Space oddities: the twins helping us reach for the stars

Rodiano Bonacci
Апреля 13, 2019

From March 2014 to March 2015, astronaut Scott Kelly spent 340 days on the International Space Station while his identical twin, former astronaut Mark Kelly, remained on Earth as part of a NASA and Russian Federal Space Agency study on the health effects of long-term space flight. His body acted as if it were under attack.

"I got people coming to my house, right, for tubes of blood", responded Mark Kelly.

"We can not send humans to Mars without knowing how spaceflight affects the body, including the microbes traveling with humans to Mars", said Northwestern's Fred W. Turek, who led the microbiome study. But the report shows anew that the human body is adapted for life on the surface of Earth and goes haywire in zero gravity.

But while nothing so radical as a DNA transformation or a new mutation occurred, this data still provides NASA with valuable information about the changes an astronaut's body can go through in space - and we can use that information to better protect our astronauts who venture out into orbit, to the moon, to Mars, and eventually, beyond.

The good news was, Kelly's immune profile returned more or less to baseline after he came home. Telomeres, which are the protective caps on the ends of chromosomes, get shorter as humans age. But that's no fountain of youth, the study found, because the telomeres shortened dramatically when he returned to Earth.

"The Twins Study is the most comprehensive review of the response of the human body to spaceflight ever conducted", said Dr Susan Bailey of Colorado State University.

In the current study, Scott's biological samples were shipped back to Earth immediately, but in the future, astronauts may need to process and store samples on the spacecraft. His performance on cognitive tests improved throughout much of the mission, but performance on tests created to measure his ability to recognize emotions in other people declined. "You probably wouldn't do as well", Kelly said. 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 felt like I had the flu", he said.

"The return was much worse than the adaptation of getting up there, especially for the year flight", Kelly told reporters. "The most worrisome symptoms I had, which was swelling in my legs, the rashes, were gone after a couple of weeks". But most of these astronauts travel on spaceflight missions of six months or less, not the longer missions required to travel to Mars or elsewhere.

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

Scientists have long monitored and studied the physiological effects of space travel on astronauts.

Numerous findings have been previously reported, but today's open-access research paper and supporting materials provided broader context for the NASA Twins Study - and pointed to concerns that are likely to be addressed in future space experiments.

"There were ten teams of researchers but only one article", said Martha Vitaterna, first author of the Northwestern study. "I was exhausted for really long time".

"That was very much a surprise to us", said Bailey.

Mark Kelly is six minutes older than his brother.

Although researchers have a solid understanding of how shorter space missions affect the body, there is little research about long-term space travel impacts because only four people have participated in space missions lasting at least one year. Einstein's special theory of relativity leads to a "twins paradox" in which someone moving at a high velocity, such as 17,500 miles per hour in low Earth orbit, ages more slowly than a twin on Earth.

"We did compare Scott with Mark, which was interesting", said Turek, the Charles and Emma Morrison Professor of Neurobiology in Northwestern's Weinberg College of Arts and Sciences and director of the Center for Sleep and Circadian Biology. "He's busy running for office".

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