Lewis also participated in the actual launch operations, including the prelaunch countdown. Independent verification and validation analyses are normally conducted for Titan IV missions to assure mission success. Coupled loads, spacecraft dynamic testing, software, vehicle guidance and control, mission design, separation dynamics, and flight performance must all be assessed. Although these analyses are normally performed by a subcontractor, NASA Lewis took advantage of the extensive experience and specialized expertise available at Lewis by performing these analyses for the Cassini mission as part of its integration responsibility. When to Launch NASA Lewis also was involved in determining when to launch Cassini.
Every planetary mission has an ideal launch day.
However, there is never a guarantee that a launch will be able to take place on the ideal day because the weather may be poor or there may be a problem with the launch vehicle or spacecraft. Most planetary spacecraft, like Cassini, are designed to be launched within a window of 30 days. If the launch window had been extended to November 15, additional propellant would have been needed. Such an extension proved unnecessary when Cassini successfully began its trek to Saturn on October 15. Traveling Waves to Better Science Cassini's data would be useless without a way to send it to Earth, and Earth will be over a billion miles away.