A major effect of long-term weightlessness involves the loss of bone and muscle mass. Without the effects of gravity, skeletal muscle is no longer required to maintain posture and the muscle groups used in moving around in a weightless environment differ from those required in terrestrial locomotion.
Marina /ma-ri-na/ [3 sylls.] as a girls' name is pronounced mah-REE-nah. It is of Latin origin, and the meaning of Marina is from the sea. From marine. A saint's name. Shakespeare gave the name to Pericles' daughter in his play Pericles, Prince of Tyre.
Marna /mar-na/ [2 sylls.] as a name for girls is of Latin origin, and the meaning of the name Marna is from the sea; star of the sea; from Magdala. Marna is an alternate form of Marina (Latin): from marine. Marna is also a variation of Marlene (German, Latin, Greek).