The race to the Moon and Mars has begun, but a study published in Nature Medicine it seems destined to change the projects that are so talked about: scientists have discovered that the human organism is not made to travel in space. In fact, a long stay in the Earth’s orbit is enough to significantly reduce the number of red blood cells in the blood, and without red blood cells you can’t go anywhere.
The research involved 14 astronauts on a mission to the Space Station for six months, who were asked to exhale at regular intervals into some containers, which were then sealed and returned to Earth for analysis. The scientists then tested the amount of carbon monoxide in the astronauts’ breath, by analogy measuring the amount of red blood cells that “die” when air is emitted from the lungs.
Red blood cells carry oxygen from the lungs to the body’s tissues and carry some of the carbon dioxide back from the tissues to the lungs to be eliminated by breathing. By doing this they age and eventually die, replaced by other red blood cells that are produced by the bone marrow.
By examining the carbon dioxide of astronauts, the researchers found that the amount of erythrocytes that become inactive when a human is in space is 52% higher than what happens on Earth. Not only that, the state of anemia caused by the stay in orbit persists even after the return of the astronauts, with individuals who have suffered from it for years.
Excessive hemolysis, the technical term for the destruction of red blood cells, can cause fatigue, shortness of breath and tachycardia, all conditions unsuitable for a long and demanding journey such as that required to reach Mars. Normally, every day we lose 1-2% of the red blood cells in the blood, which are quickly replaced. But in the astronauts the replacement process fails to cope with the losses, generating significant conditions of anemia.
More studies will be done, because it is not yet clear the reason for the excessive disappearance of red blood cells when it remains for a long time in orbit, but this problem is just one of the many that astronauts will have to face on a journey to Mars, which the billionaire Elon Musk optimistically expects to accomplish within a few years. In space, muscle mass and bone mass decrease, generating osteoporosis phenomena. Liquids are concentrated in the upper part of the body, swelling the neck and head, cognitive capacity decreases, eye movements become more strenuous.
If all this were not enough, then there is the problem of cosmic radiation from which, on Earth, the planet’s magnetic field protects us. Every year in Italy we undergo the equivalent of 11 chest x-rays equivalent to 3.3 millisieverts, the unit of measurement that quantifies them. Those who go to Mars, in the three years of travel, will receive about 1,200 mSv: upon arrival, the bold astronauts who will have to found the first colony will be exhausted, anemic, almost devoid of muscles and practically radioactive. Better perhaps to keep sending us only the robots.