From Anonymous Posts: Space Shuttle damaged by simple hail

Original Anonymous Post By: anon_98748
www.cnn.com...

CNN is reporting that
• Hail storm damages Atlantis' external fuel tank
• Hundreds of dings found on upper third portion of the tank
• NASA mangers going over the scene, don't know if damage will postpone launch
• Shuttle being prepped for March 15 launch

What I'm wondering is how the shuttle's hull is strong enough to withstand great heat and the possibility of being struck by either space junk or naturally occuring space debry, but simple hail causes enough damage to possibly withhold a scheduled flight. Can someone please explain this to me?

Just saw this in anon posts and figured someone here could answere this person's questions regarding the shuttle.