It’s no secret that NASA has taken on an impossible task: to send people to Mars by the 2030s. Why too much? Because it is enough to understand that the usual trip there will take from three to six months, and the crew will have to stay on the planet for up to two years before the alignment of the planets will allow him to return home. This means that astronauts will have to live in reduced (micro) gravity for at least three years — this is significantly higher than the current record of continuous stay in space, set by Russian cosmonaut Valery Polyakov: 438 days.
In the early days of space travel, scientists worked hard to figure out how to overcome the force of gravity so that the rocket could launch from a catapult into space and land people on the moon. Today, gravity is also on the agenda of science, but this time we are more interested in how low gravity affects the health of astronauts, especially their brains. After all, we evolved to exist in earth gravity (1 g) rather than in the weightlessness of space (0 g) or the microgravity of Mars (0.3 g).
“Brain in a VAT”
So how does the brain cope with microgravity? In short, it is very bad — however, information about this is limited. We know that the faces of astronauts blush and swell in weightlessness-this phenomenon is affectionately called “Charlie brown effect”. This happens mostly because the fluid, consisting mainly of blood (cells and plasma) and cerebrospinal fluid, is shifted to the head, resulting in the face become puffy and rounded, and legs — thin.
These fluid displacements are also associated with” space sickness ” (similar to sea sickness), headaches, and nausea. Recently, they were also associated with blurred vision due to the increase in pressure with increasing blood flow; the brain itself seems to float to the top of the skull, putting pressure on it. Despite the fact that NASA considers visual impairment and brain displacement the main risk to the health of any person on Mars, to find out what causes it, as well as how to prevent it, has not yet happened.
Professor of physiology and biochemistry Damien Bailey of the University of South Wales believes that certain parts of the brain end up getting too much blood, because the bloodstream accumulates nitric oxide — an invisible molecule that usually floats there. The arteries supplying the brain with blood relax, so they open up more. As a result of this rise in blood flow, the blood — brain barrier — the “shock absorber” – becomes overloaded. Water slowly accumulates, the brain swells, the pressure increases.
Imagine if the river comes out of the banks. The most important thing in all this is that there is not enough oxygen in some parts of the brain. This is a big problem that can explain the blurred vision, as well as other effects that manifest themselves on the ability of astronauts to think, concentrate, reason and move.
A trip on the “vomit comet”
To test an idea, scientists must put it into practice. But instead of asking NASA for a trip to the moon, they just decided to break out of the fetters of earth’s gravity by simulating weightlessness on a special plane called “vomit comet”, “vomit comet”.
Rising into the air and then descending, this aircraft perform up to 30 parabolic figures in one flight to simulate the feeling of weightlessness. Free fall lasts only 30 seconds, but the face has time to inflate and for these half a minute.
Securely securing all the equipment, the scientists conducted measurements among eight volunteers, each of which made one flight every day for four days. They measured blood flow in different arteries supporting the brain using portable Doppler ultrasound, which causes high-frequency sound waves to bounce off the circulating red blood cells. Nitric oxide levels were also measured in blood samples taken from the forearm vein, as well as other invisible molecules including free radicals and brain — specific proteins (which reflect structural brain damage) – they could tell if the blood-brain barrier was forcibly opened.
Initial findings confirmed exactly what was expected. Levels of nitrogen oxides increased after repeated “attacks” of weightlessness, and this coincided with an increase in blood flow, especially in the arteries supplying the back of the brain. The blood-brain barrier opened, although there was no evidence of structural damage to the brain.
Now, scientists plan to continue these studies with more detailed assessments of blood and fluid changes in the brain, using imaging techniques like magnetic resonance to confirm the results. They also want to consider the possibility of introducing countermeasures like rubber pants, which create negative pressure in the lower body and help to “pump” blood from the astronaut’s brain — as well as drugs that counteract the increase in nitric oxide. The results of such work can not only improve the health of astronauts in space travel, but also provide valuable information about why “gravity” is useful for the brain.