Ok, I shall add the official dissenting opinion here.
To me, there were not heroes. They were people doing their jobs, albeit a dangerous one. To me, a hero is someone who goes out of his/her way to perform an unrequired, selfless act of sacrifice in order to bring about good while not expecting anything in return. For example, a passerby who puts him/herself in danger to help someone out of a burning building is a hero. A fireman responding to the call is not.
Those astronauts knew the risks involved with their job. They chose and were required to undertake the journey. They died while doing their job. Therefore, this does not make them heroes. I know this is not the politically correct thing to say at this time, but I'd rather hear the awful truth than be consoled by a pretty lie. Every profession has its risks. One has to decide for one's self if the risks are worth the possible advantages. This still does not make one a hero.
I believe the word hero is far too overused in our society.