For each of the following questions, 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 1970s to create 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.