Astronauts will be in space for 36 months on their way to Mars. When in space the astronaut can't exercise and workout as effectively as they would of on Earth. NASA says that “Bone loss that is known to occur in space significantly increases the amount of calcium in the urine which can lead to the formation of renal (kidney) stones” . When bones are dissolved the calcium enters into the blood flow and goes to the kidneys. Exercise can prevent this by moving and working the muscles and bones. This model has 3 square ferromagnetic metals, and in order for it to work they must be close to each other with the astronaut’s foot in the middle. When the foot is in the middle he or she will feel the magnetic force and work against it. This will create a tension and work the astronaut’s muscles .