The Boeing-developed Inertial Upper Stage (IUS), an unpiloted, upper-stage booster rocket, could be launched from the Titan 34D or Titan IV expendable launch vehicles or from the Space Shuttle. In 1989, the IUS sent the Magellan and Galileo spacecraft to Venus and Jupiter, respectively. In 1990 it sent the Ulysses spacecraft to the sun. A typical Boeing IUS mission launched from a Titan IVB involves IUS separation from the rocket's second-stage booster approximately nine minutes into flight. The IUS takes over responsibility for the remainder of the powered portion of the flight. For the next six hours and 54 minutes, the IUS autonomously performs all functions to place the spacecraft into its proper orbit, some 22,000 miles above the Earth. The first IUS rocket burn occurs a little over one hour into the IUS booster flight. The IUS second solid rocket motor ignites about six-and-a-half hours into the flight, followed by a coast phase, and then, separation of the spacecraft. Between 1983 and 2001, the Boeing Inertial Upper Stage successfully deployed more than 20 critical U.S. defense and interplanetary satellite missions into high Earth orbits.