Remember Challenger - a memory that spurs us on.

There are a lot of tragedies in this world, ongoing today and throughout history. The destruction of the Challenger space shuttle, and the loss of its seven crew are no more or less against this backdrop: Seven people snuffed out. 
 

Above: The Challenger crew.

They died believing that humanity could achieve amazing as well as terrible things, and set out that day to prove it. Their mission may have ended in their deaths, but looking at all the great things that have been done with space travel, to help humankind and to learn more about our universe, I cannot say it ended in failure.