Scientists are coming closer to understanding exactly how space affects the human body.

Scientists are coming closer to understanding exactly how space affects the human body.

In the largest study of its kind, scientists are coming closer to understanding exactly how space affects the human body.

Back in 2019, NASA published the first ever space twin study. This compared twins Mark and Scott Kelly before, during, and after Scott spent 340 days in space—that’s the longest any U.S. astronaut has consecutively spent in spaceflight—while Mark stayed here on Earth. That study gave us so much insight into how the human body changes in microgravity: from telomere shortening to gut microbiome changes to rapid alteration of gene expression. It also told us there was still so much to learn…and 2020 delivered.

A set of nineteen new studies builds on the results of the Kelly Twins study, reanalyzing some of that data and comparing those results to measurements between 56 astronauts in total. Plus ten more papers are in pre-print now, being reviewed and set for publication soon to add even more to this data set. This is the largest study of its kind, the most information EVER collected about what happens to the human body in space.

The researchers have identified, for the first time, a core set of mammalian adaptations in response to spaceflight. We see these changes across species: humans, mice and other animals. The biggest one? Mitochondrial dysfunction. You may think of the mitochondria as that famous ‘powerhouse of the cell’—it generates most of the energy a cell needs and so enables the proper function of all your tissues and organs. And as you might imagine, keeping your mitochondria working is pretty important. Using new techniques that allowed a really in-depth look at changes in the astronauts’ genomes and protein expression, mitochondrial changes were consistent across the dataset. And even though the scientists are still unsure what EXACTLY may be the underlying cause of this mitochondrial disturbance, they think it’s likely oxidative stress caused by the extreme environment of space. This, essentially, is damage caused to cells by stress. Stress releases these harmful compounds called reactive oxygen species, causing genetic changes that, in turn, cause changes in metabolic pathways.