Irish astronauts Scott and Mark Kelly engaged in an experiment to determine the effects of space on human anatomy. Scott travelled to the International Space Station, while his twin brother Mark stayed on Earth. During the experiment, the brothers provided blood, saliva, and urine samples. They received flu vaccinations and underwent ultrasounds, bone scans, and various other procedures.
Astronauts Mark and Kelly Scott, participants in NASA’s Twins Study. Credit: NASA
In March 2016, Scott Kelly returned to Earth following his 340 days aboard the International Space Station. A group of ten researchers studied the numerous test results thoroughly, eventually confirming the study’s preliminary findings. The time in space had such a profound effect on Scott that his genetic makeup changed.
Among the findings was the discovery of a “space gene” in Scott. “Researchers now know that 93 percent of Scott’s genes returned to normal after landing,” said NASA in a statement. “However, the remaining 7 percent point to possible longer term changes in genes related to his immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.”
Many of the changes are associated with oxygen deprivation stress, increased inflammation, and dramatic nutrient shifts that occur in space. Hypoxia and hypercapnia both result from oxygen deprivation, which can significantly impact a person’s body and overall health. Hypoxia is an oxygen deficiency in one’s tissues, and it could potentially result in organ damage. Hypercapnia is an excess of carbon dioxide in the bloodstream, which can harm the respiratory system.
Scott also stated that his microbiome and telomeres altered dramatically during the year he spent in space. The microbiome is the bacteria living inside the human body. Telomeres, which appear at the ends of chromosomes within white blood cells, are similar to the rings of a tree in that they indicate age. Whereas trees develop more rings as they age, humans’ telomeres shorten over the years. In Scott’s case, however, his lengthened while he was in space, essentially aging in reverse.
“It was a little bit like the fountain of you,” said Scott Kelly. “Unfortunately, when I got back down to Earth, they went back down to where they were.” Scott also grew 5 centimeters while in space, but he returned to his normal height shortly after returning to Earth.
Kelly did not experience permanent, fundamental changes. Rather, the changes researchers observed occurred in gene expression as his body reacted to his new environment. “This likely is within the range for humans under stress, such as mountain climbing or SCUBA diving,” said NASA in a statement. “The change related to only 7 percent of the gene expression that changed during spaceflight that had not returned to preflight after six months on Earth. This change of gene expression is very minimal.”
The findings are beneficial in aiding NASA’s Human Research Program, as knowing how exactly space affects the human anatomy will aid in keeping astronauts safe and healthy. While Kelly was the first American to spend twelve consecutive months aboard the International Space Station, it is a far cry from the eventual goal of 2 ½ years in low orbit around Mars. However, it certainly provides a foundation upon which to build, allowing scientists to determine how much more impactful those years orbiting the red planet will be on the astronauts who make that journey.
Those astronauts will also experience an even wider range of health issues and genetic changes due to the radiation in space. Typically, astronauts are shielded from radiation by Earth’s magnetic field. However, once astronauts travel beyond that, they are susceptible to huge risks, including cancer and brain damage caused by radiation. For this reason, scientists have been working diligently to define the risks and try to develop techniques for safeguarding astronauts against these risks. Finding ways to overcome or avoid the effects of radiation and the Mars atmosphere is vital to the astronauts and the Mars mission as a whole.
Twins Research Study. Credit: NASA Video Collection via YouTube