Your heart may shrink and bones could dissolve: Deadly reality of sending humans to Mars

Mars missions pose unprecedented biological challenges that could prove deadlier than any engineering problem. The six-to-nine month journey subjects astronauts to muscle atrophy, bone density loss of 1% monthly, heart shrinkage, and DNA alterations from cosmic radiation. Unlike shorter ISS missions, Mars travelers face three years of isolation, communication delays up to 40 minutes, and limited medical support while their bodies deteriorate in ways current countermeasures cannot fully prevent.