CNN News:NASA将40只转基因老鼠送上太空

Which of these cartoon characters first appeared in a short called the Mouse of Tomorrow in 1942? Mickey Mouse, Mighty Mouse, Jerry or Fievel? Originally known as "Super Mouse", the character that became Mighty Mouse made his debut in '42.
As far as television goes, Mighty Mouse hasn't been on the air in years but he has been in space in a manner of speaking. These have been called "mighty mice". They're genetically modified mice that have twice the muscle mass than unaltered mice and 40 of them were recently sent into space for a study on muscle mass.
Without the daily force of gravity, people and mice normally lose muscle. NASA says in spaceflights lasting five to 11 days, astronauts can lose as much as 20 percent of their muscle. Those who spend months on the International Space Station regularly exercise to help prevent this loss, but this kind of training might not be possible during long-term space flight.

So scientists have been experimenting with "mighty mice" to see if a drug could be produced one day that could help astronauts keep their muscle in a microgravity environment. Of course, drugs, especially those related to maintaining or increasing muscle mass have an array of unwanted side effects, so researchers are looking to create treatments that avoid those.
And as far as the mice were concerned, the genetically altered ones were able to keep more of their muscle mass in space and recover it faster once they got back down to Earth.