Arrange sentences A, B, C and D between sentences 1 and 6 to form a logical sequence.
1. Voyager-I was very high in the ecliptic plane.
A. They are triumphs of human engineering and one of the glories of the American space programme.
B. In 1981, it had made a close pass by Titan, the giant moon of Saturn.
C. The two Voyager robots have explored four planets and nearly sixty moons.
D. Its sister ship, Voyager, was patched on a different trajectory, so she was able to perform her celebrated explorations of Uranus and Neptune.
6. They will be in the history books when much else about our time is forgotten.