QUESTION:
How long does it take to plan and carry out a mission like Cassini?

ANSWER from FAQ on June 11, 1999:
About 5-8 years are required from approval to launch for a sophisticated
mission like Cassini. For example, Voyager 2 was approved in May 1972
and launched in August 1977. Cassini was approved in October 1989, and
its launch is planned for October 1997. Cassini is the last of the
current series of giant missions to the outer planets of our solar
system. Smaller, less complex spacecraft can be developed and launched
in 2-3 years. In the case of Cassini, the mission is designed to last at
least 11 years after the launch: 7 years getting to Saturn, and 4 years
investigating the Saturnian system. The end of a spacecraft mission is
defined according to a specific plan, but this doesn't mean the
spacecraft won't outlive that plan. For example, although the Voyagers'
grand scientific tours of outer planets are complete, scientists are
still in touch with the Voyager spacecraft as they hurtle away from the
Solar System toward interstellar space. Astronomers hope that Voyager 2
will discover the boundary between the region of space that is
influenced by our Sun (the heliosphere) and the realm of space between
the stars (the interstellar medium).