Invulnerability: Superman is nearly invulnerable to weapons used by normal humans in warfare and we believe that, fully powered, he could survive a near-direct nuclear strike with a ten megaton warhead. In his battle with Doomsday, he was the of the only metahumans able to hold his own against the creature. The battle eventually destroyed over half of Metropolis. He can survive in an environment completely devoid of atmosphere and suffer no ill effects, provided that he carries his own air resources He can operate for periods of up to 30 minutes without air. Extremes of heat and cold have no effect on him and he has been see to skirt the photosphere of the sun (10,000,000 degrees F) with no long term side effects, probably due to a feedback loop of solar energy powering his biomatrix field.