What could going to Mars do to your body?

As our own planet heaves a final dying breath, it’s time to start thinking about our move to Mars. Four spacecraft are expected to head to Mars next year and three Mars-sample return missions are currently in their developmental stages. If successful, they’ll not only bring back specimens which will tell us what we can expect to find on the red planet, but in getting them home, we’ll be significantly closer to cracking the code of how to bring humans back from Mars too (no spacecraft has managed the return journey yet).

On average (it changes regularly), there are 140 million miles between us and Mars, but it’s not just the distance that makes it tricky for us to stop in.

Heading into deep space poses numerous risks to physical and mental health. For a start, there’s prolonged exposure to radiation. On Earth, we are protected from 99.9% of the universe’s harmful radiation thanks to our magnetic field. When we venture outside of it though, it’s a different story. The ​“radiation environment” in space is made up of charged particles – everything from hydrogen up to iron. All of these are energetic and very fast. Travelling at speed, they can penetrate a spacecraft and everything in it – us fleshy humans included. In the process, they rip through DNA molecules, and can damage or even divide them, leading to a huge number of illnesses – for instance, cancer.

Obviously we’ve sent man into space before but the amount of time that astronauts currently spend in space isn’t long enough to cause any long-term damage (or so research suggests). An astronaut working on the International Space Station (ISS), for instance, will typically spend about six months there. For a mission to the moon – the crew aboard Apollo 11 managed it in just over eight days.

But a trip to Mars? You’re looking at roughly nine months just to get there, a further three to four months on the planet waiting for it to align with Earth so that the return journey is as efficient as possible, and another nine months to travel back. That’s 21 months in total. What sort of damage could radiation do in that time?

It’s a question Professor Charles Limoli and a 16-strong team of researchers set out to investigate. In a newly-established low dose-rate neutron irradiation facility in the United States, over a period of six months, 40 mice were exposed to neutron irradiation of the same dose-rates found in deep space.

LEARNING AND MEMORY IMPAIRMENT

The research, which was published by the journal eNeuro last month, uncovered some interesting results – and by ​“interesting”, we mean terrifying. In short, chronic radiation exposure produced both neurological and behavioural defects in the mice. ​“The animals showed significant learning and memory impairment,” explains Limoli. “[And they] showed significant impairment in almost every one of our behavioural tests.”

“I’m not going to say this is exactly what’s going to happen to astronauts – translating this work to humans is an imperfect science,” Limoli adds. ​“But suffice to say, when you look at the impairments, and the magnitude, and you run some of the algorithms … there is a concern that astronauts could develop some mission critical performance decrements.”

Though the researchers can’t accurately predict what the ​“mission critical” impairments the astronauts might suffer are, Limoli says that, ​“If they encounter an unexpected situation, or have to do some on-the-spot problem-solving, some reasoning or quick decision-making, they may be prone to making a mistake.” Basically, they’ll be space drunk. Not exactly ideal when you’re a hundred million miles from home. While the experiment revealed the mice’s memory problems seemed to be linked to adaptive-learning rather than long-term impairment – ​“I don’t think, for example, you would forget your parents or your best friend” – depending on the amount of time an astronaut is exposed to this radiation, longer-lasting effects couldn’t be ruled out.

NERVE DEGENERATION

Neuro degeneration occurs naturally through ageing, however, exposure to radiation can make it happen quicker. We know this because cognitive impairment has been reported by some cancer patients who have undergone radiotherapy for the treatment of brain tumours. It is therefore possible that following deep space travel, astronauts might experience this as well.

Limoli says ​“enhanced demyelination” is another potential outcome. Myelin insulates our nerves; when it’s damaged, the nerve deteriorates (hence ​“demyelination”). This can lead to demyelinating illnesses, the most common of which is multiple sclerosis. ​“They could [also] show some early signs of dementia,” Limoli adds.

As radiation is one of the biggest potential problems of sending man to Mars, it’s also the one that is being researched most. Sue Horne, Head of Exploration at the UK Space Agency, says there are a number of solutions currently under consideration. ​“There’s some speculation about building a mini magnetosphere around the spacecraft to protect it from the environment,” she reveals. ​“I’ve even heard of some research looking at hibernating animals, which are less susceptible to radiation doses. Could you put your astronauts into deep sleep mode?”

The most obvious solution, she says, would be to use lead in the construction of the spacecraft. Lead is of high density and high atomic number and is capable of reducing the impact of certain kinds of radiation. However, it would be impractical to build a spacecraft out of it, because it’s incredibly heavy so the rocket power needed to launch it into space would be huge.

Instead, NASA are looking into the development of hydrogenated boron nitride nanotubes, a new, lightweight material made up of minuscule nanotubes of carbon, boron, and nitrogen, with hydrogen interspersed throughout the empty spaces left in between the tubes. Hydrogen makes for an effective radiation blocker as it’s a similar size to the charged particles in space, while boron is ​“also an excellent absorber [of] secondary neutrons,” says NASA.

Limoli doesn’t think the answer lies with a nifty new spacecraft. ​“There’s really no magical configuration or material that protects you,” he argues. ​“We’re coming up with some pharmacologic countermeasures to protect the body and brain of the astronaut against the adverse affects of radiation exposure. We have a number of candidate compounds that are able to reduce the oxidative burden in the brain to reduce inflammation. And we think by the time NASA sends an astronaut to Mars, we will probably have some agents that are pretty helpful in preventing some of [the problems].”

