NASA publishes the first results of the Twins Study
NASA publishes the first results of the Twins Study. Image: NASA.

NASA’s Human Research Program has come up with the first round of results for the Twins Study. The latter is a multidisciplinary research focused on the astronaut brothers Mark and Scott Kelly after one year on Earth and in space respectively.

Preliminary findings show a clear difference in several biological indicators that may have to do with the effects of living in space conditions for extended periods of time.

Scott Kelly spent nearly a year in orbit between 2015 and 2016, returning back to Earth on March last year. The 52-year old identical twins will undergo further rounds of testing as scientists continue to analyze and contrast their samples.

What is the Twins Study?

The Twins Study is a NASA initiative under the Human Research Program that seeks to find clues about extended stays in space and their effects on human life for future, longer missions.

Using Scott and Mark Kelly as test subjects, scientists from 12 different universities, NASA’s biomedical lab, and the National Space Biomedical Research Institute are carrying out ten separate investigations on the identical twins.

Mark, a retired astronaut with 54 days in space under his belt, and Scott, also retired after arriving from the International Space Station (ISS) last year, have been under constant monitoring to look at differences in the major health areas of the human body.

First results show puzzling changes in Scott Kelly

Scott Kelly served as the “true” subject of the Twins Study, while Mark remained on Earth with NASA serving as a control “sample.” The in-orbit brother spent 340 days aboard the ISS as part of the Year-Long Mission.

That mission provided the perfect opportunity for scientists to perform the once-in-a-lifetime study that has now revealed its first results. As it turns out, living in space may affect both body and mind at unsuspected levels.

First off, the telomeres at the end of Scott’s chromosomes grew longer while in space, suggesting increased regenerative functions and even the potential to revert the effects of aging. Typically, telomeres shorten with one’s age.

The space brother also showed a slight decrease in cognitive performance, but his mind was still sharp enough to carry out ISS tasks without raising any concerns. Just a little slower.

Bone formation levels went down, and gastrointestinal bacteria changed while Scott Kelly was not on Earth. Nothing worrying, but certainly different than those of his brother Mark. These indicators returned to normal after he came back down.

Last but not least, the genetically identical twins now presented 200,000 different RNA molecules. NASA researches will continue to look for clues as to why this happened and if space had a role to play in the modified genes.

A full report of the Twins Study will not see the light of day for at least a couple of years, but a complete summary of preliminary findings will be published by NASA later this year according to the agency.

Source: NASA / NASA’s Twin Study


  1. Earth is flat and motionless. There is no outer space. Scientific fact is when it can be physically demonstrated witnessed by more than one person. Nobody has ever demonstrated a ball with water on its surface and a atmosphere spinning and flying through a vacuum. That is physically impossible. Water lays flat it always finds its level. That is a scientific fact. You have been fooled by CGI, photoshop, animation, special effects and double talk jibber jabber jive.