Astronauts face dementia and memory loss from ionizing radiation.
Will the astronaut be able to remember something after returning from Mars? Collage: cosmicvue, fragments of NASA photos are used.
We are building plans for the colonization of Mars, considering the delivery of astronauts and cargo to the Red Planet is the most difficult problem. The mission is very complicated and expensive. The Martian base will constantly need supply. Colonists need supplies of oxygen, food, medicine, tools. But it may turn out that this will not be their biggest problem. Experiments have shown that a long journey to Mars and back can lead to serious cognitive dysfunctions, including memory loss and dementia.
Travel to Mars, like other space travel, will inevitably affect the health of astronauts. Scientists have long been studying the effects of a long stay in space. Unfortunately, the results of these studies do not look very optimistic.
During the flight to Mars, astronauts are bound to be exposed to high-energy highly ionized particles, known as cosmic rays of galactic and solar origin (GCR and SCR). By the number of particles, cosmic rays are 92% composed of protons, 6% are helium nuclei, about 1% are heavier elements, and about 1% are electrons. The energy spectrum of cosmic rays by 43% consists of the energy of protons, another 23% - of the energy of helium (alpha particles) and 34% of the energy transferred by the other particles.
On the surface of the Earth, people are well protected from the GCR and SCR magnetosphere, but in space there is no such protection. Due to the extremely high energy of more than 10 MeV, these particles pass through the lining of the spacecraft and through the soft tissues of astronauts, including the brain.
In the human body, ionizing radiation causes a variety of damage at the molecular level, including disrupting cell repair processes and slowing down the healing of damaged tissues. Restoration after damage from GCR is also hampered by secondary ionizations from delta radiation from traces of primary particles, which increases the radius of damage and the degree of cell damage in the body. This was shown by previous studies conducted in 2010 and 2011 ( 1 , 2 ).
The potential danger of GCR for astronauts is known to NASA and other space agencies, so they are planning to develop a protection against cosmic radiation (so far this has not been created).
How great is the damage to the body, what exactly will be the damage? It is known that GCR can cause disturbances in the nervous system that threaten the execution of critical tasks by astronauts associated with cognitive actions. There are also long-term health risks.
Previous studies clearly demonstrated the deterioration of mental abilities under the influence of GCR , which is associated with damage to neurons and impaired synaptic integrity of specific regions of the brain.
The question is how long is the process of recovery after exposure to GCR. Previous experiments on mice found that 6 weeks after irradiation, no or practically no signs of recovery and restoration of lost mental abilities were found in mice.
Specialists from the Department of Radiation Oncology at the University of California, Irvine, have now conducted additional research to check the longer-term effects of GCR on the brain. This time, the condition of the mice was checked at 12 and 24 weeks after irradiation.
Unfortunately, the results were again disappointing. Even 12-24 weeks after exposure to low doses of ionizing radiation (5 or 30 doses of 48 Ti or 16O) in experimental animals, there are obvious signs of cognitive dysfunction - effects associated with the simplification of the dendritic structure, changes in protein levels in synapses and inflammation of the nervous tissue.
Decreased mental abilities in various tests 12 weeks after irradiation: (a) a novelty test (memory test for recognition); (b) spatial memory conservation test; © Temporal Order task, checking memory of recently explored objects
As you can see, in almost all memory tests, mice showed a significant deterioration in performance 12 weeks after irradiation. Particularly alarming is the sharp decline in performance in the test of memory of recently studied objects. It may be that after returning from Mars, the astronauts simply can not remember anything. In addition, dementia and memory loss will persist for at least six months after returning to Earth. Perhaps longer. Longer tests on mice have not yet been performed.
Apparently, without effective radiation protection, it is very risky to let people go to long-term space missions: after all, they may not be able to cope with control and not complete scientific and engineering tasks.
Scientific article publishedOctober 10, 2016 in Scientific Reports journal (doi: 10.1038 / srep34774).
