During a 3 year trip to Mars, microgravity causes loss of strength in bones and muscles. ”NASA has learned that without gravity working on your body, your bones lose minerals, with density dropping at over 1% per month.” Astronauts would lose 36% of their bone density or possibly more. Every day, astronauts spend at least 2 hours a day excercising. A big part of the human body that needs to be kept strong in space are the hands. My invention is a glove type contraption that makes you squeeze your hand to a fist against tight, strong rubber. Along with the making of the item on a 3D printer, astronauts will need to bring up 7 medium sized safety pins. The base is made from cloth. Five other tight rubber strings with finger holes at the end will be made seperately, but will still clip on to the base. This part of the Tenshy is rubber to fit all sizes of hands. Another rubber piece is made as a strap that will be put on the cloth with the clips to keep the Tenshy in place on the hand.