Astronaut Scott Kelly Is Two Inches Taller Than Twin Brother Mark After #YearInSpace

U.S. astronaut Scott Kelly is now two inches taller than his identical twin brother, Mark Kelly, as a result of his recent year in space aboard the International Space Station.

The Inquisitr reported on Wednesday that astronaut Scott Kelly had returned to Earth after spending a year in space on the International Space Station. Now scientists are investigating the physical effects of spending all that time on the ISS, which was, of course, the intention of his long stay up there. Researchers will be finding out just how well humans can endure in space, not only in their bodies but also in their mind and spirit.

The first thing that has been noted is the fact that Scott Kelly has literally grown two inches while up in the ISS and is now taller than his identical twin, Mark Kelly. Reportedly, when they were small, their mother used to draw a mustache on Mark’s face to be able to tell them apart, but it seems she will no longer have a problem knowing which one of the twins is Scott and which is Mark, due to their new height differences.

The height difference is apparently due to the near-absence of gravity on the International Space Station, which causes the astronauts’ spines to stretch, reportedly as much as 3 percent. Without gravity constantly pushing the vertebra in their spines together, they expand and relax in the confines of the ISS.

Apparently, his new-found tallness will only be short-lived, however, as reportedly most astronauts return to their original height after a few months back on the planet. Back in 2013, reported that a new ultrasound machine is being used by astronauts to carefully measure any changes in their spines after certain intervals in space, and due to his unprecedented long stay up on the ISS, Scott’s measurements will be particularly valuable in the ongoing research.

According to a report by Inverse, besides growing taller, there is a long list of effects on the human body when time is spent in micro-gravity environments like the International Space Station, many of which scientists still don’t fully understand. These effects involve bone density, vision, muscle composition, their immune systems, and other factors experienced during long periods spent up in space. Research in this field is vital for any future manned mission to Mars.

A fellow astronaut, Scott Kelly’s twin brother Mark has spent significantly less time than his brother up in space, so he also takes a vital role in the research, as he is the perfect control tool for studying the effects of long-term spaceflight.

While so far Scott says he “feels pretty good” after his year up on the International Space Station, he will now undergo a further year-long project to monitor his health after his experience up there.

Both Kelly brothers will reportedly be spending a lot of their time with NASA’s scientists, as they run exhaustive tests to compare the twins’ bodies and minds following their journeys up into space.

As reported by CNBC, the National Space Biomedical Research Institute and NASA will be on the lookout for several physical effects from long-term microgravity.

As astronauts cannot walk normally on a spacecraft in micro-gravity, they have to float. This causes problems with the bones in the legs, hips, and spine due to such a significant decrease in load bearing on those bones. The effects can cause bone breakdown and a release of calcium, which leaves the bone more brittle and weak. The release of the calcium can also reportedly increase the risk of kidney stone formation and bone fractures.

Similarly, existing in a micro-gravity environment causes muscles to begin to weaken or atrophy due to less work for the legs and back while up in the ISS. Another effect is, with blood flowing more in the upper body and less in the lower extremities, astronauts often have a puffy face, and at the other end of the scale, their legs become smaller in circumference.

Existing in micro-gravity can also cause the heart to grow smaller, as it doesn’t have to work quite so hard up there. There is also the danger that radiation in space may affect endothelial cells, the lining of the blood vessels, and this might initiate or accelerate coronary heart disease and lead to heart attacks.

There is also the problem of balance, as the inner ear is sensitive to gravity and no longer functions correctly up in the International Space Station. On arrival in space, astronauts often experience disorientation and a loss of direction and can suffer from space motion sickness. When returning to terra firma, their system needs to readjust to Earth’s gravity, and this can cause problems for the astronauts when standing, walking, turning, and stabilizing their gaze.

Cancer is also a risk for astronauts who spend extended periods off-planet due to the higher levels of radiation in space. This can potentially lead to cancer and cataracts.

When living on the International Space Station, an astronaut’s body clock gets messed up, as there is no normal 24-hour day cycle up in space. This means that on return to Earth, it takes a while to adjust back to normal.

Then there is, of course, the fact that, like with Scott Kelly, astronauts grow a little taller in space. On planet Earth, disks are slightly compressed due to the normal gravity, but in space, with no compression happening, those same disks expand. The result is a longer spine and the astronaut is then taller.

In the meanwhile, while all the necessary tests are run on him and his brother Mark Kelly, Scott Kelly will also reportedly be getting involved in helping NASA with their plans to journey to Mars, so it looks like he has a lot on his plate for the future.

[Photo Scott Kelly and Mark Kelly by Bill Ingalls/NASA via Getty Images]