Final answer:
Reagan likely framed the Challenger tragedy within the context of American dedication to space exploration and its risks, reflecting national pride and the pioneering spirit.
Step-by-step explanation:
The student's question asks for the means by which President Ronald Reagan contextualized the Challenger explosion in his Address to the Nation on the explosion's day. Given the context provided in the information, it seems that Reagan would have likely situated the tragic event in the broader narrative of the United States' commitment to space exploration and the inherent risks involved in pioneering ventures, as shown by the historical backdrop of the space race, advancements in space technology, and both triumphs and tragedies associated with space missions.
This approach would align with Reagan's well-documented communication skills and his understanding of the American spirit, which often involved invoking national pride and the pioneering nature of American endeavors.