Still, he adds, ​“We can’t stop the radiation from going through the ship. We can’t stop the radiation from going to the brain and the rest of the body. So part of this research is to understand what the consequences of that are so NASA’s not catastrophically surprised. You have to go up there and be prepared for what space radiation environment can do to you. After that, we can start to develop countermeasures to mitigate the effects of the radiation exposure on your health.”

VISUAL DEGRADATION

If the health risks posed by radiation exposure weren’t enough, there is also the matter of those caused by prolonged exposure to zero-gravity. These could include – and get ready, because it’s a long list – a loss of bone density (owing to mineral loss), which could leave you open to such nasties as fractures on account of osteoporosis; a loss of muscle strength, if not enough exercise is taken during the mission, which is likely as exercising in space is difficult; cardiovascular de-conditioning, since floating requires little physical excursion; the development of kidney stones, owing to dehydration and calcium secretion from the bones; and vision impairment.

It’s the latter that has made headlines in recent years. It is not known why exposure to zero-gravity can cause problems to sight, although the most recent theory is that it comes down to a newly coined syndrome, ​“visual impairment intracranial pressure” (VIIP). In a nutshell, gravity usually pulls cerebrospinal fluid downwards towards the feet, but in zero gravity, more of this fluid flows into the head. This increases pressure on both the brain and the back of eye, flattening it, and this, it is believed, leads to sight problems – for instance, farsightedness.

It’s a common complaint of astronauts. Research carried out by the US National Academy of Sciences involving 300 astronauts since 1989, revealed that, of those who spent between five and six months aboard the ISS, 60% reported impairment to their vision – and the problem wasn’t exclusive to those who did long-term stints in space either; 29% of astronauts who spent just two weeks in space, on shuttle missions, also reported ​“degradation of visual acuity”. The fear is that this could lead to permanent blindness, the longer a person remains in space.

LUNG DISEASE

While those are some of the predicted health risks of travelling out to Mars, they don’t account for what man may come up against on the planet itself. Perchlorate, a chemical compound, has been found on Martian soil – a potential source of oxygen, perhaps, but it’s incredibly toxic to humans and ​“can cause problems with the thyroid,” Horne explains.

“There are also silicates [minerals] such as olivine, pyroxene and feldspar, which, in dust form, can cause lung disease,” she adds.

It’s possible space suits could be designed to mitigate some of these threats, however as Horne says, ​“we found, on the moon, that the dust gets into the astronaut’s space suits and in the mechanisms”. In short, they may not make effective armour. And in case you’re wondering whether space suits might make effective radiation-repelling armour on Mars instead, Horne says that while this will be looked into, ​“it may not be possible to do much with the space suit”.

She says instead: ​“One of the thoughts is to have an inflatable habitation [or tent] that you then pile Mars soil over… so that depth of soil will protect the astronaut inside. So the only [time they] would get the radiation dose is when they go outside.”

PSYCHOLOGICAL ISSUES

It’s a long shot, but if there was a way to sidestep the health risks, the length and conditions of the mission would surely take a psychological toll. After all, not many would choose to spend up to two years in an enclosed space, in the company of a handful of people, away from family and friends and, you know, nature, and for good reason too.

“My biggest problem with going to Mars is the current length of time the trip would take, and being confined with four or five people… I think would be a strain,” Limoli says.

Of course, the selection process would be stringent, and there would be intensive training involved. As Horne explains, historically, astronaut selection has been biased towards people who are stretched by less physically active endeavours (think, IT gurus); those who are team players; and people who can manage differences with others that will undoubtedly happen over that period of time in such a confined space.

But regardless of how suitable a person might be, and in spite of rigorous training, as NASA points out, behavioural issues ​“are inevitable”. If you don’t experience them on account of radiation exposure, you may experience a different form of them anyway, owing to the cooped up conditions of travel. Such issues may include a decline in mood, cognition, morale or interpersonal interaction. Depression is listed as another a possible consequence, and fatigue perceived as also ​“inevitable”.

Other pointers to note, the absence of fresh food could also impact cognitive function – not to mention physiological functions – and the time it takes to contact Earth may add to feelings of isolation, frustration and loneliness. ​“Once you’re out on Mars, it takes 20 minutes for a signal to get there from Earth, and then 20 minutes the other way back,” says Horne. ​“So you can’t have a [normal] conversation. It’s more like letter-writing – if you ask a question, it would be an hour before you got the answer back.”

This tardy communication rate would become norm. In an age when we expect instant responses to everything from WhatsApp messages to emails – when you feel like tearing your hair out if your web page takes more than seconds to load – how easy would that be to adapt to?

All things considered, is a trip to Mars worth it? For humanity, perhaps, but for the individual it seems a bit dicey. Elon Musk thinks we’re four years away. Limoli says 20. Horne suggests 30. Time will tell. Though with the recent discovery of methane on Mars suggesting there could be life – microbial – on the planet, would it even be appropriate for us to disturb it? Just because we might, one day, find a way to get to and from Mars safely, given what we’ve done to our own planet perhaps the question is, should we chance it?

Read our article with Alyssa Carson who has dedicated her young life to taking part in a mission to Mars.