I believe after Columbia, one of the measures NASA took was to have visual inspections of the outside of the space shuttle before re-entry to make sure there were no obvious signs of hull damage. Another thing NASA did was to decommission all space shuttles so NASA does not launch space shuttles into space anymore.
Space program is a big waste of money. When I think of all that could have been done with that money, it makes me sick. Same with the mars curiosity. Hey! There was once water on mars. Hey! Everyday children around the world are dying from the lack of clean water, food and medical care! Where are our priorities?