Of all the challenges of getting humans to Mars, the one we might be farthest from solving has nothing to do with rockets, habitats, or complex water filtration systems. The big problem we have to face up to is the limitations of the human body.
Our bodies are incredibly adaptive to different environments here on Earth, but not so much when it comes to the environment on other planets.
We spoke to two experts in space medicine to learn about how you treat ill or injured patients in space and what some of the big open questions are when it comes to the health of the astronauts we plan to send out into the solar system.
This article is part of Life On Mars, a 10-part series that explores the cutting-edge science and technology that will allow humans to occupy Mars
We already know a lot about how the human body reacts to space missions thanks to two-plus decades of studies on the International Space Station (ISS). The microgravity environment there leads to a range of changes to the body, including bone loss, muscle atrophy, and the redistribution of fluids (when there’s no gravity to pull fluids down, they end up pooling in the upper part of the body), as well as other related issues like impaired vision. These symptoms appear in the typical tours of six months to one year that astronauts perform on the ISS, which is roughly comparable to the amount of time a mission would take to travel to Mars.
The good news is that researchers have found many ways to counteract these effects, such as the importance of several hours of daily exercise to prevent muscles from wasting away.
Filippo Castrucci, flight surgeon at the European Space Agency, told Digital Trends that a long-term space flight such as a mission to Mars would be in many ways medically similar to a stay on the ISS. And that means we can be reasonably confident that astronauts would be able to travel to Mars without a health emergency occurring.
“In the 20 years of permanent ISS habitation, no health conditions requiring medical evacuation have presented to date on orbit,” he said, adding that this has been helped by the careful selection of astronauts who are at the peak of health and who are monitored for at least two years before being sent on a mission. “Therefore, the likelihood of a medical event occurring on a Mars mission, although possible, is low, as the current evidence on ISS shows.”
However, a low chance of a medical emergency isn’t the same thing as no chance of an emergency. A Mars mission crew would have to be ready to deal with anything from common space-related complaints to accidental injuries to unexpected illnesses.
Every astronaut is trained in basic medical skills, and within each crew there are typically at least two members who are given extra medical training to become Crew Medical Officers (CMOs). CMOs are trained to a level similar to paramedics, and are able to use medical supplies, distribute medication, and use a defibrillator.
However, Castrucci says that even well-trained CMOs might not be enough medical support for a Mars mission, so a longer space mission would likely need trained doctors to travel as part of the crew.
“On travel to Mars with no evacuation possible, any emergency exceeding the current CMO capabilities may significantly reduce the patient chances for survival. Therefore, a physician-level capability is a requirement on extended mission away from [low-Earth orbit],” he said. “Two emergency care physicians, to ensure redundancy, with surgical and internal medicine skills should be part of the crew.”
One of the challenges of treatment on a potential Mars mission is the communication delay between the crew and Earth. When astronauts are on the ISS, medical support can be provided in real time by doctors on the ground. But as a spacecraft gets further away from Earth, communications are delayed more and more, with a delay of up to 20 minutes between Earth and Mars. That means a Mars crew would have to operate more autonomously in the event of an emergency, so support from the ground will come mostly in the form of preparations and instructions.
Procedural issues also arise when trying to use certain treatments in space, so training has to be tailored to a microgravity environment.
Castrucci gave the example of cardiopulmonary resuscitation (CPR) maneuvers, which on Earth involve the patient being faceup on a hard surface so the rescuer can use their body weight to compress on the chest. That doesn’t work in microgravity, though.
In space, craft must come equipped with special flat surfaces that are attached to the frame and to which an injured crew member can be secured. The rescuer has to secure themselves to the frame as well, so they can compress the chest without being pushed away. And they have to push harder as they can’t use their body weight in the chest compressions.
All of this makes CPR slower and harder to perform in space than on the ground, and that’s just one example of how tricky space medicine can be.
These are the kinds of challenges that come up when treating a medical issue in space, and they are mostly related to living in microgravity. Once astronauts reach Mars, they’ll get some gravity back – Mars gravity is around 40% that of Earth – but the planet will present new challenges of its own.
Mars is an extremely dusty environment and this could cause skin rashes and eye irritations, as well as respiratory irritation and congestion. That’s not to mention the fatigue, stress, and poor sleep that can be expected from a highly stressful mission, as well as the interplay between psychology and physical health.
But the really big problem on Mars is something invisible to the naked eye: Radiation. Here on Earth, our planet has a magnetosphere that protects us from radiation from cosmic rays and solar wind, but there’s no such thing on Mars. Exacerbating the problem is Mars’ thin atmosphere, which is only around 1% the density of Earth’s atmosphere.
