Mini orbiter 19948/9/2023 ![]() ![]() This limit would have been exceeded after three orbits if perijove had been allowed to stay at 4 Jupiter radii, where the radiationenvironment is very severe. A large 400 Newton engine burn was performed at the first apojove in order to raise perijove from 4 Jupiter radii to about 9 Jupiter radii, thus allowing the mission to complete 10 targeted satellite encounters without exceeding the allowed total accumulated radiation exposure at the spacecraft. ![]() The initial orbit period was about 200 days. The Probe mission and data relay lasted 58.6 minutes, after which JOI was performed, slowing the Orbiter down relative to Jupiter by about 630 meters/second. A few minutes after perijove passage, the Probe entered the Jovian atmosphere and beganrelaying data back to the Orbiter. Perijove at 4.00 Jupiter radii occurred at 21:53:44 UT on the same day. Remote sensing observations of Io were not made at this time due to an anomaly with the onboard tape recorder associated with high speed recording that was not well understood at the time of the flyby. This flyby allowed fields and particles science observations to be made and slowed the Orbiter down relative to Jupiter by nearly 200 meters/second in order to reduce the propellant required during the Jupiter Orbit Insertion (JOI). The Orbiter used its 400 Newton engine on Jto perform a deflection maneuver to keep from following the Probe into the atmosphere of Jupiter, and to retarget the Orbiter to the proper encounter conditions requiredfor the Jupiter Orbit Insertion phase of the mission.Ī close flyby (892 kilometer altitude) of the Jovian satellite Io occurred at 17:45:58 UT on Dec 7, 1995, during the Jupiter Orbit Insertion phase. After this time, the Probe proceeded on a ballistic trajectory to its entry point (6.54 deg north latitude, 4.46 west longitude) into the atmosphere of Jupiter. The Probe separated from the Orbiter on July 13, 1995. Target-of-opportunity science observations were made at Venus (closest approach February 10, 1990), the first Earth encounter (closest approach to Earth and Moon December 8 and 9, 1990), the asteroid Gaspra (closest approach October 29, 1991), the second Earth encounter (closest approach to Earth and Moon December 8, 1992), the asteroid Ida (closest approach August 28, 1993), and distant observations of the impact of comet Shoemaker-Levy 9 intoJupiter's atmosphere from July 16-22, 1994. Since the IUS did not have the energy to inject Galileo on a direct trajectory to Jupiter, the spacecraft was launched first towards Venus for the first leg of itsVenus-Earth-Earth gravity assist (VEEGA) trajectory. The Galileo mission utilized a single launch of a combined Orbiter and Probe using the space shuttle Atlantis and an inertial upper stage (IUS) to inject the Galileo spacecraft on its interplanetary trajectory to Jupiter.
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