate. Research indicates that stressors from spaceflight, like work pressure and isolation, contribute to this issue, rather than space itself being the cause.
Although viral shedding hasn’t resulted in major health issues during space missions, the thought of it happening on a longer three-year journey to Mars is concerning.
Vision changes are a significant issue for astronauts. Since 2011, those returning from the ISS have noticed problems with their eyesight. In microgravity, fluids like blood and cerebrospinal fluid shift towards the head, raising pressure in the skull.
Research indicates that this fluid can press on the optic nerve, affecting the eye’s shape and potentially harming the retina. This situation is concerning for astronauts working in challenging conditions far from Earth.
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Even more worrisome is the risk that high fluid pressure could damage brain tissue after a prolonged time in space. Some minor but reversible changes have already been observed in astronauts after their missions. No part of the body is immune to these effects.
Astronauts face cognitive and psychological challenges. They are carefully selected, trained, and highly motivated individuals, yet they still experience issues like depression, lack of motivation, and conflicts with others. While their ability to handle these problems may vary, these psychological burdens can significantly affect their health and well-being.
Some astronauts describe the “space stupids,” where concentration and task performance in space become generally harder. Interestingly, standardized in-flight cognitive tests often fail to capture these perceived deficits.
Nevertheless, given the many stressors inherent to spaceflight, even subjective effects can make it hard to perform normal work. And none of this would be any better on a mission to Mars. Dealing with these known medical effects is hard enough, and there are countermeasures for some. But there are also unpredictable issues, and we don’t know how to deal with those yet.
Take a recent example: an episode of deep-vein thrombosis (a blood clot in the jugular vein) in an astronaut on the ISS. After 60 years of sending people into space, this was the first time this phenomenon happened, and it was discovered by accident.
The condition was managed through consultation with medical experts and rapid delivery of medical supplies to the station, but on Mars, that would not have been an option; the situation could have been fatal.
What can we learn from this? No matter how well prepared, the unexpected will happen. Mars crews must be ready to not only deal with known problems but to develop new approaches to unforeseen emergencies in real time with no immediate help.
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This challenge extends beyond medicine. A Mars expedition is a complex, interdependent system of systems: crew, spacecraft, procedures, operations, and mission goals. The mission must be resilient. When things start to break down, when the crew faces the unexpected, and when anomalies that were not anticipated occur, the mission must go on, even with reduced capability and changed goals.
That means developing onboard systems capable of detecting when subsystems are not working properly and when they are not working together in harmony. Artificial intelligence and machine-learning tools can detect anomalies, alerting the crew and, if possible, diagnosing the problem, providing early warnings of later, larger problems.
Such approaches push beyond the traditionally conservative culture of spaceflight planning and engineering. But this is not grounds for despair. Building multisystem resilience for Mars will not only enable safer exploration; it will deepen our understanding of complex human systems on Earth.
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Designing missions for multisystem resilience is challenging and requires understanding the interactions between various subsystems and human crew dynamics. Currently, few organizations are addressing the disciplinary barriers that hinder this approach.
Although NASA hasn’t fully achieved this yet, acknowledging its importance in human spaceflight may drive broader efforts across sectors like air traffic control, nuclear power, and medical infrastructure.
NASA emphasizes the benefits of space travel, like microelectronics and biomonitoring, but astronauts are motivated by exploration, including a potential Mars mission that could expand our understanding of human physiology, psychology, and resilience in space.
Reference: https://www.planetary.org/articles/are-we-ready-to-send-humans-to-mars
