One topic that really excites me is that of the human exploration of space. In October of last year, former US president Obama announced the US’ ambition to send people to Mars in 2030. This was, of course, a very exciting moment, however, were the Mars-bound astronauts to leave today, they would be confronting some very serious health risks.
Firstly, they would face the usual risks that any astronaut would face. A few examples are:
Kidney stones: This may happen because our bones demineralize in a weightless environment, and this releases salts such as calcium phosphate into the blood. These salts can concentrate in the kidneys, and in time may form kidney stones.
Cardiac problems: Thanks to microgravity, the heart doesn’t work as hard in space, which can cause a loss of muscle mass which could initiate arrhythmia and heart failure.
Radiation: Perhaps the risk that heeds the greatest accentuation for this situation – one mission to Mars could expose an astronaut to two-thirds of their safe lifetime limit of radiation. In terms of accumulated dose, it’s like getting a whole-body CT scan once every five or six days.
Galactic cosmic rays (GCR) are the main cause of this. These rays are made up of atomic nuclei from which all of the surrounding electrons have been stripped away during their high-speed passage through the galaxy.They come from other stars in the Milky Way and even other galaxies and exposure to them brings Mars-bound astronauts the very much increased risk of facing chronic dementia.
Hence the big question – will astronauts traveling to Mars remember much of it?
Studies have shown that test rodents’ exposure to charged particle irradiation (made up of fully ionized oxygen and titanium) – mirroring those found in galactic cosmic rays that bombard astronauts during extended space flights – caused them significant long term damage, which then resulted in cognitive impairments, as well as dementia.
Six months after exposure, the researchers still found significant levels of brain inflammation and damage to neurons. Imaging revealed that the brain’s neural network was impaired through the reduction of dendrites and spines on these neurons, which had disrupted the transmission of signals among brain cells. These deficiencies were parallel to poor performance on behavioral tasks designed to test learning and memory.
In addition, it was discovered that the radiation affected “fear extinction”, an active process in which the brain suppresses prior unpleasant and stressful associations, for example when someone who nearly drowned learns to enjoy water again.
Deficits in fear extinction makes one prone to anxiety, which could become very problematic over the course of a three-year trip to and from Mars.
This is not positive news for potential Mars-bound astronauts. The symptoms of dementia in humans include:
Difficulty completing familiar tasks
Problems with abstract thinking
Loss of initiative
Recent memory loss
Whilst dementia-like deficits in astronauts would take months to manifest, the time required for a mission to Mars is sufficient for such impairments to develop. Looking down this list, it’s obvious that any one of these symptoms expressed in an astronaut could end up failing the mission.
Investigating how space radiation affects astronauts and learning ways to mitigate those effects are critical to further human exploration of space.
Partial solutions are being explored:
Pharmacological strategies: these would involve compounds that scavenge free radicals and protect neurotransmission.
More mass of traditional spacecraft materials: The sheer volume of material surrounding a structure would absorb the energetic particles and their associated secondary particle radiation before they could reach the astronauts. However, putting this idea into practise would be prohibitively expensive, since more mass will in turn equal more fuel required to launch the spacecraft in the first place.
Hydrogenated boron nitride nanotubes: Since protons and neutrons are similar in size, one element blocks both extremely well—hydrogen. These nanotubes are tiny, and are made of carbon, boron, and nitrogen, with hydrogen interspersed throughout the empty spaces left in between the tubes. Boron is also an excellent absorber secondary neutrons, making hydrogenated BNNT’s an ideal shielding material.
This material is really strong—even at high heat—meaning that it’s great for structure. Remarkably, researchers have successfully made yarn out of BNNTs, so it’s flexible enough to be woven into the fabric of space suits, providing astronauts with significant radiation protection even while they’re performing spacewalks in transit or out on the harsh Martian surface.
I feel like it’s impossible to predict how cutting-edge technologies used to develop manned missions to Mars and habitats on Mars will benefit other fields like medicine. However what can we do with history except learn from it? During its first three years in space, NASA’s prized Hubble Space Telescope snapped blurry pictures because of a flaw in its engineering. The problem was fixed in 1993, but to try to make use of the blurry images during those initial years, astronomers developed a computer algorithm to better extract information from the images.
It turns out the algorithm was eventually shared with a medical doctor who applied it to the X-ray images he was taking to detect breast cancer. The algorithm did a better job at detecting early stages of breast cancer than the conventional method, which at the time was the naked eye.
From stories like this, we learn that research often leads to breakthroughs, and whether it may be in the way the researchers intended or not, research saves lives.
I’m looking forward to watching humans take their first steps on mars, but I sure do hope they’ll remember it!