Plans for long-term missions to send the astronaut to the moon and Mars were given a new blow by a long-term study of health without gravity.
Astronauts who spend several months at the international space station have a significant reduction in the size and density of the main muscles in their spine after returning to Earth, reports a study in Spine.
It contributes to an ever-growing list of major health problems that confront those who undertake long-term missions.
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Astronauts who spend several months at the international space station have a significant reduction in the size and density of the main muscles in their spine after returning to Earth, reports a study in Spine. Pictured, British astronaut Major Tim Peake
WILL DEEP SPACE TRAVEL LEAD TO CANCER?
Deep space travel can leave astronauts terminally ill, new research suggests.
Experts believe that exposure to radiation in long-range, intergalactic trips can significantly damage their stomachs and intestines.
This is likely to result in long-term functional limitations, such as ineffective absorption of nutrients or cancer.
Scientists made the discovery after exposing mice to low doses of electrically charged iron particles, one of the most harmful forms of galactic cosmic radiation (GCR).
The changes in the composition of the muscles are still present up to four years after a long-term space flight, according to the new study by Katelyn Burkhart, MS, from the Massachusetts Institute of Technology and colleagues.
They write: & # 39; Space-induced changes in paraspinal muscle morphology can contribute to back pain often reported by astronauts. & # 39;
The researchers analyzed computer tomography (CT) scans of the lumbar (lower) spine of 17 astronauts and cosmonauts who flew with missions at the International Space Station.
Scans obtained before and after missions were analyzed to determine changes in the size and composition of the paraspinal muscles.
The average time in space was six months.
Previous studies of astronauts have linked space flight to muscle atrophy, especially of the muscles that maintain posture and stability while standing upright on earth in normal gravity.
Many astronauts experience low back pain during and immediately after space missions, and they appear to have an increased risk of spinal disc herniation.
The new research showed that the paraspinal muscles are the most at issue, running up and down the spinal column and playing a key role in the movements and posture of the spinal column.
Previous studies have found reduced paraspinal muscle mass after prolonged time in space, suggesting muscle atrophy can occur without the resistance provided by gravity.
The CT scans showed reductions in the size of paraspinal muscles after space flight.
For individual muscles, muscle size decreased by 4.6 to 8.8 percent.
In follow-up scans performed a year later, the size for all muscles was at least normal, but showed significant increases in the amount of adipose tissue present in the paraspinal muscles.
Accordingly, the muscle density of the astronauts, which is inversely proportional to the fat content, decreased by 5.9 to 8.8 percent.
For most muscles, the composition has become normal again for one year.
For two muscles – the quadratus lumborum and psoas muscles – however, the fat content remained even two to four years after the astronaut returned from space above the pre-flight values.
Some changes in the paraspinal muscles appear to be affected by exercise, indicating possible approaches to avoid the adverse effects of long-term space flight on the health and function of the spine.
Ms. Burkhart and co-authors conclude: & # 39; While NASA has plans for future missions to Mars and beyond, these results can be used to guide future countermeasures to reduce declines in the morphology of the trunk muscle and the associated functional deficits. # 39;
HOW WAS SCOTT KELLY & # 39; S CHANGE DNA IN SPACE?
After 340 days on board the International Space Station, the American astronaut Scott Kelly returned to Earth in March 2016.
NASA has since conducted tests to study the effects that live in orbit around the planet, using its identical twin brother Mark – who had remained on Earth – as a control person.
The Kelly brothers have almost identical genomes, which allows an unprecedented view of the physical effects of long-term spaceflight.
While astronaut Scott Kelly (right) aboard the international space station lived for 340 days, his identical twin brother Mark (left) remained on Earth – and researchers have now found some differences between the two
Blood and other biological samples were collected from the pair before, during and after Scott Kelly's mission.
The agency discovered that Kelly came home 5 cm (2 inches) longer than his twins – a change had resolved within two days of his return.
The height difference was caused by the microgravity conditions of the ISS that prolonged the spinal column – but the effect was only temporary.
Nasa discovered that while 93 percent of Kelly's genes became normal after returning home, seven percent were permanently altered.
These long-term changes affect genes related to the immune system, DNA repair, bone formation and the way in which tissues absorb oxygen and carbon dioxide.
Kelly & # 39; s telomeres – the caps at the end of each chromosome – are extended in space.
Telomeres are the key to protecting DNA from damage and tend to shorten with age. Kelly's telomeres were again shortened once he was back on earth.
Scientists reported their preliminary results at a meeting for Nasa's Human Research Program in January 2017. Pictured are some of the areas studied by the team
Nasa says that Kelly's longer telomeres are related to his diet and training routine at the station.
The ratio of two groups of intestinal bacteria shifted while Kelly was in space, probably as a result of his change in diet. This also returned to normal shortly after his return.
NASA research has observed hundreds of diverging genetic mutations in the genome of Kelly and Mark.
The research team speculates that a & # 39; space & # 39; might have been activated while Kelly was in orbit around the earth.