On a trip to Mars there is no gravity at all. This means that you are floating through the air with no control of where to go. For somebody to gain the slightest bit of control they would have to probably tense up their muscled. This could tend to leave a lot of stress in your body and cause you to easily pull a muscle. Pulling a muscle on a space mission is not a good thing because on this journey you have to stay moving and healthy. With a pulled muscle that would either prevent you from doing anything or slow you down while you are doing it. Now, because of this set back that you could encounter I have created something to help you massage your muscles while you are in space. It is a PLA plastic sphere with spikes all around it. The spikes on the ball roll into your skin which kneads your muscles. Because of the pushing into your back you also are using your strength and keeping your bones from becoming to weak for you to move when you get back to where there is gravity.