For the following question, arrange the sentences A, B, C, and D between sentences 1 and 6 to form a logical sequence with sentence 1 and sentence 6 as the starting sentence and the concluding sentence respectively:
(1) NASA's Shuttle program was begun in the I970s to create a reusable craft for transporting cargo into space.
(A) The first shuttle, Columbia, was launched in 1981.
(B) They were followed by the shuttles Discovery in 1983 and Atlantis in 1985.
(C) One year later, the Shuttle Challenger rolled off the assembly line as the second shuttle of the US fleet.
(D) Previous spacecraft could only be used once, and then were discarded.
(6)
The Space Shuttle Challenger flew nine successful missions before that fateful day of the disaster in 1986.