What Can Twins Tell Us About Life in Space?

James Marshall
April 12, 2019

This time, NASA-funded scientists looked for a gamut of physiologic and genomic changes that Scott Kelly experienced in space, comparing them to his DNA double on the ground, former astronaut Mark Kelly.

This has been observed in other astronauts on previous expeditions. In 2015, Kelly rode a rocket into space and spent almost a year on the International Space Station in low Earth orbit, while his identical twin brother, Mark Kelly, stayed on Earth's surface for NASA's celebrated "twins study", created to see what spaceflight does to the human body.

The findings were published in Friday's edition of the journal Science, on some notable space anniversaries - when Soviet cosmonaut Yuri Gagarin became the first person in space in 1961, and the first launch of the space shuttle in 1981.

In addition, NASA says its study found that Kelly's immune system responded appropriately while in space, including in response to the flu vaccine. His body acted as if it were under attack.

Mark Kelly served as the comparison subject for the experiment. Both are now retired as NASA astronauts, and Mark is running for a U.S. Senate seat in Arizona. From his eyes to his immune system, Scott's body sometimes reacted strangely to almost a year in orbit, at least compared to his Earth-bound brother _ but research published on Thursday, April 11, 2019 shows nothing that would cancel even longer space treks, like to Mars. But the report shows anew that the human body is adapted for life on the surface of Earth and goes haywire in zero gravity. Upon Scott Kelly's return, NASA studied the effects space exposure had on his health by comparing his data to that from his brother, Mark. Most of these gene expression changes (roughly 91.3 percent) reverted to baseline once he came back to Earth, but a small subset continued to exist for six months.

His telomeres - structures that protect the ends of chromosomes, much like the plastic caps on the ends of shoelaces, and which erode over time as part of the natural aging process - lengthened in space. Those tips gradually shorten as we get older, and are thought to be linked to age-related diseases including some cancers.

The study found there were both temporary and lasting changes to Scott Kelly's cells, tissues, genes and physical characteristics. "It´s reassuring to know that when you come back things will largely be back to the same". Blood, urine and stool samples were sent back to Earth on resupply vessels.

He performed more poorly on cognition tests half a year after the mission ended. In his memoir, "Endurance", he wrote about suffering from skin rashes, burning sensations and horribly swollen legs as well as nausea in the days after he returned. I can't say I felt a change in my immune system, but I definitely felt not well. Six months later, the length returned to average; Mark Kelly's telomere length remained stable through the same period of time.

He said one of the hardest problems he faced was adjusting to an unscheduled existence, in sharp contrast to life on the space station.

"When you get back, you feel a little bit directionless", he said. The discovery shocked scientists at NASA's Human Research program, who had chose to use telomeres as a way to measure aging.

"The Twins Study has been an important step toward understanding epigenetics and gene expression in human spaceflight", J.D. Polk, chief health and medical officer at NASA Headquarters, told CNN. But because only two people were in the study, they said it's impossible to conclude the variances between Mark and Scott Kelly were caused by space travel alone. If we had hundreds of identical twins, would we see that same result? Interplanetary spaceflight, or journeys to the moon, will expose astronauts to much higher levels of radiation.

"The unique thing is that because they´re twins, essentially they have the same genetic code", said Dr. Andy Feinberg of Johns Hopkins University.

Gene expression can also be impacted by space travel: Samples taken before, during, and after Scott Kelly's space station mission showed some changes in gene expression, and even though Mark Kelly had normal-range gene expression changes on Earth, they weren't the same as Scott Kelly's changes.

Other reports by Click Lancashire

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