Expedition 46 Commander Scott Kelly of NASA rest in a chair outside of the Soyuz TMA-18M spacecraft just minutes after he and Russian cosmonauts Mikhail Kornienko and Sergey Volkov of Roscosmos landed in a remote area near the town of Zhezkazgan, Kazakhstan on Wednesday, March 2, 2016 (Kazakh time). Kelly and Kornienko completed an International Space Station record year-long mission to collect valuable data on the effect of long duration weightlessness on the human body that will be used to formulate a human mission to Mars. Volkov returned after spending six months on the station. Photo Credit: (NASA/Bill Ingalls)
Space travel altered Kelly's chromosomes
00:57 - Source: CNN
CNN  — 

As humans explore worlds beyond Earth on longer missions in the future, it’s crucial to understand how our bodies may react to a sustained lack of gravity and radiation exposure.

The 2019 NASA Twins Study provided an all-encompassing look at the effects of spending nearly a year in space on the human body when NASA astronaut Scott Kelly spent 340 days on the International Space Station while his identical twin Mark (now a US Senator-elect from Arizona) was on Earth.

Now, scientists have gathered the largest set of data about space biology to date based on astronauts including the Kelly twins, mice and insects that have flown on the space station.

The 30 studies, authored by more than 200 researchers from around the world, represent the largest body of information on the risks of space flight to the human body.

The studies identify six key molecular changes that may have a significant impact on astronaut health. Understanding these changes is key for preparing for long-term spaceflight missions to the moon and Mars in the future.

The Biology of Spaceflight collection of 30 studies published Wednesday in the journals Cell, Cell Reports, Cell Systems, Patterns and iScience.

Risks of deep space missions

The six molecular changes that occur during spaceflight include DNA damage, oxidative stress, alterations of telomere length, shifts in the microbiome, mitochondrial dysfunction and gene regulation.

Oxidative stress happens when free radicals overwhelm antioxidants in a cell, encouraged by the space environment. This type of stress was found to be largely connected to the other molecular changes the researchers observed.

These changes on a cellular and molecular level can have a significant impact on astronaut health, both during and after their missions. These impacts have been observed on the cardiovascular, central nervous, musculoskeletal, immune and gastrointestinal systems, as well as causing disruptions to circadian rhythms and changes in vision.

Increased cancer risks have also been associated with these changes.

One of the new studies also identified clonal hematopoiesis, when blood cells carrying mutations spread more quickly than others, as a potential risk among astronauts for cardiovascular disease, lymphoma and leukemia. Clonal hematopoiesis was identified in blood samples from astronauts 20 years before the average age when it is normally detected at age 70, compared to 157 cancer patients.

So far, missions to the space station have not exceeded a year, but deep space missions to Mars could last up to five years.

“Understanding the health implications from the (6) features and developing effective countermeasures and health systems are key steps in enabling humanity to reach the next stage of space exploration,” the authors wrote at the conclusion of their study spanning the effects of spaceflight.

DNA damage

Telomeres act like caps at the ends of chromosomes to protect them and they shorten as people age.

During the Twins Study, the telomeres