Canadian astronaut and online sensation Chris Hadfield piqued the interests of millions of people worldwide when he published breathtaking photos of the planet during his commanding stint aboard the International Space Station. He continued to make headlines upon his return, but for another reason--he lost one per cent of his bone density for each month he spent in space and, in his own words, was "tottering around like an old man." Dr. Raffi Kuyumjian, Chief Medical Officer of the CSA, explained "Scientists are using Chris as a subject for their science experiments in order to collect data to better understand these effects and how to treat them, which will be important for our aging population."
NASA is studying these effects as well, most recently in an MRI study published June 19 called . The study used several methods including MRI to study when, how and why cardiac atrophy (decrease in heart size) occurs during zero gravity missions.
The NASA study followed 12 astronauts before, during and after space travel over the course of one year, discovering "...cardiac atrophy may be progressive, without a clear plateau over at least 12 weeks of bedrest, and thus may be a significant limiting factor for extended duration space exploration missions."
As the study concluded under the headline 'Science Results for Everyone': "Perhaps the Grinch was an extraterrestrial since the size of heart muscle decreases in space...Data  are being collected and analyzed in order to develop effective ways to maintain a strong heart for long-duration space missions."