As nations strive to put humans farther into space for longer periods of time, the real loser in this new space race could be the astronauts themselves. That's because experiments conducted on the International Space Station involving cells that line the inner surfaces of blood vessels (endothelial cells) show that microgravity accelerates cardiovascular disease and the biological aging of these cells. These findings are presented in a new research report published in November 2013 issue of The FASEB Journal.

Yet another physiological issue in a long line of issues surrounding the notion of human interstellar travel. If we ever go to the stars, it will have to be extremely rapid AND biologically safe for flesh and blood humans.  To read more, click here.