Previous missions to Mars, like the Mars Odyssey spacecraft, have found radiation levels 2.5 times higher than those on the ISS. And there were times when radiation spiked (likely related to solar activity) to much higher levels that.
So how do you protect astronauts from this invisible threat?
We know that being exposed to radiation puts people at a higher risk for cancer and degenerative diseases, and that it can damage the nervous system. It can also contribute to the development of medical conditions like cataracts or sterility. Just recently, doctors like Manon Meerman, a cardiovascular specialist investigating the health effects of radiation from long-term space missions, have found that the heart and cardiovascular system can be sensitive to space radiation as well.
Meerman told us that one of the worrying things about radiation exposure in space is that we don’t know enough to confidently predict what the health effects would be. It’s unlikely that astronauts would get sick or die from it during a Mars mission, but in the long term, they would be at a higher risk for life-threatening medical conditions like cancer.
“If we eventually want to expand space travel to the moon or to Mars, we really have to dive deeper into what the effects of that type of radiation are on the human body.”
The information we do have about radiation in space beyond low-Earth orbit comes from a tiny sample: The very few people who have visited the moon, which doesn’t provide enough data to draw broad conclusions. We can gather more information from comparable sources such as patients who have been treated with radiotherapy or people who have been exposed to radiation in nuclear accidents like the Chernobyl disaster in 1986. But these can only provide a limited comparison.
That’s because there are two types of radiation to consider for a Mars mission: Firstly, there are galactic cosmic rays, which result in continuous exposure to penetrating ions. Secondly, there are also occasional and very powerful spikes in radiation caused by solar flares. When it comes to how each type of radiation will effect health in the long term, there’s a lot we simply don’t know.
“If we eventually want to expand space travel to the moon or to Mars, we really have to dive deeper into what the effects of that type of radiation are on the human body,” Meerman said.
With radiation being such a significant issue for space travel, it’s a topic that has seen huge growth in research in recent years. As well as traditional research methods such as animal studies, one approach Meerman and others are working on is “organ on a chip” research. This involves building a chip containing lab-created cells to simulate the responses of a real human organ. This can be used for research into which studies would be dangerous or impossible to perform on a living person.
This is a big topic of research currently being performed on the ISS, with the hope that using this method can teach us more about how the space environment affects human organs. In the future, it could be a promising avenue for research into space radiation as well.
Another approach is to simulate space radiation in labs here on Earth. Re-creating the radiation environment of space isn’t easy, though, which is why special laboratories like NASA’s Space Radiation Lab, which uses a Heavy Ion Collider to simulate radiation, are so important.
There are ideas and research about how to protect astronauts from space radiation. Currently, space agencies limit astronauts’ lifetime exposure to low levels that should not create undue risk. But for a mission to Mars, it would help to have more flexibility in terms of how long astronauts spend in space.
The most practical approach to protecting astronauts’ health is the use of shielding, in which thick sheets of metal are used to stop radiation and keep astronauts safe. Shielding can be applied to a spacecraft or a habitat, allowing astronauts to move freely inside, and there is also work being done on protective vests or suits that have built-in shielding should an astronaut need to move outside the safe environment.
The big drawback of shielding is that it’s very heavy, which is a problem for both launching a rocket with minimal mass, and for humans trying to move around while wearing a lot of extra weight.
Another approach is to look at drugs that could protect people from the effects of radiation, though we’re nowhere near having a pill tht can keep astronauts safe. An issue Meerman raised is that even if we could create effective drugs on Earth, we don’t know how these drugs would work in the space environment. The human body goes through so many changes in space that the ways drugs are absorbed might be different, and we just don’t know enough to predict what this might look like.
One final area that could potentially help keep astronauts healthy is to find ways to boost their own natural immune systems, such as by including antioxidant-rich foods in their diet. This is a promising concept as it is much easier to implement than other solutions, though this research is very much in its early stages as well.
The big issue for medical doctors like Meerman is how many unknowns there are when it comes to the health of astronauts going to Mars. We just can’t say for sure what the long-term health effects of radiation exposure might be, and we also don’t have a sure way to protect astronauts from these potential effects yet.
So while we might be technologically ready to send people to Mars right now, there’s a question of the morality of making that choice while the medical research is still in its infancy. “We should ask ourselves if we are willing to travel to Mars without knowing the exact risks we’re exposing the astronauts to,” she said. “It’s more of an ethical question than a scientific one.”