Ronald Reagan initially planned on giving his state of the Union address on January 28th, 1986. The space shuttle Challenger tragedy took place early that morning after exploding 73 seconds after takeoff. He is the only president to ever postpone the state of the Union address, in order to deliver a speech to the nation about the event.
At the very beginning of the speech he explains how instead of speaking about the state of the Union, he will discuss the tragedy because "Today is a day for mourning and remembering." He emphasized the plan change to show importance to the event. He states that it's a national loss and that all people of the country are experiencing pain from the event. This was used to gather a sense of nationalism for the American people and to unite everyone together in the moment of tragedy.
Reagan alludes to the Apollo1 space craft disaster in his speech, but emphasized the uniqueness of this event so as to not make light of the situation at all, claiming that "We've never had a tragedy like this". Then he makes sure that the seven crew members went known as heroes, and claimed that they did their jobs brilliantly. He says all of their names and then states that "we mourn their loss as a nation" once again, adding more emphasis to united nationalism during the time of tragedy.
He specifically reaches out to the families and stresses how everyone is thinking of them so much during their time of loss. He then reemphasizes the fact that they were heroes that "served all of us". He did this to comfort those that were affected the most during the disaster and to display his sorrows along with the nations.
Within the speech he discusses how the space program is still new, and how things are still being learned. This seems as if it was said in order to give an excuse for what happened. He then commends anyone who works for NASA and comments on their dedication and professionalism, so as to relieve any guilty burdens they may carry. He then goes on to compare the crew to the explorer Sir Francis Drake.
He also addresses schoolchildren that viewed the crash on television. In many schools the launch was broadcast, partially due to the first citizen (a school teacher: Christa McAuliffe) being aboard. He sends his words to the children to help them understand the situation, and once again claims the crew was "brave" in order to let them be remembered as heroes.