Here's Everything That NASA Discovered Happens To The Human Body After Space Travel

NASA have published the results of their Twins Study, a comprehensive research project that assessed the changes that occur in the body after one year in space.

The study, published this week in Science, observed the identical twin astronauts, Scott and Mark Kelly in order to understand how human physiology is affected by long-distance space travel.

Ten teams of specialist scientists from all over the US were involved in researching the physiological, molecular, and cognitive changes that occurred in Scott after his year on the International Space Station (ISS) -- while his brother remained firmly on Earth.

The research was conducted under the umbrella Human Research Program that was launched by NASA in 2004 to prepare for long-distance space travel such as human flights to Mars that are planned for the 2020s and 2030s.

Identical twin astronauts, Scott and Mark Kelly. Source: NASA.

Confinement, isolation, micro-gravity, radiation, and noise, are all factors that can prove extremely stressful on humans in space.

The Twin Study looked closely at the molecular changes that occurred in Scott during his 340-day stay on ISS (a record consecutive stay for a U.S. astronaut that is dwarfed by Russian astronaut, Valeri Polyakov, who spent 438 days on a former Russian space station).

Earlier research indicated that protein expression, the immune system, body fluids, muscle mass, bone density, emotional state, and motion perception are all affected by space travel in the short term.

So, What Did The Twins Study Discover? 

1. Telomeres lengthen in space 

Telomeres can be thought of as the protective caps at the end of our DNA strands that protect the ends from degrading and stop DNA from producing inappropriate responses to damage, which can lead to development of cancerous cells.

You may recognise telomeres for their association with ageing -- the length of our telomeres decreases with cell division and environmental stressors such as pollution or radiation.

Scott's telomeres noticeably increased in length in space (by 14.5 percent) but these changes weren't long-lasting and they returned to pre-flight measures within two days of his return to Earth.

Scott and Mark Kelly. Source: Getty.

2. Radiation from space affects DNA 

Scott's DNA appeared to suffer damage as a result of exposure to infrared radiation galactic cosmic radiation in space.

The researchers noticed that gene expression was altered during flight and there was an unusual rearrangement of chromosomes and this affect appeared to persist after he returned from space.

3. Immune responses change 

Scott's cells showed evidence of inflammation and the number of cytokines (protein cells associated with modulating immune response) were heightened in his body -- this affect continued six months after he came home.

READ MORE: 'Something Truly Remarkable': Scientists Use Harpoon To Skewer Space Junk

However, both Scott and Mark were given flu vaccines halfway through the year that Scott was in space and they both showed similar immune reactions in the number of immune T cells that their bodies produced.

4. Poo changes in space 

The microbiota (gut bacteria) in Scott's poo changed significantly in space, with a changing ratio of the bacteria species in his stomach.

In addition to this, the compounds associated with metabolism and lowering inflammation decreased in Scott's stomach.

5. Cardiovascular issues occur 

The amount of blood pumped by Scott's heart (cardiac output) decreased by 10 percent in space, as well as the overall blood pressure in his arteries.

In addition to this, the walls of Scott's carotid arteries thickened -- a cardiovascular problem that's been observed before in astronauts returning from space.

Scott Kelly on board the ISS. Source: Getty.

6. Body mass changes 

Scott lost 7 percent of his body mass in space -- the amount of his pee decreased (just in case you wanted to know) and the production of new bone cells decreased in the last six months of his flight.

7. The brain takes more risks and cognition speeds up -- at least in the short term 

On a risk-taking cognitive assessment, Scott showed an increased tendency to take risks compared to his brother.

The speed of Scott's cognition also increased in the short-term after he entered the ISS. Spatial orientation and the cognition directing motor control also increased in accuracy.

However, these effects wore off over the duration of his time on the space station and his test scores actually got worse from his pre-flight tests by the time he left space.