Deployment of Galileo and the IUS from the cargo bay of STS-34 Atlantis at 7:15 p.m.
EDT on October 18, 1989. P-35213
Mission Specialist Shannon Lucid started Galileo's deployment by pushing a button;
automatic systems then took over to separate Galileo from the shuttle. As deployment
finished Commander Donald E. Williams declared "Galileo is on its way to another world.
It's in the hands of the best flight controllers in this world - fly safely."
Beginning an hour after deployment, two rocket stages of Galileo's IUS booster fired one
after the other. Galileo separated from the IUS's second stage at 9:05 p.m. and began its
ballistic (or "freefall") flight to Venus for the first of three gravity assisted flybys, which
would take Galileo to Jupiter.
Galileo was the second spacecraft to be launched using the IUS ( Magellan, the Venus
radar mapping mission, was the first. Interestingly, even though Magellan was launched
first (in April of 1989), Galileo reached Venus first.). Built by Boeing for the Air Force, the
IUS, which uses solid (as opposed to liquid) fuel, gave Galileo an additional speed of 4.0
kilometers per second (8,640 miles per hour).