Scott Kelly is two inches taller than when he left earth a year ago. That is all.
NASA scientists already knew that Kelly would walk a little taller when he emerged from the Soyuz capsule. But he’ll have changed in other, less obvious ways, too, and that’s the whole point of his record-breaking mission. Kelly and Russian cosmonaut Mikhail Kornienko spent 342 days on the space station to help scientists measure the effects of long-term spaceflight on the human body.
OK, so I lied. That’s not all. One of the purposes of the trip was, as noted above, to study the effect of long-term spaceflight. Kelly’s twin brother submitted himself to the same battery of tests to help us better understand what happens to a person in space versus staying on earth.
The hope is that scientists can come up with a plan for protecting the men and women who might eventually journey to Mars. It’s likely that the flight to our closest neighboring world will take about nine months each way. Once a crew touches down on the sandy surface, NASA will want them to stay awhile. After all, it would be a shame to spend 18 months in a tin can for a day or two on the surface of a new planet. So it seems likely that the first Mars mission will be a multi-year commitment.