For centuries, people dreamed about leaving Earth and traveling to other worlds. Then, in 1957, the Soviet Union made the first small step into space by launching a small satellite, called Sputnik. Today, countries such as China, India, South Korea, Israel and Brazil are developing their own space industries.
Life in the microgravity environment of space brings many changes to the human body. The loss of bone and muscle mass, change in cardiac performance, variation in behavior, and body-wide alterations initiated by a changing nervous system are some of the most apparent and potentially detrimental effects of microgravity.
Preliminary findings from NASA indicate that 7% of Scott Kelly's genetic expression did not return to normal once he was back on Earth. Scott Kelly was also diagnosed with cancer from his time in space. His genes warped, and changed. He grew two inches in space, but once back on earth, he shrunk down back to normal.